bluuebunny/crossref_metadata_2025_split huggingface dataset:
Developmental appearance, antigenic profile, and proliferation of glial cells of the human embryonic spinal cord: An immunocytochemical study using dissociated cultured cells
Authors: Aloisi Francesca , Giampaolo Adele , Russo Giovanni , Peschle Cesare , Levi Giulio 
Published: May 2005

AbstractWe have investigated the time of appearance of the earliest differentiating glial cell types of human spinal cord using a panel of antigenic markers to identify them in cultures from 6‐ to 9‐week‐old human embryos. Immunolabeling performed at 14 h in vitro with the O4 mAb, an early oligodendrocyte marker, showed the presence of oligodendrocytes during the 7th week of age. At 8 weeks only a few of the O4+ cells expressed galactocerebroside (GalC), a marker of more differentiated oligodendrocytes. All the O4+ and GalC+ cells were vimentin+ and some of the GalC+ cells were A2B5+, GD3+ and SSEA‐1+. During the first week in vitro many of the O4+ cells exhibiting a more immature, bi‐ or tri‐polar morphology incorporated [3H]thymidine into their nuclei. Cells expressing the astrocyte‐specific marker GFAP could be first observed at 8 weeks; almost all of these GFAP+ cells, which should correspond to radial glia on the basis of the current literature, were vimentin+, A2B5+, GD3+, and SSEA‐1+. At 2 days in vitro incorporation of [3H]thymidine could be shown in a small fraction of these cells. The finding that radial glia and oligodendrocytes expressed similar antigenic features and the additional observation that a small, but consistent fraction of the cells were simultaneously labeled by O4 and anti‐GFAP antibodies support the hypothesis that, in the human spinal cord, radial glial cells can give rise to both oligodendrocytes and astrocytes; in this respect, radial glial cells may be similar to the A2B5+, GD3+, vimentin+ bipotential glial progenitors previously identified in cultures from developing rat CNS, which also express A2B5, GD3, and vimentin.
Mechanisms of pH recovery from intracellular acid loads in the leech connective glial cell
Authors: Szatkowski Marek , Schlue Wolf‐Rüdiger 
Published: May 2005

AbstractWe used double‐barrelled, neutral carrier, pH‐sensitive microelectrodes to study the mechanisms by which the intracellular pH (pHi) is regulated in the connective glial cells if the medicinal leech. In HEPES‐buffered, nominally CO2/HCO3−‐free solutions the recovery of pHi from intracellular acidosis is Na+‐dependent and reduced by at least half in the presence of amiloride, suggesting the action of Na+:H+ exchange. The rate of pHi recovery by this mechanism can be increased by raising the extracellular buffering power or by increasing extracellular pH. The presence of CO2/HCO3− greatly increases the rate of pHi rocovery from intracellular acidosis. This CO2/HCO3−‐stimulated recovery is also dependent on external Na+, largely Cl−‐independent, inhibited by DIDS, and accompanied by membrane hyperpolarization. This is consistent with it being mediated by the electrogenic cotransport of Na+ and HCO3− into the cells. A Cl−‐dependen component to Na+‐ and HCO3−‐dependent regulation is most easily explained by the added presence of a Na+‐dependent exchange of HCO3− and Cl−.
Regulation of receptor‐mediated shape change in astroglial cells
Authors: Shain W. , Bausback D. , Fiero A. , Madelian V. , Turner J. N. 
Published: May 2005

