bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of mouse type‐2‐like astrocytes: Demonstration of glutamate and GABA transmitter activated responses
Authors: Magoski N. S. , Walz W. , Juurlink B. H. J. 
Published: January 2005

AbstractWe have identified mouse type‐2‐like astrocytes and examined some of their electrophysiological properties. Cultures were prepared from P4 mouse neopallia. We demonstrate that mouse type‐2‐like astrocytes can be identified using the following criteria: presence of glial fibrillary acidic protein (GFAP), presence of chondroitin sulfate polysaccharide, and presence of γ‐aminobutyric acid (GABA). A2B5‐binding is not a sufficient criterion to identify O2A lineage cells in mouse neopallial glial cultures since the monoclonal antibody A2B5 binds not only to O2A lineage cells but also to a subpopulation of large, flat type‐1‐like astrocytes. Mouse type‐2‐like astrocytes have resting membrane potentials of −76.2 ± 2.1 mV—i.e., similar to that of mouse type‐1‐like astrocytes. The input resistance of 44.2 ± 0.5 MΩ is an order of magnitude greater than that of type‐1‐like astrocytes suggesting the type‐2‐like astrocytes are not extensively electrically coupled either to each other or to type‐1‐like astrocytes. Glutamate application caused an 8.8 ± 1.7 mV depolarization of type‐2‐like astrocytes. Application of glutamate to barium treated astrocytes caused a fast depolarization with a peak amplitude of 21.4 ± 1.8 mV; the cells repolarized from this peak by about 10 mV and upon removal of glutamate returned to its pre‐glutamate value. Application of GABA caused a transient depolarization of 14.0 ± 1.7 mV. The presence of barium resulted in a steady‐state GABA‐induced depolarization of 10.3 ± 2.0 mV. Neither SITS nor β‐alanine interfered with the amplitude of the glutamate and GABA responses. © 1992 Wiley‐Liss, Inc.
Cloning of a novel TGF‐β related cytokine, the vgr, from rat brain: Cloning of and comparison to homologous human cytokines
Authors: Sauermann U. , Meyermann R. , Schluesener H. J. 
Published: January 2005

AbstractHere we describe cloning of a TGF‐β related cytokine from a rat brain cDNA library. This novel cytokine, the vgr (vegetal related), is homologous to the vegetal (Vg1) gene of Xenopus (DL Weeks and DA Melton, Cell, 51:861–867, 1987).In rat brain mRNA a single 3.5 kb RNA could be detected by Northern blot analysis. Thus, this new cytokine is constitutively expressed in the central nervous system.A monoclonal antibody reactive with a synthetic peptide of vgr revealed a faint vgr‐like immunoreactivity throughout the CNS, with more pronounced staining of hippocampal neurons, ependymal cells, cells of the choroid plexus, and hypophysis.Using the rat cDNA, two homologous human cytokine cDNAs encoding the human vgr and op‐1 were cloned. © 1992 Wiley‐Liss, Inc.
β/A4 domain of APP: Antigenic differences between cell lines
Authors: Wolozin B. , Zheng B. , Loren D. , Lesch K. P. , Lebovics R. S. , Lieberburg I. , Sunderland T. 
Published: January 2005

AbstractThe expression of amyloid precursor protein (APP) in olfactory neuroblasts has been examined with a panel of antibodies directed against varied regions of the APP molecule. The pattern of reactivity was compared to that in the transformed human glial cell line SVG, human cortical brain tissue, and in kidney epithelial 293 cells containing stably transfected and overexpressed human APP751. Antibodies directed against the C‐terminus and extracellular domains of amyloid precursor protein (APP) react more strongly on immunoblot with transfected 293 cells and brain tissue than with olfactory neuroblasts (ON) or SVG cells. Antibodies directed against the β/A4 region of APP show a contrasting pattern of reactivity, yielding greater reactivity with ON and SVG cells than with transfected 293 cells or brain tissue. Analysis of the APP transcripts using polymerase chain reaction indicates that ON and SVG both make predominantly APP770 and 751, as does the transfected 293 cell line. In the absence of any differences in APP transcripts among the cell lines, the difference in availability of the β/A4 region appears likely to be due to posttranslational modification. These data therfore indicate that processing of APP varies among cell lines and thus may vary from tissue to tissue. © Wiley‐Liss, Inc.
Growth control of cultured microglia
Authors: Ganter S. , Northoff H. , Männel D. , Gebicke‐Härter P. J. 
Published: January 2005

