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PubMedDate not supplied

Stimulation of oligodendrocyte differentiation in culture by growth in the presence of a monoclonal antibody to sulfated glycolipid.

Perturbation of myelinogenesis by monoclonal antibodies against galactolipids is being used to study the role of these lipids in oligodendrocyte differentiation. We report here a marked stimulatory effect on oligodendrocyte differentiation when mixed primary cultures initiated from 19-21 day fetal rat telencephala are grown in the presence of a monoclonal antibody against sulfogalactolipids. When such cultures were grown in the presence of the IgM antibody 04 [Sommer and Schachner, Dev Biol 83:311-327 1981], the oligodendrocytes formed aggregates connected by fasciculated processes. Immunofluorescence microscopy and biochemical analyses of treated cultures demonstrated 2-3 fold increases in the fraction of 04-positive cells expressing myelin basic protein, and in the levels of myelin basic protein RNA, myelin basic protein, 2',3'-cyclic nucleotide 3'-phosphohydrolase activity, and 35SO4 incorporation into sulfatide. Greater than 90% of the cells positive for myelin basic protein in treated cultures were in aggregates. The specific activities of oligodendrocyte markers were unaffected in control cultures grown with nonspecific myeloma IgM. Since there was no increase in the total number of 04-positive cells in treated cultures, the increases in the specific activities of the myelin protein markers appears to be due to an increase in the fraction of cells expressing these markers. Time course studies demonstrated that both the rate and extent of oligodendrocyte differentiation were enhanced in treated cultures. These data are discussed with regard to possible mechanisms of the stimulation, considering not only potential direct effects of the antibody on the cell physiology, but also possible indirect effects due to antibody-induced aggregation.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1991

Correlation between morphological and biochemical effects of ethanol on neuroblast-enriched cultures derived from three-day-old chick embryos.

We have shown that ethanol exposure during embryogenesis affects a variety of parameters of neuronal growth. In this study we examined the direct effects of ethanol exposure on developing neuroblasts in culture. Neuroblast-enriched cultures derived from 3-day-old whole chick embryos were grown in the presence of ethanol at doses ranging from 12.5 to 50 mM from culture day 3-14. Cholinergic and GABAergic phenotypic expression were both significantly reduced following ethanol exposure as assessed by the activities of choline acetyltransferase and glutamate decarboxylase, respectively. Morphometric analysis of the growth patterns showed significant differences between control and ethanol-treated cultures. Control cultures exhibited the characteristic pattern of growth consisting of neuronal aggregation with neuritic arborization, i.e., neuritic bundles and fasciculation. Cultures grown in ethanol from culture day 3 consisted of aggregates that measured significantly greater in size than those observed in control cultures. In addition, in ethanol-treated cultures, the primary pattern of neuritic bundles was replaced by a complex network of individual neurites radiating from the central aggregate, forming a defined "neuritic field." Morphometric analysis revealed that both neurite number and neurite length were significantly reduced in ethanol-treated cultures. The biochemical data confirm earlier reports from this laboratory suggesting that ethanol exposure during early embryogenesis alters the normal neuronal pattern of phenotypic expression. In addition, we have presented evidence in this study that ethanol alters the morphological growth patterns of developing neurons. Although ethanol does not alter the ability of these cells to aggregate, there is a significant alteration in neuritic outgrowth.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Structure, expression, and function of Ng-CAM, a member of the immunoglobulin superfamily involved in neuron-neuron and neuron-glia adhesion.

