bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redox modulatory site of the NMDA receptor–channel complex: Regulation by oxidized glutathione
Authors: Sucher N. J. , Lipton S. A. 
Published: January 2005

AbstractWe monitored increases in both intracellular calcium concentration ([Ca2+]i) and whole‐cell current responses induced by N‐methyl‐D‐aspartate (NMDA), applied with co‐agonist glycine, using fura‐2 digital imaging and patch‐clamp recording techniques. Extracellular application of oxidized glutathione (GSSG), but not reduced glutathione (GSH), inhibited responses mediated by activation of the NMDA subtype of glutamate receptor in cultures of rat cortical and retinal ganglion cell neurons. The NMDA responses were persistently inhibited by GSSG (500 μM to 10 mM) until introduction of a selective sulfhydryl reducing agent, dithiothreitol, which resulted in complete recovery of the responses. Exposure of the neurons to 5,5‐dithio‐bis‐2‐nitrobenzoic acid (DTNB), an efficacious oxidizing agent, also resulted in persistently smaller responses to NMDA. The addition of GSSG following exposure to DTNB, however, did not result in a further decrement in NMDA responses in our experimental paradigm. These findings suggest that a predominant action of GSSG is oxidation of vicinal thiol groups to form a peptide disulfide bond(s) comprising the redox modulatory site of the NMDA receptor–channel complex. Evidence for such regulatory sulfhydryl centers associated with the NMDA receptor has been presented previously. Moreover, the fact that DTNB produced little if any additional attenuation of the NMDA [Ca2+]i response when administered alter GSSG implies that GSSG is also an efficacious oxidant at this site. GSSG displayed little or no effect on [Ca2+]i responses elicited by high extracellular K+ or by kainate, suggesting that, at least under the conditions of the present experiments, GSSG was somewhat selective for the NMDA redox modulatory site. Based on these observations, we suggest that GSSG exerts its NMDA‐specific redox effects in a novel extracellular manner.
Calbindin‐D28K and ischemic damage of pyramidal cells in rat hippocampus
Authors: Rami A. , Rabié A. , Thomasset M. , Krieglstein J. 
Published: January 2005

AbstractAn antibody against rat calbindin‐D28K, a calcium‐binding protein present at high concentration in certain neurons of the central and peripheral nervous systems, was used to determine the progression of the pathological events in the rat hippocampus following experimental cerebral ischemia. Calbindin‐D28K immunoreactivity is present in dentate granule cells and in the CA1–CA2 pyramidal cells. CA1 subfield contains a higher proportion of calbindin‐D28K‐positive pyramidal cells than does the CA2 subfield and CA1 cells are more immunoreactive than the CA2 cells. The pyramidal cells of the CA1 and CA2 subfields are vulnerable to ischemia. The cells in the C A 1 became necrotic within 3–4 days after ischemia while those of the CA2 became necrotic within 2 days. There was a concomitant decrease in calbindin‐D28K immunoreactivity in the whole hippocampal regio superior after ischemia which peaked 3 days postischemia. The difference in CA2 and CA1 vulnerability seemed to be inversely correlated with the calbindin‐D28K contents of the CA2 and CA1 pyramidal cells. The decrease in the calbindin‐D28K contents of these neurons was accompanied by cell damage. We therefore suggest that calbindin‐D28K is an important factor for the survival of pyramidal cells in the hippocampal formation after ischemia.
Phenotypic plasticity of avian embryonic sympathetic neurons grown in a chemically defined medium: Direct evidence for noradrenergic and cholinergic properties in the same neurons
Authors: Barbu M. , Pourquié O. , Vaigot P. , Gateau G. , Smith J. 
Published: January 2005

AbstractAvian embryonic sympathetic ganglia possess both catecholaminergic and cholinergic features and can synthesize noradrenaline (NAd) and acetylcholine (ACh) simultaneously. In the present study we sought to determine (1) whether or not this coproduction of NAd and ACh corresponds to the existence of two non‐overlapping populations, and (2) to what extent the levels of synthesis are influenced by non‐neuronal ganglion cells. We have focused on the correlation between the immunocytochemically demonstrable presence of the noradrenergic and cholinergic enzymes tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT), respectively, and the synthesis of the corresponding neurotransmitters in embryonic quail sympathetic neuronal and non‐neuronal cells purified by fluorescence‐activated cell sorting. We show that (1) freshly sorted neurons synthesize both NAd and ACh, whereas non‐neuronal cells produce neither; (2) the overwhelming majority of the sympathetic neurons display TH immunoreactivity; (3) about half of the TH‐positive neurons are recognized by an anti‐ChAT antibody in an artificial medium that selectively enhances synthesis and/or accumulation of ACh; (4) the non‐neuronal cells are important for survival of the neurons and potentiate their synthesis of ACh in this medium, and (5) finally, we present evidence that expression of TH in noradrenergic neurons and in small intensely fluorescent cells of sympathetic ganglia is differentially regulated. © 1992 Wiley‐Liss, Inc.
Time lapse study of neurite growth in hypothalamic dissociated neurons in culture: Sex differences and estrogen effects
Authors: Díaz H. , Lorenzo A. , Carrer H. F. , Cáceres A. 
Published: January 2005