AbstractActivation of adenylate cyclase in astroglial cells in culture results in a rapid change in cell shape that appears to occur by the active movement of cytoplasm from peripheral cell regions to the perinuclear space with processes being formed along regions that remain extended. Three series of experiments were designed to determine how shape change occurred. First, the Ca2+‐dependency of shape change was determined by reducing intracellular Ca2+ concentrations to ≤50 nM or increasing intracellular Ca2+ concentrations to ≥1 μM. Neither of these changes significantly affected the rate of receptor‐mediated shape change. Second the role that longer‐lived, acetylated microtubules play in receptor‐mediated shape change was assessed by visualizing microtubules using a polyclonal antibody to brain 6S tubulin or a monoclonal antibody to oligomers of tubulin to monitor total tubulin distribution and a monoclonal antibody to acetylated tubulin to describe the distribution of these microtubules. Three‐dimensional distribution of microtubules was observed by optical sectioning of cultures using a laser scanning confocal imaging system. The distribution of acetylated tubules in control cells was similar to that observed with the antibodies to tubulin. Following treatment with 100 nM isoproterenol to stimulate shape change, there was a dramatic redistribution of microtubules; however, the distribution of acetylated tubules was again similar to the total microtubules. Analysis of the optical sections recorded using the confocal attachment revealed that while control cells were relatively flat (cell height = 4 μm), the perinuclear region of isoproterenol‐treated cells extended much higher above the substrate (cell height = 13 μm). Third, the role of microtubule assembly and disassembly were assessed using colchicine and taxol. Results from these experiments suggest that microtubule reassembly is necessary for receptor‐mediated shape change. Control experiments indicated that colchicine or taxol treatment did not inhibit either cAMP synthesis or another cAMP‐dependent process, receptor‐mediated taurine release. Together these results indicate that receptor‐mediated shape change in astroglial cells occurs by a Ca2+‐independent mechanism that results in active movement of cytoplasm to the perinuclear region. This process is dependent on microtubule reassembly suggesting that shape change may occur by active movement of material along microtubules or by microtubule redistribution.
Functional characterization of neurokinin‐1 receptors on human U373MG astrocytoma cells
Authors: Eistetter Harald R. , Mills Ann , Brewster Rachel , Alouani Sami , Rambosson Christine , Kawashima Eric 
Published: May 2005

AbstractThe neurokinin‐1 (NK‐1, substance P) receptor belongs to the class of seven transmembrane domain (7‐TM) receptors that interact with cellular effector systems via guanine nucleotide binding regulatory proteins (G‐proteins). In this study, coupling mechanisms of functional NK‐1 receptoirs endogenously expressed in a human astrocytoma cell line (U373MG) were analyzed. Stimulation with substance P (SP) resulted in 1) a rapid increase in inositol 1,4,5‐trisphosphate (IP3) synthesis; 2) a rise in cytosolic free calcium concentration ([Ca2+]); 3) induction of immediate early gene transcription as monitored by c‐fos and c‐jun expression; and 4) a significant increase in de novo DNA synthesis. Thus, the functional responses induced by stimulation of NK‐1 receptors on U373MG strongly correlate with those observed after treatment of primary astrocytes with SP and make U373MG cells a useful in vitro model system for the analysis of NK‐1 receptor function on astrocytes in vivo. © 1992 Wiley‐Liss, Inc.
Oligodendrocytes and myelin formation along the optic tract of the developing hamster: An immunohistochemical study using the rip antibody
Authors: Jhaveri Sonal , Erzurumlu Reha S. , Friedman Beth , Schneider Gerald E. 
Published: May 2005

AbstractThe monoclonal antibody Rip recognizes an antigen specific to oligoderdrocytes and their processes (Friedman et al: Gila 2:380, 1989). We have used this antibody to document the appearance of oligodendrocytes and the sequence of ensheathment of axons along the optic tract (OT) and within its major target areas in neonatal (P3–P21) and adult hamsters.Myelination of axons in the visual pathway follows an overall proximo‐distal gradient. On P3, immunopositive, pre‐ensheathing oligodendrocytes are detected in the OT ventral to the lateral geniculate body (LGB) whereas myelin segments are present around OT axons by P5. The first pre‐ensheathing oligodendrocytes are detected medially in the LGB on P7 and myelinated axons in the overlying OT by P11. In the superior colliculus, pre‐ensheathing oligodendrocytes are prsent in the optic fiber layer (SO) on P7, but not in the superficial gray layer (SGS) until P11. Myelination of axons within SO proceeds along a marked rostro‐caudal gradient. On P14, axons in rostral SO are heavily myelinated; thereafter, ensheathment continues caudally within the SO and the SGS.The progressive invasion of oligodendrocytes along the proximo‐distal axis of the optic pathway, and the corresponding myelination of OT axons, are discussed in the context of a possible inhibitory role of oligodendrocytes in regulating the regenerative propensity of retinotectal axons. © 1992 Wiley‐Liss, Inc.
Serotonin uptake by astrocytes in situ
Authors: Anderson E. J. , McFarland D. , Kimelberg H. K. 
Published: May 2005

