bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oligodendroglial structures and distribution shown by carbonic anhydrase immunostaining in the spinal cords of developing normal and shiverer mice
Authors: Cammer W. , Sacchi R. , Kahn S. , Sapirstein V. 
Published: January 2005

AbstractThe spinal cords of young and adult normal and dysmyelinating mutant (shiverer) mice were immunostained with anticarbonic anhydrase to investigate (1) the distribution of oligodendroglial populations into the gray‐ and white‐matter regions in the developing normal and mutant animals; (2) the morphology of oligodendrocytes and their processes at the light microscopic level in gray matter and white matter; and (3) the apparent gliosis in the gray matter, as well as the white matter, of the mutants. Immunocytochemistry and enzyme assays revealed consistent increases in carbonic antigenicity and specific activity in controls and mutants between the ages of ˜ 15 days and ˜ 60 days. As shown previously in adult animals, oligodendroglia in larger than normal proportions were situated at the periphery of the “white‐matter” columns, as compared to gray matter, in the shiverers, with, however, significant numbers of oligodendroglia also occurring in gray matter. In normal white matter, at all ages, the oligodendroglia were heterogeneous with respect to shapes, configuration of processes, and intensity of carbonic anhydrase immunostaining. In the shiverer “white matter” the oligodendrocytes were smaller than normal, and their shapes and arrangement were relatively irregular. In the normal gray matter short oligodendroglial processes appeared to be associated with neuronal perikarya, and those processes were more pronounced at ˜ 90 days than at ˜ 20 days of age. Background staining in normal gray matter suggested that oligodendroglial processes were, in addition, tightly wound around many axons. In shiverer gray matter the oligodendrocytes were smaller, and their processes appeared to be wrapped more loosely around smaller numbers of conspicuous axons and to be associated less frequently with neuronal perikarya. This finding suggests that the deficiency in the myelin basic protein in the mutant may affect interaction betwen oligodendrocytes and neurons in the gray matter as well as in the white matter. The astrocytic “marker,” glial fibrillary acidic protein, was detected in gray and white matter of shiverers as young as 16 days, and the differences from carbonic anhydrase localization supported the conclusion that the processes enwrapping axons in the shiverer mouse CNS are derived from oligodendrocytes, not astrocytes.
Laminin supports short‐term survival of rat septal neurons in low‐density, serum‐free cultures
Authors: Pixley S. K. R. , Cotman C. W. 
Published: January 2005

AbstractSeptal neurons from embryonic rats do not survive for 24 hr when dissociated and cultured at low density in a serum‐free medium. Lamunin at 5–40 μg/ml acts as a survival‐promoting agent in the presence of 1 mM pyruvate. Laminin is effective in promoting survival only if it is added before or during cell plating; it does not support survival if added after cell attachment. Variations in laminin concentration do not effect the total number of cells attaching to the culture plate. The percentage of septal cells with neurites is increased in a dose‐dependent manner by laminin as early as 45 min after cell plating, suggesting an effect of laminin on the rate of neurite initiation. Neurite extension at 24 hr is also dependent on laminin concentration. This study suggests that some interaction between cells and the substrate, independent of cell attachment, has a profound effect on cell physiology, increasing both cell survival and the rate of neurite extension. This study also defines the survival requirements of septal neurons in a chemically defined environment in a low‐density situation where cellular interactions are at a minimum.
Characterization of antibodies against major fish CNS myelin protein: Immunoblot analysis and immunohistochemical localization of 36K and IP2 proteins in trout nerve tissue
Authors: Jeserich G. , Waehneldt T. V. 
Published: January 2005

AbstractAntisera against the trout CNS myelin proteins 36K and IP2 were prepared in rabbits and characterized by immunoblot analysis and immunohistochemistry. The anti‐36K antiserum exclusively stained its corresponding antigen from trout CNS myelin but failed to recognize any myelin polypeptide from either trout PNS or mammalian CNS and PNS. Antibodies against the IP2 glycoprotein specifically cross‐reacted with related intermediate proteins (IP) of both CNS and PNS myelin from trout but only faintly labeled the P0 protein of mouse peripheral nerve. Immunohistochemical localization of both antigens in the CNS of young trout was confined to the myelin sheath, except that anti‐36K antiserum also stained oligodendrocytes. Nodes of Ranvier, neuronal cell bodies, and dendrites, as well as other glial elements, were negative. Specificity of the immunofluorescent reaction was established by crossed immunoadsorption experiments. Whereas on adjacent sections through trout brain both antigens exhibited a nearly identical distribution pattern, immunostaining in peripheral nerves was seen only with anti‐IP2 antibodies.
Gangliosides inhibit phospholipid‐sensitive Ca2+‐dependent kinase phosphorylation of rat myelin basic proteins
Authors: Kim J. Y. H. , Goldenring J. R. , DeLorenzo R. J. , Yu R. K. 
Published: January 2005