AbstractCultures of dissociated hypothalamic cells taken from rat fetuses of 19 days of gestation were studied using time‐lapse recording and sequential microphotography from 1 to 5 days in vitro (DIV) and at 7 and 21 DIV. Cultures were seeded with cells taken from fetuses grouped by sex or sexually mixed; experimental cultures were raised in medium containing 17‐β‐estradiol 100 nM (E2). Cells were plated on poly‐D‐lysine‐coated coverslips at a culture density of approximately 4,000 cells/cm2. Immunocytochemistry of cell cultures was performed using a Tau monoclonal antibody (clone Tau‐1 PC1C6) and a monoclonal antibody against MAP‐2 (clone AP‐20). Cells started to produce lamellipodia and neuritic processes approximately 4 hr after plating. Forty‐eight hours later a few neurons had defined their morphological polarity by the differentiation of an axon‐like process that grows faster than the others; at 5 DIV almost all neurons had defined their axons. At this time, monoclonal antibody against MAP‐2 clearly stained soma and dendrites, but not axons. Tau immunoreactivity (lots CCA101 and CCA101N from Boeringher Mannheim) was differentially distributed, with a clear predominance in axon and soma. Results on the morphometric analysis of control and E2 treated neurons provide direct evidence for the existence of sex related differences in the neurite out‐growth response of hypothalamic neurons, since cultured neurons taken from female fetuses differentiated axons later and had fewer primary neurites and shorter dendrites than neurons taken from male fetuses or sexually mixed cultures. Also, it was demonstrated in living neurons that E2 effectively enhances outgrowth and elongation in axons. The frequency distribution curves of axonal length for control and E2 treated cultures was unimodal, suggesting that the effect of E2 was a uniform increase in the axonal length of all neurons. The structural differences between neurons from both sexes and the changes induced by E2 may contribute to explain the differences in brain function found between the sexes. © Wiley‐Liss, Inc.
Biosynthesis and expression of the myelin‐associated glycoprotein in cultured oligodendrocytes from adult bovine brain
Authors: Yim S. H. , Quarles R. H. 
Published: January 2005

AbstractThe biosynthesis and expression of myelin‐associated glycoprotein (MAG) were investigated in cultured oligodendrocytes isolated from adult bovine brain. Western blotting revealed two prominent MAG bands that were present in comparable amounts; the larger component electrophoresed above the 97 kD standard but was slightly smaller than the MAG band in purified bovine myelin, and the smaller component electrophoresed below the 97 kD standard. In comparison to other precursors of oligosaccharides, inorganic [35S]sulfate was a relatively specific isotope for labeling MAG relative to other glycoproteins in the cells. Sulfate labeled only the larger of the two MAG components, which contains complex N‐linked oligosaccharides, but which appears to be glycosylated to a lesser extent than MAG in vivo. The smaller MAG band in the cells is a form with high‐mannose oligosaccharides and was not detected in purified bovine myelin. Both the large and small MAG components were expressed on the oligodendrocyte surface as indicated by their sensitivity to neuraminidase and/or trypsin treatment of live cells. MAG was also released by the oligodendrocytes into the culture medium. The MAG in the medium was slightly smaller than that in the cells, suggesting that it may be released from the cell surface by limited proteolysis. The release of MAG by myelin‐forming cells could be relevant to physiological roles that have been postulated for soluble forms of MAG and other adhesion proteins. Published 1992 by Wiley‐Liss, Inc.
Specific binding of cytotactin to sulfated glycolipids
Authors: Crossin K. L. , Edelman G. M. 
Published: January 2005

