bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neurobiology of human oligodendrocytes in culture
Authors: Kim S. U. 
Published: January 2005

AbstractEnriched populations of oligodendrocytes were isolated from adult human brains of 3‐15 hours postmortem using the trysinin digestion‐Percoll density gradient method and were cultured for an extended period of time up to 6 months. Cell type specific antigens that were expressed by oligodendrocytes were galactocerebroside, myelin basic protein, proteolipid protein, 2'3'‐cyclic nucleotide 3'‐phosphehydrolase and myelin‐associated glycoprotein. In addition, HLA‐A, B, C and HLA‐DR, respectively, Class I and Class II antigens of the major histocompatibility complex, were demonstrated on oligodendrocytes. Three classes of gangliosides, GM1, GM4, and GD3, were also demonstrated on oligodendrocytes, while GM1 and GM4 gangliosides were detected on the surface of astrocytes. The presence of “transitional” or “bipotential” glial cells that were derived from oligodendrocytes and that expressed both oligodendroglial and astrocytic phenotypes was demonstrated. Treatment of the cells by cyclic AMP and its derivatives reversed this dual phenotypic expression back to the oligodendroglial trait. Electron microscopic examination of oligodendrocytes indicated that they were capable of synthesizing and assembling myeiin sheaths in culture in the absence of any neuronal signal input.
Distribution of proteolipid protein and myelin basic protein in cultured mouse oligodendrocytes: Primary vs. secondary cultures
Authors: Konola J. T. , Tyler B. M. , Yamamura T. , Lees M. B. 
Published: January 2005

AbstractThe distribution of proteolipid protein (PLP) and myelin basic protein (MBP) was examined in differentiating Oligodendrocytes of primary and secondary mouse brain cell cultures by single‐ and double‐label indirect immunofluorescence. In primary cultures, MBP and PLP were differentially located in Oligodendrocytes. MBP became concentrated as fine punctate dots lining the edges of processes and as coarse grains in flattened sheet‐like structures. PLP was distributed diffusely throughout cell bodies and processes but was limited to the perimeter of sheets and some processes within sheets. To compare the detailed distribution of PLP and MBP in the absence of underlying cells, a simple method for the growth of isolated Oligodendrocytes in secondary cultures was developed. Cells were maintained in primary culture for 39‐41 days, harvested by scraping, enriched for Oligodendrocytes, and plated at low cell density. After 1 week, isolated Oligodendrocytes had developed long processes and large flattened membranous sheets. MBP and PLP were differentially localized in these cell structures. The sheets contained fine‐grained patches of MBP, which were surrounded by networks of MBP− processes. In contrast, PLP was initially seen throughout the cell bodies and processes. In older cultures, PLP became strikingly concentrated in curvilinear membranous profiles. The observations show that PLP and MBP aie differentially located in cultured mouse Oligodendrocytes. Further‐more, the precise distribution of these myelin‐specific antigens is dependent on culture conditions.
Beta amyloid precursor protein mediates neuronal cell‐cell and cell‐surface adhesion
Authors: Breen K. C. , Bruce M. , Anderton B. H. 
Published: January 2005

AbstractThe beta‐amyloid precursor protein (APP) is a membrane‐bound glycoprotein which has been proposed to play a role both as a growth factor and a mediator of cell adhesion. Using the Ncuro‐2A neuroblastonia cell line, we have investigated the capacity of APP to mediate neural cell adhesion. The cells express the protein at a high level, the immunohistochemical staining pattern at the level of the membrane having a punctate pattern. Fab' fragments of antibodies to the extracellular portion of the molecule were found to inhibit cell binding to a collagen substrate, but not to laminin, fibronectin, or poly‐I‐lysine. Fab' fragments of antibodies to the nerve cell adhesion molecule N‐CAM also inhibited binding of Neuro‐2A cells specifically to collagen. This inhibition of cell‐surface binding was accompanied by a repression of neurite outgrowth in differentiating cells in the presence of antibodies. APP antibodies also inhibited neuron‐neuron and neuron‐glial binding, but not glial‐glial cell adhesion. These data suggest that the APP, which is expressed primarily on differentiated neuronal cells, may play a role in the mediation of both cell‐cell and cell‐substrate adhesion.
Identification of a cis‐acting positive regulatory element of glial fibrillary acidic protein gene
Authors: Sarid J. 
Published: January 2005