The neuron-glia cell adhesion molecule (Ng-CAM) mediates neuron-neuron adhesion by a homophilic mechanism and neuron-astrocyte adhesion by a heterophilic mechanism. The protein is expressed on neurons and Schwann cells but not on astrocytes. It is most prevalent during development on cell bodies of migrating neurons and on axons during formation of nerves. Ng-CAM expression is greatly increased following nerve injury. Anti-Ng-CAM antibodies inhibited migration of granule cells along Bergmann glia in cerebellar explants and fasciculation of neurites in outgrowths from explants of dorsal root ganglia. The combined results indicate that Ng-CAM on neurons binds to Ng-CAM on adjacent neurons and to as yet unidentified ligands on astrocytes. Ng-CAM is synthesized in chicken neurons from a 6 kb mRNA as Mr approximately 200,000 forms which are cleaved to yield two components of Mr 135,000 and 80,000. It is glycosylated and can be phosphorylated. Amino acid sequence analysis indicates that it contains six immunoglobulin domains, five fibronectin type III repeats, a transmembrane domain and a cytoplasmic region. Structural analyses indicate that Ng-CAM is most closely related to the mammalian glycoprotein L1 but significant differences between them strongly suggest that they are not equivalent molecules. The recent identification of another structurally related molecule in the chicken called Nr-CAM underscores the notion that these molecules are members of a subfamily of neural cell adhesion molecules within the immunoglobulin superfamily that have related or complementary functions in the nervous system.

Animals↗
PubMed1992

Substratum-induced modulation of acetylcholinesterase activity in cultured dorsal root ganglion neurons.

Acetylcholinesterase (AChE) has been shown to be transiently expressed in the developing nervous system during periods of neuronal migration and axonal outgrowth. We are investigating the possible interaction of substratum with AChE activity in dorsal root ganglion neurons (DRGN) cultured on substrata with varying degrees of permissiveness for neurite outgrowth: (1) extracellular matrix substrata: reconstituted basal lamina Matrigel (MGEL), laminin (LAM) and type I collagen (COL), and (2) organotypic substrata: unfixed, frozen sections of sciatic nerve (SN) and spinal cord (SC). In group 1, histochemical staining for AChE in DRGN was lowest on MGEL where outgrowth was most vigorous, intermediate on LAM, and highest on COL where neurite outgrowth was reduced by 55% compared to Matrigel and highly fasciculated. A similar trend was seen when the cultures were assayed biochemically, 2.84 +/- 0.14 nmoles ACh hydrolyzed/ganglion/hr (MGEL), 4.42 +/- 0.19 (LAM), 5.79 +/- 0.37 (COL). In group 2, SN supported an expansive outgrowth with lower AChE activity than in DRGN grown on SC where outgrowth was minimal. These studies show that the levels of AChE activity can be modulated by substratum, perhaps in proportion to the permissiveness of the substratum to neuritic outgrowth. These results are discussed in relation to possible non-cholinergic roles of AChE.

Acetylcholinesterase↗
PubMed1996

CD9 of mouse brain is implicated in neurite outgrowth and cell migration in vitro and is associated with the alpha 6/beta 1 integrin and the neural adhesion molecule L1.

We describe here a novel monoclonal antibody (mab H6) which recognizes CD9, an integral cell surface constituent previously described in cells of the hematopoietic lineage and involved in the aggregation of platelets. Mab H6 was raised against membranes of immature mouse astrocytes and reacted with a protein of 25-27 kD in detergent extracts of adult mouse brain membranes. Sequence analysis of the N-terminal amino acids revealed an identity of 96% with CD9 from mouse kidney. CD9 was localized in the central and peripheral mouse nervous systems: in the spinal cord of 11-day-old mouse embryos, CD9 was strongly expressed in the floor and roof plates. In the adult mouse sciatic nerve, myelin sheaths were highly CD9-immunoreactive. Mab H6 reacted with the cell surfaces of both glial cells and neurons in culture and inhibited migration of neuronal cell bodies, neurite fasciculation and outgrowth of astrocytic processes from cerebellar microexplants. Neurite outgrowth from isolated small cerebellar neurons was increased in the presence of mab H6 on substrate-coated laminin, but not on substrate-coated poly-L-lysine. Addition of mab H6 elicited an increase in intracellular Ca2+ concentration in these cells on substrate-coated laminin. Immunoprecipitates of CD9 from cultured mouse neuroblastoma N2A cells contained the alpha 6/beta 1 integrin. Moreover, preparations of CD9 immunoaffinity-purified from adult mouse brain using a mab H6 column contained the neural adhesion molecule L1, but not other neural adhesion molecules. CD9 bound to L1, but not to NCAM or MAG. Both the alpha 6/beta 1 integrin and L1 could be induced to coredistribute with CD9 on the surface of cultured neuroblastoma N2A cells. The combined observations suggest that CD9 can associate with L1 and alpha 6/beta 1 integrin to influence neural cell interactions in vitro.

