Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Fasciculation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed1989

Morphological changes and neural cell adhesion molecule expression in mouse cerebrum primary cultures following long-term exposure to phorbol ester.

The effect of phorbol 12-myristate 13-acetate (PMA) on development of brain cells in culture was investigated. Chronic treatment of brain cells from fetal ICR mouse with PMA resulted in a time-dependent loss of specific [3H]phorbol 12,13-dibutyrate binding, generally called 'down-regulation'. In contrast to control culture, neurons cultured in PMA (162 nM)-containing medium exhibited aggregation and neurite fasciculation, and then the neural cell adhesion molecule (N-CAM) was expressed selectively on neurons. Also, the number of astrocytes, which were positively stained with anti-glial fibrillary acidic protein antibody, decreased by treatment with PMA. These results suggest that the normal development of cultured brain cells is interrupted by PMA treatment, which may involve protein kinase C (PKC) in the differentiation of neural cells and cell-cell (neuron-neuron, neuron-astrocyte etc.) interaction as PKC is believed to be a receptor for PMA and is down-regulated by chronic treatment with PMA.

Animals↗
PubMed1991

Changes of endogenous ganglioside composition in mouse cerebrum primary cultures following long-term exposure to phorbol ester.

Changes in endogenous gangliosides caused by phorbol 12-myristate 13-acetate (PMA, 162 nM) were examined using mouse cerebrum primary cultures. The total ganglioside content was significantly decreased by 25% and 40% in PMA-treated cultures compared to control cultures on days 1 and 8, respectively. In addition, changes in the pattern of ganglioside composition were also observed in which the percentage of GM1 and GD3 in total gangliosides was significantly increased and, in contrast, the percentage of GD1a and GT1b was reduced. Treatment of neurons with PMA induced the change of morphology. These results suggest that the decrease in the total ganglioside content and changes in ganglioside composition produced by long-term exposure to PMA are related to the appearance of neuronal cell aggregation and neurite fasciculation.

Animals↗
PubMed1981

Age-related changes in brain RNA of noise stressed mice.

Correlative data were obtained on RNA levels of cerebrocortical neurons, adrenal fasciculate cell RNA content and serum corticosterone levels in 10, 40 and 100 week old male C57BL/6J mice immediately following a 30 interval of continuous noise stimulation (100 dB re 2 x 10(-5) N/m2, 0.35-20 kHz) and at 1 hr and 4 hr recovery intervals. Quantification of cellular RNA levels entailed use of scanning-integrating microdensitometry of azure B stained tissue sections. Hormonal analyses were done by radioimmunoassay. Noise stimulation induced a mild to moderate adrenocortical activation and a moderate elevation of serum corticosterone levels in all age groups. Noise exposure also resulted in an increase in the RNA content of cerebrocortical neurons. However, maximal neuronal RNA levels proved to be considerably lower (32-36%) in 100 week old mice as compared to both 10 and 40 week old mice during the post-exposure intervals. The overall data support the existence of a lower neuronal capacity for sensory induced RNA synthesis in 100 week old mice. The data also suggest that age dependent differences in neuronal responsiveness are not directly related to the extent of adrenal RNA activation or to a lower availability of circulating glucocorticoids.

Adrenal Cortex↗
PubMed1985

Mechanisms involved in the development of tolerance to DFP toxicity.

Rats treated daily with diisopropylfluorophosphate (DFP) (0.5 mg/kg, sc), an inhibitor of acetylcholinesterase (AChE) activity, exhibited the symptoms of cholinergic hyperactivity between Days 3 and 5 similar to those observed 15 min after a single acute dosage (1.5 mg/kg, sc). A significant (p less than 0.05) decrease in the activities of both AChE and cholinesterase (BuChE) (greater than 80%) occurred in muscles and in brain regions and of aliesterases in liver (greater than 92%) at this time. Further administration of DFP (0.5 mg/kg, for 7-14 days) led to behavioral tolerance, where symptoms of toxicity disappeared such as muscle fasciculations, tremors, and muscle necrosis. The activity of aliesterases in liver and AChE in muscles significantly (p less than 0.01) recovered, while no such recovery was seen in brain AChE. DFP toxicity was potentiated in rats that were pretreated with BuChE inhibitors, such as iso-OMPA (3 mg/kg, sc) or mipafox (0.05 mg/kg, sc), 30 min prior to DFP (0.5 mg/kg, sc). The severity of cholinergic hyperactivity and inhibition of aliesterase in liver, AChE and BuChE activity in brain and muscles was greater when compared to the effects of DFP alone. Both iso-OMPA and mipafox completely abolished the tolerance development to DFP, since no animal survived more than 5 days of combined treatment. The observed adaptation to DFP toxicity appears to be due to recovery of aliesterase, BuChE, and AChE activity as well as decreased nicotinic binding sites at the neuromuscular junction, as previously reported.

