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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this communication we describe serum-free culture conditions for the serial propagation of the C6 glioma cell line. The growth rate, saturation density, and morphology of these cells are equivalent to those of their serum-grown counterparts when cultured in a 3:1 mixture of Dulbecco's modified Eagle's medium and Ham's medium F-12 supplemented with trace elements, insulin, transferrin, fibroblast growth factor, linoleic acid complexed to fatty acid-free bovine serum albumin, and a serum-spreading factor (SSF) partially purified from human plasma. The requirement for SSF in the medium can be satisfied by preincubating the tissue culture dishes with SSF. Tissue culture dishes sequentially pretreated with poly-D-lysine and purified cold insouluble globulin will also substitute for this requirement. The fatty acid-free bovine serum albumin/linoleic acid complex increases the growth rate of these cells but has no appreciable effect on their morphology, saturation density, or ability to grow with repeated subculture. The growth stimulation caused by this complex appears to be dependent on the fatty acid, as the fatty acid-free bovine serum albumin alone has no effect on the growth rate. Linoleic acid is cytotoxic in the absence of bovine serum albumin, and the fatty acid-free bovine serum albumin prevents this toxicity. Other fatty acids including oleic, arachidonic, and palmitic only partially substitute for the growth-promoting effect of linoleic acid.
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PMID:Continuous culture of rat C6 glioma in serum-free medium. 700 Jul 95

The usefulness of proliferating cell nuclear antigen (PCNA) immunostaining for estimating the growth fraction in glial tumors was evaluated in ethylnitrosourea-induced rat gliomas. The PCNA labeling index was compared with the bromodeoxyuridine (BrdU) labeling index, using alternate serial sections fixed either in 10% formalin or in periodonate-lysine-paraformaldehyde (PLP). The PCNA labeling index was significantly correlated with the BrdU labeling index if cells with only faint PCNA staining were excluded. Differences in PCNA staining were noted between the two fixatives. The number of PCNA-positive cells in PLP-fixed material was greater than in 10% formalin-fixed material, but showed a poorer correlation with BrdU labeling index. Over-fixation in formalin reduced the number of positive cells. Although peritumoral tissue did not exhibit overexpression of PCNA, the ependymal lining was weakly stained even in areas distant from the tumor. PCNA labeling index is a useful method to estimate the growth fraction when the materials are processed in a controlled way. When clinical specimens with uncertain preparation are used, care is required in interpreting the results.
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PMID:Proliferating cell nuclear antigen expression in rat glioma model: comparison with bromodeoxyuridine labeling index. 751 46

In the present study we investigated uptake of the nitric oxide (NO) synthase inhibitors NG-methyl-L-arginine and NG-nitro-L-arginine by the mouse neuroblastoma x rat glioma hybrid cell line NG108-15. Uptake of NG-methyl-L-arginine was characterized by biphasic kinetics (Km1 = 8 mumol/L, Vmax1 = 0.09 nmol x mg-1 x min-1; Km2 = 229 mumol/L, Vmax2 = 2.9 nmol x mg-1 x min-1) and was inhibited by basic but not by neutral amino acids. Uptake of NG-nitro-L-arginine followed Michaelis-Menten kinetics (Km = 265 mumol/L, Vmax = 12.8 +/- 0.86 nmol x mg-1 x min-1) and was selectively inhibited by aromatic and branched chain amino acids. Further characterization of the transport systems revealed that uptake of NG-methyl-L-arginine is mediated by system y+, whereas systems L and T account for the transport of NG-nitro-L-arginine. In agreement with these data on uptake of the inhibitors, L-lysine and L-ornithine antagonized the inhibitory effects of NG-methyl-L-arginine on bradykinin-induced intracellular cyclic GMP accumulation, whereas L-tryptophan, L-phenylalanine, and L-leucine interfered with the effects of NG-nitro-L-arginine. These data suggest that rates of uptake are limiting for the biological effects of NO synthase inhibitors.
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PMID:Characterization of neuronal amino acid transporters: uptake of nitric oxide synthase inhibitors and implication for their biological effects. 753 32

