Showing papers in "Muscle & Nerve in 1980"
TL;DR: The conduction speed of any given fiber reflects a number of parameters and is not determined by any single structural characteristic.
Abstract: This article reviews the determinants of conduction velocity in myelinated nerve fibers. For fibers exhibiting geometric similarity, conduction velocity is nearly proportional to diameter. However, in classes of geometrically similar fibers, myelin thickness and internode distance are linearly related to diameter. Therefore, it is not possible to assess the relative contributions of each of these factors. The relative effects of changes in each of these parameters on conduction velocity can be assessed from studies on fibers representing different similarity classes or from theoretical parametric studies. These studies show that for a fixed axon diameter, conduction velocity increases with myelin thickness. For a fixed total fiber diameter, there is an optimal ratio of axon diameter to total fiber diameter (and therefore to myelin thickness) at which conduction velocity is maximized. Conduction velocity is dependent on internode distance, with a broad maximum centered around the value observed in normal peripheral fibers. Conduction velocity is also dependent on temperature and the properties of the axonal milieu. Thus, the conduction speed of any given fiber reflects a number of parameters and is not determined by any single structural characteristic.
569 citations
TL;DR: Several indirect lines of evidence suggest that the surface membranes of skeletal muscle are affected, and impaired regulation of intracellular calcium content could be responsible for the hallmarks of the disease—progressive weakness and degeneration of muscle.
Abstract: In Duchenne muscular dystrophy, as in other genetic diseases, there must be a biochemical abnormality. This fundamental genetic fault has not been identified, but several indirect lines of evidence suggest that the surface membranes of skeletal muscle are affected. The biochemical evidence implies abnormal egress of soluble enzymes and other proteins from muscle, abnormal permeability, and altered properties of membrane-bound enzymes. As a result of the presumed genetic abnormality, functional properties are altered, and impaired regulation of intracellular calcium content could be responsible for the hallmarks of the disease--progressive weakness and degeneration of muscle. The evidence is by no means conclusive, however, and some of it is contradictory. Technical advances must be made before isolated membranes can be characterized biochemically. Other theories are also being evaluated.
251 citations
TL;DR: With this technique, type 1, 2A, and 2B fibers can be distinguished in a single‐step procedure for human biopsy samples.
Abstract: A new method for fiber typing based on staining for actomyosin Ca, Mg-ATPase is presented. Inclusion of ethanol in the medium enhanced the differentiation of type 2A and 2B fibers. With this technique, type 1, 2A, and 2B fibers can be distinguished in a single-step procedure for human biopsy samples.
117 citations
TL;DR: It is suggested that this disease entity is not caused by a hereditary sensory neuropathy, but rather that it derives from a developmental defect.
Abstract: A nine-year-old child presented with congenital insensitivity to pain and anhidrosis. Quantitative studies and electron microscopy of the cutaneous branch of the radial nerve revealed almost complete absence of small myelinated and unmyelinated fibers and a disproportionate number of nerve fibers with a diameter of 6-10 micrometers. A grouping of both type 1 and type 2 muscle fibers was also seen. We suggest that this disease entity is not caused by a hereditary sensory neuropathy, but rather that it derives from a developmental defect.
110 citations
TL;DR: “Secondary” carnitine deficiency may occur in patients with malnutrition, liver disease, chronic hemodialysis, and, possibly, mitochondrial disorders, and the biochemical error remains to be identified.
Abstract: 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 triglycride 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.
107 citations
TL;DR: Where clinical circumstances warrant cytotoxic immunosuppression in patients with myasthenia gravis, consideration should be given to the simultaneous employment of plasmapheresis, in order to maximize benefit to the patient from a given exposure to drug therapy.