Amino Acid Sequence↗
PubMed2003

Cerebral amyloid angiopathy and motor neurone disease presenting with a progressive supranuclear palsy-like syndrome.

We describe a 68-year-old woman who presented with falls, mild limb bradykinesia, axial rigidity, and a severe supranuclear gaze palsy, which failed to benefit from levodopa. She subsequently developed severe apraxia, progressive dysarthria, dysphagia, and a frontal cognitive impairment. Pyramidal weakness with fasciculations and widespread chronic partial denervation appeared shortly before her death from bronchopneumonia, 6 months after disease onset. A severe cerebral amyloid angiopathy diffusely involving the cerebral hemispheres and cerebellum was present at autopsy as well as a second pathological condition indicative of motor neurone disease. Cerebral amyloid angiopathy may rarely present with a progressive supranuclear palsy-like phenotype.

Aged↗
PubMed1992

Machado-Joseph disease in New England: clinical description and distinction from the olivopontocerebellar atrophies.

Experience is described in 25 patients from southern New England with Machado-Joseph Disease, examined serially at annual screening clinics. The disorder is dominantly inherited, with a wide range of phenotypic variation. Core clinical features described include ataxia, nystagmus, dysarthria, facial fasciculations, and lid retraction, producing a characteristic staring expression. In addition, young onset patients have spasticity, extrapyramidal rigidity, and dystonic manifestations. Late onset patients often have distal atrophy and sensory loss. Postural instability is often an early feature. We discuss the distinction of this entity from the olivopontocerebellar atrophies.

Adolescent↗
PubMed2003

Physiology of conduction block in multifocal motor neuropathy and other demyelinating neuropathies.

Conduction block is an important functional consequence of demyelination whereby nervous transmission is abolished. Its mechanism has been discussed with respect to the loss of insulation due to disruption of myelin. Recent development of threshold tracking techniques, which enabled noninvasive assessment of axonal membrane potentials and ion channels, has provided evidence that axonal excitability changes significantly and contributes to conduction failure. This view, based upon axo-glial interaction, clarifies the mechanism of muscle fatigue and fasciculation associated with peripheral demyelination and possibly explains selective motor involvement in multifocal motor neuropathy.

Demyelinating Diseases↗
PubMed2003

Fatigue and abnormal neuromuscular transmission in Kennedy's disease.

We describe a patient with Kennedy's disease (X-linked bulbospinal neuronopathy) who experienced leg muscle fatigue with long-distance running. The patient also reported muscle twitching involving the face and extremities and long-standing muscle cramps. Aside from mild facial and tongue weakness (and fasciculations), his examination was normal, including completely preserved muscle strength in the extremities. Electrodiagnostic evaluation revealed evidence for a chronic motor axonopathy/neuronopathy and abnormal sensory nerve action potentials. In addition, repetitive nerve stimulation studies were normal, but neuromuscular jitter tested in the same muscle was markedly abnormal. The normal clinical strength and repetitive nerve stimulation studies in a muscle showing markedly increased neuromuscular jitter suggested a mechanism for this patient's symptoms of muscle fatigue, related to failure of neuromuscular transmission at a critical number of endplates during extremes of physical activity.

Electromyography↗
PubMed2003

Compressive lumbar myelopathy presenting as segmental motor neuron disease.

Four patients presented with slowly progressive, bilateral, asymmetric weakness and muscle atrophy in the lower extremities, accompanied by cramps and fasciculations. Sensory symptoms were insignificant. There was no bladder or bowel disturbance. Upper extremities and cranial nerves were normal. Weakness was found in lumbosacral myotomes, ranging from L2 to S1. The tendon reflexes varied, and extensor plantar responses were found in one case with proximal leg involvement. Nerve conduction studies were normal, but segmental chronic and often active denervation confined to the weak myotomes in the lower extremities was found in the electromyogram. Magnetic resonance imaging showed evidence of spondylotic lumbosacral myelopathy associated with disc herniation or osteophytic arthropathy at the T11/T12 spinal level in all patients, with increased signal within the adjacent cord. This unusual purely motor presentation may result from ischemic myelopathy secondary to compression of the anterior spinal artery.