AbstractGangliosides inhibit the phosphorylation of both small and large rat myelin basic proteins (SMBP, LMBP) by an endogenous phospholipid‐sensitive Ca2+‐dependent protein kinase (C‐Kinase). Using a rat brain myelin preparation in an in vitro phosphorylation assay system, we determined the inhibition constants (IC50's) of the gangliosides GM1, GD1a, GD1b, and GT1b to be approximately 160 μM, 65 μM, 65 μM, and 40 μM, respectively. Asialoganglioside GA1, ceramide, and Nacetylneuraminic acid (NANA, sialic acid) failed to produce similar inhibition, suggesting that both the lipid and the sialic acid moieties are necessary, but neither alone is sufficient to produce inhibition. The results indicate that gangliosides may regulate protein kinase C activities in the nervous system.
Primary retinal and cortical glial cell cultures: Effects of medium and serum on attachment and growth
Authors: Trachtenberg M. C. , Hokanson K. M. 
Published: January 2005

AbstractGlial cells of the retina are anatomically distinctive and are thought to contribute importantly to retinal electrophysiology. However, no adequate preparation exists for studing them in isolation, in vitro. This report provides guidelines for primary retinal glial cultures (RET) and compares basal tissue culture features with those for neocortical glia (CX) and the well‐studied rat glial line, C6.Cell attachment and growth of RET, CX, and C6 are unique. These differences are explored by the use of specific media and sera. RET attachment, unlike that for CX or C6, was far more sensitive to medium than serum. RET cells attached least quickly, CX most quickly; 4 hr after plating 20% of RET remained unattached. RET growth was poor and relatively insensitive to medium.In contrast, growth of CX or C6 was medium dependent. Serum had substantial effects on the growth of all three glial lines. Pig, goat, horse, and dog sera were particularly effective, often comparing favorably to fetal calf serum. Medium or serum optimal for cell attachment, typically, was not optimal for growth and serum effects were more dramatic than those of medium. By all measures, CX and C6, both derived from brain, were more alike than were the two rabbit primaries, CX and RET. The data reveal substantial differences between presumably similar cells and indicate a need for an empirically based choice of both basal‐salt media and serum to optimize specific aspects of cell development in culture.
Neurite‐promoting activity from fetal skeletal muscle: Partial purification of a high‐molecular‐weight form
Authors: Steele J. G. , Hoffman H. 
Published: January 2005

AbstractNeurite extension from sensory neuroblasts dissociated from chick embryo dorsal root ganglia can be stimulated by precoating the polylysine culture surface with extracts of skeletal muscle from bovine fetuses. The active factor(s) may be partially purified from cytosolic extracts of muscle by chromatography on Sepharose 6B and affinity chromatography on wheat germ agglutinin or Helix pomatia agglutinin columns. Extract concentrations of 10–50 μg protein per 1 ml were active in promoting neurite extention when the neurons were cultured without serum or nerve growth factor (βNGF). However, levels of 1–10 μ/m1 produced dramatic neurite extension when 10% (v/v) fetal or newborn calf serum or 0.5 ng/ml βNGF was added to the medium. The biological activity was not blocked by antiserum that was raised against purified mouse laminin and that abolished the neurite‐promoting activity of mouse laminin. The activity of the muscle extract was destroyed by trypsin or heparitinase, in contrast to the biological activity of purified mouse laminin, which was not abolished by heparitinase treatment. The activity could be resolved into two broad peaks on a Sepharose 2B column (apparent Mr between 2 × 106 and in 10 × 106 in native form). Treatment with dithiothreitol was necessary to dissociate the factor for electrophoresis in 4.25% polyacrylamide‐SDS gels, revealing three major polypeptide bands at Mr = 160,000, 195,000 and 200,000. This preliminary charcterization indicates that the neurite‐promoting activity from bovine skeletal muscle tissue consists of a high‐molecular‐weight complex, one essential component of which is a heparan sulfate.
An immunochemical analysis of a myelin basic protein serum factor: Cross reactivity with residues 69–71 of the rabbit encephalitogenic sequence 65–74 of myelin basic protein
Authors: Potter N. T. , Hashim G. A. , Day E. D. 
Published: January 2005