AbstractCo‐localization of glial fibrillary acidic protein (GFAP) and radioactivity was examined after intraventricular injection of [3H]5‐HT in adult rat brains. Radioactivity localized over GFAP‐positive astrocytes was seen, especially when image‐enhancing techniques were applied to the data. Also slices prepared from astrogliotic hippocampi of rats pretreated with kainic acid showed a twofold increased uptake of [3H]5‐HT compared to control slices. This indicates that the uptake of [3H]5‐HT seen in primary astrocyte cultures also occurs for astrocytes in situ. Also, as with astrocyte cultures, only some of the GFAP(+) astrocytes in situ showed localization of radioactivity, supporting the concept of intraregional heterogeneity of astrocyte functions. © 1992 Wiley‐Liss, Inc.
Glial calcium
Authors: Finkbeiner Steven M. 
Published: May 2005

AbstractThis review summarizes current knowledge relating intracellular calcium and glial function. During steady state, glia maintain a low cytosolic calcium level by pumping calcium into intracellular stores and by extruding calcium across the plasma membrane. Glial Ca2+ increases in response to a variety of physiological stimuli. Some stimuli open membrane calcium channels, others release calcium from intracellular stores, and some do both. The temporal and spatial complexity of glial cytosolic calcium changes suggest that these responses may form the basis of an intracellular or intercellular signaling system. Cytosolic calcium rises effect changes in glial structure and function through protein kinases, phospholipases, and direct interaction with lipid and protein constituents. Ultimately, calcium signaling influences glial gene expression, development, metabolism, and regulation of the extracellular milieu. Disturbances in glial calcium homeostasis may have a role in certain pathological conditions. The discovery of complex calcium‐based glial signaling systems, capable of sensing and influencing neural activity, suggest a more integrated neuro‐glial model of information processing in the central nervous system. © 1993 Wiley‐Liss, Inc.
Thyroid hormone up‐regulates thyroid hormone receptor β gene expression in rat cerebral hemisphere astrocyte cultures
Authors: Lebel Jean‐Marc , L'Hérault Sylvie , Dussault Jean H. , Puymirat Jack 
Published: May 2005

AbstractOligonucleotide probes complementary to specific regions of three thyroid receptor cDNAs were used to study the effects of thyroid hormone on the expression of the mRNAs encoding two α (α1 and α2) and one β‐thyroid (β1) receptors isoforms in rat cerebral hemisphere astrocyte cultures. Both genes are expressed by type 1 astrocytes. The levels of the α1‐, α2‐, and β1‐mRNAs did not significantly change between day 8 and day 22, in cultures grown in the absence of thyroid hormone. L‐triiodothyronine (L‐T3) treatment of the cultures increased the levels of β1‐mRNAs by fivefold without changing either the levels of the α1‐ and α2‐mRNAs or L‐T3 binding capacity. The effect of L‐T3 on β1‐mRNAs was observed after 4 h of treatment and was independent of protein synthesis, suggesting that this effect is likely to be a direct one. Treatment of the cultures by cytosine arabinosine, a drug that kills dividing cells, specifically decreased level of the α1‐ and α2‐mRNAs by 60% and 38%, respectively. Finally, by immunocytochemistry, we showed that the β1 receptor‐immunoreactivity was either located in the perinuclear region and the cytoplasm or in the nuclei of astrocytes.Taken together with previous data obtained in neuronal cultures where no effect of L‐T3 was observed on the levels of the β1‐mRNAs, our findings indicate that the β1 gene is differentially regulated in neurons and astrocytes. Furthermore, our results are also in favor of specific functions for both types of thyroid receptors during astrocyte differentiation. © 1993 Wiley‐Liss, Inc.
Effects of tumor necrosis factor on inward potassium current and cell morphology in cultured human oligodendrocytes
Authors: McLarnon James G. , Michikawa Makoto , Kim Seung U. 
Published: May 2005

AbstractThe effects of recombinant human tumor necrosis factor‐α (rhTNF‐α) on inward rectifier potassium [K(IR)] currents and on cell morphology have been studied in cultured human oligodendrocytes. Cell‐attached patches were used to isolate and record unitary currents through an inward rectifier K+ channel with a conductance of 23 pS. In control oligodendrocytes the mean open times showed an exponential dependence on patch potential with an e‐fold decrease over a patch hyperpolarization of 28 mV. Treatment of oligodendrocytes with rhTNF (at 250 ng/ml for 24–48 h) had significant actions to diminish the mean open times of K(IR) relative to control values. At cell resting potential the mean open times were reduced by 60% after rhTNF application; the amplitudes of unitary currents or the extrapolated zero‐current potentials were not significantly changed by the cytokine. The rhTNF treatments were not cytotoxic to cultured human oligodendrocytes; however, in some experiments rhTNF caused evident retraction of cell processes. © 1993 Wiley‐Liss, Inc.
A Ca2+ ‐ and pH‐Dependent K+ Channel of rat C6 glioma cells and its possible role in acidosis‐induced cell swelling
Authors: Strupp Michael , Staub Frank , Grafe Peter 
Published: May 2005