Acetylcholinesterase↗
PubMed1986

Sublethal acute toxicity of carbosulfan [2,3-dihydro-2,2-dimethyl-7-benzofuranyl(d i-n-butylaminosulfenyl)(methyl)carbamate] in the rat after intravenous and oral exposures.

Sublethal toxicity of car-carbosulfan, 2,3-dihydro-2,2-dimethyl-benzofuranyl(di-n-butylaminosulfenyl++ +)(methyl)carbamate , was evaluated in female Sprague-Dawley rats. Erythrocyte acetylcholinesterase (AChE) activity was maximally inhibited 1 min after iv administration (38, 23, and 15% of pretreatment activity after 86, 250, and 690 micrograms/kg, respectively) and recovered by 4 hr. Maximum AChE inhibition (63% of pretreatment activity) was measured 45 min after oral dosing (690 micrograms/kg) and activity recovered after 5 hr. Signs included urination, defecation, facial muscle fasciculations, salivation, and tremors. Carbosulfan was less toxic when given orally. Metabolic activation of carbosulfan to carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranol methylcarbamate) was investigated by measuring plasma concentrations 4, 30, and 240 min after iv (80-120 or 620-640 micrograms/kg) and oral (540-700 or 2030-2190 micrograms/kg) dosages of [carbonyl-14C]carbosulfan. Peak plasma concentrations were measured at 4 and 30 min after iv and oral exposure, respectively. Carbosulfan was rapidly activated to carbofuran. Reduction in AChE activity was better correlated (r = 0.97) with plasma concentration of [carbosulfan + carbofuran] and plasma carbofuran (r = 0.96) than with plasma carbosulfan (r = 0.73). Signs generally occurred when AChE activity was less than 65% of pretreatment levels, corresponding to 40 pmol/ml [carbosulfan + carbofuran] in plasma. Based on regression analysis and metabolic studies, both carbosulfan and carbofuran contributed to the observed AChE inhibition; however, carbofuran, a more potent in vitro inhibitor and the usual predominant inhibitor in plasma, was responsible for most of the erythrocyte AChE inhibition.

Acetylcholinesterase↗
PubMed1985

Histotypic pattern formation in cerebellar reaggregate cultures in the presence of antibodies to L1 cell surface antigen.

Reaggregate cultures of cerebella from 5-day-old C57BL/6J mice were cultured in the presence of Fab fragments of polyclonal antibodies against the cell surface adhesion molecule L1. Light microscopic examination showed that histotypic differentiation, as observed by the appearance of radially oriented glial processes and the sorting out of mature and immature neurons, was not affected by the antibody. Electron microscopic observation showed no effect on the synapse formation and the packing density of fasciculated neurites. These observations show that under the culture conditions used, L1 antibodies do not alter the particular cell interactions investigated in this study.

Animals↗
PubMed1989

Immunocytochemical localization of cell adhesion molecule L1 in developing rat pyramidal tract.

L1 is a representative of a family of carbohydrate neural cell adhesion molecules. The expression of L1 was studied during postnatal development of the rat pyramidal tract by immunohistology using polyclonal antibodies to L1 in spinal cord cervical intumescences. On postnatal day 1 (P1), L1 immunoreactivity was present in the entire dorsal funiculus, consisting of the ascending fasciculus gracilis and fasciculus cuneatus and the descending pyramidal tract. At that time the cervical pyramidal tract contains the first outgrowing corticospinal axons. At P4 both the fasciculus gracilis and the pyramidal tract are immunoreactive whereas the fasciculus cuneatus is negative. At P10 the pyramidal tract is intensely labelled whereas both ascending bundles are negatively stained. In the period between P4 and P10 the pyramidal tract is characterized by a massive outgrowth of corticospinal axons. During pyramidal tract myelination, between P10 and the end of the third postnatal week (P21), L1 immunoreactivity is progressively reduced. These observations suggest that L1 may play a prominent role in outgrowth, fasciculation and the onset of myelination of rat pyramidal tract axons. The differential L1 immunoreactivity of the pyramidal tract and the earlier developing ascending systems in rat dorsal funiculus indicate that this polyclonal antiserum is a useful differentiating marker for outgrowing fibre tracts.

