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Biomedical subjects

F J Seil

Publications and source records attributed to F J Seil.

At least 55 records · Page 3Linked to original sources
PubMed1987

Astrocytes play a role in regulation of synaptic density.

Exposure of neonatal cerebellar explants to cytosine arabinoside destroys granule cells and arrests surviving glia in an early stage of maturation. Purkinje cells lack astroglial ensheathment and are hyperinnervated by sprouted Purkinje cell recurrent axon collateral terminals. Such granuloprival cultures were transplanted with optic nerve in order to supply mature glial cells. It was observed that not only were Purkinje cells almost completely ensheathed by astroglia, but there was a greater than 60% reduction in the number of somatic synapses compared to the non-transplanted granuloprival cultures. This astroglial ensheathment, which may be neuronally directed, could be the physical element provoking the reduction in the number of synapses.

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PubMed1987

Cerebellum plus locus coeruleus in tissue culture. II: Development and metabolism of catecholamines.

In contrast to locus coeruleus neurons in vivo, dopamine was the predominant catecholamine synthesized, stored, and released by neonatal mouse locus coeruleus cultures which included target cerebellar tissue, and norepinephrine was present in these cultures only at very low levels. Developmentally, norepinephrine increased slightly in the explants during the first 4 days in vitro and declined thereafter to barely detectable levels, whereas dopamine began to rise after 4 days and reached maximal levels by 7 days. Dopamine beta-hydroxylase was present in these cultures throughout maturation. These results suggest that the high ratio of dopamine to norepinephrine in locus coeruleus cultures cannot be attributed to the absence of appropriate target tissue or to a lack of the enzyme, dopamine beta-hydroxylase.

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PubMed1987

Enhanced Purkinje cell survival in granuloprival cerebellar cultures.

The number of large cortical neurons that survived in cerebellar cultures in which granule cells had been destroyed by exposure to cytosine arabinoside was 3-4 times the number in normal cultures. Transplantation of granuloprival cerebellar cultures with granule cells and glia resulted in a reduction of the large cortical neuron population (predominantly Purkinje cells) to normal, while the number of such neurons remained elevated after transplantation with glia alone. These results indicated that granule cells were critical for the reduction of large cortical neurons. The rescue of large cortical neurons in granuloprival cultures was attributed to an expanded target field for Purkinje cell axon collateral projections.

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PubMed1986

Influence of subcortical neurons on the functional development of cerebral neocortex in tissue culture.

The role of subcortical input and/or output pathways in the development of cortical networks was examined in organotypic tissue cultures derived from neonatal mouse brain. Comparisons were made between cultures of cerebral neocortex grown with large amounts of subcortical tissue and those that were completely isolated or included small amounts of subcortical tissue. Extracellular electrophysiological recordings showed differences in excitability and spatial distribution of responses elicited by electrical stimulation of the dorsal edge of cerebral neocortex. Cultures with proportionately greater amounts of subcortical tissue showed enhanced cortical excitability and also displayed a sharper columnar arrangement than was evident in explants that were completely isolated from subcortical influences. The data suggest that subcortical inputs and/or target fields may provide signals that influence the progressive functional development of cerebral neocortical circuitry.

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PubMed1986

Severity of demyelination in vivo correlates with serum myelination inhibition activity in guinea pigs having a new form of experimental allergic encephalomyelitis.

Guinea pigs received a suboptimal transfer of lymphocytes sensitized to myelin basic protein (BP) and were then immunized with guinea pig BP, BP plus chicken brain or chicken myelin, or chicken brain alone. Sera from these animals were tested for the presence of myelinotoxic antibodies, as detected by the myelination inhibition assay. Myelination inhibition activity correlated with the histologic severity of demyelination.

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PubMed1985

Evidence against neurotransmitter mediation of sprouting in granuloprival cerebellar cultures.

Cerebellar cultures derived from neonatal mice undergo a remarkable sprouting of Purkinje cell recurrent axon collaterals after exposure for the 1st 5 days in vitro to cytosine arabinoside to destroy granule cells. Such cultures were simultaneously exposed to large concentrations of the putative neurotransmitters glutamate and GABA, with subsequent continued exposure to the amino acids until the time of fixation at 15 or 16 days in vitro. Axon collateral sprouting was not prevented by glutamate or GABA, suggesting the sprouting is not mediated by the relevant neurotransmitters, but is more likely due to an alteration or lack of development of some trophic interaction between granule cells and their target Purkinje cells.

