bluuebunny/crossref_metadata_2025_split huggingface dataset:
Astrocytic gap junction removal, connexin43 redistribution, and epitope masking at excitatory amino acid lesion sites in rat brain
Authors: Ochalski P. A. Y. , Sawchuk M. A. , Hertzberg E. L. , Nagy J. I. 
Published: May 2005

AbstractWe previously reported that kainic acid (KA) lesion sites in rat brain exhibit an absence of astrocytic gap junctions at 1 week post‐lesion. Loss of immunocytochemical reactivity with a sequence‐specific antibody against the astrocytic gap junctional protein connexin43 (Cx43) suggested epitope masking since persistence of Cx43 was observed on Western blots. Here we determined the fate of Cx43 at various times after thalamic KA and straital NMDA lesions. In normal tissue and at 6 hr post‐KA lesion, Cx43 immunoreactivity predominated at typical astrocytic gap junctions. Immunolabelled junctions were still seen at 3 days, with epitope masking already present, and were virtually absent by 6 days post‐lesion. Gap junction remodeling was indicated by the appearance of intercellular immunostained annular profiles and uncharacteristically extensive gap junctions between symmetrically immunolabelled membranes and between labelled astrocytic and unlabelled oligodendrocytic membranes. Labelled multivesicular clusters emerged at 2 days, were numerous at 3 days and constituted the sole Cx43 sequestration site by post‐lesion day 6. Ultrastructural disruption and gap junction disassembly progressed more slowly in NDMA‐injected tissue where immunoreactivity persisted, albeit at markedly decreasing levels until the final survival time examined (16 days). Intense Cx43 immunolabelling was seen in filopodia of putative reactive astrocytes at the lesion periphery at 6–8 days and was associated at 16 days with an increased number of gap junctions primarily between fine astrocytic processes. These results demonstrate that massive neuronal loss alone or in conjunction with direct actions of excitotoxins on astrocytes precipitates an astrocytic reaction accompanied initially by removal of their gap junctions followed by redistribution of Cx43, and suggest that the astrocytic syncytium may undergo reorganization in a manner leading to isolation of the lesion site. © 1995 Wiley‐Liss, Inc.
Molecular cloning of IL‐2Rα, IL‐2Rβ, and IL‐2Rγ cDNAs from a human oligodendroglioma cell line: Presence of IL‐2R mRNAs in the human central nervous system
Authors: Otero Glen C. , Merrill Jean E. 
Published: May 2005

AbstractIn the present study, we analyzed human adult brain, fetal spinal cord, and an interleukin‐2 (IL‐2)‐responsive human oligodendroglioma subclone, TC620.6A2, for the presence of mRNAs for the α, β, and γ chains of the interleukin‐2 receptor (IL‐2Rα, IL‐2Rβ, and IL‐2Rγ). IL‐2Rβ mRNA, but notIL‐2Rα or IL‐2Rγ was detectable by Northern blot analysis in adult human brain tissues. Northern blot analysis of TC620.6A2 and human fetal tissues revealed mRNAs of 1.5 kb and 1.3 kb that hybridized to the IL‐2Rα cDNA at low to medium stringency. Reverse transcriptase‐polymerase chain reaction (RT‐PCR) experiments were done on the TC620.6A2 cell line utilizing primers to IL‐2Rα, IL‐2Rβ, and IL‐2Rγ. Southern blot analysis of the TC620.6A2 RT‐PCR reactions detected products identical in size to the peripheral blood lymphocyte (PBL) positive controls at high stringency. Several of the TC620.6A2 IL‐2Rα, IL‐2Rβ, and IL‐2Rγ cDNAs were cloned and sequenced. The sequences were found to be identical to the known IL‐2R sequences. To our knowledge, these experiments are the first to demonstrate the presence of authentic IL‐2R mRNAs in a human oligodendrocyte‐like cell line. Demonstration of mRNA for IL‐2Rβ in human adult brain, IL‐2Rα in fetal brain, and IL‐2Rα, IL‐2Rβ, and IL‐2Rγ in a malignant neural cell line suggests the possibility of a role for IL‐2/IL‐2R interactions in development and disease. © 1995 Wiley‐Liss, Inc.
Three different thyroid hormone receptor isoforms are detected in a pure culture of ovine oligodendrocytes
Authors: Fierro‐Renoy Juan Francisco , Szuchet Sara , Falcone Maria , Macchia Enrico , Degroot Leslie 
Published: May 2005