Aging↗
PubMed1986

The autonomic innervation of the rat diaphragm.

The innervation of the diaphragm has been studied by three methods--cobalt tracing of the nerves, demonstration of cholinesterase activity and fluorescence microscopy for catecholamines and VIP. The cobalt method reveals the peripheral nerve fibers with a sharpness similar to that shown at the level of the central nervous system where this method has so far been more widely applied. The cobalt method helps to outline the distribution pattern of the nerve fibers and it can be of particular interest at the level of the viscera in order to show the different sources of the axons. Fibers giving a positive response to cholinesterase staining are shown at the level of the motor end plates and surrounding the blood vessels. It is suggested that the axons of phrenic origin contribute to the motor end plates while those coming from the vagus are distributed along the connective tissue surrounding the vascular system. Noradrenergic innervation is scarce, appearing as fine varicosities around the vascular beds. The VIPergic fibers are probably, together with the cholinergic ones, the most widespread. They are distributed among the muscle fascicules as well as being in close connection with the blood vessels.

Adrenergic Fibers↗
PubMed1983

The effects of Bothrops jararacussu venom and its components on frog nerve-muscle preparation.

The effect of Bothrops jararacussu venom was studied in cutaneous pectoris nerve muscle preparations and in the desheathed sciatic nerve of the frog. The venom rapidly inhibited muscle twitch--tension, evoked either directly or indirectly through the motor nerve and abolished the compound action potential of the muscle and of the sciatic nerve. After fractionation of the venom by Sephadex G-50 column chromatography, all the activity was recovered in a fraction containing 30% of the total venom protein and highly enriched in two polypeptides with apparent Mr of 13-15,000, as revealed by two-dimensional polyacrylamide gel electrophoresis. The concentration of active subfraction required to obtain 50% paralysis in 1 h was 8 micrograms protein/ml. The active subfraction contained low levels of phospholipase A activity, whereas no proteolytic activity was detected. The paralyzing activity of the active subfraction on nerve-muscle preparations was not dependent on the presence of Ca2+, suggesting that phospholipase A activity is not required for the toxic effect. The active subfraction was found to cause an initial spontaneous contracture and fasciculation of the nerve-muscle preparation, and a rapid depolarization of the muscle membrane. The frequency of miniature endplate potentials was normal throughout the period of exposure to the active subfraction, although occasionally initial transient bursts were observed. At the end of the incubation, nerve endings still responded to high [K+] and to black widow spider venom. The exposure (1-2 h) to blocking concentrations of venom active subfraction provoked different degrees of morphological alteration of the muscle fibers. In contrast, no ultrastructural alterations were observed in nerve terminals, giving further support to the idea that terminals are not a prime site of the venom action. In addition to its effect on the nerve muscle-preparation, the active subfraction at higher concentrations, showed a Ca2+-dependent hemolytic activity. In the light of these results, the properties of the active subfraction of B. jararacussu venom are compared with those of other known membrane-active toxins.

Animals↗
PubMed1984

Localization and organization of geniculocortical and corticofugal fiber tracts within the subcortical white matter.

Reciprocal connections are formed between the dorsal lateral geniculate nucleus and the striate cortex in the mammalian visual system. The question of whether fibers of these corticopetal and corticofugal pathways are segregated or intermingled within the white matter is still open. In order to examine the organization of these fiber tracts within the white matter, we have used orthograde axonal transport of radiolabelled proteins and neuronal degeneration following kainic acid lesions in the geniculocortical and corticofugal pathways of the rat. Within the white matter the two pathways reside in different layers and are segregated from one another over a significant portion of their course, geniculocortical fibers lying in the external sagittal stratum and corticofugal fibers lying in the internal sagittal stratum of the white matter. In addition, the corticofugal pathways projecting to subcortical structures appear fasciculated in both the transport and the degeneration studies suggesting that axons of cortical output neurons are organized into fiber bundles. The separation of fibers within the white matter may be of potential use for selectively stimulating afferent and efferent pathways in electrophysiological studies in situ and in cortical slice preparations. In addition, the corticofugal fiber bundles may play an important role in guiding axons therein to appropriate targets during axonogeneis and may carry the output of columnar units within visual cortex.