AbstractA partially purified myelin basic protein serum factor (MBP‐SF), cross‐reactive with residues 65–74 (TTHYGSLPQK) of myelin basic protein, has been employed in an immunochemical study to identify the nature of the cross‐reacting determinant, more precisely. To probe the structural requirements of this determinant, Scatchard inhibition analyses and competitive peptide inhibition radioimmunoassays were employed with a series of peptide analogs of the 65‐74 region and with three different reagent antisera: a rabbit anti‐rat myelin antiserum (#My05) and two antisera, one rabbit (#162) and one chicken (#66), raised against synthetic peptide S24 (TTHYGSLPQKG). Scatchard inhibition analyses with MBP‐SF revealed specific inhibition of binding of 125I‐S24 to #162 and #My05, but not to #66. Further delineation of the structural requirements of the cross‐reactive determinant, employing a liquid‐phase radioimmunoassay, revealed a unique reactivity pattern for the chicken anti‐S24 antiserum which, unlike #162 and #My05, did not cross‐react under high‐affinity conditions with synthetic peptide S20 (GSLPQK, representing the C‐terminal half of S24). This, in concert with the Scatchard data, is suggestive of the presence of a cross‐reactive determinant centered around residues 69–71 of MBP.
Acetylcholinesterase of Schistosoma mansoni: Purification and characterization
Authors: Goldlust A. , Arnon R. , Silman I. , Tarrab‐Hazdai R. 
Published: January 2005

AbstractLarval acetylcholinesterase (acetylcholine acetylhydrolase) EC 3.1.3.7 of the trematode Schistosoma mansoni was characterized and purified by affinity chromatography. The enzyme was solubilized from sonicated cercarial tissue and showed a Km value of 1.83 mM and a Vmax value of 102 U/mg protein. It was characterized as a true AChE since it hydrolyses acetylthiocholine more than seven times faster than butyrylthiocholine, and since it was inhibited by high concentrations of substrate. The enzyme was purified by affinity chromatography on a Sepharose column of the inhibitor [N‐(6‐aminocaproyl‐6‐aminocaproyl)‐maminophenyl] trimethyl ammonium. The purified enzyme eluted from the column by decamethonium bromide migrated as a single band of 500 kD on nondenaturing polyacrylamide gel electrophoresis (PAGE), whether stained for proteins or for enzymatic activity. Analysis by SDS‐PAGE revealed two major polypeptide bands of 76 kD and 30 kD. By labeling the enzyme with 3H‐DFP (di‐isopropyl‐fluorophosphate), the 30‐kD polypeptide was shown to contain the active site of the enzyme, with an additional labeled band of 110 kD also being detected.On the basis of our data we suggest that the principal species of S. mansoni AChE is a tetramer of four subunit polypeptides each of MW ca. 110 kD which are not linked by disulfide bonds, and which are further cleaved into two fragments, one of MW 76,000 and one of MW 30,000, the latter bears the active site.
An efficient approach for the selective isolation of specific transcripts from complex brain mRNA populations
Authors: Rhyner T.A. , Biguet N. Faucon , Berrard S. , Borbély A.A. , Mallet J. 
Published: January 2005

AbstractAs a consequence of the complexity of the nervous system, many characteristic proteins are only expressed at low levels, and their detection and purification often represents a formidable task. A strategy based on liquid hybridizations, which greatly facilitates the identification of the mRNA transcript for this kind of protein, is presented here. A ten‐fold‐enriched recombinant library was generated from cDNA transcribed from forebrain mRNA after subtraction of cerebellum sequences. Clones specific to forebrain could then be revealed with cerebellum subtracted probes, by colony hybridization. The use of selected cDNA populations greatly enhanced the sensitivity of the screening procedure; clones corresponding to transcripts present at an abundance as low as 0.0005% could still be detected. About 5% of specific clones were recognized with an enriched forebrain probe. Additional clones were revealed with subtracted probes from restricted areas such as cerebral cortex, brainstem, and hippocampus. The important features and potential applications of this approach are discussed.
Developmental expression of myelin basic protein mRNA in a hypermyelinating mouse
Authors: Miskimins R. , Yu R.K. 
Published: January 2005