AbstractThe aim of the present study was to explore whether a change in membrane K+ conductance contributes to acidosis‐induced swelling of cultured rat C6 glioma cells. Electrophysiological studies were perfomed using whole‐cell and single‐channel recordings in combination with cell volume measurements in cell suspension by flow cytometry. Whole‐cell recordings revealed a voltage‐dependent K+ conductance. The predominant K+ channel in single‐channel recordings with symmetrical high K+ concentrations was inwardly rectifying and had conductances of 35 and 15 pS, respectively. A raised internal free Ca2+ concentration and membrane depolarization increased the open probability of this channel. Internal acidosis (pH 6.4−5.4), on the other hand, reduced open probability and single‐channel conductance. Both whole‐cell and single‐channel K+ currents were blocked by quinidine (0.1−1 mM), which was therefor used to analyze the functional consequences of an inhibition of this conductance for volume. Thereby, quinidine (1 mM) produced a small (5%) and transient cell swelling of C6 glioma cells. In contrast, acidosis (pH 5.6) caused a much larger (about 20%) and maintained swelling. Since quinidine produced only a minor swelling of C6 cells, it is unlikely that inhibition of the K+ conductance caused acidosis‐induced cell swelling. Other mechanisms, such as activation of ion transporters, must therefore be responsible. © 1993 Wiley‐Liss, Inc.
Kainic acid induced alterations in antibody recognition of connexin43 and loss of astrocytic gap junctions in rat brain
Authors: Hossain M. Z. , Sawchuk M. A. , Murphy L. J. , Hertzberg E. L. , Nagy J. I. 
Published: May 2005

AbstractIntracerebral administration of kainic acid (KA) in rats was previously shown to abolish immunohistochemical labelling for the astrocytic gap junction protein connexin43 (Cx43) at sites depleted of neurons (Vukelic et al: Neurosci Lett 130:120–124, 1991). This response of Cx43 has now been further investigated with a number of different sequence‐specific anti‐Cx43 antibodies. At lesion sites in the thalamus, striatum, and hippocampus examined immunohistochemically with an antibody against amino acids (aa's) 346–363 in the Cx43 sequence, the antibody used in the earlier study, Cx43‐immunoreactivity was increased 5 h after KA injections, absent by 24 h and for up to 2 weeks post‐injection, and began to return to less than normal levels by 2 to 3 weeks post‐injection. Analyses of KA lesion sites with antibodies against other sequences of Cx43 (amino acids 283–298, 253–270, 241–260, 113–123, and 49–61) revealed not only the presence but in some cases an increased density of Cx43 immunoreactivity after a survival time of 1 week. Immunolabelling patterns at these sites consisted of relatively large, coarse profiles rather the fine punctate labelling typically seen in sections of normal brain. In homogenates of KA‐injected striatum analyzed by Western blots, Cx43 was detected at near normal or slightly increased levels at various survival times examined. The 43 kDa phosphorylated form of Cx43 and its faster migrating 41 kDa dephosphorylated form which is generated post‐mortem by a brain phosphatase were both present after standard methods of tissue preparation for Western blot analysis, while only the 43 kDa form was present in normal and KA‐injected striatum after inactivation of brain metabolism by focused cranial microwave irradiation. Ultrastructural investigations of lesions sites within the thalamus revealed a virtual absence of astrocytic gap junctions. These results demonstrate that Cx43 levels initially increase after intracerebral KA treatment, that its molecular organization in resident astrocytes is altered such that epitopes that are normally accessible to antibody are hidden while those that may be hidden or relatively inaccessible are exposed, and that this molecular alteration in Cx43 is associated with loss of astrocytic gap junctions. © 1994 Wiley‐Liss, Inc.
Microtubule‐associated protein 1B (MAP1B) is present in glial cells phosphorylated different than in neurones
Authors: Ulloa Luis , Ibarrola Nieves , Avila Jesúas , Díez‐Guerra F. Javier 
Published: May 2005

