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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The Ca2+ inward current (ICa) and a slow outward current in differentiated cells of mouse neuroblastoma clone N1E-115 have been studied under voltage-clamp conditions. 2. ICa shows voltage- and time-dependent inactivation when evoked by step-wise depolarizations in Na+-free solution containing high [Ca2+] (20 nM) and tetraethylammonium (TEA, 25 mM). Ba2+ and Sr2+ can substitute for Ca2+. 3. Holding potentials below -70 mV maximal activate ICa. Half inactivation occurs at -56 mV and ICa is completely inactivated beyond holding levels of -30 mV. Maximum peak currents are of the order of 10(-4) A/cm2 and the reversal potential ranges from +40 to +60 mV. The ICa inactivation time course follows first-order kinetics with a voltage-depedent time constant ranging from 25 to 100 msec. 4. The striking resemblance between ICa and the Ca2+ current in the unfertilized mouse oocyte (Okamoto, Takahashi & Yamashita, 1977) is discussed. 5. A slow outward current with a rise time of several seconds is recorded on voltage steps beyond -20 mV in high [Ca2+] solutions. It is carried primarily by K+ on account of the value of the reversal potential and its dependence on [K]0. This K+ current is TEA-insensitive and is blocked by Ca2+ antagonists. 6. The slow K+ current (IK(Ca)) is suggested to be mediated by Ca2+ influx, but the voltage-dependence of the underlying conductance (GK(Ca)) differs significantly from the ICa voltage-dependence. 7. The results are consistent with the hypothesis that IK(Ca) depends both on ICa and on membrane potential. An alternative hypothesis is briefly discussed.
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PMID:The calcium current and the activation of a slow potassium conductance in voltage-clamped mouse neuroblastoma cells. 49 Mar 59

The authors examined both hard and soft glass evacuated blood-drawing tubes for possible effects on clinical chemistry measurements. Using routine laboratory procedures, no clinically or statistically significant difference could be detected in 34 analytes using 66 different methods. A special high-precision study utilizing an adaption of the NBS round-robin procedures for calcium, magnesium, sodium, and potassium detected no difference between paired sera when drawn or stored for 72 hours, or both, in the two types of glass. The authors conclude that the type of glass used in production of the evacuated blood-drawing tubes does not affect the clinical chemistry results obtained.
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PMID:A comparison of hard and soft glass blood-drawing tubes. 51 61

Cholinergic agonists inhibit the basal and PGE1-activated adenylate cyclase activity in membranes isolated from the mouse neuroblastoma x glioma hybrid cell NG108-15. Inhibition is observed with acetylcholine, acetyl-beta-methylcholine and carbachol and is blocked by two specific muscarinic antagonists, atropine and quinuclydinylbenzilate. Inhibition of basal and PGE1-activated activity is only partial. Carbachol-directed inhibition has an apparent Km of 6 microM in the presence or absence of PGE1. Both the guanine nucleotide GTP and the monovalent cation Na+ are required for this muscarinic inhibition of basal and PGE1-activated NG108-15 adenylate cyclase. The selectivity observed for monovalent cations (all chloride salts) in this process is Na+ congruent to Li+ greater than K+ greater than Choline+ with the ED50 for Na+ congruent 40 microM. Of the nucleotides tested, only IT (and not ATP, UTP or CTP) replaces GTP in this process. GTP at 10 microM represents a saturating nucleotide concentration. Opiate-directed inhibition of NG108-15 adenylate cyclase has recently been shown to exhibit a similar requirement for GTP and Na+ [Blume, A. J., Lichtshtein, D. and Boone, G. (1979) Proc. National Academy of Sciences, USA, in press]. The data presented here therefore support the hypothesis that the general transfer of inhibitory information from membrane receptors to adenylate cyclase involves both a Na+ and GTP-sensitive process.
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PMID:Muscarinic receptor regulation of NG108-15 adenylate cyclase: requirement for Na+ and GTP. 52 45