AbstractPolysomal poly (A)+ RNA and total cellular RNA were isolated from the brains of C57BL/6J (B6), DBA/2J (D2), and F1 hybrid mice. Both types of RNA were isolated at 9, 12, 16, 21, and 30 days of age. By using a 32P‐labelled cDNA probe for myelin basic protein (MBP; pMBP‐1) the amounts of RNA coding for MBP present in the three strains at each age were determined. For both the polysomal poly(A)+ and total cellular RNA the peak of MBP RNA accumulation was at about 16–18 days for all three strains. These results imply that the developmental pattern of MBP RNA synthesis for F1 mice is not shifted with respect to the parental strains. For the polysomal poly(A)+ RNA, F1 had the greatest amount of MBP mRNA, B6 the least, and D2 an intermediate amount. F1 again had the greatest amount of MBP RNA from the total cellular pool at all ages. However, B6 had a greater amount of MBP RNA in the total cellular RNA pool than did D2. This demonstrates elevated transcription of the MBP gene in the F1 or an increase in message stability in this strain. It also suggests some form of translational control for MBP RNA in the B6 strain. In addition a second species of MBP RNA was found in the total cellular RNA pool. This species is larger than the major polysomal RNA band and may be a nuclear precursor.
The hormonal regulation of gene expression of glial markers: Glutamine synthetase and glycerol phosphate dehydrogenase in primary cultures of rat brain and in C6 cell line
Authors: Kumar S. , Holmes E. , Scully S. , Birren B.W. , Wilson R.H. , de Vellis J. 
Published: January 2005

AbstractIncreases in the mRNA levels of two neuroglial markers, glutamine synthetase (EC 6.3.1.2; GS) and glycerolphosphate dehydrogenase (EC 1.1.1.8; GPDH), were observed in hydrocortisone‐treated cultures of astrocytes and oligodendrocytes, respectively, and in C6 cells by Northern blot analysis and in situ hybridization. In vitro transcription assays demonstrated increased GS transcription in isolated nuclei from hydrocortisone (HC)‐treated primary cultures of astrocytes and C6 cells, relative to untreated cells. This increased transcription is reflected in increased GS mRNA levels in the cytoplasm and increased levels of GS protein synthesis. Sodium butyrate (NaB) blocked the glucocorticoid‐mediated increase in GS transcription in the primary cultures of astrocytes but not in C6 cells. From our earlier observations (Kumar et al: J Neurochem 43:1455–1463, 1984) we found NaB in combination with HC to increase the levels of GS mRNA and GS protein synthesis (Weingarten et al: FEBS Lett 126:289–291, 1981). We now report that NaB, alone or in combination with HC, does not increase the rate of transcription, suggesting that NaB plays a role in post‐transcriptional regulation of GS in C6. In addition, we report the presence of two distinct sizes of GS mRNA, 2.9 and 1.8 kb, in the primary cultures of astrocytes and C6 cells.
Myelin basic protein‐specific protein methylase I activity in shiverer mutant mouse brain
Authors: Kim S. , Tuck M. , Ho L.‐L. , Campagnoni A.T. , Barbarese E. , Knobler R.L. , Lublin F.D. , Chanderkar L.P. , Paik W.K. 
Published: January 2005

AbstractMyelin basic protein (MBP)‐specific protein‐arginine N‐methyltransferase (protein methylase I) activity in homozygous shiverer (shi/shi) mutant mouse brain is significantly higher than in than normal littermate brain at the onset of myelination. While the enzyme activity (expressed as pmol os S‐adenosyl‐L‐[methyl‐14C] methelination used /min/mg enzyme protein) increase coincidently during the period of myelination in the normal brain (15–18 days of age), it decreases significantly in the mutant brain during this period of time. These results are in contrast to those found with another dysmyelinating mutant, jimpy (jp/Y) mice, in which the enzyme activity in the mutant brain is similar to that in the normal animals but remains unchanged during the myelination process. There is no difference in the weight and protein concentration of the normal and shiverer mutant brains with corresponding ages, and the histone‐specific portein methylase I activity is also unaffected in the shiverer brain.
Correlation between inhibition of myelin basic protein (arginine) methyltransferase by sinefungoin and lack of compact myelin formation in cultures of cerebral cells from embryonic mice
Authors: Amur S.G. , Shanker G. , Cochran J.M. , Ved H.S. , Pieringer R.A. 
Published: January 2005