AbstractMicroglia, the resident macrophages of the brain, typically react to injuries or chronic diseases with proliferation and expression of differentiated features, such as production of cytokines associated with inflammatory events. Regulation and control of microglial cytokine expression, therefore, is a major focus of scientific interest. It has been shown that GMCSF and Il‐3 are potent mitogens for microglia. Moreover, Il‐3 and other cytokines are products of microglia. It is shown here that interleukin‐1 (Il‐1) as well as tumor necrosis factor (TNFα) increased microglial proliferation in mixed astrocyte‐microglial cultures but had no mitogenic effects on isolated microglia. © Wiley‐Liss, Inc.Lipopolysaccharide (LPS), the bacterial endotoxin, irreversibly inhibited microglial cell division in both mixed astrocyte‐microglial cultures and in isolated microglial cultures. By contrast, the corticosteroids hydrocortisone and aldosterone and the synthetic glucocorticoid dexamethasone reversibly inhibited microglial proliferation. They also antagonized the stimulatory effects of Il‐3 and granulocyte macrophage colony‐stimulating factor (GMCSF). Estradiol and progesterone had no significant effects on mixed cultures but inhibited microglial proliferation in isolated cultures. Conditioned media from mixed cultures, isolated cultures, from the WEHI‐2B cell line, or from fresh (serum‐supplemented) media stimulated microglial proliferation to various extents.In summary, cytokine‐mediated microglial proliferation can be down‐regulated by a variety of steroid hormones. Along with their unimpaired access to brain cells in general, corticosteroids likely maintain an inhibitory tonus on microglial proliferation. It is hypothesized that this inhibition is overcome locally and temporally in brain injury and repair. © Wiley‐Liss, Inc.
Isolation of activated adult schwann cells and a spontaneously immortal schwann cell clone
Authors: Bolin L. M. , Iismaa T. P. , Shooter E. M. 
Published: January 2005

AbstractSuccessful mammalian peripheral nerve regeneration is dependent on activated Schwann cells. Schwann cells facilitate neuronal regrowth through the production of tropic cell membrane molecules, neurotrophins, and extracellular matrix components. To better understand Schwann cell function in the regenerating nerve, we have designed a method of isolating proliferating adult Schwann cells from the injured rat sciatic nerve. Relying on the mitotic signal that is present after a crush injury, we can obtain sufficient numbers of dividing Schwann cells within one week of initial culture. A spontaneously immortal Schwann cell clone (iSC) was observed in and isolated from one of these primary cultures. These cells were transformed at a time of maximal Schwann cell activation in response to injury. Both the primary Schwann cells and the iSC have been characterized as Schwann cells by morphology, immunohistochemistry and gene expression. © Wiley‐Liss, Inc.
Proliferation and differentiation of O4+ oligodendrocytes in postnatal rat cerebellum: Analysis in unfixed tissue slices using anti‐glycolipid antibodies
Authors: Warrington A. E. , Pfeiffer S. E. 
Published: January 2005

AbstractWe report the study of the in vivo morphology, differentiation, and proliferation of oligodendrocytes (OLs) and their progenitors identified by the antiglycolipid antibodies O4, R‐mAb, and O1 in postnatal rat cerebellum, using a novel immunocytochemical staining protocol which allows the analysis of the expression of OL‐specific glycolipids in live, unfixed brain slices. An analysis of the individual cells identified in double label immunocytochemistry indicated that the order of antigen expression in OLs during in vivo development is, first, antigens recognized by O4, second, antigens recognized R‐mAb, and third, antigens recognized by O1. This order of antigen expression is correlated with increasing morphological complexity and is a pattern mimicked in many culture systems. In vivo O4 identified 3 distinct stages of the OL lineage: (1) morphologically simple proligoden‐drocyte antigen+ (POA+) R‐mAb− blast cells localized at the leading edge of myelinogenesis; (2) morphologically more complex R‐mAb+O1− cells; and (3) actively myelinating O1+ [i.e., galactocerebroside+ (GalC)] OLs residing within the white matter. Only the POA+R‐mAb− cells incorporated BrdU in animals that were prelabeled 3 hr before immunocyto‐chemistry. We have demonstrated in vivo the subdivision of pre‐GalC+ OL progenitors into shorter, biologically noteworthy, stages of maturation. A spatial comparison of the cell populations identified by O4, R‐mAb, and O1 demonstrated a progressive wave of OL maturation from the base of the cerebellum toward the folia. The data are consistent with the hypothesis that multiprocessed O4+GalC− progenitors are the most mature stage of the OL lineage with significant proliferative capacity and the first postmigratory stage in normal development. © Wiley‐Liss, Inc.
3H‐D‐aspartate release from cerebellar granule neurons is differentially regulated by glutamate‐ and K+‐stimulation
Authors: Belhage B. , Rehder V. , Hansen G. H. , Kater S. B. , Schousboe A. 
Published: January 2005

