bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies of glial lineage and proliferation in vitro using an early marker for committed oligodendrocytes
Authors: Knapp P. E. 
Published: January 2005

AbstractThe potential of immature glial cells to differentiate into astrocytes (ASs) or oligodendrocytes (OLs) has been examined using a monoclonal antibody (007) that is specific for OLs in vivo. Cells were dissociated from 2‐day postnatal mouse cortex and labeled with the 007 antibody 2 hr after plating. The cells which were labeled during this single, brief exposure to the antibody retained the antibody on their surfaces over the course of the experiments. Cells were double stained at various timepoints for residual 007 antibody and either galactocerebroside (GC) or glial fibrillary acidic protein (GFAP). Shortly after plating, most 007 + cells were GC − and none expressed GFAP. These cells were round, although some had begun to extend very short processes. After 96 hr, >95% of cells with residual 007 on their surfaces also expressed GC. By this time, all the 007 + cells had several processes of varying lengths extending from their cell bodies. Cells expressing both 007 and GFAP were never seen. The 007 + /GC + OLs were not induced to differentiate from 007 + bipotential progenitors since they were grown in fetal calf serum. These results show that under our culture conditions the 007 antibody is OL specific. Immunostaining for bromodeoxyuridine, a marker for dividing cells, revealed that some 007 + cells were proliferating. The majority of these proliferating cells had already extended three or more processes. We therefore conclude that immature, process‐bearing cells can be committed to the OL lineage at times before they express detectable amounts of GC. Since these young 007 + OLs are actively proliferating, committed cells can serve as an important source of new OLs.
Regulation of neuronal differentiation in neuron‐enriched primary cultures from embryonic rat cerebra by platelet activating factor and the structurally related glycerol ether lipid, dodecylglycerol
Authors: Ved H. S. , Gustow E. , Pieringer R. A. 
Published: January 2005

AbstractPrimary cultures enriched in neurons dissociated from embryonic rat cerebra were used to demonstrate that platelet activating factor and the structurally related ether glycerolipid, dodecylglycerol, are readily taken up in small amounts by neurons and that they stimulate the differentiation of neurons. The stimulation of neuronal differentiation was observed as a precocious development of axon‐like extensions which correlated with a concentration — dependent increase in neuronal‐specific enzyme activities. This stimulation of morphological and neurochemical factors by either platelet activating factor or dodecylglycerol was almost completely abolished by triazolam, a known inhibitor of platelet activating factor function. Neither platelet activating factor nor dodecylglycerol at the concentrations used to achieve stimulation of neuronal differentiation compromised the plasma membrane, as indicated by the lack of leakage of cytoplasmic lactic acid dehydrogenase.
Conditioned media derived from glial cell lines promote survival and differentiation of dopaminergic neurons in vitro: Role of mesencephalic glia
Authors: Engele J. , Schubert D. , Bohn M. C. 
Published: January 2005