Adult↗
PubMed2003

Progressive arm weakness and tonic hand spasm from multifocal motor neuropathy in the brachial plexus.

A 50-year-old waitress presented with a 10-year history of progressive weakness in her right arm without atrophy and with tonic hand spasms suggesting a central motor disorder. Electromyography, however, disclosed chronic neurogenic changes including fasciculations and atypical cramps. Isolated motor conduction block in the right brachial plexus suggested a variant of multifocal motor neuropathy. Strength recovered and cramps disappeared after intravenous immunoglobulins. Motor neuropathies may thus manifest with features of central motor disorders.

Action Potentials↗
PubMed2004

Proposed modification to data analysis for statistical motor unit number estimate.

Motor unit number estimation (MUNE) is an important electrophysiological technique for quantitative measurement of motor neuron loss. Although commonly used, there is no consensus concerning the optimal procedure for statistical MUNE, particularly regarding several operator-dependent variables. To assess the variables, we analyzed 500 sequential, submaximal compound muscle action potential (CMAP) responses at three or four stimulus intensities in 10 controls and 10 patients with amyotrophic lateral sclerosis (ALS). In both controls and ALS patients, we found that posttest filtering data based on 20% or 25% windows or 2, 2.5, or 3 SD excludes <5% of data. Windows of 10% or 15% excluded <5% of data in controls but not in ALS patients. Excluding data based on +/-2 SD, the coefficient of variation for final MUNE was 12% in controls and 6% in ALS patients. Group sizes of 30 or 50 and sample sizes of 300 to 500 sequential CMAP responses per run yielded the lowest coefficient of variation. We propose that statistical MUNE data should be analyzed based on excluding data >2 SD from the mean, because this is operator independent, includes the majority of data, effectively excludes clearly outlying data, such as fasciculations or movement artifact, and has a reasonable coefficient of variation.

Adult↗
PubMed2005

Lewis-Sumner syndrome and multifocal motor neuropathy.

We compared the clinical, electrophysiological, laboratory, and pathological features of 13 patients with Lewis-Sumner syndrome (LSS) with those of 20 patients with multifocal motor neuropathy (MMN). LSS and MMN patients have several common clinical features: age at onset, weakness in the distribution of individual peripheral nerves, mild wasting, cramps and fasciculations, partial areflexia, and frequent stepwise disease course. Cerebrospinal fluid protein level was normal or slightly elevated, but always less than 100 mg/dl. Conduction blocks are the electrophysiological hallmarks of these two neuropathies, and no differences in distribution and number of blocks were found. Contrary to MMN, lower-limb involvement at onset was frequent in LSS but extension to the upper limbs was a frequent later feature of the disease. Cranial nerve involvement was noted in 4 LSS patients during relapses and absent in all MMN patients. The major distinguishing features were the clinical and electrophysiological sensory involvement in LSS, and the lack of anti-GM1 antibodies in LSS, whereas IgM anti-GM1 were found in 40% of MMN patients. Some LSS patients responded to steroid therapy, whereas this was ineffective in MMN. From these features, LSS can be considered an entity distinct from MMN, with its own clinical, laboratory, and electrophysiological characteristics, and as an intermediate link between chronic inflammatory demyelinating polyneuropathy and MMN.

Action Potentials↗
PubMed2006

Clinicopathological phenotype of ALS with a novel G72C SOD1 gene mutation mimicking a myopathy.

A 71-year-old woman with a family history of amyotrophic lateral sclerosis (ALS) was investigated for symmetrical, proximal limb and abdominal muscle weakness. Initial examination showed mild proximal muscle weakness in the arms and legs, slightly elevated serum creatine kinase (CK) level, and normal electromyographic (EMG) findings. A myopathy was the presumed diagnosis. Over the next year, weakness became severe and tendon reflexes became unelicitable; no upper motor signs were present. EMG then showed acute and chronic denervation and a muscle biopsy showed target fibers and grouped atrophy. DNA analysis revealed a G72C CuZn-superoxide dismutase (SOD1) mutation. Fasciculations were absent throughout the disease. The patient died 53 months after symptom onset and autopsy revealed loss of lower motor neurons (LMN) and SOD1-positive inclusions. This case expands the phenotypic spectrum of ALS associated with SOD1 mutations to include presenting features that mimic a myopathy.

