bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differentiation‐regulated loss of the polysialylated embryonic form and expression of the different polypeptides of the neural cell adhesion molecule by cultured oligodendrocytes and myelin
Authors: Trotter J. , Bitter‐Suermann D. , Schachner M. 
Published: January 2005

AbstractThe expression of the neural cell adhesion molecule (N‐CAM) on cultured murine oligodendrocytes, their precursors, and myelin was examined by indirect immunofluorescence, biosynthetic radiolabeling followed by immunoprecipitation and Western blot analysis, using antibodies specific for various forms of the molecule. In all culture systems studied, whether the oligodendrocytes were cultured as an enriched fraction containing precursor cells or in the presence of astrocytes and neurons, a similar differentiation stage‐related expression of N‐CAM was seen. At early developmental stages many tetanus toxin receptor and A2B5 antigen‐positive putative oligodendrocyte precursors with bipolar morphology were seen and found to express N‐CAM in its embryonic form. Of the 04 antigen‐positive immature oligodendrocytes with few slender processes most expressed N‐CAM, but few the embryonic form of N‐CAM. The more mature 01 or 010 antigen‐positive oligodendrocytes were found to express exclusively the adult form of N‐CAM. Oligo‐dendrocytes synthesized the 120 and 140 kD forms of N‐CAM (N‐CAM 120 and N‐CAM 140), but not N‐CAM 180, although with differentiation, N‐CAM 120 predominated in oligodendrocytes and also in pure myelin. N‐CAM 120 could be released from oligodendrocytes and myelin by phosphatidylinositol‐specific phospholipase C, suggesting that in both oligodendrocytes and myelin N‐CAM 120 is inserted into the membrane by covalent linkage to phosphatidylinositol.
Neurotransmitter phenotype plasticity in cultured dissociated adult rat dorsal root ganglia: An immunocytochemical study
Authors: Schoenen J. , Delree P. , Leprince P. , Moonen G. 
Published: January 2005

AbstractCulturing sympathetic ganglion neurons in vitro may modify phenotypic expression of some neurotransmitters. For dorsal root ganglia (DRG), contradictory results have been reported; most studies have used immature material. We have therefore performed a detailed immunocytochemical analysis of the transmitter content of cultured adult rat DRG neurons. To demonstrate possible modifications of neurotransmitter phenotypes, we have compared the results obtained with the same techniques on neurons cultured for 3 days and on freshly dissociated DRG cells. Also, the transmitter profile of cultured neurons was compared with that known from in situ studies.Out of 22 antigens studied, 20 were detected in cultured DRG neurons. All of them were expressed in small and/or intermediate‐sized cells. Large neurons only contained CGRP, VIP, NPY, β‐END, ENK, and GABA. The percentage of immunostained neurons varied for the various antisera: < 10% of cultured neurons were positive for ENK, β‐LPH, β‐END, DYN, VASO, and OXY; 10–30% for SOM, CCK, CAT, and SP; and > 30% for NPY, CRF, GLU, NT, VIP, GABA, GRP, CGRP, 5‐HT, and TRH. In the latter two groups of transmitters (except CGRP), the proportion of immunoreactive neurons was by far larger in cultured than in freshly dissociated DRG. The most pronounced ( > 25%) increase in the proportion of positively stained neurons after culturing was observed for the GRP, CRF, TRH, and 5‐HT antisera. Serotonin was the only transmitter identified in cultured but not in freshly dissociated cells.These data indicate, on one hand, that various antigens, for example, CAT, GABA, NT, TRH, NPY, β‐LPH, and β‐END, which up to now have not been described in DRG in situ, can be detected immunocytochemically a few hours after dissociation of adult rat DRG. On the other hand, several transmitters, for example, VIP, NPY, SP, GABA, GLU, NT, GRP, CRF, TRH, and 5‐HT, are expressed in a significantly higher proportion of cells in cultured than in freshly dissociated preparations. This might reflect a change in the phenotypic expression of transmitters due to the new environment generated by the culture conditions, a hypothesis that can be tested by measuring specific mRNA levels. Moreover, considering the plasticity and multipotentiality of their transmitter phenotype, cultured adult DRG neurons might represent an interesting material for autografts into the injured central nervous system.
Isolation and structural characterization of the bovine tyrosine hydroxylase gene
Authors: D'Mello S. R. , Turzai L. M. , Gioio A. E. , Kaplan B. B. 
Published: January 2005