AbstractNeuronal differentiation is influenced by extracellular factors; however, only a few such factors have been identified for central neurons. To address this issue, we have screened media conditioned (CM) by several glial cell lines for neurotrophic effects on dopaminergic neurons in dissociated cell cultures of the E14.5 rat mesencephalon grown in serum‐free conditions. To establish culture conditions under which dopaminergic cell survival depends on the exogenous support from neurotrophic factors, cell suspensions were seeded at varying densities and the number of tyrosine hydroxylase‐immunoreactive (TH‐IR) neurons was determined. This number was maximal at plating densities greater than 175,000 cells/cm2 and was 10‐fold lower at the plating density of 80,000 cells/cm2. Cell density had only a minimal effect on [3H]dopamine uptake per TH‐IR neuron. Treatment of cultures plated at 80,000 cells/cm2 with CM derived from the glial cell line, B49, the neural retina glial cell line, R33, and the Schwannoma cell line JS1, increased the number of surviving TH‐IR neurons 160–330%. These effects were dose dependent and heat sensitive. All CM stimulated neurite elongation of TH‐IR neurons, while only the B49‐CM increased [3H]dopamine uptake. The neurotrophic effects of these media were not confined to dopaminergic neurons but increased overall neuronal density in culture by 50–100%. Moreover, all three CM were mitogenic for mesencephalic glia as demonstrated by glial fibrillary acidic protein (GFAP)‐immunocytochemistry in combination with [3H]thymidine‐autoradiography. By contrast, medium conditioned by the pheochromocytoma cell line, PC 12, did not increase the number of astrocytes or promote the survival of dopaminergic neurons. Inhibition of glial proliferation reduced the neurotrophic effects of the B49‐, R33‐, and JS1‐CM by 40–80%.These observations suggest that the glial cell lines B49, R33, and JS1 secrete factors that promote the survival of dopaminergic neurons and induce proliferation of glial precursors. The partial decrease of the survival‐promoting effects of these CM on dopaminergic neurons in glial‐free mesencephalic cultures further suggests that the observed neurotrophic effects result from the combined action of cell line‐derived substances directly on neurons and indirectly via effects on mesencephalic astrocytes or astrocyte precursors.
Internalization of the inhibitor of the N‐acetylgalactosaminyltransferase by chicken embryonic retina cells: Reversibility of the inhibitor effects
Authors: Quiroga S. , Panzetta P. , Caputto R. 
Published: January 2005

AbstractRetina cells from 6‐day‐old chicken embryos were cultured in the resence of an 125I‐labeled protein inhibitor of the UDP‐N‐acetylgalactosamine:GM3,N‐acetylactosaminyltransferase. The cells were labeled and did not lose the incorporated radioactivity when treated with 0.125% trypsin or 1 M NaCl at 37°C for 1 hr, indicating that the iodinated inhibitor was inside the cells. Immunostaining procedures using an anti‐inhibitor was antibody were applied to the cells cultured in the presence of the inhibitor after permeabilization of the cells. The inhibitor was found inside the round cells virtually devoid of neurites, but not in flat glial‐like cell or in process‐bearing neural cells. Also found was an apparent self‐recovery effect of the cells for both the anti‐neuritogenic effect and the modification of the pattern of labeled gangliosides produced by the inhibitor when the agent was withdrawn from the culture medium after the initial period of 20 hr. This recovery was clearly observed 72 hr after the removal of the inhibitor.
Host response during successful engraftment of fetal xenogenic astrocytes: Predominance of microglia and macrophages
Authors: Booss J. , Baumann N. , Collins P. , Jacque C. 
Published: January 2005

AbstractGrafting of fetal rabbit brain fragments into the brains of newborn mice results in the successful establishment and migration of xenogenic astrocytes in the majority of recipients. This can be demonstrated by the use of Tp‐GFAP1 monoclonal antibody which binds with rabbit, but not with murine glial fibrillary acidic protein. In the first phase, donor astrocytes are found in more than 80% of recipients 3 and 4 weeks after grafting. In the second phase, there is a decline and disappearance of donor astrocytes by the tenth week. We have recently demonstrated that the decline and disappearance of donor astrocytes was coincident with infiltration of T cells into the brain, compatible with T‐cell‐mediated graft rejection. In the present studies, we wished to characterize the types of host cells responding during the period of graft success, in the first 4 weeks after transplantation. It was found that responses by microglia, macrophages, and astrocytes occurred promptly and were sustained throughout this period. Host responses occurred at the graft site and at sites of migration. Examination of sham transplanted control mice revealed responses by the same types of cells. No expression of donor Ia antigen was observed, and the expression of Ia antigen by the host was variable and of low magnitude. T cells were rarely present in transplanted brains during this period.Taken together with previous findings, the present studies demonstrate a clear difference in the host response in the brain at the time when xenogenic astrocytes migrate and survive compared to the period when they disappear. The biphasic nature of the model should facilitate studies to examine mechanisms of brain graft rejection as well as the design of protocols to prevent rejection.
Isoprenoid modification permits 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase to bind to membranes
Authors: Braun P. E. , De Angelis D. , Shtybel W. W. , Bernier L. 
Published: January 2005