AbstractNeurotransmitter release in response to either 55 mM K+ or 25 μM glutamate as well as its dependency on Ca2+ from different sources was compared in cultured glutamatergic cerebellar granule cells from rat brain. The intracellular Ca+ concentration was monitored at the single cell level in neurites as well as cell bodies employing the fluorescent Ca2+ indicator fura‐2. Transmitter release was assayed using 3H‐D‐aspartate to label the exogenously accessable glutamate pools, which in these neurons is believed to also include the transmitter pool. In an attempt to distinguish whether transmitter release was dependent on an intact cytoskeleton or not, the colchicine‐like drug Nocodazole, which also blocks transport of vesicles, was used. K+‐stimulated transmitter release consisted for the major part (around 70%) of a Ca2+ dependent, Nocodazole sensitive release component and this K+‐induced release appeared to be almost exclusively dependent on N‐type Ca2+ channels. In contrast, 50% of the glutamate‐induced Ca2+‐dependent release was triggered by Ca2+ from a Dantrolene sensitive intracellular Ca2+ pool. Since these neurons undergo a pronounced maturational change in which neurotransmitter vesicles become increasingly prominent, the Ca2+ responses and transmitter release evoked by the two different stimuli were investigated as a function of the culture period. K+ and glutamate were found to increase intracellular [Ca2+] differentlly. In 1‐day‐old cultures K+ elicited a small albeit significant increase in [Ca2+]i while glutamate was completely without effect. In 7‐day‐old neurons both agents induced a large increase in [Ca2+]i. However, K+ induced equal Ca2+ responses in cell bodies and neurites, whereas glutamate induced an almost 4 times lower Ca2+ response in neurites compared to cell bodies.These findings suggest that K+ and glutamate may recruit transmitter and release‐triggering‐Ca2+ from different pools. This could be of pivotal importance for the understanding of glutamate homeostasis during physiological as well as pathological conditions. © 1992 Wiley‐Liss, Inc.
The role of microtubule‐associated protein 2 (MAP‐2) in neuronal growth, plasticity, and degeneration
Authors: Johnson G. V. W. , Jope R. S. 
Published: January 2005

AbstractMicrotubule associated protein 2 (MAP‐2) historically has been perceived primarily as a static, structural protein, necessary along with other cytoskeletal proteins to maintain neuroarchitecture but somewhat removed from the “mainstream” of neuronal response mechanisms. Quite to the contrary, MAP‐2 is exquisitely sensitive to many inputs and recent investigations have revealed dynamic functions for MAP‐2 in the growth, differentiation, and plasticity of neurons, with key roles in neuronal responses to growth factors, neurotransmitters, synaptic activity, and neurotoxins. These discoveries indicate that modification and rearrangement of MAP‐2 is an early obligatory step in many processes which modify neuronal function. © 1992 Wiley‐Liss, Inc.
The gp120 glycoprotein of HIV‐1 binds to sulfatide and to the myelin associated glycoprotein
Authors: Van Berg L. H. Den , Sadiq S. A. , Lederman S. , Latov N. 
Published: January 2005

AbstractWe investigated the binding of the gp120 glycoprotein of the human immunodeficiency virus (HIV‐1) to neural glycolipids and glycoproteins by ELISA. The gp120 protein bound to sulfatide (GalS), a sulfated glycolipid autoantigen implicated in sensory neuritis, and to the myelin associated glycoprotein (MAG), an autoantigen in demyelinating neuropathy. Binding of gp120 to MAG was inhibited by the HNK‐1 antibody, which recognizes a sulfated glucuronic acid epitope, suggesting that the interaction involves carbohydrate determinants. Sulfatide and MAG are potential receptors for gp120 in peripheral nerve and may have a role in the neuropathy associated with HIV‐1 infection. © 1992 Wiley‐Liss, Inc.
Developmental expression of neuronal calmodulin mRNA species in the rat brain analyzed by in situ hybridization
Authors: Ni B. , Landry C. F. , Brown I. R. 
Published: January 2005