AbstractThyroid hormones are important for the normal development of the central nervous system. In humans, the period around the end of the intrauterine life and the first few months of neonatal life is critically dependent on the presence of normal amounts of thyroid hormone. There are significant events occurring during this time; mydelination is one. Myelin is synthesized by oligodendrocytes. A panel of site‐ specific polyclonal antibodies against α‐1 thyroid hormone receptor (TR), α‐2 variant TR, and β‐1 TR isoforms has been employed to investigate the presence of TR isoforms in a pure culture of ovine oligodendrocytes by the avidin‐biotin peroxidase immunocytochemical method. Strong nuclear staining was obtained with all the anti‐TR antibodies; no reaction products were detected in the cytoplasm or cellular processes. By contrast, an anti myelin basic protein antibody gave strong cytoplasmic and process staining; no nuclear staining was seen. These latter results served to 1) confirm that the cells under study are oligodendrocytes; and 2) prove that the nuclear staining with anti‐TR antibodies is specific. Preimmune sera were totally negative. Scatchard analysis of [125I] T3 binding by isolated oligodendrocyte nuclei demonstrated the existence of high‐affinity low‐capacity T3 binding sites with a Ka of ≈ 6 × 10−9 M and a maximal binding capacity of ≈ 20 fmol/100 μg of DNA. Our results demonstrate that differentiated oligodendrocytes express α‐1 and α‐2 variant and β‐1 isoforms of TR at the protein level and support the notion of a direct impact of thyroid hormones on oligodendrocytes in their regulation of myelin synthesis. © 1995 Wiley‐Liss, Inc.
Regulation of neurofibromin expression in rat sciatic nerve and cultured Schwann cells
Authors: Wrabetz Lawrence , Feltri Maria Laura , Kim Haesun , Daston Maryellen , Kamholz John , Scherer Steven S. , Ratner Nancy 
Published: May 2005

AbstractLoss of function mutations at the NF1 locus may act intrinsically in Schwann cells to cause the formation of benign Schwann cell tumors (neurofibromas) in patients with type 1 neurofibromatosis. To identify contexts in Schwann cells in which such mutations may play an important role, we measured the levels of NF1 mRNA and neurofibromin in rat sciatic nerve during development, after axotomy, and in cultured rat Schwann cells. NF1 mRNA was present in developing sciatic nerve throughout the period of active Schwann cell proliferation and myelination. After nerve transection, no alteration in NF1 message level was detected, but neurofibromin levels increased, as assessed by immunohistochemistry and Western blotting, suggesting that, in vivo, neurofibromin expression in Schwann cells is post‐transcriptionally induced during Wallerian degeneration. Cultured rat Schwann cells constitutively expressed NF1 mRNA and neurofibromin. Schwann cell proliferation induced by exposure to serum and forskolin was not associated with changes in NF1 mRNA or neurofibromin expression, whereas Schwann cell proliferation induced by extracts of embryonic brain membranes was associated with increased NF1 message and neurofibromin expression. Thus, Schwann cells, both in vivo and in vitro, express NF1 mRNA constitutively; the expression of NF1 mRNA and neurofibromin is modulated by only some mitogenic stimuli in Schwann cells. © 1995 Wiley‐Liss, Inc.
Dehydration‐induced proliferation of identified pituicytes in fully adult rats
Authors: Murugaiyan P. , Salm A. K. 
Published: May 2005