AbstractThe myelination‐related enzyme 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNP), a relatively abundant protein in the CNS possesses the C‐terminal isoprenylation consensus domain found in a small family that includes the ras oncoproteins and their relatives, some G‐proteins, and nuclear lamins. We found that CNP, like these other proteins, is modified post‐translationally by an isoprenoid derived from mevalonic acid. It appears that only the smaller of the two CNP isoforms (CNP1) is isoprenylated, but similar modification of CNP2 cannot be excluded. Inhibition of isoprenoid synthesis by Lovastatin blocks the binding of newly synthesized CNP to cell membranes; binding is restored upon addition of mevalonate to the culture medium. This shows that isoprenylation is permissive for the well‐known avid association of CNP with membranes.
Effect of acetyl‐L‐carnitine on the dopaminergic system in aging brain
Authors: Sershen H. , Harsing L. G. , Banay‐Schwartz M. , Hashim A. , Ramacci M. T. , Lajtha A. 
Published: January 2005

AbstractWe studied the effect of acetyl‐L‐carnitine (ALCAR) on dopamine release and the effect of long‐term acetyl‐L‐carnitine treatment on age‐related changes in striatal dopamine receptors and brain amino acid levels.In striatal tissue that had been incubated with [3H]dopamine, acetyl‐L‐carnitine increased the release of [3H]dopamine evoked by electrical stimulation. In striatal tissue from aged mice administered acetyl‐L‐carnitine for 3 months, the release of [3H]dopamine evoked by electrical stimulation was higher than that of its aged control; the release after a second stimulation was similar in the two groups.There was a significant decline in the number of D1 striatal dopamine receptors with age. The Bmax was 51% lower in 1.5‐year‐old mice than in 4‐month‐old animals. Administration of acetyl‐L‐carnitine for 3 months diminished the reduction in the binding of [3H]SCH‐23390. [3H]Spiperonebinding to D2 receptors was not decreased with age and was not affected by acetyl‐L‐carnitine treatment.Age‐related decreases in levels of several amino acids were observed in several brain regions. Acetyl‐L‐carnitine lessened the reduction in the level of taurine only in the striatum.The findings confirm the multiple effects of acetyl‐L‐carnitine in brain, and suggest that its administration can have a positive effect on age‐related changes in the dopaminergic system.
Evidence that protein constituents of postsynaptic membrane specializations are locally synthesized: Time course of appearance of recently synthesized proteins in synaptic junctions
Authors: Steward O. , Pollack A. , Rao A. 
Published: January 2005

AbstractPrevious studies have led to the hypothesis that some protein constituents of postsynaptic membrane specializations are locally synthesized near postsynaptic sites. The present study focuses on one prediction of this hypothesis, specifically, that if some proteins of the postsynaptic membrane specialization are locally synthesized, then the delay between synthesis and assembly into synaptic junctional membrane could be short. We evaluate the time course of appearance of recently synthesized protein in synaptic junctions by pulse‐labeling hippocampal slices maintained in vitro with radiolabeled protein precursors, and then isolating subcellular fractions enriched in synaptic plasma membranes (SPM) and synaptic junctional complexes (SJC). We report that there is no evidence of a delay in the appearance of recently synthesized proteins in SPM and SJC fractions. Labeled proteins could be detected as early as 15 min after the initiation of the pulse‐labeling period, and the extent of labeling increased monotonically thereafter. The labeling could not be accounted for by contamination of synaptic membrane fractions with other membranes, because the relative specific activity of the SPM and SJC fractions was the same or higher than that of the less pure fractions from which these synaptic fractions were derived. One‐dimensional PAGE‐fluorography was used to provide an initial characterization of which proteins were labeled in SJC fractions. We found that the most prominent labeled bands were at apparent molecular weights of approximately 43–44, 55–56, and 60 kd, with more lightly labeled bands at about 38 and 116 kd. In some preparations, there was a labeled doublet at about 36–38 kd. There were also other lightly labeled bands at other molecular weights. These bands were much less heavily labeled than the bands at 43–44, 55–56, and 60 kd, however. There was little labeling in the molecular weight range of the “major psd protein” (the alpha subunit of CAM‐kinase), although there was diffuse labeling throughout the 45–52 kd region. These results are consistent with the hypothesis that some of the protein constituents of the postsynaptic junctional complex are synthesized by polyribosomes which are selectively localized beneath synaptic junctions.
Association between vascular basement membrane components and the lesions of Alzheimer's disease
Authors: Perlmutter L. S. , Barrón E. , Saperia D. , Chui H. C. 
Published: January 2005