AbstractThe temporal and spatial distribution of calmodulin mRNAs which are preferentially expressed in neurons was determined during postnatal development of rat central nervous system. Expression of these mRNAs was strongly detected in the developing neocortex, hippocampus, and cerebellum. Differences in the pattern of expression of a 1.8 and 4.0 kb neuronal calmodulin mRNA species were identified in the developing cerebellum. Expression of the smaller mRNA appeared to correlate with proliferating and developing cerebellar granule neurons while the larger mRNA was present in the mature granule neuron population. A transient elevation in the neuronal calmodulin mRNA species was observed in the suprior and inferior colliculus and in the thalamus at postnatal days 5 and 10. © 1992 Wiley‐Liss, Inc.
In search of the central respiratory neurons: I. Dissociated cell cultures of respiratory areas from the upper medulla
Authors: Fitzgerald S. C. , Willis M. A. , Yu C. , Rigatto H. 
Published: January 2005

AbstractDissociated cells from the areas of the nucleus ambiguus and the nucleus tractus solitarius obtained by tissue punch or block dissection from coronal slices of the medulla at the level of the obex were cultured from fetal rats at 18 to 21 days gestation. The dissociated neurons were plated either directly in vitrogen‐coated 35 mm tissue culture dishes or in such dishes which had been seeded with subcultures of cortex‐ or medulla‐derived astrocytes. After the astrocytes reached confluency and were treated with an antimitotic agent, dissociated nucleus ambiguus or nucleus tractus solitarius was plated at 0.5–1.0 × 106 cells per dish. Neurons grew well on monolayers of medullary or cortical astrocytes, but survived poorly on vitrogen‐coated dishes without a cellular substrate. Rat medulla was preferred as the source of astrocytes. Tissue dissociation with papain rather than trypsin produced less cellular debris, and the neuronal yield from the tissue was higher. The neuronal population was heterogenous in morphology including small and large bipolar, pyramidal, and multipolar cells. Neurons sensitive to CO2 and/or low pH (Rigatto et al., J Neurosci Res 33:590–597, 1992) did not appear to have any definitive morphologic characteristics, but most were multipolar. These neurons stained well with antibodies to neuron‐specific enolase and Fragment C of tetanus toxin, but not to choline acetyltransferase (ChAT). These findings suggest that neurons possibly responsible for the central regulation of respiration can be maintained for several weeks in dissociated cell culture, providing a system for neurotransmitter, electrophysiological, and morphological studies. © 1992 Wiley‐Liss, Inc.
Elevation of extracellular potassium facilitates the induction of hippocampal long‐term potentiation
Authors: Ballyk B. A. , Goh J. W. 
Published: January 2005

AbstractHippocampal long‐term potentiation (LTP) is widely believed to be a cellular substrate for learning and memory. A likely physiological stimulus for initiating LTP is repetitive neuronal activity, which also results in K+ accumulation extracellularly. Therefore, the involvement of elevated extracellular K+ concentrations in the induction of LTP of the stratum radiatum‐CA1 neuronal synapse was investigated in the hippocampal slice preparation. Increasing the K+ content in extracellular perfusing medium from 3.1 to 15 mM resulted in facilitation of LTP induction in weak excitatory postsynaptic potentials (EPSPs). Since changes that occur to generate LTP are thought to be localized to synaptic regions, it would be relevant to selectively increase synaptic K+ levels. To this end, the following experiments were conducted: (i) baclofen, a GABAB receptor agonist which, in addition to having a disinhibitory presynaptic action, activates a K+ conductance in CA1 neuronal dendrites, was applied to the slice; (ii) K+ was directly applied by iontophoresis. At a concentration of 5 μM baclofen, as well as with K+ iontophoresis (200–300 nA), LTP of weak EPSPs was facilitated. The present data suggest that an increase in synaptic K+ levels can fulfill the condition of cooperativity for LTP induction, raising the possibility that an elevation of this monovalent ion plays a physiological role in triggering LTP. © 1992 Wiley‐Liss, Inc.
Haloperidol prevents induction of the hsp70 heat shock gene in neurons injured by phencyclidine (PCP), MK801, and ketamine
Authors: Sharp F. R. , Butman M. , Wang S. , Koistinaho J. , Graham S. H. , Sagar S. M. , Noble L. , Berger P. , Longo F. M. 
Published: January 2005

AbstractThe non‐competitive NMDA receptor antagonists, PCP (phencyclidine), MK801, and ketamine produce psychosis in humans and abnormal vacuoles in posterior cingulate and retrosplenial rat cortical neurons. We show that PCP (≥5 mg/kg), MK801 (≥0.1 mg/kg), and ketamine (>20 mg/kg) induce hsp70 mRNA and HSP70 heat shock protein in these vacuolated, injured neurons, and PCP also induces hsp70 in injured neocortical, piriform, and amygdala neurons. The PCP, MK801, and ketamine drug induced injury occurs in 30 day and older rats, but not in 0–20 day old rats, and is prevented by prior administration of the antipsychotic drugs haloperidol and rimcazole. Since haloperidol and rimcazole block dopamine and sigma receptors, and since M1 muscarinic cholinergic receptor antagonists also prevent the injury produced by PCP, MK801, and ketamine, future studies will be needed to determine whether dopamine, sigma, M1, or other receptors mediate the injury. © 1992 Wiley‐Liss, Inc.
Neurotoxicity of HIV coat protein gp120, NMDA receptors, and protein kinase C: A study with rat cerebellar granule cell cultures
Authors: Savio T. , Levi G. 
Published: January 2005