Animals↗
PubMed1985

Ultrastructural features of a human neuroblastoma cell line treated with retinoic acid.

This report examines the morphological changes that occur in a line of human neuroblastoma cells (LA-N-5) following treatment with retinoic acid, in vitro. The results demonstrate that retinoic acid induces pronounced differentiation of these cells. Perikarya aggregate into tight clusters and extend long processes that are frequently fasciculated. Growth cones appear at the ends of these processes. Transmission electron microscopy reveals that after 10 days of treatment these long neurites give rise to varicosities which contain clusters of large dense-core vesicles and smaller clear vesicles. After 18 days of treatment the cultures cease to differentiate further. The pattern of neurite outgrowth is very complex by this point and the frequency of growth cones and vesicle-containing varicosities is greatly increased compared with shorter treatments. Most of these varicosities contain a mix of large dense-core vesicles and smaller clear vesicles and in some profiles the clear vesicles are round while in others they are pleomorphic. Despite this increase in the number of vesicle-containing profiles no membrane specializations were seen that resemble mature synapses. The present results demonstrate that retinoic acid can produce morphological changes in these cells in culture, and that these changes closely mimic those of normal differentiating neurons in culture. Considered with previous studies, these findings suggest that this cell line might provide a useful model system for studying neural differentiation.

Cell Differentiation↗
PubMed1996

Cell surface molecules (NCAM and L1) in intrastriatal transplants of embryonic mesencephalon in rats.

Cell surface molecules, NCAM and L1, reported to have a role in synaptogenesis, growth and fasciculation of the neurites in the brain, were traced in the embryonic nigral transplants in the host striatum of adult rats. Substantia nigra of five, 15 and 25 postnatal days were also examined for the same molecules. Tyrosine hydroxylase label was used as a marker to localize the nigral neurons and glial fibrillary acidic protein to detect if glial scar present. In the control as well as transplants large neurons had expressed tyrosine hydroxylase. By 15th postnatal day tyrosine hydroxylase neurons appeared mature and were scattered, suggesting a well-formed neuropil. NCAM and L1 reaction was seen as a peripheral rim in most of the cells on the fifth postnatal day. The reaction was mainly in relation to the large cells and more extensive on the 15th day. Thereafter on the 25th day, activity was negligible. Large neurons demonstrated strong reactivity for NCAM and L1 during early post-transplantation days. After 30 days only smaller cells were reactive, many of which could be identified as neurons. Strong reaction for these molecules was present only until 60 days, though faint reaction could be detected even on the 90th day. These observations indicate that the growth promoting molecules, the type seen in the neonatal period, can be detected normally only until the neurons mature. Prolonged expression of these molecules by the grafted neurons indicate delay in the maturation of these cells due to absence of adequate target sites for synaptic connections. Some of the smaller cells expressing these molecules after 30 days of transplantation could be astroglia, either proliferating or reactive.

Animals↗
PubMed1996

Immunohistochemical expression of cell adhesion molecule L1 during development of the human brain.

We demonstrated the expression of neural cell adhesion molecule, L1, during human brain development by immunostaining with anti-L1 fibronectin domain antibody. In the human cerebellum, the inner half of the external granular and molecular layers, mostly parallel fibres, and the Purkinje cell layer were immunoreactive for L1 from the early foetal period of 13-15 gestational weeks (GW). Immunoreactivity was strongest in the molecular layer in the perinatal period. The subcortical white matter and dentate layer were immunoreactive in foetal life. In the human cerebrum, the outer half of the molecular layer, together with Cajal-Retzius cell bodies, were positively stained until 30-34 GW, when afferent fibres develop over the entire cortex. The fibres in the white matter were strongly immunopositive in the fascicles until early infancy. These results suggest that L1 is temporally and spatially expressed in the developing brain, and may play important roles in neural cell migration, neurite elongation, and axonal fasciculation.

Adolescent↗
PubMed1990

A developmental study of soluble L1.