AbstractA relationship between the microvasculature and Alzheimer senile plaques has been suggested by several lines of evidence. Besides close anatomic and biochemical relationships, both extrinsic (fibronectin) and intrinsic [heparan sulfate proteoglycan (HSPG)] components of the vascular basement membrane (VBM) have been colocalized with amyloid plaques. The present study was designed to examine the association between three intrinsic components of the VBM [HSPG, collagen type IV (CIV), and laminin] and the histopathologic lesions of Alzheimer's disease (AD).Six cases with neuropathologically confirmed AD were immunocytochemically labeled for the presence of HSPG, CIV, laminin, or tau‐2 (a marker for degenerating neurites) and examined at the light and electron microscopic levels. For light microscopic analyses, sections were counterstained with a fluorescent marker for amyloid. The present study illustrates an involvement of VBM components in the lesions associated with AD. First, we replicate our previous finding that HSPG antibodies immunolabel a subset of neurons; ultrastructural analyses indicate that at least some of these are actually extracellular neurofibrillary tangles. Second, we report that CIV and laminin immunoreaction product was not associated with neurons but did label several perivascular cells with the morphologic characteristics of microglia. Finally, we demonstrate that all three intrinsic VBM components, CIV and laminin as well as HSPG, are localized to senile plaques. Both light and electron microscopic studies indicate that the VBM components are associated with amyloid rather than degenerating neurites. These findings suggest that the VBM or its components may play a role in the AD pathogenetic cascade.
Immunolocalization of Alzheimer β‐amyloid peptide precursor to cellular membranes in baculovirus expression system
Authors: Currie J. R. , Ramakrishna N. , Burrage T. G. , Hwang M.‐C. , Potempska A. , Miller D. L. , Mehta P. D. , Kim K. S. , Wisniewski H. M. 
Published: January 2005

AbstractOne characteristic of Alzheimer's disease (Aβ disease) is the accumulation of amyloid deposits within the extracellular space of the brain and meninges. A 40 amino acid peptide called β‐peptide or A4 protein is the subunit of the amyloid fibrils found in these deposits. The sequence of β‐peptide is contained within those of a family of larger proteins called the Alzheimer β‐amyloid peptide precursor (APP). These APPs contain, in addition to a signal sequence, a hydrophobic sequence that is believed to span cell membranes. Although biochemical studies indicate that some APPs have properties of integral membrane proteins, morphological confirmation of this has not been reported. We recently described an expression system in which human APP751 cDNA was placed under the transcriptional regulation of the polyhedrin gene promoter in the baculovirus Autographica californica infecting a Spodoptera frugiperda cell line (Ramakrishna et al., Biochem Biophys Res Commun 174:983–989, 1991). As part of a larger biochemical and molecular biological study of APP, we have carried out an immunocytochemical study using antibodies directed against several epitopes within APP to reveal, at both the light and the electron microscopic levels, the cellular localization of APP in the baculovirus expression system. These studies demonstrate that APP751 is abundantly synthesized and inserted into certain of the membrane compartments of the cell. As early as 24 hr postinfection, APP751 is found associated with all membrane compartments excepting mitochondrial membranes. The patterns of immunolabeling are consistent with our biochemical findings that the protein is processed in these cells so as to release the extracellular domain and to retain a transmembrane and intracellular segment. These data provide the first morphological demonstration of the membrane location of APP751 its posttranslational processing to a secreted fragment, and its exclusion from the mitochondrial membranes. This system is especially valuable for identifying conditions under which antibodies raised against APP or appropriate synthetic peptides will react with native APP.
Structure, expression, and function of, Ng‐CAM a member of the immunoglobulin superfamily involved in neuron‐neuron and neuron‐glia adhesion
Authors: Grumet M. 
Published: January 2005