AbstractThe neuronal loss observed in AIDS patients may be partly due to the neurotoxicity of HIV coat protein gp120, whose mechanism of action has been suggested to involve an interaction with voltage‐dependent Ca2+ channels and NMDA receptors (Lipton, Trends Neurosci 15:75–79, 1992). In the present investigation we analyzed the acute neurotoxicity of gp120 on a purified neuronal population (rat cerebellar granule cell cultures) amply used for studies on glutamate toxicity. Cultures of 7–8 days were exposed for 15 min to a buffered Locke's solution containing the substances under study, washed, and cultured for another 24 hr in their original medium. The cells were stained with the nuclear dyes propidium iodide (for dead cells) and Hoechst 33258 (for total cells) and counted. Average cell death in controls was 8%. gp120 (1 pM‐10 nM) caused an increase of cell death of about 80%. The effect was totally antagonized by NMDA antagonists (1 mM APV and 10 μM MK‐801), by 1 üM nifedipine, and by anti‐gp120 antibodies. At a concentration of 100 μM glutamate caused an average 130% increase of cell death, which was totally antagonized by APV. The effect of gp120 or glutamate did not appear to be mediated by the secretion of neurotoxins by nonneuronal cells present in a low proportion in the cultures nor to be due to the inactivation of (or competition with) neurotrophic factors present in the medium. The simultaneous administration of gp120 and glutamate (in various combinations of concentrations) had an effect that was less than additive. The combined effect of the two substances was partially antagonized by anti‐gp120 antibodies and totally prevented by the combined action of anti‐gp120 antibodies and NMDA antagonists. Surprisingly, however, NMDA antagonists prevented only partially the neuronal death elicited by gp120 + glutamate. In order to determine whether gp120 affected one of the events potentially involved in NMDA‐mediated neurotoxicity [protein kinase C (PKC) translocation to the plasma membrane], we studied the effect of gp120 and glutamate on the binding of 4β‐[3H]phorbol‐12,13‐dibutyrate, a specific ligand for membrane PKC. While glutamate caused a dose‐dependent, APV‐sensitive increase in binding, gp120 determined a decrease in basal binding, suggesting that its mechanism of action does not involve PKC translocation. © 1993 Wiley‐Liss, Inc.
Regulation of NCAM by growth factors in serum‐free myotube cultures
Authors: Lyles Joan M. , Amin W. , Bock E. , Weill C. L. 
Published: January 2005

AbstractRegulation of the neural cell adhesion molecule (NCAM) was examined in primary cultures of chick skeletal muscle grown in serum‐free defined medium. Relative levels of NCAM (per μg protein) increased 20–30% in myotubes grown on Matrigel, a reconstituted basement membrane preparation, compared to those grown on collagen; total NCAM levels on Matrigel were increased 40–55% due to the additional increase in total protein. A dose dependent increase in relative NCAM levels in myotubes grown on Matrigel in defined medium was observed with the addition of adsorbed horse serum, while relative NCAM levels in myotubes grown on collagen were unaffected by altering the serum concentration. Thus, extracellular matrix molecules and soluble factors exert trophic effects on myotube NCAM expression. Similar developmental changes in the expression of the different molecular size forms of NCAM occurred in myotubes grown on collagen and Matrigel: levels of 150K and 135K Mr forms decreased during development, while 125K remained prominent in older myotubes. Relative NCAM levels were specifically enhanced 11–26% by several factors: nerve growth factor, thyroxine, insulin‐like growth factor II, dibutyryl cyclic AMP, veratridine (a sodium ion channel agonist), and nisoldipine (a calcium ion channel agonist). Total protein and overall myotube development in serum‐free cultures were enhanced by fetuin, insulin‐like growth factor II, acidic fibroblast growth factor, calcitonin gene‐related peptide, dibutyryl cyclic AMP, and veratridine. Thus, changes in extracellular matrix, intracellular calcium, and sodium ions, as well as extracellular trophic factors, such as nerve growth factor, thyroxine, and insulin‐like growth factor II, may regulate muscle NCAM expression during embryonic development. © 1993 Wiley‐Liss, Inc.