Abstract: Plasmapheresis in the treatment of myasthenia gravis has led to disparate results when applied by different investigators because of considerable differences in the volume, number, and tempo of plasmaphereses and in the type and amount of concomitant immunosuppressive drug therapy. Used as short-term crisis intervention, plasmapheresis produces temporary clinical improvement and reduction in titer of antibody to acetylcholine receptor, even without accompanying drug therapy. When applied as long-term primary therapy under optimal conditions, plasmapheresis is capable of generating stable improvement in most patients. This response appears to result from a synergistic action with immunosuppressive drugs, since it is characterized by a sustained reduction in titer of antibody to acetylcholine receptor. Where clinical circumstances warrant cytotoxic immunosuppression in patients with myasthenia gravis, consideration should be given to the simultaneous employment of plasmapheresis, in order to maximize benefit to the patient from a given exposure to drug therapy.
86 citations
TL;DR: Clinical, electrodiagnostic, and morphological studies were performed on three patients with localized hypertrophic neuropathy and found that the tumor is a perineurioma, a rare tumor that can occur both in generalized neurofibromatosis and in isolated form and appears to be the cause of localized hypertrophe neuropathy.
Abstract: Clinical, electrodiagnostic, and morphological studies were performed on three patients with localized hypertrophic neuropathy (LHN). LHN is characterized clinically by slowly progressive motor mononeuropathy without significant pain or numbness. Nerve conduction studies and needle electrode examination show severe focal motor and sensory axonal loss. Morphological findings in the localized areas of enlarged nerves are different from those of generalized hypertrophic neuropathy, entrapment neuropathy, and neurofibroma, and consist of primary perineurial cell hyperplasia. The tumor is thus a perineurioma. This rare tumor can occur both in generalized neurofibromatosis and in isolated form and appears to be the cause of localized hypertrophic neuropathy.
79 citations
TL;DR: Two patients with phosphofructokinase (PFK) deficiency had exercise intolerance and increased serum activity of creatine kinase; one presented with hemolytic anemia, hyperuricemia, and gouty arthritis, and the glycogen concentration in the muscle of these patients was about twice normal.
Abstract: Two patients with phosphofructokinase (PFK) deficiency had exercise intolerance and increased serum activity of creatine kinase; one presented with hemolytic anemia, hyperuricemia, and gouty arthritis. The glycogen concentration in the muscle of these patients was about twice normal. PFK activity was virtually absent in muscle, but antibodies against the M subunits of the normal human PFK showed cross-reacting material in muscle from both patients. The PFK level in red blood cells, studied in one case, was lower than normal in the patient and both parents. Morphologically, there was extensive deposition of normal glycogen underneath the sarcolemma and in the intermyofibrillar space. In addition, 2% to 3% of the myofibers contained hyaline, PAS-positive, diastase-resistant inclusions that had a filamentous fine structure; histochemical reactions suggested an insoluble form of glycogen. Similar inclusions have not been described previously in PFK deficiency. Accumulation of an abnormal polysaccharide in muscle may be due to a second undiscovered enzymatic defect or may be a metabolic consequence of PFK deficiency.
74 citations
TL;DR: In this paper, indirect evidence of a lesion in the brachial plexus affecting discrete fiber bundles destined to form the anterior interosseous nerve was presented, rather than the nerve in the forearm.
Abstract: Neuralgic amyotrophy may present as a picture of anterior interosseous nerve palsy. In such a case, rather than a lesion of the nerve in the forearm, we offer indirect evidence of a lesion in the brachial plexus affecting discrete fiber bundles destined to form the anterior interosseous nerve.
71 citations
TL;DR: Calcium and copper levels were significantly elevated in patients with DMD compared to controls, and one presumptive carrier also showed an elevated calcium concentration, and comparisons with morphological data showed a significant positive correlation between calcium concentration and the percentage area of type 2 fibers in controls.
Abstract: Concentrations of calcium, iron, copper, and zinc were simultaneously measured by x-ray fluorescence spectrometry in muscle biopsies from 11 normal subjects, 13 patients with Duchenne muscular dystrophy (DMD), and 3 DMD carriers. Calcium and copper levels were significantly elevated in patients with DMD compared to controls, and one presumptive carrier also showed an elevated calcium concentration. Comparisons with morphological data for the same samples showed a significant positive correlation between calcium concentration and the percentage area of type 2 fibers in controls, but no other correlations were found to be significant. These results illustrate the value of x-ray fluorescence spectrometry and provide further evidence for the involvement of calcium in dystrophic processes.