AbstractA bovine tyrosine hydroxylase (TH) cDNA probe was used to screen a charon 30 genomic library. Screening of approximately 1 million recombinant phage resulted in the identification of one clone, γB1, containing the entire bovine TH gene. Results derived from restriction endonuclease mapping and sequence analysis reveal that the bovine gene contains 13 exons spanning approximately 7 kb of genomic DNA. Determination of the transcription initiation site indicates that the TH gene has a 5′ untranslated region of 27 bp. A TATA‐box sequence is located between positions −29 and −24 from the transcription initiation site and a cyclic AMP regulatory element (CRE) between −45 and −38. Although the TH gene appears to be glucocorticoid responsive in vitro, no regions bearing identity to the consensus sequence for the glucocorticoid regulatory element (GRE) were detected within approximately 1.5 kb of 5′ flanking sequence. A cross‐species comparison of the 5′ flanking sequences of the bovine, rat, and human TH genes reveals strong sequence and positional conservation of seven sequence elements. An analysis of the nucleotide sequence within these elements reveals similarity to the consensus sequences reported for known cis‐acting regulatory elements and transcription factor binding sites, suggesting that they may play a role in the regulation of TH gene expression.
Identification of basic fibroblast growth factor as a cholinergic growth factor from human muscle
Authors: Vaca K. , Stewart S. S. , Appel S. H. 
Published: January 2005

AbstractDissociated embryonic chick ciliary ganglion cells in culture were used as a bioassay to isolate a cholinergic growth‐promoting protein from extracts of autopsied adult human muscle. An active protein was purified after acid and salt precipitation of extract, cation exchange, molecular sieving, heparin affinity chromatography, and in some cases, SDS‐PAGE. This protein increased levels of choline acetyltransferase activity and ACh synthesis with time in culture. The protein was identified as basic FGF by several criteria. It shared the high affinity for heparin and was the same approximate molecular weight, 18 kD, as basic FGF. Activity was removed from solution by antibodies specific for basic FGF. Recombinant human basic FGF was equally effective in stimulating CAT activity, but was not additive with our purified protein at saturating concentrations. Basic FGF was also found in extracellular matrix and conditioned medium from cultured embryonic chick muscle. The activity could be released from extracellular matrix by treatment with heparinase or high salt extraction. Basic FGF stimulates neurite outgrowth as well as the capacity for transmitter synthesis. Thus, basic FGF is present in embryonic and adult muscle and capable of acting as a growth regulator for cholinergic neurons.
Sodium‐independent transport of noradrenaline in mouse and rat astrocytes in primary culture
Authors: Paterson I. A. , Hertz L. 
Published: January 2005

AbstractThe uptake of noradrenaline by primary cultures of mouse and rat astrocytes was investigated in order to examine whether an inhibition of extraneuronal noradrenaline uptake was the mechanism whereby some trace biogenic amines potentiate neuronal responses to noradrenaline. In the presence of inhibitors of the enzymes monoamine oxidase and catechol‐O‐methyl transferase, it was found that astrocytes took up noradrenaline by a temperature‐dependent, sodium‐independent mechanism that was saturable with a Km = 3.4 × 10−7 M and a Vmax = 1.6 pmole/mg protein/2 min. This uptake mechanism did not concentrate noradrenaline within the cell. The uptake of noradrenaline was inhibited by ascorbic acid (IC50 = 3.4 × 10−7 M), adrenaline (IC50 = 7.9 × 10−7 M), and dopamine (IC50 = 1.5 × 1.0−6 M). It was not inhibited by the tricyclic antidepressants amitriptyline and desmethylimipramine or the trace biogenic amines β‐phenylethylamine, phenylethanolamine, p‐ and m‐tyramine and p‐ and m‐octopamine. Nor was the uptake inhibited by fluoxetine or 5‐hydroxytryptamine. It is concluded that astrocytes take up noradrenaline by a facilitated‐diffusion mechanism and that this uptake resembles the extraneuronal uptake described in preparations of brain tissue. It is also concluded that the trace biogenic amines do not potentiate neuronal responses to noradrenaline by inhibiting extraneuronal uptake.
Changes in free fatty acids, phospholipids, and cholesterol following impact injury to the rat spinal cord
Authors: Demediuk P. , Daly M. P. , Faden A. I. 
Published: January 2005