AbstractThe 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 ∼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 fibronec‐tin 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.
Glycerophosphorylcholine phosphocholine phosphodiesterase activity in cultured oligodendrocytes, astrocytes, and central nervous tissue of dysmyelinating rodent mutants
Authors: Yuan J. , McCartney D. G. , Monge M. , de Los Monteros A. Espinosa , Zalc B. , de Vellis J. , Kanfer J. N. 
Published: January 2005

AbstractThe levels of GPC phosphocholine phosphodiesterase, pNP phosphocholine phosphodiesterase, CNPase, and UDP galactose: ceramide galactosyltransferase activities were estimated with pure cultures of oligodendrocytes and astrocytes; mixed primary glial cells cultures; C‐6 cells; and CNS tissue of the dysmyelinating md rat, the jimpy mouse, and the quaking mouse. The highest activity of GPC and pNP phosphocholine phosphodiesterases as with CNPase and C gal T was found in the pure cultured oligodendrocytes. C‐6 cells had very low or undetectable activities for these two phosphodiesterases but possessed very high CNPase activity. The activity of GPC phosphocholine phosphodiesterase was significantly decreased in the CNS tissue of the md rat and the jimpy and the quaking mouse. Similar reductions were observed for the pNP phosphocholine phosphodiesterase, CNPase, and C gal T activities. The selective cellular enrichment in oligodendrocytes of the GPC phosphocholine phosphodiesterase activity and decreases of its activity in three dysmyelinating mutants in the same ratio as for CNPase and C gal T suggest that GPC phosphocholine phosphodiesterase is a myelin marker enzyme and it may reflect the quantity of myelin and oligodendrocyte present.
Interaction between oligodendroglia and immune cells: Mitogenic effect of an oligodendrocyte precursor cell line on syngeneic T lymphocytes
Authors: Yamamura T. , Sun D. , Aloisi F. , Klinkert W. E. F. , Wekerle Hartmut 
Published: January 2005

AbstractWe analyzed cellular interactions between T lymphocytes and a recently established immortal glial line, L3 that retains several properties of immature oligo‐dendrocytes (Aloisi et al., J Neurosci Res 27:16–24, 1990). L3 oligodendrocytes (L3‐OL) cannot be induced to express class II antigens, nor do they specifically present antigen to syngeneic specific T lymphocyte. However, L3‐OL strongly enhance the proliferation of freshly activated, interleukin‐2(IL‐2)‐dependent T‐line lymphocytes and concanavalin A (ConA)‐activated lymphoblasts, irrespective of their antigen specificity or surface phenotype (CD4+ or CD8+). Resting and some activated T cells were susceptible to the mitogenic effect of L3‐OL only in the presence of exogenous IL‐2, not of other cytokines. The mitogenic effect of L3‐OL did not depend on cell viability. It was observed in paraformaldehyde‐fixed L3‐OL cells and in membrane preparations, but not in culture supernatant. Neither intact L3‐OL cells nor membrane preparations had direct IL‐2 activity. The conclusion that the mitogenic effect of L3‐OL cells is exerted by membrane structures acting as a costimulatory factor(s) of IL‐2 is supported by the finding that it is largely blocked by a monoclonal anti‐IL‐2 receptor antibody. The effect is distinct from membrane‐bound IL‐1, membrane‐bound tumor necrosis factor‐α (TNF‐α), IL‐3, or IL‐6 and cannot be reconstituted by these cytokines. © 1992 Wiley‐Liss, Inc.