69 citations
TL;DR: SDS gel electrophoresis of Troponin and myosin extracted from chicken myofibrils pretreated with Ca‐activated neutral protease showed a pattern similar to that observed in the muscles of patients with Duchenne muscular dystrophy, that is, a decrease in troponin‐l and tropon in‐C with relative preservation of trop onin‐T and degradation of the heavy chain of myos in vitro.
Abstract: SDS gel electrophoresis of troponin and myosin extracted from chicken myofibrils pretreated with Ca-activated neutral protease showed a pattern similar to that observed in the muscles of patients with Duchenne muscular dystrophy, that is, a decrease in troponin-I and troponin-C with relative preservation of troponin-T and degradation of the heavy chain of myosin. Also, alpha-actinin and troponin-C were released from myofibrils. Two inhibitors of Ca-activated neutral protease, leupeptin and E-64, inhibited the degradative action of Ca-activated neutral protease on intact myofibrils in vitro.
TL;DR: Instilling anesthetic into the point of entrapment may relieve the pain completely, but superior gluteal neurolysis may be required to effect a permanent cure.
Abstract: Entrapment of the superior gluteal nerve can occur as a result of compression by anterior-superior tendinous fibers of the piriformis muscle and cause aching claudication-type buttock pain, weakness of abduction of the affected hip with a waddling gait, and tenderness to palpation in the area of the buttock superolateral to the greater sciatic notch. Instilling anesthetic into the point of entrapment may relieve the pain completely, but superior gluteal neurolysis may be required to effect a permanent cure.
TL;DR: The literature concerning red blood cell and fibroblast protein studies in Duchenne and myotonic muscular dystrophy is critically reviewed and methodological and technical considerations are emphasized.
Abstract: The literature concerning red blood cell and fibroblast protein studies in Duchenne and myotonic muscular dystrophy is critically reviewed. In this review, we emphasize methodological and technical considerations in order to promote an appreciation of the complexities of this area of research to clinical scientists interested in muscle disease.
TL;DR: This is a review of the application of the freeze fracture technique to the study of human neuromuscular disease, illustrated by a study of skeletal muscle plasma membrane in Duchenne muscular dystrophy.
Abstract: This is a review of the application of the freeze fracture technique to the study of human neuromuscular disease. The advantages and limitations of the method are discussed, and the application of the technique is illustrated by a study of skeletal muscle plasma membrane in Duchenne muscular dystrophy.
TL;DR: The fact that central core lesions were produced in the fibers of soleus and medial gastrocnemius but not in the extensor digitorum longus may be related to the lesser reduction in sarcomere length following tenotomy of the latter muscle.
Abstract: The medial belly of the gastrocnemius and the extensor digitorum longus muscles of rats were tenotomized. One day following tenotomy, the mean sarcomere length of the fast medial gastrocnemius was 1.8 microns, a value comparable to that of tenotomized slow soleus. The mean sarcomere length of the tenotomized extensor digitorum longus, however, was 2.0 microns, a figure which differed significantly from the values obtained for both the soleus and the gastrocnemius. Histological preparations showed the presence of central core degeneration in slow fatigue-resistant fibers of the tenotomized gastrocnemius comparable to that seen in the soleus. No changes were found in the fibers of the tenotomized extensor digitorum longus. The fact that central core lesions were produced in the fibers of soleus and medial gastrocnemius but not in the extensor digitorum longus may be related to the lesser reduction in sarcomere length following tenotomy of the latter muscle.
TL;DR: It is suggested that major alterations of the predominant membrane lipids are not involved in these diseases and RBCs should be important in defining how such membrane perturbations affect transport mechanisms.