AbstractDevelopmental regulation of astrocyte‐specific expression of the glial fibrillary acidic protein (GFAP) gene reflects transition of immature glioblasts to mature astrocytes. Described here is the cloning and sequencing of the 5′‐flanking region of the mouse GFAP gene. It contains a glial‐specific positive cis‐acting regulatory element that directs preferential expression of a linked reporter gene when transfected into GFAP‐positive glioblasioma cells. Sequence analysis of this region revealed the presence of a putative AP‐1 binding site, implying a possible role for AP‐1 factors in the astroglial‐specific expression of the GFAP gene.
Excitatory amino acid‐induced alterations of cytoplasmic free Ca2+ individual cerebellar granule neurons: Role in neurotoxicity
Authors: Milani D. , Guidolin D. , Facci L. , Pozzan T. , Buso M. , Leon A. , Skaper S. D. 
Published: January 2005

AbstractThe effects of glutamate on intracellular free Ca2+ [Ca2+]i, and neurotoxicity were compared in cerebellar granule neurons in vitro. [Ca2+]i, was measured with fura‐2 and digital fluorescence imaging microscopy; neurotoxicity was monitored using a vital dye and colorimetric analysis. Glutamate produced dosedependent increases in [Ca2+]XSi transient for glutamate concentrations in a range of : 0.01–0.5 μM and sustained for higher levels of glutamate. The ED50 for the [Ca2+]i response to glutamate was. 6 μM. The LQ50 for glutamate‐induced neurotoxicity was similar, i.e., 10 μM The effect of glutamate on [Ca2+]i was greatly dmiinished when external Ca2+ was removed and blocked by Mg2++ N‐methyl‐D‐aspartate (NMDA)‐type receptor antagonists. The latter conditions as well as preloading granule neurons with the intracellular Ca2+ chelator quin2 largely prevented glutamate cytotoxicity. The neurotoxic effect of glutamate required incubations with the stimulus for 10–20 min at 25°C. Withdrawal of glutamate after this period was accompanied by a prolonged alteration in [Ca2+]i. Pretreatment cells with the ganglioside GM1 reduced this late increase in [Ca2+]i, as well as the neurotoxic effects of glutamate. This indicates that glutamate‐induced neurotoxicity results from a composite of diverse temporal alterations in Ca2+ homeostasis and that blunting any of these components reduces excitotoxicity.
Platelet‐activating factor increases glutamine synthetase activity in early and late passage C‐6 glioma cells
Authors: Kentroti S. , Baker R. , Lee K. , Bruce C. , Vernadakis A. 
Published: January 2005

AbstractPrevious studies from this laboratory have shown that C‐6 rat glioma cells (2B clone) exhibit specific phenotypic characteristics depending on passage in culture and that these populations respond differentially to addition of various exogenous compounds to the medium. Early passage (<25) C‐6 glial cells express low glutamine synthetase activity (a marker for astrocytes) and with increasing cell passage (>70) C‐6 glial cells express more astrocytic properties with respect to both glutamine synthetase (GS) and morphology. In this study, cells from both early (glioblastic) and late (astrocytic) passage were examined for their response to the phospholipid, platelet‐activating factor (PAF). We found that PAF increased GS activity in early passage (glioblastic) cells and more importantly it increased GS activity in late passage cells, already committed to the astrocytic pheriotype. Furthermore, cells from both passages failed to respond to addition of lyso‐PAF, the non‐biologically active analog of PAF, to the medium, By following the uptake of 3H‐PAF into cells, we observed that >90% of the phospholipid was taken into the cells within the first hour of incubation. We compared the PAF effects with that of dibutyryl cyclic AMP (dBcAMP) and RO20‐1724, a phosphodiesterase inhibitor. Cells from the early passage responded to both dBcAMP and RO20‐1724 treatments with a significant increase in GS activity whereas cells from the late passage showed no significant change, confirming earlier reports from this laboratory. These findings indicate that the response of C‐6 glioma cells to PAF (at least in the late passage) is not mediated via cyclic AMP. We suggest that in early passage cells PAF promotes expression of the astrocytic phenotype and in late passage cells PAF mediates a gliosis‐type response.
Oligodendroglial cell death induced by oxygen radicals and its protection by catalase
Authors: Kim Y. S. , Kim Seung U. 
Published: January 2005