AbstractThe mitotic activity astrocytes in the adult central nervous system (CNS) is of interest due to their roles in gliosis and tumorigenesis, and their potential in aiding recovery of function following injury or disease. The posterior pituitary offers a potentially powerful model to study proliferation in vivo, since its resident astrocytes, called pituicytes, have been reported to divide concurrently with hormone release from the neurosecretory terminals there. Our aim in this study was to confirm and characterize this proliferative response during dehydration and rehydration in fully adult animals, using contemporary techniques. Adult male rats were given 2% saline in substitution for water for 0–9 days. Proliferation of pituicytes was quantified in tissue sections triple‐labeled with the proliferation marker, 5‐bromodeoxyuridine (BrdU), the astrocyte marker glial fibrillary acidic protein (GFAP), and the DNA marker 4,6, diamidino‐2‐phenylindole, HC1 (DAPI). A robust proliferative response began within three days of dehydration and continued at a constant rate thereafter. In animals allowed to rehydrate, this response continued. After 9 days of dehydration, approximately 35% of pituicytes had participated in mitosis. While cell density remained constant across conditions, a reversible increase in posterior pituitary area was seen, suggesting that some cell death also occurs simultaneously. A significant proportion of non‐pituicytes also underwent similar changes. These results indicate that pituicytes in the adult posterior pituitary retain characteristics necessary for reentering the cell cycle in response to local factors present during neurosecretory activity. We hypothesize that this proliferative response is directly related to the morphological changes previously reported for these cells under activating conditions. © 1995 Wiley‐Liss, Inc.
Changes in ion channel expression during in vitro differentiation of trout oligodendrocyte precursor cells
Authors: Glassmeier G. , Jeserich G. 
Published: May 2005

AbstractVoltage‐gated ionic currents were studied in cultured trout oligodendrocyte precursor cells derived from larval trout brain with the whole‐cell mode of the patch‐clamp technique. These bipolar cells which carry the ganglioside epitope A2B5 on their surface differentiated in vitro into immature multipolar oligodendrocytes expressing the myelin glycoprotein IP2, which signifies the initial step of oligodendroglial development in fish CNS. Depolarization above ‐40 mV activated a fast transient sodium inward current that was eliminated by substituting Na+ for choline and blocked in the presence of 1 μM TTX. The kinetics and the voltage‐dependence of inactivation (half‐maximal inactivation at ‐68 mV) resembled those of sodium currents described in mammalian oligodendrocyte precursor cells and CNS neurons. The expression of Na+ channels was developmentally regulated, since high amplitudes were measured only in A2B5+ cells with a characteristic bipolar morphology of glial progenitors. Depolarizing voltage steps, additionally elicited outward potassium currents that were sensitive to external 4‐AP. In a subpopulation of cells this outward current consisted of a sustained and a transient component. The amplitude of both components were dependent on the prepulse potential. © 1995 Wiley‐Liss, Inc.
O‐2A progenitors of the mouse optic nerve exhibit a developmental pattern of antigen expression different from the rat
Authors: Fanarraga Monica L. , Sommer Ilse , Griffiths Ian R. 
Published: May 2005

AbstractIn a previous study we demonstrated that differentiation and development of mouse oligodendrocytes is similar to that of the rat after the stage at which O4 is acquired. In this present study we compare directly the early differentiation of oligodendrocytes in the mouse and rat post natal optic nerve and show that the two species differ at the O‐2A progenitor and proligodendroblast stages. Mouse progenitors show a variety of morphologies compared to the typical bipolar appearance in the rat. Many murine cells fail to immunolabel with A2B5, GD3, O4, and RmAb, classical markers for rat progenitors, proligodendroblasts, and immature oligodendrocytes. We find that these “unlabeled” cells stain for GAP‐43 and that expression of GAP‐43 overlaps A2B5 and GD3 in the earlier progenitors and 04, RmAb, and 01 in the later proligodendroblasts and immature oligodendrocytes.Our data suggest that in the development of the mouse O‐2A progenitor cells there is a developmental discontinuity between the earlier markers such as A2B5 and GD3 and the later marker O4, which can be filled by GAP‐43. We therefore consider that GAP‐43 could be used in the mouse, in addition to the classical O‐2A markers, for the study of the early oligodendrocyte lineage as it labels an otherwise undetectable O‐2A population. © 1995 Wiley‐Liss, Inc.
Glial reactivity in the retina of adult rats
Authors: Huxlin Krystel R. , Dreher Zofia , Schulz Mark , Dreher Bogdan 
Published: May 2005