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PubMed1985

Cerebellum plus locus coeruleus in tissue culture: I. Catecholamine histofluorescence and extracellular electrophysiology.

Neonatal mouse cerebellar cultures with incorporated dorsal pons contained groups of catecholamine histofluorescent locus coeruleus neurons that projected axons to cerebellar cortical regions. Electrical stimulation of local areas of the dorsal pontine fragments evoked complex inhibitory extracellular cortical responses that resembled cerebellar cortical responses to locus coeruleus stimulation in vivo. The apparent structural and functional integrity of the coeruleo-cerebellar system in tissue culture indicates that this model might reasonably be used for biochemical studies of catecholamine development and metabolism.

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PubMed1985

Catecholaminergic fiber sprouting in granuloprival coeruleo-cerebellar cultures.

Neonatal mouse coeruleo-cerebellar explants exposed to cytosine arabinoside to destroy granule cell precursors demonstrated sprouting of catecholaminergic fibers after 15 days in vitro. Levels of dopamine in granuloprival coeruleo-cerebellar cultures were more than twice those of control cultures. As granuloprival cerebellar cultures also demonstrate Purkinje cell axon collateral sprouting, the granuloprival coeruleo-cerebellar system, in which there is sprouting of two different neuronal groups, may provide a model to investigate the nature and specificity of the signal or signals that induce axonal sprouting.

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PubMed1984

Identification of antibodies in anti-CNS and anti-PNS myelin sera by immunoblot, characterization by immunohistochemistry, and their effect in tissue culture.

Immunoblot analysis of antiserum to rat central nervous system (CNS) myelin revealed antibodies to myelin basic protein (MBP), proteolipid protein (PLP), and numerous high molecular weight proteins. In addition, anti-CNS myelin serum exclusively immunostained 4 basic proteins of rat peripheral nervous system (PNS) myelin. Similarly, anti-PNS myelin sera immunostained many high molecular weight proteins in both CNS and PNS myelin in addition to P0 and 4 basic proteins. Purified MBP and PLP were immunostained by anti-CNS myelin sera and MBP and P0 by anti-PNS myelin sera, indicating that antigenic sites are preserved during protein purification. Immunohistochemical localization with antisera was confined to the myelin sheath except that antisera to CNS myelin also stained oligodendrocytes during the active period of myelination. While anti-CNS myelin sera specifically demyelinated centrally myelinated fibers in culture, none of the anti-PNS myelin sera used here demyelinated organotypic spinal cord-dorsal root ganglion cultures.

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PubMed1983

Demyelinating and myelination-inhibiting factors induced by chloroform-methanol insoluble proteins of myelin.

A host of proteins was seen when the chloroform-methanol insoluble protein (CMIP) fraction of bovine brain myelin was transferred from polyacrylamide gels to cellulose nitrate sheets. Inoculation of rabbits with the CMIP fraction generated a number of antibodies which were demonstrated by the immunoblot technique. These antisera against CMIP contained antibodies which induced demyelination and inhibited myelin formation in central nervous system cultures. The demyelinating factor was specific for centrally myelinated fibers, and did not demyelinate peripherally myelinated axons.

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PubMed1983

Climbing fibers in mouse cerebellum co-cultured with inferior olive.

Cerebellar explants derived from neonatal mice were co-cultured with medulla containing inferior olive. The explants exhibited extracellular climbing fiber-like responses to electrical stimulation. On ultrastructural examination, many terminals with a high packing density of round, clear vesicles in a dark filamentous cytoplasm were present. Similar terminals, characteristic of climbing fibers, had not been identified in previous studies with cerebellar explants incorporating dorsal pons, but excluding medulla. The climbing fiber terminals formed appropriate synapses with Purkinje cell dendritic spines. The findings suggest that when climbing fibers are introduced into cerebellar cultures, accurate functional and morphological units are established.