AbstractThe cytotoxic effects of oxygen radicals have been studied in enriched population of mature bovine oligodendrocytes in culture. Oxygen radicals were generated enzymatically by glucose and glucose oxidase, and hypoxanthine and xanthine oxidase combinations. Cytotoxicity was assessed by trypan blue exclusion and percentage lactate dehydrogenase release into the culture media. Incubation of bovine oligodendrocytes with these oxygen radical‐generating systems for 4 hr resulted in significant cell death, especially in the glucose oxidase system. The oligodendrocytes were completely protected by catalase from the cytotoxic effects of both oxygen radical generating systems. However, superoxide dismutase, dimethylsulfoxide and antioxidants such as vitamin E and glutathione did not protect oligodendrocytes from the oxidant‐mediated cytotoxicity. It appears that hydrogen peroxide produced in these oxygen radical‐generating systems gives rise to toxic radicals that induce the cell death of bovine oligodendrocytes in culture.
Developmental and regional expression of choline acetyltransferase mRNA in the rat central nervous system
Authors: Ibáñez Carlos F. , Ernfors P. , Persson H. 
Published: January 2005

AbstractThe developmental and regional expression of choline acetyltransferase (ChAT) mRNA was examined in the rat brain and spinal cord by northern blot analysis and in situ hybridization. ChAT mRNA expression in the brain showed a biphasic increase during development, with a first peak at two weeks postnatally, a marked decrease by the third week, and a second increase between the third and fifth week after birth, indicating that emergence of the cholinergic phenotype occurs at different times in different brain regions. In the spinal cord, ChAT mRNA was detected at similar levels from embryonic stage 13 (E13) until birth, increasing thereafter until adulthood. In the adult rat central nervous system, high levels of ChAT mRNA were detected in the spinal cord and brain stem structures. Lower levels were seen in midbrain, septum, striatum, thalamus, and olfactory bulb. ChAT mRNA containing cells were identified by in situ hybridization in the olfactory tubercule, piriform cortex, striatum, several basal forebrain nuclei, and spinal cord. A nearly twohyphen;fold increase in adult spinal cord ChAT mRNA levels were seen one week after a bilateral crush lesion of the sciatic nerve, indicating that ChAT mRNA expression is regulated during mooneuron regeneration.
Effects of sphinigosine on phorbol ester‐mediated changes in astrocyte morphology and protein phosphorylation
Authors: Hamson Beth C. , Staskavage D. L. , Mobley Philip L. 
Published: January 2005

AbstractPrevious studies indicate that phorbol myristate acetate (PMA) can induce morphological changes in astrocytes cultured from the rat neocortex. PMA also increased 32 P incorporation into several proteins, including glial fibrillary acidic protein (GFAP), vimentin, and proteins with molecular weights of 80,000 (pI 4.5), 50,000 (pI 4.9), and 30,000 (pI 5.5). The present studies were conducted to determine if the morphological effect and the phosphorylation effect of PMA could be blocked by treatment with sphingosine, a protein kinase C inhibitor. Treatment with 15 μM sphingosine inhibited the effect of PMA on astrocyte morphology. This agent also inhibited the increase in phosphorylation mediated by PMA. The percent inhibition ranged from approximately 20% for the 30,000‐M protein to 70% for GFAP. Analysis of phosphorylation sites on GFAP and vimentin using two‐dimensional tryptic mapping techniques indicate that the partial inhibition of phosphorylation is likely the consequence of partial inhibition of protein kinase C rather than a selective inhibition at some phosphorylation sites and not others. In addition to increasing 32P incorporation into various proteins, PMA alsodecreased 32P incorporation in several 20,000‐Mr proteins (pI values of 6.7, 6.4, 6.2, 4.9). However, this effect was not blocked by treatment with sphingosine. This suggests that the actions of PMA to increase and decrease 32P incorporation are mediated by different mechanisms.
Early alterations of Gi/Go protein‐dependent transductional processes in the retina of diabetic animals
Authors: Abbracchio Maria P. , Cattabeni F. , Giulio A. M. Di , Finco C. , Paoletti A. M. , Tenconi B. , Gorio A. 
Published: January 2005

AbstractThe early alterations of G‐protein‐dependent transductional mechanisms have been characterized in the retina of alloxan‐treated diabetic rats. Five weeks after alloxan injection, pertussis toxin radiolabeling of Gi/Go proteins was markedly reduced in the retina of diabetic animals, suggesting either a reduced expression and/or the presence of some structural modification of these G‐protein subtypes. The functional activity of Gs proteins, measured as stimulation of membrane adenylate cyclase by dopamine, did not seem to be impaired at this stage of the pathology; basal adenylate cyclase activity was indeed increased in diabetic rats, consistent with the observed reduction of Gi/Go inhibitory proteins. Such functional alterations of the cAMP producing system were causally related to diabetes induction, since they were reversed by treatment of diabetic animals with insulin. These results suggest that G‐protein dependent transduction mechanisms are altered in the retina of diabetic animals, and that a defect of Gi/Go proteins could represent an early transductional damage in the development of diabetic retinopathy.
Acetylcholinesterase distribution in subpopulations of murine thymocyte
Authors: Rossi Adelaide , Vicini E. , Scarsella G. , Biagioni S. 
Published: January 2005