Abstract: Biochemical, morphologic, and biophysical studies support the concept that the red blood cell (RBC) membrane is altered in both myotonic muscular dystrophy (MyD) and Duchenne muscular dystrophy (DMD). These studies have not identified a primary metabolic defect that would explain the various alterations of membrane properties. Since the lipid milieu of the membrane affects most membrane properties, it has been extensively investigated in MyD and DMD. Although some studies have suggested specific lipid abnormalities, no reproducible alterations have been reported in the major lipid constituents of the RBC membrane in these disorders. These findings suggest that major alterations of the predominant membrane lipids are not involved in these diseases. Furthermore, studies of the RBC membrane do not provide definitive statements as to the inborn error of metabolism, whether proteins or lipid constituents are primarily affected, or even whether the described alterations are intrinsic to the membrane or are secondary to some circulating factors. Nevertheless, RBCs have proved useful in demonstrating the involvement of the plasma membrane in muscle disorders and should be important in defining how such membrane perturbations affect transport mechanisms.
TL;DR: Muscle carnitine levels were studied in 12 cases of lipid‐storage myopathy and in cases of other muscle diseases, including Duchenne muscular dystrophy in children, and there was no significant difference between children and adults in the serum and skeletal muscle levels.
Abstract: An assay for evaluating carnitine levels in normal children and adults is described. After a 12-hour period of fasting, individual variations in 24-hour urinary excretion of carnitine were observed in adults. In children, there was a significant decrease in excretion from the 10th month to the third year, and then an increase until the 10th year. There was no significant difference between children and adults in the serum and skeletal muscle levels. Muscle carnitine levels were also studied in 12 cases of lipid-storage myopathy and in cases of other muscle diseases, including Duchenne muscular dystrophy in children.
TL;DR: 4‐AP is effective in overcoming both presynaptic and postsynaptic blockade of neuromuscular transmission, suggesting a potential role for this drug in the treatment of neurmuscular diseases.
Abstract: The effects of 4-aminopyridine (4-AP) on neuromuscular transmission were studied in vitro in the rat flexor digitorum longus muscles. 4-AP produced dose-dependent increases in endplate potential (EPP) amplitude, in rise time to peak, and in the average number of acetylcholine quanta released by presynaptic nerve impulses. The neuromuscular blocking effects of d-tubocurarine or low Ca2+/high Mg2+ concentrations could be completely reversed by 4-AP, and EPPs developed into muscle action potentials (APs). The drug had minimal effects on the amplitude or frequency of spontaneous miniature endplate potentials, but increased the duration of indirectly elicited muscle APs. The action of 4-AP required the presence of extracellular Ca2+; thus, its effect may be to promote Ca2+ entry into the motor nerve terminal, and thereby increase the neurally evoked transmitter release. 4-AP is effective in overcoming both presynaptic and postsynaptic blockade of neuromuscular transmission, suggesting a potential role for this drug in the treatment of neuromuscular diseases.
TL;DR: 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.
Abstract: 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.
TL;DR: The soleus muscle of the rat undergoes degenerative changes after tenotomy, after which follows a period of recovery which is effected by means of peripheral myofibril splitting and de novo synthesis of my ofibrils within the central portion of the fiber.
Abstract: The soleus muscle of the rat undergoes degenerative changes after tenotomy. The effects are maximal one week postoperatively, after which follows a period of recovery. Muscle histology eventually returns to normal six weeks after tenotomy. Recovery is effected by means of peripheral myofibril splitting and de novo synthesis of myofibrils within the central portion of the fiber.
TL;DR: Electrophysiological, histochemical, ultrastructural, and biochemical studies demonstrated features of immature muscle fibers suggesting a fetal defect as in the Werdnig‐Hoffmann (W‐H) form of SMA, suggesting that the defect in K‐W SMA probably takes place in fetal life at a stage later than in W‐H SMA.