AbstractThe binding of the glial glycoprotein, cytotactin, to a variety of purified glycolipids was examined. Clear‐cut evidence was found for binding of radiolabeled cytotactin to sulfatides purified from bovine brain, but the molecule did not bind to gangliosides or cerebrosides. The sulfatide binding was sensitive to pH and ionic strength and was dependent on the presence of divalent cations. Binding was inhibited by purified unlabeled cytotactin, by polyclonal antibodies to cytotactin, and by several monosaccharides and polysaccharides. It was not inhibited by fibronectin, a chondroitin sulfate proteoglycan, or the HNK‐1 monoclonal antibody, all of which are known to bind to cytotactin. These findings raise the possibilities that sulfated glycolipids may function as cellular receptors for cytotactin and that binding by sulfatides may modulate the varied effects of cytotactin on cellular processes. © 1992 Wiley‐Liss, Inc.
L2/HNK‐1 carbohydrate and protein‐protein interactions mediate the homophilic binding of the neural adhesion molecule P0
Authors: Griffith L. S. , Schmitz B. , Schachner M. 
Published: January 2005

AbstractThe neural adhesion molecule P0, the most abundant glycoprotein in peripheral myelin of mammals, is a member of the immunoglobulin superfamily and expresses the L2/HNK‐1 and L3 oligosaccharides at a single N‐glycosylation site. It acts in both homophilic and heterophilic binding mechanisms. To investigate the molecular requirements for homophilic interaction, we have used P0 from human sciatic nerve and the extracellular domain of P0 expressed in bacteria to determine binding of P0 to P0 in solid phase and bead aggregation assays. The binding of P0 to P0 could be partially inhibited in both assays by antibodies to the L2/HNK‐1 epitope and by the L2/HNK‐1 carbohydrate, but not by L3 antibodies or other carbohydrates. Inhibition of binding was also seen with polyclonal antibodies reacting with the protein backbone of P0. These observations indicate that both carbohydrate and protein structures are involved in the binding of P0 to P0 and that P0 acts as a presenter of and a receptor for a functionally important carbohydrate. © 1992 Wiley‐Liss, Inc.
Distinct hypomyelinated phenotypes in MBP‐SV40 large T transgenic mice
Authors: Jensen Niels A. , Smith G. M. , Shine H. D. , Garvey J. S. , Hood L. 
Published: January 2005

AbstractTo study the effect of SV40 large T‐antigen expression in myelin‐forming cells of both the central and peripheral nervous system, a series of transgenic mice were generated expressing the SV40 large T‐antigen under control of the myelin basic protein (MBP) promoter. Two neurologic phenotypes, designated A and B, appeared among individual transgenic founders and their progeny. The A mice developed a severe action tremor at about 10 days of age that progressed into periods of convulsions and early death by three to four weeks of age. In contrast, the B mice exhibited a progressive hindlimb ataxia and had a more normal lifespan. The A mice displayed hypomyelinating lesions in the central nervous system (CNS), whereas the B mice had lesions in either the peripheral nervous system (PNS) alone or in both the PNS and CNS. Immunohistochemical staining of spinal cord sections of a type A mouse showed a substantial depletion in MBP. Moreover, T‐antigen‐positive cells appeared prodominantly in white matter tracts as randomly distributed single cells. Double labeling immunocytochemistry demonstrated that some of these T‐antigen‐positive cells were positive for oligodendrocyte differentiation markers MBP and O4. Thus, T‐antigen expression appeared to coincide with a terminal stage of oligodendrocyte differentiation. © 1993 Wiley‐Liss, Inc.
Microtubule‐associated protein MAP1B expression precedes the morphological differentiation of oligodendrocytes
Authors: Vouyioukiis D. A. , Brophy P. J. 
Published: January 2005

AbstractThe microtubule‐associated protein MAPIB is belieyed to play an important role in the outgrowth of neurites from neurons (Tucker and Matus, Dev Biol 130:423–434, 1988). We have investigated the possibility that MAPIB might participate in the formation of processes incultured oligodendrocytes by an anal‐ ysis of the expression of MAPIB during oligodendrocyte progenitor development. The appearance of the antigens recognized by the monoclonal antibodies A2B5, O4, and O1 which define distinct stages in the maiuration of progenitors, was compared with the developmental expression of MAPIB. MAPIB is first detectable in O4 + preoligodendrocytes prior to the acquisition ofgalactocerebroside and immediately before they develop the complex process‐bearing mor‐ phology characteristic of terminally differentiated myelin‐forming oligodendrocytes in the CNS. In contrast, astrocytes have negligible amounts of MAP1B. These results demonstrate that the expression of MAP1B precedes the development of the mature oligodendrocyte phenotype and suggest that interactions between microtubules and MAP1B might have a role in the formation and stabilization of myelinforming processes. © 1993 Wiley‐Liss, Inc.
Secretion of amyloid precursor protein and laminin by cultured astrocytes is influenced by culture conditions
Authors: Shea T. B. , Beermann M. L. , Honda T. , Nixon R. A. 
Published: January 2005