AbstractFree fatty acids (FFA), phospholipid, and cholesterol levels were measured in spinal cord samples from rats subjected to low (25 g‐cm), moderate (50 g‐cm), or severe (100 g‐cm) impact trauma to the T10 spinal segment. All degrees of injury caused early (15 min) declines in total phospholipids after trauma; phospholipid levels remained significantly below controls in rats subjected to moderate and severe injuries for up to 3 days, whereas phospholipids had returned to baseline values by 4 hr in the low injury group. Rapid and persistent decreases in cholesterol levels were observed for all injury groups. Severe trauma was associated with biphasic increases in FFA levels: levels were elevated at 5 and 15 min post‐trauma and had declined by 30 min; a second elevation was observed at 1 hr, progressively increasing to reach a maximum at 24 hr, before declining over the next 6 days. Low and moderate injuries caused similar early total FFA increases; later increases were significantly smaller than in the severely injured group. Among the free fatty acids, significant increases were observed in palmitate, stearate, oleate, linoleate, linolenate, arachidonate, and docosahexaenoate. These findings indicate that traumatic spinal cord injury results in early, transient, postinjury membrane phospholipid hydrolysis, the magnitude of which is relatively independent of the severity of injury. More delayed and sustained lipid hydrolysis also occurs after trauma, the magnitude of which is related to the severity of injury.
Oligodendrocytes express a normal phenotype in carbonic anhydrase II‐deficient mice
Authors: Ghandour M. S. , Skoff R. P. , Venta P. J. , Tashian R. E. 
Published: January 2005

AbstractThe nervous system of a mouse mutant characterized by a carbonic anhydrase II (CA II) deficiency was examined with light and electron microscopy and with immunocytochemistry using different glial cell markers.No major morphologic abnormalities at either the cellular or subcellular level are detectable in the brains of CAII‐deficient mice, even though CAII is the main isozyme of CA in the brain. The oligodendrocytes, which characteristically express high levels of CA II, do not exhibit signs of degeneration or abnormalities even in 1‐year‐old CA II‐deficient mice. Similarly, neurons and astrocytes have a normal structure and distribution. Oligodendrocytes show a normal staining pattern and distribution for galactocerebroside (GC), 2′, 3′‐cyclic nucleotide 3′‐phosphohydrolase (CNP), and myelin basic protein (MBP). Astrocytes have a normal morphology and distribution when stained for GFAP and S100 protein. The lack of major degeneration in the brain due to a CA II deficiency suggests these mice utilize other enzymatic or physiological pathways to compensate for the enzyme absence.
Neurotrophic activity of monomeric glucophosphoisomerase was blocked by human immunodeficiency virus (HIV‐1) and peptides from HIV‐1 envelope glycoprotein
Authors: Mizrachi Y. 
Published: January 2005

AbstractGlucophosphoisomerase (GPI), a glycolytic enzyme, was recently described to share 90% sequence homology with neuroleukin, a recently discovered growth factor which promotes motor neuron regeneration in vivo, survival of peripheral and central neurons in vitro, and affects B cell immunoglobulin synthesis.Interestingly, neuroleukin activity was described to be antagonized by the human immunodeficiency virus (HIV‐1) envelope glycoprotein (gp120), with which neuroleukin was found to share partial sequence homology. In this study, reduced GPI demonstrated similar activity to neuroleukin in a novel bioassay using human and rat neuroblastoma cell lines. In the presence of reduced GPI, these cells were found to differentiate, in terms of enhanced neurite extension at a reduced proliferation rate. These results demonstrate the existence of a novel growth factor activity of an evolutionary ancient enzyme. The nonreduced commercial form of GPI, probably the dimer, was found to be inactive in this bioassay. Using the neuroblastoma cells model system, we further investigated the significance of the region of homology to HIV‐1 envelope glycoprotein (gp120) as the putative binding site of GPI to its receptor on neuronal cells.
Complete sequence of a cDNA encoding an active rat choline acetyltransferase: A tool to investigate the plasticity of cholinergic phenotype expression
Authors: Brice A. , Berrard S. , Raynaud B. , Ansieau S. , Coppola T. , Weber M. J. , Mallet J. 
Published: January 2005