Abstract: Twelve children who had developed Kugelberg-Welander (K-W) spinal muscular atrophy (SMA) before the age of six years were investigated. Electrophysiological, histochemical, ultrastructural, and biochemical studies demonstrated features of immature muscle fibers suggesting a fetal defect as in the Werdnig-Hoffmann (W-H) form of SMA. Comparison with known patterns of human myogenesis and of experimental denervation of immature muscle suggested that the defect in K-W SMA probably takes place in fetal life at a stage later than in W-H SMA. In contrast to W-H SMA, a considerable percentage of mature fibers of normal structure and diameter were present. The immature fibers impair the normal development of muscle cells by preventing the increase in number of mature fibers and causing an overloading of the normal fibers with consequent hypertrophy and eventually destructive changes. This is the pattern in K-W disease that distinguishes the juvenile form of SMA from W-H disease.
TL;DR: Subluxation of the tendon of origin of the long head of the biceps femoris muscle (or snapping bottom) is a rare, previously unreported degeneration ofThe tendinous attachment of the muscle at the ischial tuberosity.
Abstract: Subluxation of the tendon of origin of the long head of the biceps femoris muscle (or snapping bottom) is a rare, previously unreported degeneration of the tendinous attachments of the muscle at the ischial tuberosity. It occurs in a patient who wears out this attachment through a lifetime of hyperflexion hip movements, such as are required in bending to reach the floor. The snapping of the tendon across its point of origin causes pain and swelling in the buttock. In the older nonathlete, if conservative measures fail, the treatment of choice is simple tenotomy. The condition should not be confused with weaver's bottom (ischiogluteal bursitis), even though it may be a cause for that bursitis.
TL;DR: The changes in capillary and endomysial basement membrane collagens (Types IV and V) as well as the proliferation of perimysial Type III collagen are discussed in relation to the muscle atrophy observed during the disease.
Abstract: Type-specific antibodies to the polymorphic types of collagen have been used to study their distribution in polymyositis. Dramatic increases were observed in the staining with antibodies to Type III collagen and, to a lesser extent, with antibodies to Types I, IV, and V. The changes in capillary and endomysial basement membrane collagens (Types IV and V) as well as the proliferation of perimysial Type III collagen are discussed in relation to the muscle atrophy observed during the disease.
TL;DR: Family patterns for 50 reported probands with congenital nemaline myopathy were compared with expected patterns derived from various possible genetic hypotheses, which could be explained by an autosomal dominant mode with a reduced penetrance.
Abstract: 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.
Journal Article•
TL;DR: The ELISA may prove valuable as a clinical diagnostic tool for the human disease myasthenia gravis because of the relative simplicity of the ELISA in comparison to radioimmunoassay procedures currently used to measure anti‐AChR antibodies.
Abstract: Both acetylcholine receptor (AChR) and antibodies capable of binding to the AChR can be measured using the recently developed enzymelinked immunosorbent assay (ELISA). The assay is very sensitive and reproducible. Because of the relative simplicity of the ELISA in comparison to radioimmunoassay procedures currently used to measure anti-AChR antibodies, the ELISA may prove valuable as a clinical diagnostic tool for the human disease myasthenia gravis.
TL;DR: In control subjects and in uremic patients, the proximal sensory (1a) nerve conduction velocity (SNCV) was faster than the proximate motor nerve conduct velocity (MNCV), a finding which is attributed to the larger diameter and therefore faster conduction properties of 1a fibers.
Abstract: The nerve conduction velocity along the whole length (knee to the spinal cord) of the 1a sensory and motor fibers of the tibial nerve, innervating the gastrocnemius and soleus muscles, of 29 control subjects and 32 patients with chronic renal failure was estimated with recently introduced electrophysiologic F-wave and H-reflex methods. In control subjects and in uremic patients, the proximal sensory (1a) nerve conduction velocity (SNCV) was faster than the proximal motor nerve conduction velocity (MNCV), a finding which is attributed to the larger diameter and therefore faster conduction properties of 1a fibers. In uremic patients, the proximal 1a SNCV and MNCV were significantly slowed in comparison with the values in control subjects, while the terminal M-response latency was not significantly prolonged.