AbstractThe presence of acetylcholinesterase has been detected in the thymus of several species both biochemically and histochemically.In this study we have investigated the molecular forms and the level of this enzyme in separate compartments of the murine thymus and in different thymocyte subpopulations.Similar levels of acetylcholinesterase activity are present both in thymocytes and in the stromal component. Sucrose density gradient analysis revealed the presence of a single molecular form of about 5 S, presumably a dimeric form.Moreover the results demonstrate a preferential association of AChE with mature thymocyte subsets (Peanut Agglutinin negative and Corticoresistant).This finding correlates with the preferential sensitivity of these cells to cholinergic drugs and supports the hypothesis that acetylcholinesterase modulates the cholinergic effects on thymocytes.
Phosphyorylation of brain (NA+,K+) ‐ATPase alpha catalytic subunits in normal and epileptic cerebral cortex: I. The audiogenic mice and the cat with a freeze lesion
Authors: Guillaume D. , Grisar T. , Delgado‐escueta A. V. , Bureau‐heeren M. , Laschet J. 
Published: January 2005

AbstractPartially purified (Na+k+) ‐ATPase (E.C. 3.6.1.3)was investigated in the epileptic cortex of audiogenic DBA/2 mice and in the primary and secondary foci of cats with acute of chronic freeze lesions. No difference in specific activities measured at 3 mM K+ were observed between elliptic and control cortex, except an increase of enzymic activities in the primary focus of acutely lesioned cats. The (Na+, K+) ATPase capalytic subunits were resolved by SDS‐gel electrophoresis and their phosphorylation levels were measured in presence of K+ ions and phenytoin.K+ was more effective in including maximal de phosphorylation of (Na+, K+)‐Atpase in C57/BL, with identical affinity in the two strains. Phenytoin decreased the net phosphorylation level of (Na+, K+)‐ATPase by about 50% in C57/bl mice, but only by 20% in DBA/2 mice. Both K+ and phenytoin dephosphorylating influence were decreased in primary and secondary foci of acutely lesioned cats. Those changes were limited to the alpha(–) subunit. In chronic cats, the dephosphorylating step of the (Na+, K+)‐ATPase catalytic subnit recovered a normal affinity to K+, but its sensitivity to phenytoin remained decreased.Those differences in K+ and phenytion influences in brain (Na+, K+)‐ATPase between control and epileptic cortex might be responsible for the ictal transformation and seizure spread. In cats, the alteration of the alpha(–)isoform could mainly affect the glial cells.
Developmental modulation of physicochemical variants of the tailed asymmetric (16S) acetylcholinesterase by neuromuscular activity and innervation in the mouse embryo
Authors: Houenou L. J. , Garcia L. , Verdière‐Sahuqué M. , Villageois A. P. , Rieger F. 
Published: January 2005

AbstractWe have studied the physicochemical properties of acetylcholinesterase (AChE) during embryonic development of normal and functionally impaired mouse skeletal muscle, focusing on the tailed asymmetric (16S) form of the enzyme. The muscle‐specific 16S AChE exists in two different variants. One is associated with extracellular matrix and is high‐salt soluble (HSS, also termed hydrophilic AChE), whereas the other form is anchored to cell membranes and is detergent extractable (DE, or hydrophobic AChE). Before innervation during normal embryonic development, both hydrophilic and hydrophobic 16S AChE exist in equal amounts. After muscle innervation, there was an increase (amounting three‐fold on E18) in the levels of hydrophilic vs. hydrophobic 16S AChE. This alteration of the relative proportions of the two variants of 16S AChE did not occur in chronically inactive muscles either from the mouse mutant, muscular dysgenesis, or from tetrodotoxin‐treated mouse embryos. Taken together with previous reports, the present results suggest that postsynaptic membrane depolarization‐induced Ca2+ important in modulating not only the synthesis of 16S AChE, but also the relative proportions of both physicochemical variants of this molecular form of AChE.
Human monoclonal antineurofilament antibody cross‐reacts with a neuronal surface protein
Authors: Sadiq Saud A. , van den Berg L. H. , Thomas F. P. , Kilidireas K. , Hays A. P. , Latov N. 
Published: January 2005