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PubMed1983

Reorganization in granuloprival cerebellar cultures after transplantation of granule cells and glia. I. Light microscopic and electrophysiological studies.

Granuloprival cerebellar cultures were transplanted after 9 or 16 days in vitro with cerebellar explants that had been exposed to kainic acid. The latter contained granule cells and differentiated glia, elements lacking in granuloprival cultures. Changes induced by transplantation observed by light microscopy included interposition of granule cells among the large cortical neurons of host explants; a reduction of the excess neurites of the Purkinje cell axon collateral system that is characteristic of granuloprival explants; and the appearance of myelinated fibers in previously unmyelinated cultures. The most notable electrophysiologic consequence of transplantation was the disappearance of inhibition of cortical spontaneous activity in response to antidromic stimulation of Purkinje cell axons, correlating with the disappearance of excess neurites, and suggesting that Purkinje cell recurrent collateral inhibition was no longer the dominant mode of cortical inhibition. Restoration of missing elements in granuloprival cultures incited development of structural and functional characteristics resembling those of normal cerebellar explants.

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PubMed1983

Reorganization in granuloprival cerebellar cultures after transplantation of granule cells and glia. II. Ultrastructural studies.

Cytosine arabinoside-induced granuloprival cerebellar cultures lack both granule cells and differentiated glia and demonstrate marked synaptic reorganization. After kainic acid-exposed cerebellar explants, which contain granule cells and mature glia, were transplanted to the granuloprival cultures, the following ultrastructural features were noted: (1) parallel fibers formed normal synapses with Purkinje cell dendritic spines as well as with basket/stellate cell somata; (2) sprouted Purkinje cell recurrent axon collateral terminals were markedly reduced in number; (3) Purkinje cells matured and lost perisomatic spines; (4) astroglia formed sheaths around Purkinje cell somata and dendrites; and (5) axonal myelination occurred. The transplanted cultures demonstrated ultrastructural restitution toward normal after addition of missing elements.

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PubMed1983

Serum demyelinating factors in multiple sclerosis.

Sera from 21 patients with multiple sclerosis were applied to myelinated spinal cord cultures and evaluated for demyelinating activity. Samples were collected at various times when patients were on or off therapy with myelin basic protein or prednisone or both, and at various stages of disease. Five of 31 serum samples from 17 patients exhibited demyelinating activity when tested in a 40% concentration in tissue culture nutrient medium. Four of the 10 serum samples taken from patients with active or remitting multiple sclerosis (2 samples from the same patient) were demyelinative; 1 of 21 sera collected during stationary periods of disease was positive. There was no correlation between serum demyelinating activity and the presence or absence of treatment. Sera positive for demyelinating activity failed to inhibit myelin formation in initially unmyelinated cerebellar cultures.

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PubMed1983

Subcortical neurons in cerebellar tissue cultures: a Golgi study.

Subcortical neurons incorporated with mouse cerebellar explants were subjected to analysis with Golgi methods. Intracerebellar nucleus neurons included multipolar and spindle-shape cells with complex dendrites having both spinous and aspinous branches. Dorsal pontine neurons were multipolar, with generally long, spinous dendritic branches. The dendritic complexity of these neurons maintained in relatively isolated in vitro conditions is indicative of considerable intrinsic developmental capability.

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PubMed1982

Mature Purkinje cells in cerebellar tissue cultures: an ultrastructural study.

Mature Purkinje cells in mouse cerebellar tissue cultures were morphologically analyzed by electron microscopy. Explants maintained for 19 to 31 days in vitro contained Purkinje cells that were similar in most respects to those described in vivo except for incomplete arborization of the dendritic trees. Typical features included (1) absence of Purkinje cell perisomatic spines; (2) a paucity of naked Purkinje cell dendritic spines; (3) a 1:1 relationship of Purkinje cell dendritic spines to parallel fiber terminals; and (4) almost complete astroglial investment of Purkinje cell somata and dendrites. Minimal extracellular space was present in the neuropil of the explants and unusual synapses involving Purkinje cells were absent. Atypical features described by some investigators may be a function of retarded development in suboptimal culture conditions and do not represent the limit of tissue culture methodology.

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