AbstractA panel of four anti‐MAP1B antibodies have been used to study the presence and post‐translational modification of MAP1B in primary cultures of glial cells. Two antibodies (150 and 125) recognize phosphorylated epitopes whereas the other two (531 and 842) recognize non‐phosphorylated phosphorylatable epitopes on the MAP1B molecule. Immunofluorescence and Western blot analysis with antibodies 531 and 842 revealed the presence of small amounts of MAP1B‐like immunoreactivity in type 1 astrocytes and a greater content in more differentiated glial cells found in long‐term cultures. By immunofluorescence, these latter cells gave positive immunostaining with antibody 125, which recognizes a phosphorylated epitope phosphorylated by casein kinase II. Antibody 150, which reacts to a phosphorylated epitope on the MAP1B molecule, did not show any detectable immunoreactivity in glial cells cultures, either by immunofluorescence or Western blot. All four antibodies recognized hippocampal neurones in culture, with especially intense immunostaining in cell bodies and axons, and reacted strongly with protein present in hippocampal neurones extracts showing an electrophoretic mobility similar to that of brain MAP1B. In mixed optic nerve glial cell cultures, anti‐galactocerebroside (Ga1C) positive cells gave also positive staining with antibodies 531 and 125. We propose that MAP1B is present in cultures of glial cells in moderate amounts and with a phosphorylation state different than in neurones. Thus, less differentiated glial cells, such as type 1 astrocytes, have a small amount of MAP1B, mainly in a non‐phosphorylated form, which is spread diffusely in the cytoplasm and probably does not interact with microtubules. More differentiated glial cells, such as oligodendrocytes, show a greater content in MAP1B which, at least in part, is phosphorylated by a casein kinase II‐like activity. © 1994 Wiley‐Liss, Inc.
Characteristics of Na+ current in Schwann cells cultured from frog sciatic nerve
Authors: Miyazaki T. , Tasaka J. , Sakai S. , Hashiguchi T. , Padjen A. L. , Tosaka T. 
Published: May 2005

AbstractCharacteristics of voltage‐dependent currents in cultured frog Schwann cells were investigated by the whole‐cell clamp technique. An inward current was detectable at a membrane potential level more positive than‐50 mV and reached a maximum value at about‐10 mV, while no rectifying channel was present. The inward current was carried by Na+ ions, because the extrapolated reversal potential of the current agreed with the calculated ENa, and the current was sensitive to tetrodotoxin. The membrane potential for half‐maximal inactivation was‐82 mV. The inactivation curve indicated that more than 90% of the Na+ channels were inactivated at the resting membrane potential, suggesting that the cultured frog Schwann cells could not generate an action potential under physiological conditions. The time constant for the inactivation at a maximum current was 5.3 ms (‐10 mV, 13°C).The electrophysiological characteristics of the Na+ current in the cultured frog Schwann cells were compared with those in other tissues. This Na+ current was quantitatively different from that observed in the amphibian node of Ranvier but was similar to that in the mammalian Schwann or glial cells, especially in the more hyperpolarized half‐maximal inactivation potential and in the slower inactivation time course. © 1994 Wiley‐Liss, Inc.
The immortalized astroglial cell line RC7 is a new model system for the study of nerve growth factor (NGF) regulation: Stimulation by interleukin‐1β and transforming growth factor‐β1 is additive and affected differently by dibutyryl cyclic AMP
Authors: Hahn Martina , Lorez Hanspeter , Fischer Güunther 
Published: May 2005

AbstractNerve growth factor (NGF) synthesis was studied with an astroglial cell line derived from rat cerebellar astrocytes by transfection with a simian virus 40 T containing retroviral vector. As in primary astrocytes, NGF synthesis/secretion could be stimulated dose‐dependently with interleukin‐1βsZ (IL‐1βsZ) and transforming growth factor‐1βsZ (TGF‐βsZ1). We therefore have used this cell line as a model system to analyze putative intracellular signalling pathways underlying the effects of these factors. Protein kinase C inhibitors (calphostin and Ro 31–8830) as well as a lipoxygenase inhibitor (nordihydroguaiaretic acid) did not affect stimulation of NGF synthesis/secretion by IL‐1βsZ or TGF‐βsZ1. However, dibutyryl cyclic AMP partly inhibited the stimulation by TGF‐βsZ1 but did not affect that evoked by IL‐1βsZ. This finding, together with the fact that IL‐1βsZ and TGF‐βsZ1 stimulate NGF production/secretion in an additive manner, indicates that different intracellular signalling pathways are involved in the mediation of IL‐1βsZ and TGF‐βsZ1 induced NGF production/secretion. © 1994 Wiley‐Liss, Inc.