AbstractIncreased titres of anti‐neurofilament antibodies have been reported in neurodegenerative disorders, and it has been suggested that such antibodies might be pathogenic. We investigated the specificity of an IgA monoclonal antibody (MAb) from a patient with amyotrophic lateral sclerosis which reacted with neurofilaments and bound to the surface of neuroblastoma cells. In Western blots, the immunoaffinity‐purified IgA bound to the 220–kD, high‐molecular‐weight neurofilament protein (NFH) and cross‐reacted with several closely migrating protein bands with apparent mobility of 62–68 kD in neuroblastoma cs and extracts of normal human spinal cord. Following crosslinking to the surface of radiolabeled neuroblastoma cells, the IgA MAb immunoprecipitated a 65–kD protein, indicating that the protein was present on the cell surface and available to the antibodies for binding. Several other MAbs to NFH did not immunostain the surface of neuroblastoma cells or bind to the 65‐kD protein, indicating that the protein was not a fragment of NFH. Thus, antibody binding to the 65–kD protein, possibly by cross‐reacting with NFH, may have contributed to the neuronal degeneration.
Developmental expression of the gene encoding growth‐associated protein 43 (GAP43) in the brains of normal and aneuploid mice
Authors: Capone G. T. , Bendotti C. , Oster‐Granite M. L. , Coyle Joseph T. 
Published: January 2005

AbstractThe gene encoding growth‐associated protein 43 (Gap43), a neuronal phosphoprotein associated with axonal outgrowth and synaptic plasticity, is located on mouse chromosome 16 (MMU16). We examined the developmental expression of Gap43 in normal, trisomy 16 (Tsl6), and trisomy 19 (Tsl9) mouse brain using northern blot analysis and in situ hybridization as a first step toward understanding the neurobio‐logic consequences of increased gene dosage on brain development. Gap43 expression was detected by in situ hybridization throughout the mesencephalon, rhombencephalon, spinal cord, and first branchial arch in whole embryos as early as (Jay 10 of gestation (E10). By E15, Gap43 expression was localized to cells in the retina, the olfactory bulbs, and anterior olfactory structures, the cortical plate, the basal telen‐cephalon, diencephalon, midbrain, hindbrain, ana spinal cord. Northern blot analysis detected a threefold increase in Gap43mRNA levels in the brains of normal mice between E12–E18. At E15, Gap43 mRNA levels were increased 35–40% in Tsl6 mouse brain and decreased 10% in Tsl9 mouse brain, relative to euploid littermate controls. Using in situ hybridization we found that overexpression of Gap43 occurred in the diencephalon, medial and lateral basal telencephalon, and cortical plate region in Tsl6 mice relative to littermate controls. Thus, the degree of overexpression of Gap43mRNA in Ts16 mice is consistent with that expected from gene dosage effects.
Temporal pattern of innervation in the developing mouse inner ear: An immunocytochemical study of a 66‐kD subunit of mammalian neurofilaments
Authors: Galinovic‐Schwartz V. , Peng D. , Chiu F. C. , Van De Water T. R. 
Published: January 2005

AbstractWe have examined the expression of a 66‐kD neurofilament protein (NF‐66) in the developing inner ear. Mouse embryos, fetuses, and neonates were fixed in Methacarn, embedded in paraffin, and sectioned. A polyclonal antiserum raised specifically to NF‐66 and unreactive to NF‐L, ‐M, ‐H, and peripherin was used for immunocytochemical staining. NF‐66 immunostaining was first detectable in the rhombencephalon at embryonic day (E) 9.5. Immunoreactivity was first detected in the statoacoustic ganglion (SAG) early on E10.5. By late E10.5, the first SAG axons were detectable within the intraepithelial spaces of the otocyst. At E12, NF‐66 positivity was detectable in neurites that projected into areas of presumptive vestibular sensory epithelium. Neurites projecting into the presumptive acoustic sensory epithelium were negative. However, at E13, the projections from both the vestibular and the acoustic ganglion (i.e, cochlear duct) were both NF‐66 positive. In the cell bodies, NF‐66 expression appeared earlier in the vestibular than in the auditory neurons. By E16, neuronal somas in both ganglia were NF‐66 positive.