AbstractAlthough normally quiescent, astrocytes in the adult brain respond to various types of brain injury by rapidly dividing, swelling, extending cellular processes, and expressing increased amounts of glial fibrillary acidic protein (GFAP). These phenomena are collectively referred to as “astrogliosis.” Similarly, astroglia in primary culture stop dividing when they attain confluency, yet, as seen in situ, they retain their proliferative capacity for extended periods and resume rapid division when subcultured. To examine the impact of glial division on secretion of neuritepromoting factors, conditioned medium (CM) was removed from subconfluent, newly confluent, and longterm confluent (“aged”) neonatal rat astrocyte cultures, and from aged confluent cultures that had been repassaged, “Lesioned” (scraping with a rubber policeman), or triturated 3 days before harvest. Secretion of neurite‐promoting factor(s) by glial cells into these CM was then assayed by treating neuroblastoma cultures with these various CM and quantitating neurite elaboration. Extensive neurite sprouting was elicited by CM from cultures just reaching confluency and from repassaged, lesioned, or triturated cultures. CM from aged confluent cultures did not induce sprouting. These results indicate that secretion of neurite‐promoting factors(s) is regulated by glial division, and suggest that gliosis in situ may contribute to neurite sprouting by similar mechanisms. Immunoblot analysis demonstrated the presence in CM of varying amounts of laminin and amyloid precursor protein (APP), including isoforms containing the Kunitz‐type protease inhibitor domain. CM from subconfluent cultures contained trace amounts of these protiens, but CM from cultures just reaching confluency contained significant amounts. Although CM from aged cultures contained barely detectable levels of either protein, trituration or repassage of aged cultures dramatically increased secretion of these proteins. APP‐and laminin‐enriched CM fractions promoted neuritogenesis to a similar level as respective unfractionated CM; anti‐APP and antilaminin antisera blocked this effect. Purified human brain APP promoted neuritogenesis when added to non‐conditioned medium and aged CM. Increased secretion of APP and laminin therefore mediates at least a portion of CM‐induced neuronal sprouting; these proteins may perform analogous functions during astrogliosis in situ. © 1994 Wiley‐Liss, Inc.
Autocrine regulation of proliferation of cerebellar granule neurons by nerve growth factor
Authors: Muller Y. , Duperray C. , Caruso F. , Clos J. 
Published: January 2005

AbstractPremigratory cerebellar granule neurons, which highly express nerve growth factor (NGF), low (gp75NGFR) and high (gp140trkA) affinity NGF receptors, were used as a physiological model to investigate the effects of NGF on neuronal replication. Studies in vivo and on cultures showed that NGF stimulates DNA synthesis, mitotic activity and related cell acquisition by initiating the entry of cells into the S phase and regulating their time in the G1 and S phases. The NGF‐induced effects were blocked in vivo and in vitro by both monoclonal anti‐NGF and anti‐gp75NGFR antibodies. These results clearly demonstrate that NGF is essential for the crucial first step of cerebellar ontogenesis and support the idea that low affinity receptors are involved in the biological response, possibly by interacting with gp140trkA. By comparison with a number of well known mitogens, the high affinity form could be the main transducer of the mitogenic signal pathway. The early developing cerebellum appears therefore to be the first autocrine (and/or paracrine) model of NGF action on neurogenesis in the CNS. © 1994 Wiley‐Liss, Inc.
Brain macrophages stimulate neurite growth and regeneration by secreting thrombospondin
Authors: Chamak B. , Morandi V. , Mallat M. 
Published: January 2005

AbstractThe presence of macrophages in the developing or lesioned central nervous system (CNS) led us to study the influence of these cells on neuronal growth. Macrophages were isolated from embryonic rat brain and we observed that factors released in vitro by these cells stimulate neurite growth and regeneration of cultured CNS neurons. This effect was inhibited by antibodies directed against thrombospondin, an extracellular matrix protein that we found to be synthesized and released by brain macrophages. Immunodetection of thrombospondin in the adult rat brain lesioned by kainic acid confirmed the production of this protein by brain macrophages and indicated an early intraparenchymal accumulation of thrombospondin following injury. These results suggest that brain macrophages contribute actively to neurite growth or regeneration during the development or in pathological contexts. © 1994 Wiley‐Liss, Inc.
Retrograde axonal transport of locally synthesized proteins, e.g., actin and heat shock protein 70, in regenerating adult frog sciatic sensory axons
Authors: Edbladh M. , Ekström P. A. R. , Edström A. 
Published: January 2005