TL;DR: The cardiac function of 36 males with Duchenne muscular dystrophy was evaluated by echocardiography, and the results were compared with the results of other tests of cardiac involvement, including serum creatine kinase isoenzyme evaluation, electrocardiography, chest x‐ray, and physical examination of the heart and lungs.
Abstract: The cardiac function of 36 males with Duchenne muscular dystrophy was evaluated by echocardiography, and the results were compared with the results of other tests of cardiac involvement, including serum creatine kinase isoenzyme evaluation, electrocardiography, chest x-ray, and physical examination of the heart and lungs. Although correlation between the various methods of assessment was not impressive, the echocardiographic technique appeared to be useful in evaluating and following the cardiomyopathy in these patients. Several aspects of left ventricular function were abnormal in most patients, and only two of the 36 had normal left ventricular size and function. Electrocardiographic abnormalities were also apparent in all patients, although the changes were mild in four of the 36. Clinical evaluation, isoenzyme determinations, and chest x-rays have not been useful in assessing cardiac function. The echocardiographic data on these 36 patients are presented in detail and the patients will now be followed sequentially to attempt evaluation of ongoing changes.
TL;DR: A mechanism of dying‐back degeneration of the longest sensory fibers is the most plausible explanation for neurological and pathological abnormalities in alcoholic neuropathy with trophic changes and in familial and sporadic cases, axonal loss is more severe and unmyelinated fibers are more severely affected than in alcoholic acrodystrophic neuropathy.
Abstract: Sixteen patients presenting with trophic changes associated with a peripheral neuropathy were investigated. Muscle power was normal in all patients, but neurogenic muscle atrophy was demonstrated in 4 of the 7 patients who had a muscle biopsy. Alcoholism was responsible for the neuropathy in 11 patients. In the other patients, one had primary hemochromatosis without diabetes and another a dominantly inherited primary hypertrophic neuropathy. Qualitative and quantitative light and electron microscopic studies, including teased nerve fiber preparations, showed axonal loss as the most salient feature. In the alcoholic patients, the large myelinated fibers were primarily involved, followed by small myelinated and unmyelinated fibers. The lesions were predominant distally as shown in patients who had a sural nerve biopsy at both calf and ankle levels. A mechanism of dying-back degeneration of the longest sensory fibers is the most plausible explanation for neurological and pathological abnormalities. In alcoholic neuropathy with trophic changes, loss of sensory fibers is more important than in alcoholic neuropathy without trophic changes. In familial and sporadic cases, axonal loss is more severe and unmyelinated fibers are more severely affected than in alcoholic acrodystrophic neuropathy. Patients with peripheral neuropathies who present with loss of pain sensation but have preserved muscle power are especially exposed to the development of trophic changes induced by usual trauma in insensitive tissues.
TL;DR: The fact that the sections retained Ca sensitivity at 37°C, in contrast to myofibrils, which have been reported to loseCa sensitivity at this temperature, indicates that the structural integrity of the contractile and regulatory apparatus is preserved to a higher degree in sections than in isolated my ofibrils.
Abstract: A method for the quantitative study of the actomyosin ATPase activity (Ca,MG-ATPase) in thin sections cut in a cryostat is presented. This method is based on the liberation of 32P from [gamma 32P]ATP or 45Ca phosphate precipitation. The advantage of this method lies in the requirement for only a small muscle sample and the availability of serially cut sections for other assays including Ca uptake by sarcoplasmic retciulum and histochemical tests for oxidative and glycolytic enzymes. The actomyosin ATPase activity for various types of muscles determined by this method showed the same sequence found in isolated protein, that is, fast-twitch skeletal greater than slow-twitch skeletal greater than cardiac. The Ca,Mg-ATPase of cryostat sections showed Ca sensitivity. The fact that the sections retained Ca sensitivity at 37 degrees C, in contrast to myofibrils, which have been reported to lose Ca sensitivity at this temperature, indicates that the structural integrity of the contractile and regulatory apparatus is preserved to a higher degree in sections than in isolated myofibrils.