AbstractA cDNA clone encoding the complete sequence of an active, rat choline acetyltransferase (ChoAcTase; acetyl‐CoA:choline O‐acetyltransferase, EC 2.3.1.6) has been isolated. Analysis of the deduced amino acid sequence reveals 85% and 31% identity with the porcine and Drosophila melanogaster enzymes, respectively. To further elucidate the molecular basis of neurotransmitter‐related phenotypic plasticity, the expression of ChoAcTase mRNA was compared with that of tyrosine hydroxylase [TH; tyrosine 3‐monooxygenase, L‐tyrosine, tetrahydropteridine: oxygen oxidoreductase (3‐hydroxylating), EC 1.14.16.2], in neurons from superior cervical ganglia grown in the following conditions: (1) normal medium, (2) high K+ medium, and (3) normal medium supplemented with 50% muscle‐conditioned medium (CM). TH mRNA was expressed in all three media; its level rose in high K+ and decreased strikingly in the presence of CM. ChoAcTase mRNA could be visualized in CM, but fell to undetectable levels in normal and high K+ media. These results suggest that translational or post‐translational mechanisms do not play a major role for the modulation of neurotransmitter‐associated phenotype.
Quantitative analysis of the localization of adrenergic binding sites in chick brain
Authors: Dermon C. R. , Kouvelas E. D. 
Published: January 2005

AbstractIn the present work [3H]‐WB4101, [3H]‐DHA, and [3H]‐clenidine were used for the study of the localization of α1, α2, and βT adrenergic receptors in the chick brain.The highest concentration of [3H]‐WB4101 was observed in the nucleus pretectalis, followed by the nucleus brachium conjuctivum descendens. The supercial layers of stratum griseum fibrosum superficiale, the nucleus mesencephalis lateralis pars dorsalis, and the locus coeruleus showed concentrations of [3H]‐WB4101 binding higher than 300 fmoles/mg protein. Concentrations of [3H]‐DHA binding higher than 300 fmoles/mg protein were observed in the paleostriatum, the external part of nucleus pretectalis, the nucleus isthmi parvocellularis, the nucleus mesencephalis lateralis pars dorsalis, the dorsal nucleus of oculomotor center, and the molecular layer of cerebellum. Locus coeruleus was the only area of chick brain which showed concentration of [3H]‐clonidine binding higher than 300 fmoles/mg protein. With few exceptions, [3H]‐clonidine binding was very low and in the telencephalon it was undetectable.
Heme precursor 5‐aminolevulinic acid alters brain tryptophan and serotonin levels without changing pineal serotonin and melatonin concentrations
Authors: Daya S. , Nonaka K. O. , Buzzell G. R. , Reiter R. J. 
Published: January 2005

AbstractThe daytime administration of the heme precursor 5‐aminolevulinate (5‐ALA) has been shown to reduce brain tryptophan and serotonin levels owing to saturation of liver tryptophan pyrrolase. Saturation of this enzyme with heme results in enhanced activity, leading to increased catabolism of tryptophan and thus making less tryptophan available to the brain. Tryptophan is also the precursor of melatonin, a primary secretory product of the pineal gland. Reduced melatonin levels, which could be a consequence of altered tryptophan metabolism, have been associated with depressive disorders in humans. In view of this, in the present study we examined the effects of 5‐ALA administration on forebrain tryptophan and serotonin levels as well as pineal serotonin, melatonin, and the pineal melatonin‐forming enzymes N‐acetyltransferase (NAT) and hydroxyindole‐O‐methyltransferase (HIOMT). 5‐ALA induced a reduction in forebrain tryptophan and serotonin levels during the light phase and caused the opposite effect in the dark phase. Allopurinol, an inhibitor of hepatic tryptophan pyrrolase activity, prevented the reduction in the indole levels induced by 5‐ALA. Although 5‐ALA induced these changes in the forebrain, it did not alter either daytime or nighttime pineal NAT, HIMOT, serotonin, or melatonin levels. It appears that high serotonin levels and melatonin production in the pineal are conserved even in the face of low circulating tryptophan levels, changes which alter brain tryptophan and serotonin concentrations.
Increase of transferrin receptors and iron uptake in regenerating motor neurons
Authors: Graeber M. B. , Raivich G. , Kreutzberg G. W. 
Published: January 2005

AbstractAfter injury, motor neurons exhibit a number of metabolic and protein changes that are assumed to be part of an inherent neuronal regeneration program, which, when activated, eventually leads to functional restitution. The mechanisms underlying this regeneration are unclear, but it may be expected that factors supporting neuronal growth or survival play an important role in the restoration of neuronal integrity. A number of neuronal growth‐associated proteins have been identified, but their functional roles remain unclear. This paper shows that axotomy results in a strong increase in transferrin receptors (TfRs) in regenerating motor neurons and that this phenomenon is functionally associated with an elevated uptake of exogenous iron. The association of TfR expression in regenerating motor neurons with direct uptake of iron into the brain provides evidence that iron uptake into neural tissue may be related to neuronal metabolic activation. We suggest that the enhanced capacity of regenerating motor neurons to bind transferrin and to take up iron plays an important role in neuronal repair.
Stimulation of rat B‐lymphocyte proliferation by corticotropin‐releasing factor
Authors: McGillis J. P. , Park A. , Rubin‐Fletter P. , Turck C. , Dallman M. F. , Payan D. G. 
Published: January 2005