Aged↗
PubMedDate not supplied

Unilateral calf enlargement following S1 radiculopathy.

Two cases of unilateral calf enlargement following S1 radiculopathy are reported. "True" muscular hypertrophy could be confirmed by computerized tomography of the muscle. Muscle biopsy disclosed that fiber hypertrophy exceeded grouped fiber atrophy. In one case both fiber types were involved, and in the other mostly type 1 fibers were affected. Electromyography revealed dense pseudomyotonic activity and fasciculations. These findings are discussed in view of the current literature.

Adult↗
PubMedDate not supplied

Acoustic myography: a noninvasive monitor of motor unit fatigue.

Acoustic myography is the recording of sounds produced by contracting muscle. These sounds become louder with increasing force of contraction. We have compared muscle sounds with surface EMG to monitor the dissociation of electrical from mechanical events (presumably, the loss of excitation-contraction coupling) which occur with motor unit fatigue. Acoustic signals were amplified using a standard phonocardiograph, recorded on FM magnetic tape, and digitally analyzed. Muscles were examined at rest, with intermittent contractions, and with sustained contractions. We found that with fatigue, the acoustic amplitude decayed, but the surface EMG amplitude did not. With decreased effort, however, the acoustic and the surface EMG amplitudes declined simultaneously. By simultaneously recording acoustic signals and needle EMG, individual motor units were resolved acoustically in two muscles with decreased numbers of motor units and increased motor unit size. Fasciculations also produced acoustic signals, although no acoustic signal has yet been found that correlates with fibrillations. Analysis of acoustic signals from muscle provides a noninvasive method for monitoring motor unit fatigue in vivo. It may also be useful in distinguishing muscle fatigue from decreased volition.

Acoustics↗
PubMedDate not supplied

Recent views on amyotrophic lateral sclerosis with emphasis on electrophysiological studies.

Peripheral electrophysiological studies are of particular value of elucidating the anatomy and pathophysiology of neuromuscular diseases, but they can also help in providing clues to the etiology of the disease. Recent studies of the motor units in chronic denervating conditions including amyotrophic lateral sclerosis (ALS) are reviewed. These indicate that reinnervation is a relatively active process which compensates for the progressive loss of motoneurons in ALS until more than 50% of the motoneurons have died. There seems to be no predilection for death of motoneurons of any particular size in ALS. Fasciculations may arise both proximally and distally. The dying-back change is not a major feature of ALS. These and other data cast doubt on the etiological theories that ALS arises from premature aging of motoneurons, deficiency of motoneuron trophic factors, or an inhibitor of a motoneuronal sprouting factor, and point to the need to study metabolic changes intrinsic to the motoneuron in ALS.

Amyotrophic Lateral Sclerosis↗
PubMed1988

Multifocal acquired demyelinating neuropathy masquerading as motor neuron disease.

We report five patients with pure motor neuropathy characterized by multifocal weakness, muscle atrophy that was sometimes profound, cramps, and fasciculations with relatively preserved reflexes. The clinical picture led to an initial diagnosis of motor neuron disease in all cases, but nerve conduction studies revealed multifocal conduction block confined to motor axons and predominantly involving proximal nerve segments. Routine sensory nerve conduction studies, ascending compound nerve action potentials, and somatosensory evoked potentials were all normal even through nerve segments in which motor conduction was severely blocked. Onset of symptoms was insidious, and progression was indolent. In two cases, after many years of neuropathy, sensory abnormalities developed but remained clinically trivial. These unusual cases probably have the same pathogenesis as previously described patients with persistent multifocal conduction block. Distinction from motor neuron disease is critical, since chronic demyelinating neuropathy may respond to treatment.

Action Potentials↗