AbstractSinefungin, a known inhibitore of protein methylation, inhibited the myelin basic protein (arginine) methyltransferase activity in homogenantes of cultured cererbral cells from embryonic mice. Fifty percent inhibition was achieved with 25μ M sinefungin. Electron microscopie examination of the myelin fraction, isolated by gradient density centifugation and obtained from untreated cells, revealed numerous ringlike multilamellaar membranous substructures that had a major dense line periodicity, compactness, and the general apperance expected of myelin obtained by the same technique from whole brain. Cells treated with 30 μM sinefungin, which inhibits myelin basic protein methyltrnasferase in broken cell preprations about 60%, produced ringlike structures that were devoid of multiameller periodicity and compactness reminiscent of the vacuolated myelin observed in subacute combined degeneration and in nitrous‐oxide‐ or cycloleucine‐treated animals in which methyltransferase activity is also inhibited. The sinefungin‐induced change in multiamellar periodicity cannot be attributed to a lack of myelin basic protein, since the ratio of myelin basic protein to total protein did not decrease in sinefungin‐treated cells. This primary culture system should be useful for further evaluting the hypothesis that the methylation of mylein basic protein is related to the formation of compact myelin.
Glial culture on artificial capillaries: Electron microscopic comparisons of C6 rat glioma cells and rat astroglia
Authors: Tiffany‐Castiglioni E. , Neck K.F. , Caceci T. 
Published: January 2005

AbstractThe functional association of astroglial footplates with blood vessels is important because astrocytes may provide a channel between the blood and neurons deeper in the brain parenchyma for the passage of ions and metabolites. This hypothesized function is very difficulty to study in vivo or in monolayer cultures. We have produced a three‐dimensional cell culture model of perivascular astroglia by means of an artificial capillary system. Conventional primary cultures of astroglia were first prerpard from neonatal rat cererbral hemispherers in 75‐cm2 tissue culture flasks. After 25 days, the cells were seeded in Amicon Vitafiber hollow fiber culture vessels. Direct seeding of brain cell suspensions was not successful. A culture unit consists of a bundle of hollow, semi‐permeable polysulfone fibers encased in a plastic shell. The fibers were coated with fibronectin and bovine serum albumin, and astroglia were seeded on their outer surfaces. Warmed medium was pumped through the lumina of the fibers. After 13 days the cells were fixed with paraformaldehyde and examined. Scanning electron microscopy reevealed the tubes to be uniformly covered with astroglia with short processes that contacted nearby cells. Transmission electron microscopy showed glial filaments glioma cells in hollow fiber culture. The astrocytes formed a monolayer, whereas C6 cells formed a stratified culture. Furthermore, C6 cells did not form gap junctions. Astrocytes have been hypothesized to take up K+ discharged to the extracellular space by deploarizing neurons and move it to areas of low concentration, i.e., to act as a K+ spital buffer. Our culture system should permit direct testing of this hypothesis.
A reinterpretation of tyramine sympathomimetic effect and tachyphylaxis
Authors: Raiteri M. , Levi G. 
Published: January 2005

AbstractIn this commentary, the indirect sympathomimetic effect of tyramine and the phenomenon of tyramine tachiphylaxis are reinterpreted in terms of carriermediated excahange processes. Extracellular tyramine would exchange with intraterminal noradrenaline and, upon repeated tyramine administration, with a mixture of noradrenaline and tyramine progressively more enriched in the pharmacologically inactive amine.
Central versus peripheral effects of bombesin on the release of gastrointestinal hormones in dogs
Authors: Lu Q.‐H. , Swierczek J.S. , Zhu X.‐G. , Greeley G.H. , Thompson J.C. 
Published: January 2005

AbstractThis study compared the effects of bombesin given intracerebroventicularly and intravenously on circulating levels of gastrin, pancreatic polypeptide (PP), and cholecystokinin (CCK‐33). Bilateral cannulas were implanted permanently into the lateral cerebral ventricles of five dogs. An intravenous (IV) bolus injection of bombesin (0.25 μg/kg) significantly elevated circulating levels of gastrin, PP, and CCK‐33. Vagotomy inhibited the release of PP that was induced by IV bombesin, but vagotomy did not affect gastrin and CCK‐33 responses. Intracerebroventricular injection of bombesin (5.0 μg) significantly elevated circulating gastrin levels but did not affect circulating levels of CCK‐33 and PP. Vagotomy did not alter gastrin release induced by intracerebroventricular injection of bombesin.