AbstractThe mitogenic effect of corticotropin‐releasing factor (CRF) on rat lymphocytes was investigated. When rat splenocytes were cultured for 48 hr with CFR, a dose‐dependent increase in incorporation of 3H‐thymidine (3H‐Tdr) was observed, with a maximal response at 10 nM CRF. Comparison of the proliferative effect of CRF on enriched populations of B lymphocytes, T lymphocytes, or macrophages revealed that only B lymphocytes responded following treatment with CRF. When lymphocytes derived from different lymphoid tissues were compared, CRF had a greater proliferative effect on lymphocytes derived from gut‐associated lymphoid tissue (mesenteric lymph nodes and Peyer's patches) than on lymphocytes from spleen or inguinal lymph nodes; CRF had no effect on thymocytes. Synthetic fragments of CRF were used to determine which portions of the peptide are recognized by lymphocytes. The C‐terminal fragments α‐helical CRF9–41 and CRF21–41 were as potent as native CRF in stimulating B‐lymphocyte proliferation, whereas CRF1–20 did not stimulate proliferation. The activity of these peptides suggests that CRF stimulates lymphocyte proliferation by cellular recognition of structural determinants in the C‐terminal one‐half of the peptide.
Epidermal growth factor inhibits the expression of myelin basic protein in oligodendrocytes
Authors: Sheng H. Z. , Turnley A. , Murphy M. , Bernard C. C. A. , Bartlett P. F. 
Published: January 2005

AbstractThe major function of the oligodendrocyte is to myelinate axons in the central nervous system (CNS). Two of the components of myelin, galactocerebroside (galc) and myelin basic protein (MBP), have been used as markers of oligodendrocyte maturation in the developing CNS, and it has been found that galc+ cells arise initially, which then mature into MBP+ oligodendrocytes several days later. We have been interested in the control of expression of MBP and have followed its appearance in cultures of brain cells isolated from 4 day‐old mice. In low serum (0.5% foetal bovine serum), approximately 330 MBP+ cells arise per 2 × 105 brain cells after 3 days incubation. We have examined the ability of several growth factors to influence the expression of MBP in these cultures, including epidermal growth factor (EGF), platelet‐derived growth factor (PDGF), and the fibroblast growth factors (acidic and basic FGF). EGF was found to suppress strongly the developmental expression of MBP in these cultures, but the suppression was reversible, since the number of MBP+ cells approached control numbers 3 days after removal of EGF from the cultures. It was also found that MBP could be down‐regulated in mature MBP+ oligodendrocytes. The action of EGF in these cultures could be mimicked by transforming growth factor‐α (TGFα). The effects of EGF appear to be associated primarily with MBP production in oligodendrocytes since expression of galc is unaffected by EGF.
Axonal transport of a clathrin uncoating atpase (HSC70): A role for hsc70 in the modulation of coated vesicle assembly in vivo
Authors: de Waegh S. , Brady S. T. 
Published: January 2005

AbstractClathrin plays an important role in many cellular processes, including endocytosis, secretion, and sorting of membranous organelles. Both the neuronal cell body and presynaptic terminals contain numerous coated vesicles, but few are detectable in the axonal regions that connect these two regions of the neuron. Clathrin heavy chains, light chains, and assembly proteins have all been shown to be axonally transported as part of slow component b (SCb). However, the paucity of coated vesicles present in the axon indicates the existence of a mechanism regulating clathrin coated assembly in vivo. A clathrin uncoating ATP‐ase has been described that binds in stoichiometric amounts to clathrin and dissociates clathrin coats from vesicles in the presence of ATP in vitro. This clathrin uncoating ATPase is a major cytosolic protein of Mr 70 kD in bovine brain, forming 1% of soluble brain protein, and appears to be homologous with a constitutively expressed 70 kd heat shock protein (HSC70). We report here that a major 70 kD protein present in the SCb rate component of axonal transport is identical with HSC70 by both biochemical and immunochemical criteria. The cotransport of HSC70 with clathrin in SCb of axonal transport is consistent with a role for HSC70 in vivo in the regulation of clathrin function during axonal transport.