AbstractThe present study aimed to characterize the reaction of mammalian (rat) retinal macroglia (Müller cells and astrocytes) to disturbances of their environment in the form of intraorbital section of the optic nerve, intraocular insertion of a thin glass capillary (without damage to the retina) or a combination of both. Glial reactivity was assessed through the use of a battery of antibodies which recognise four different proteins—glial fibrillary protein (GFAP) and three other proteins designated repectively MA1, 4D6 and 4H11. Retinal astrocytes did not exhibit any changes in normally expressed GFAP or MA1. By contrast, the expression of GFAP and MA1 in Müller cells increased 14 days following section of the optic nerve and/or intravitreal insertions of a glass capillary. Three days postoperatively, the expression of GFAP, but not MA1, had already increased significantly in Müller cells. 4D6 and 4H11 proteins were not expressed in astrocytes. In Müller cells, the levels of these proteins increased significantly following combined optic nerve section and intraocular insertion of a glass capillary. Thus, a mechanical disturbance of the intraocular environment constitutes a more effective stimulus in increasing the expression of some Müllerian proteins than damage to the axons of retinal ganglion cells. Such changes have important implications for various ocular treatments that involve intraocular administration of drugs, as well as for the survival/regeneration potential of retinal ganglion cells undergoing Wallerian degeneration. © 1995 Wiley‐Liss, Inc.
The role of intracellular calcium and protein kinase C in endothelin‐stimulated proliferation of rat type I astrocytes
Authors: Stanimirovic Danica B. , Ball Rita , Mealing Geoff , Morley Paul , Durkin Jon P. 
Published: May 2005

AbstractThe increased expression of immunoreactive endothelin‐1 (ET‐1) in reactive astrocytes and its mitogenic effects on astrocytes and glioma cell lines, have implicated endothelins in the development of reactive gliosis. In this study, an increase in DNA synthesis in rat type I astrocytes was observed after cultures were transiently exposed to ET‐1 for 15 min, suggesting that early signal transduction events are essential and sufficient for the propagation of the ET‐1‐induced mitogenic signal. Prompt increases in inositol triphosphate (IP3) formation and [Ca2+]i were observed upon the addition of ET‐1 to these cells. The ET‐1‐evoked increase in [Ca2+]i consisted of an initial peak which was preserved in Ca2+‐free medium, and a sustained phase which was abolished in Ca2+‐free medium and partly attenuated by nifedipine. ET‐1 also increased the activity of membrane‐associated protein kinase C (PKC) and induced the in vivo phosphorylation of the 85 kD MARCKS protein, an endogenous PKC‐specific substrate. The ET‐1‐evoked increases in DNA synthesis, IP3, [Ca2+]i, membrane PKC, and 85 kD MARCKS protein phosphorylation in rat cortical astrocytes were prevented by either the selective endothelin ETA receptor antagonist, BQ‐123, or the phospholipase C (PLC)‐specific inhibitor, U‐73122. However, the inhibition of PKC activity did not affect ET‐1‐induced DNA synthesis in rat cortical astrocytes. These results suggest that ET‐1‐induced IP3 and/or [CA2+]i responses, but not the activation of PKC, are essential for the growth‐factor like actions of ET‐1 in rat cortical astrocytes. © 1995 Wiley‐Liss, Inc.
Amyloid precursor protein (APP) expression in multiple sclerosis lesions
Authors: Gehrmann Jochen , Banati Richard B. , Cuzner M. Louise , Kreutzberg Georg W. , Newcombe Jia 
Published: May 2005