beta-amyloid protein (A beta) is produced from amyloid precursor protein (APP) is mainly secreted after cleavage within the beta-amyloid protein (A beta) sequence precluding A beta production. Stimulation of APP secretion inhibits A beta production in some cultured cells, which suggests that the relationship between these two processes is alternate. In this study, we investigated the effect of the inhibition of APP secretion on A beta production using stable transformants of glioma U251 which express the mutant APP695 with a lysine-to-valine substitution at residue 612. Immunoprecipitation analysis showed that the mutant APP695 was secreted much less compared to the wild protein. The respective ratios of the amount of secreted APP to that of cellular APP for the mutant and wild forms were 0.11 and 1.01. A beta production by the mutant APP also was suppressed. The respective ratios of the amount of secreted A beta to that of cellular APP for the mutant and wild forms were 0.022 and 0.13. Both processes of APP secretion and A beta production could be inhibited simultaneously by the mutation, which suggests that they are not always alternate. Immunocytochemistry showed that the mutant APP was not transported to the cell membrane. Both APP secretory processes may require the transportation of APP to the cell membrane.
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PMID:The mutation in amyloid precursor protein inhibits both alpha- and beta-secretion. 765 74

Binding of plasmin(ogen) to rat C6 glioma cells is saturable and kringle-domain dependent. This interaction was studied as a model of plasmin(ogen) receptor interactions in nucleated mammalian cells. Apparent 125I-plasmin dissociation from C6 cell binding sites was slow; however, the dissociation rate was increased when the solution contained diisopropyl phosphoryl-plasmin (0.3 microM), fibrinogen (0.16 or 0.8 mg/ml), 1.08 mM D-Val-L-Leu-L-Lys-p-nitroanilide-HCl (S-2251), or epsilon-amino-n-caproic acid (EACA, 5.0 mM). EACA promoted the most rapid dissociation of plasmin. C6 cell-associated plasmin and plasmin in solution demonstrated similar amidase activity. Only specifically bound plasmin (75% of total binding) was active against S-2251. Plasmin that was initially bound to C6 cells digested fibrinogen in a time- and plasmin concentration-dependent manner. alpha 2-Antiplasmin (alpha 2AP, 0.1 microM) completely inhibited fibrinogenolysis by plasmin that was initially C6- or human umbilical vein endothelial-cell associated. Since alpha 2AP reacts selectively with plasmin in solution (minimally with plasmin bound to cells), fibrinogen digestion by cell-associated plasmin probably occurred only after the plasmin dissociated into solution. Crosslinked fibrin clots were formed in uniform layers over C6 cells. If the cells were incubated with plasmin before addition of fibrinogen and thrombin, the clots were rapidly lysed. alpha 2AP incompletely inhibited fibrinolysis when added after fibrin polymerization (44% inhibition with 0.1 microM alpha 2AP). Fibrinolysis was completely inhibited when alpha 2AP was added before fibrin polymerization. These studies suggest that plasmin must first dissociate from cellular binding sites to mediate fibrinogenolysis or fibrinolysis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Fibrinogenolytic and fibrinolytic activity of cell-associated plasmin. 767 97

We have investigated the effects of the C-terminal amyloid precursor protein fragment His 657-Lys 676 upon calcium currents in NG108-15 neuroblastoma x glioma hybrid cells. The amyloid precursor protein fragment His 657-Lys 676 (1-10 microM) did not affect calcium currents per se, but clearly blocked the calcium current suppression mediated by both adrenergic alpha 2B- and opioid delta receptors in a concentration-dependent manner. The reverse amyloid precursor protein fragment Lys 676-His 657 and the shorter amyloid precursor protein fragment Gly 659-Lys 676 did not affect calcium current suppression by adrenergic alpha 2B- and opioid delta receptors. The similar interaction of C-terminal amyloid precursor protein with adrenergic alpha 2B- and opioid delta receptors suggest that the effect occurs downstream of the receptor, possibly via the GTP binding protein Go.
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PMID:The amyloid precursor protein fragment His 657-Lys 676 inhibits noradrenaline- and enkephaline-induced suppression of voltage sensitive calcium currents in NG108-15 hybrid cells. 787 Feb 93