L1 is a neural cell adhesion molecule expressed by neurons and it is involved in cell interactions during axon elongation and fasciculation. L1 from rat brain consists of a membrane-inserted Mr 200,000 polypeptide from which two polypeptides of Mr 180,000 and Mr 140,000 can be derived. These latter polypeptides appear both as membrane-associated and as soluble molecules. In this report, both total and soluble L1 in rat brain have been quantified by an enzyme-linked immunosorbent assay. The amount of total L1 per gram brain varies with postnatal age showing a peak value at postnatal day 7. The variation in soluble L1 coincides with the changes in total L1. Thus, soluble L1 constitutes ca 2% of total L1 at all ages investigated. The soluble Mr 140,000 and 180,000 L1 polypeptides are also present in cerebrospinal fluid. Studies of membrane L1 catabolism in cultured fetal rat brain neurons show that the half-life of membrane L1 is less than 24 hr. As a part of membrane L1 catabolism, small amounts of soluble L1 polypeptides are released to include cell surroundings.

Animals↗
PubMed1991

Myelination and glial ensheathment of Purkinje cells in cerebellar cultures are not inhibited by antibodies to the neural cell adhesion molecule, N-CAM.

Mouse cerebellar cultures were exposed to anti-N-CAM antibodies throughout their in vitro development. Some cultures were stripped of myelinating oligodendrocytes and functionally competent astrocytes by treatment with cytosine arabinoside (Ara C), while others were left untreated and were potentially capable of forming myelin around axons and astrocytic sheaths around Purkinje cell somata and dendrites. As expected, the antibodies inhibited axonal fasciculation in the Ara C treated cultures. However, the same antibodies had no discernible effect on formation of myelin or astrocytic sheaths in cultures not treated with Ara C. N-CAM is expressed on the surfaces of neurons, oligodendroglia and astrocytes, and has been proposed as the signal molecule governing both kinds of neuron-glia interactions. The observations of the present study strongly suggest, however, that N-CAM does not have an indispensable role in such interactions.

Animals↗
PubMed1983

Isolation and characterization of a protein neurotoxin from the venom glands of the funnel-web spider (Atrax robustus).

1. Ground venom glands from male and female funnel-web spiders (Atrax robustus) were extracted with acetic acid (0.35 M). 2. A protein constituent of these extracts, atraxin, which caused muscle fasciculation when applied to the phrenic nerve-hemidiaphragm of the mouse in vitro, was isolated by the sequential application of ultrafiltration, gel permeation and ion exchange chromatography. 3. When subjected to isoelectricfocusing, amino acid analysis, ultracentrifugation, ultraviolet and 1H nuclear magnetic resonance spectroscopy, it was shown that atraxin had an approximate molecular weight of 9800, an isoelectric point of greater than 9 and that it contained 76 amino acid residues.

Amino Acids↗
PubMed1984

A comparative study of properties and toxic constituents of funnel web spider (Atrax) venoms.

The crude venoms of male and female Sydney funnel web spiders, Atrax robustus, were compared by cation-exchange and high-performance liquid chromatography, lethality to new-born mice, polyacrylamide gel isoelectric focusing, immunoelectrophoresis, phospholipase A analysis, effects on the mouse phrenic nerve hemidiaphragm and passive paw oedema in the rat and, except in the case of rat paw oedema, were found to exhibit quite different properties. Polyacrylamide gel isoelectric focusing and high-performance liquid chromatography proved to be suitable for gender and species determination when applied to the venoms of A. formidabilis, A. infensus, A. robustus and A. versutus. These venoms were also compared by lethality, promotion of muscle fasciculation and phospholipase A activity.

Animals↗
PubMed1984

In vivo actions of atraxin, a protein neurotoxin from the venom glands of the funnel-web spider (Atrax robustus).

The effects of atraxin, a neurotoxic protein from the venom glands of the funnel-web spider (Atrax robustus), have been studied in anaesthetized monkeys. At doses of 70 and 80 micrograms kg-1 i.v., atraxin caused respiratory disturbances (dyspnoea and apnoea), and profound alterations in heart rate and blood pressure. These doses also caused salivation, lachrymation, skeletal muscle fasciculation and an elevation in body temperature. Concurrent increases in firing were recorded from the phrenic nerve and from respiratory and other skeletal muscles. It is concluded that atraxin produces the same syndrome in primates as that observed with whole milked male funnel-web venom.

Animals↗