AbstractThe amyloid precursor protein (APP) is rapidly induced in reactive glial cells in response to several pathological stimuli including inflammation. In the present study, observations previously made in animal models of autoimmune central nervous system inflammation have been extended to the analysis of multiple sclerosis (MS) lesions. A total of thirty fresh‐frozen tissue blocks from six histopathologically normal control and six MS cases have been examined immunocytochemically with monoclonal antibodies directed against either C‐ or N‐terminal epitopes of APP. Histopathological evaluation of disease progression was based on hematoxylin‐eosin and oil red O staining and immunocytochemistry for T cells, macrophages/microglia, astrocytes, and oligodendrocytes. In control cases, APP immunoreactivity was generally low and confined to blood vessel walls, oligodendrocytes in white, and neurons in grey matter. In actively demyelinating plaques, however, levels of APP immunoreactivity were high, localised on T lymphocytes, foamy macrophages, activated microglia, and reactive astrocytes including astrocytic processes. In more chronic lesions, levels of APP immunoreactivity were generally lower than in acute lesions, mainly found on reactive astrocytes, their processes and a few macrophages/microglia depending on the stage of plaque development. In addition, a few 14E‐positive oligodendrocytes and, moreover, numerous axons exhibited APP immunoreactivity, which was particularly pronounced with anti‐C‐terminal antibodies. These results demonstrate that APP is induced on reactive glial cells but also on T lymphocytes during demyelination. The extent of APP expression appears to be correlated to histopathological lesion development and thus suggests that APP detection serves as a sensitive marker for disease progression in MS. © 1995 Wiley‐Liss, Inc.
Developmental pattern of GFAP and vimentin gene expression in rat brain and in radial glial cultures
Authors: Sancho‐Tello María , Vallés Soraya , Montoliu Carmina , Renau‐Piqueras Jaime , Guerri Consuelo 
Published: May 2005

AbstractIn the present study we analyze the events which occur during the early stages of astrogliogenesis by examining the pattern of both GFAP and vimentin gene expression and their corresponding immunoreactive proteins during rat brain development. This study was carried out “in vivo” (whole brain) and “in vitro” (primary culture of radial glia) using immunofluorescence, immunoblotting, and Northern blot analysis. Our results demonstrate that although GFAP immunostaining appeared late in gestation and at day 5 in radial glia cultures, GFAP mRNA expression was first detected, at very low levels, on fetal (F) day 15 and increased to F21. During postnatal development a striking increase in GFAP and its encoding messenger occurs. In contrast, the levels of vimentin and its mRNA expression were very high during the fetal stage (F15 to F21). Thereafter vimentin expression declined during postnatal (P) development until P21 and then remained constant at adult levels. In contrast, an increase in vimentin expression was observed in glial cells throughout the entire culture period. The biological significance of the developmental patterns of GFAP and vimentin expression in astroglial cells during brain development is discussed. © 1995 Wiley‐Liss, Inc.
Evidence for cyclooxygenase activation by nitric oxide in astrocytes
Authors: Molina‐Holgado Francisco , Lledó Alberto , Guaza Carmen 
Published: May 2005