Uptake of radiolabelled L-arginine was studied in four different kinds of glial cultures, in astroglia-rich primary cultures derived from neonatal rat and mouse brains, in pure murine astrocyte cultures, and in rat glioma cells C6-BU-1. A saturable component of uptake was found in all cases with KM values between 15 and 35 microM and Vmax values between 0.8 and 2.5 nmol.min-1.(mg protein)-1. In addition, in all cell types a non-saturable component dominated total uptake at high concentrations of extracellular arginine. Rates of uptake of arginine were not affected when Na+ or Cl- were absent from the incubation buffer. Carrier-mediated uptake of arginine was reduced by depolarizing concentrations of K+ and strongly inhibited by an excess of lysine or ornithine. Histidine, asparagine, glutamine, citrulline, creatine, NG-nitro-L-arginine, NG-monomethyl-L-arginine, or L-canavanine inhibited L-arginine transport to various degrees. Uptake of arginine was not reduced in the presence of serine or alanine cysteic acid, N-methyl-alpha-aminoisobutyric acid, or 2-aminobicyclo-(2.2.1)-heptane-2-carboxylic acid. Rates of uptake of arginine were increased when cells had been preloaded with lysine. Preincubation of primary cultures, but not glioma cells, with bacterial lipopolysaccharide stimulated transport of arginine by increasing the Vmax value of uptake. This stimulation was dependent on protein synthesis. The results suggest that, at physiological concentrations, arginine is taken up into the glial cells with the help of the transport system "y+" for basic amino acids. In glial primary cultures, uptake of arginine appears to be regulated by compounds which also exert influence on nitric oxide synthesis.
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PMID:Transport of L-arginine in cultured glial cells. 796 30

Poly(A)+ RNA from C6-BU-1 rat glioma cells and rat astroglial cells induced isoleucine transport activity when injected into Xenopus laevis oocytes. The Na+-independent component of isoleucine transport was inhibited by leucine, phenylalanine and 2-aminobicyclo[2,2,1]heptane-2-carboxylic acid (BCH) but neither by methylaminoisobutyric acid (MeAIB) nor lysine. A Km value of approx. 100 microM was determined for the Na+-independent transport of isoleucine. These data are in accordance with expression of a system L like transporter. By injection of size fractionated poly(A)+ RNA a length of approx. 1.9 kb was determined for the pertinent mRNA.
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PMID:Expression of Na+-independent isoleucine transport activity from rat brain in Xenopus laevis oocytes. 820 56

Three neuron-associated microtubule proteins, Class III beta-tubulin isotype, MAP-2, and tau, were evaluated in a comparative immunoblot and immunohistochemical study of the rat C-6 glioma cell line maintained for up to 31 days in vitro. Western blots on whole SDS extracts of cells grown: (i) as monolayers on plastic dishes (for 13 and 16 days); (ii) as monolayers on poly-D-lysine coated glass coverslips (for 3, 7, and 11 days); and (iii) as explants on Gelfoam matrices (for 10, 30, and 31 days) were probed with monoclonal antibodies (MoAb) specific for the above-mentioned microtubule proteins. For these and all other markers employed, immunoperoxidase histochemistry was performed only on the matrix cultures. The immunoblot experiments demonstrated that the Class III beta-tubulin isotype, MAP2, and tau were not expressed by the C-6 cell line in any of the culture conditions, nor were they found by immunohistochemistry. In contrast, explants from all culture conditions were positive for glial fibrillary acidic (GFA) protein and for a universal anti-beta-tubulin isotype MoAb by immunoblotting, as well as by immunohistochemistry in Gelfoam matrix cultures maintained in an organ culture system. Both sets of experiments indicate that these markers are not altered under three different conditions of growth over a one-month period in vitro. The expression of GFA protein and the absence of detectable levels of Class III beta-tubulin, MAP2, and tau are in keeping with the astrocytic phenotype of the C-6 cell line.
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PMID:Absence of neuron-associated microtubule proteins in the rat C-6 glioma cell line. A comparative immunoblot and immunohistochemical study. 823 55

Amyloid beta protein (beta/A4 or A beta), the main proteinaceous component of the amyloid depositions of the Alzheimer's brain, derives from the proteolytic processing of the amyloid precursor protein (APP). Cleavage of the amyloid precursor by at least two distinct secretase activities produces soluble secreted APP. The major secretase cleavage (site I) takes place between A beta 16 and 17, while the minor cleavage (site II) takes place after A beta Lys 28 and may produce potentially amyloidogenic secreted APP. Full-length cellular APP is cleaved by secretase intracellularly in the Trans-Golgi Network (TGN) or in post-Golgi vesicles. The resultant soluble APP is transported to the plasma membrane and exocytosed. The biological activity of the APP is still not completely understood, although it seems to act as a cell adhesion molecule. Recent studies have shown that in glioma cells, most of the soluble secreted APP occurs as a chondroitin sulfate proteoglycan (CSPG). In addition, full length APP CSPG has been detected in neuroblastoma and fibroblast cells as well as on the surface of glioma cells, and in human brain. These results suggest that the proteoglycan nature of the APP proteins may be important for their biological function.
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PMID:Cellular processing and proteoglycan nature of amyloid precursor proteins. 823 71


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