AbstractThe local synthesis and subsequent retrograde axonal transport of [35S]methionine‐labelled proteins was studied in the in vitro regenerating adult frog sciatic sensory axons. By the use of a three compartment culture system, proteins in the outgrowth region were selectively labelled. After 2 days in culture a rise in TCA‐insoluble radioactivity was detected in the dorsal root ganglia, which could be prevented by the addition of viblastine or 2,4‐dinitrophenol to the nerve proximal to the crush site. Two‐dimensional polyacrylamide gel electrophoresis of ganglionic proteins revealed a pattern of 35 labelled polypeptides with apparent molecular masses (Mm) ranging from < 15 to 95 kDa and with isoelectric points (pI) ranging from 4.5 to 6.5. The major ones, representing about 75% of the activity in a gel, were of Mm/pI 47/5.4, 48/6.1, ©57/6.0, 62/5.2, 65/4.9–5.0, 65/5.2, and 81/5.4 respectively. One of these polypeptides (47/5.4) was identified as actin and another (81/5.4) as a member of the heat shock protein 70 family. The spots at 65/4.9‐‐5.0 were tubulin isoforms. There was a striking similarity between transported proteins on one hand, and proteins synthesized in the injured nerve on the other, with respect to the Mm/pI of at least 14 protein species. The results suggest that selected set of proteins, synthesized by non‐neuronal cells, e.g., Schwann cells, is transferred to the ganglionic cell bodies by retrograde axonal transport.© 1994 WiIey‐Liss, Inc.
Amphiphilic properties of molecular forms of acetylcholinesterase in normal and dystrophic muscle
Authors: Cabezas‐Herrera J. , Campoy F. J. , Vidal C. J. 
Published: January 2005

AbstractAcetylcholinesterase (AChE) molecular forms were studied in normal (NM) and in dystrophic (DM) 129B6F1/J mouse muscle. Successive extractions of the tissue with saline and saline‐Triton X‐100 buffers yielded two soluble fractions, S1 and S2. Forty percent of the AChE in NM was measured in S1 and 60% in S2, and 65% and 35%, respectively, in extracts from DM. A12, A8, G4, G2, and G1 forms of AChE were found in S1 and S2 from NM and DM. A similar content of asymmetric molecules was noticed between NM and DM. G4 AChE was a minor species in DM, and G1 and G2 AChE were more abundant in DM than in NM. The amphiphilic properties of the several molecules were assessed by Triton X‐114 phase‐partitioning and hydrophobic chromatography. Thirty and 70% of the enzyme in a mixture of S1 and S2 partitioned in the detergent‐rich and in the detergent‐poor phases, respectively, whether the extracts were obtained from NM or DM. Asymmetric and G4 AChE predominated in the aqueous phase and G1 and G2 in the detergent phase. Ten and 25% of the enzyme in S1 from NM or DM, respectively, was adsorbed to the phenyl‐agarose. Elution of the retained enzyme followed by sedimentation analysis revealed that a certain amount of asymmetric and most of the G1 and G2 forms were associated with the matrix. The content of amphiphilic asymmetric and light globular forms was notably higher in DM than in NM. The results suggest that dystrophic muscle produces a specific pattern of molecular forms of AChE. © 1994 Wiley‐Liss, Inc.
Mutations in demyelinating peripheral neuropathies support molecular model of myelin PO‐glycoprotein extracellular domain
Authors: Kirschner D. A. , Saavedra R. A. 
Published: January 2005

AbstractHomophilic interactions of the major integral membrane protein of peripheral nerve myelin, P0‐glycoprotein, are thought to mediate membrane adhesion and compaction. Molecular modeling of its extracellular domain (P0‐ED), based on its resemblance to an immunoglobulin variable domain and on X‐ray diffraction measuements of inter‐membrane spacings of myelin, has suggested which amino acid sidechains may be involved in the homophilic adhesion. Recently identified point‐mutations in the human P0 gene result in amino acid substitutions in P0 protein and correlate with demyelinating motor and sensory neuropathies. The molecular model explains how these changes result in disrupted P0‐P0 interactions; indicates how compensatory changes in amino acids, as occur in P0‐ED of other species, preserve normal homophilic interactions; and predicts what other residue substitutions might underlie additional cases of demyelinating neuropathies. Copyright © 1994 Wiley‐Liss, Inc.