AbstractWe have evaluated the role of nitric oxide (NO) on the cyclooxygenase pathway in mouse glial cells. Exposure of primary cultures of neonatal mouse cortical astrocytes to bacterial lipopolysaccharide (LPS; 1 μg/ml, 18 h) caused an increase in the release of both nitrite (NO−2) and prostaglandin E2 (PGE22), products of NO synthase (NOS) and cyclooxygenase, respectively. Production of both, NO−2 and PGE2 by astrocytes, was inhibited by the exposure of the NOS inhibitor Nw‐nitro‐L‐arginine methyl ester (L‐NAME: 1, 10, and 100 μM) in a dose related manner. Besides, other NOS inhibitors such as Nitro L‐arginine (NNA: 10−3 M) prevented the increase in PGE2 release from LPS‐stimulated astrocytes. Sodium nitroprusside (SNP; 100–200 μM) used as a NO donor caused a dose‐related enhancement in the accumulation of PGE2 induced by LPS and the presence of hemoglobin blocked the SNP effects. The exposure to SNP counteracted the decrease of PGE2 production in LPS‐treated astrocytes in which NO synthesis was blocked by L‐NAME. In addition, SNP also enhanced the synthesis of PGE2 following exogenous arachidonic acid astrocytes exposure. Interestingly, this effect was blocked by indomethacin. Treatment of astrocytes cultures with dexamethasone (0.1, 1 μM) blocked dose‐relatedly the LPS‐induced release of both NO−2 and PGE2. As expected, the presence of indomethacin (1, 10, and 20 μM) prevented in a dose related fashion, PGE2 production by astrocytes following exposure to LPS. These results strongly indicate that in astroglial cells, NO is able to activate the cyclooxygenase pathway. © 1995 Wiley‐Liss, Inc.
Iron‐mediated bioactivation of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) in glial cultures
Authors: Di Monte Donato A. , Schipper Hyman M. , Hetts Steven , Langston J. William 
Published: May 2005

AbstractPrimary cultures of mouse astrocytes were treated with both the monoamine oxidase (MAO) A inhibitor, clorgyline, and the MA0 B inhibitor, deprenyl, prior to the addition of the neurotoxicant 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP). Production of the 1‐methyl‐4‐phenylpyridinium (MPP+) toxic metabolite was reduced to 11%, but not completely blocked, by MA0 inhibition. This residual MPP+ production appeared to be iron‐dependent since it was decreased (30 to 50%) by iron chelators, i.e., deferoxamine or phenanthroline, and was enhanced (by approximately 40%) in the presence of ADP‐Fe3+. ADP‐Fe3+ also enhanced the oxidation of MPTP to MPP+ which occurs in medium without cells. MPP+ formation, however, was significantly slower in plain culture medium than in astrocyte incubations pretreated with MAO inhibitors, suggesting the involvement of cells in these iron‐mediated reactions. The data indicate that oxidation via MA0 is the primary but not the only pathway of MPTP bioactivation and that transition metals may contribute to the generation of the toxic MPP+ metabolite in biological systems. © 1995 Wiley‐Liss, Inc.
Histopathology, classification, and grading of gliomas
Authors: Kleihues Paul , Soylemezoglu Figen , Schäuble Barbara , Scheithauer Bernd W. , Burger Peter C. 
Published: May 2005

AbstractNeoplastic transformation occurs in all glial cell types of the human nervous system, producing a wide variety of clinico‐pathological entities and morphological variants. Astrocytomas are most common and span an unusually wide spectrum, ranging from the slowly growing juvenile pilocytic astrocytoma to the highly malignant glioblastoma multiforme. Diffusely infiltrating astrocytomas of the cerebral hemispheres show an inherent tendency for progression towards a more malignant phenotype. This change is morphologically categorized in histologic grading schemes (e.g., WHO Grade II to IV) and is associated with the sequential acquisition of genetic alteration, including mutation in the p53 and homozygous deletion of the p16 tumor suppressor genes. Loss of heterozygosity on chromosomes 10 and 19q as well as amplification of the EGF receptor are largely restricted to malignant gliomas and thus considered late events in astrocytoma progression. Gliomas often show phenotypic expresson of different glial cell lineages (e.g., oligoastrocytoma). Recent studies sugeest that the occurrence of mixed glomas is not indicative of a polyclonal orgin but rather reflects altered gene exprssion leading to a charge in the balance of growth factors influencing glioma defferentiation. © 1995 Wiley‐Liss, Inc.