Examination of ionic membrane currents in a voltage-clamped neuronal cell line derived from the mouse C1300 neuroblastoma disclosed four kinetically different components: sodium, potassium, calcium, and leakage current. The kinetics, voltage dependence, and pharmacological properties of the sodium and potassium currents qualitatively resemble those of the corresponding currents in squid giant axon and frog myelinated nerve fiber, suggesting that the molecular structures of the sodium and potassium channels in neuroblastoma are similar to those of the non-mammalian preparations.
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PMID:Membrane currents examined under voltage clamp in cultured neuroblastoma cells. 55 42

1. Ionic currents in differentiated cells of mouse neuroblastoma clone N1E-115 have been studied under voltage-clamp conditions. 2. Depolarizing voltage steps from a holding potential of -85 mV to levels more positive than -40 mV produced fast transient inward currents followed by delayed outward currents. 3. The fast inward current is carried by Na+: it is blocked by tetrodotoxin and is absent in Na+-free solutions. Its kinetic behaviour resembles that of the Na+ current in squid giant axon. A mean value of 85 mmho/cm2 was found for the maximum Na+ conductance (GNa).4. The delayed outward current is carried primarily by K+: it is blocked by externally applied tetraethylammonium (TEA, 15 mM) and has a reversal potential (mean -71 mV) close to the theoretical K+ equilibrium potential. Its instantaneous I--V curve is linear. By analogy with the formulation of Hodgkin & Huxley (1952c), the outward current can be described by IK = -GKn2(V--EK) where GK = 12 mmho/mc2. 5. During prolonged depolarizations the delayed outward current declines. This decline, which occurs in two phases, represents a partial inactivation of the K+ conductance. 6. A weak inward current with slow activation and inactivation kinetics appears in Na+-free solution containing 10 mM-Ca2+. It is activated at a membrane potential of -55 mV and reaches its maximum at -20 mV with a time to peak of about 10 msec. This current is tetrodotoxin-resistant, reversibly blocked by Co2+ (5mM) and is suggested to be carried by Ca2+. 7. An increase in the external divalent cation concentration results in a parallel shift of the steady-state I--V curve along the voltage axis in positive direction. The activation of delayed outward currents is suggested not to depend on Ca2+ influx. 8. It is concluded that separate voltage-dependent Na+, K+ and Ca2+ channels exist in the differentiated neuroblastoma membrane with kinetic and pharmacological properties similar to those observed in non-mammalian preparations.
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PMID:Ionic currents in cultured mouse neuroblastoma cells under voltage-clamp conditions. 67 Dec 97

A goat antiserum, raised to native hog brain tubulin, was characterized by conventional immunological techniques and by employing a method for precipitation of tubulin.anti-tubulin complexes with heat-inactivated Staphylococcus aureus. Antiserum dilution experiments indicated that antibodies to native tubulin were raised, and maximal binding was observed to microtubules fixed with 1 mM glutaraldehyde. Competition experiments, using iodinated fixed microtubules as tracer, demonstrated that equivalent binding occurred with microtubules at protein concentrations 100- to 1000-fold lower than those for monomeric tubulin. A rabbit antiserum raised to sodium dodecyl sulfate-treated axonemal tubulin was also characterized. The serum bound maximally (90%) to either sodium dodecyl sulfate-treated or native iodinated hog brain tubulin, and competition for antibody binding has been observed with tubulin from diverse sources (Tetrahymena pyriformis ciliary axonemes, Lytechinus pictus flagellar axonemes, and mouse neuroblastoma extracts). Using these two antisera, radioimmunoassays are being developed for quantitation of polymeric and total tubulin in cellular systems.
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PMID:Quantitation and characterization of antibody binding to tubulin. 68 33

The neurotoxins, batrachotoxin and veratridine, are specific activators of sodium channels and cause an increase in the rate of 22Na uptake in neuroblastoma cells. Yohimbine, an indolakylamine alkaloid, inhibits this batrachotoxin-induced 22Na uptake. The dose-response curve of yohimbine suggest that the inhibitor acts reversibly on a single class of binding sites with dissociation constant of 3--4 x 10(-5) M. The dissociation constant is not affected by depolarization from--41 to 0 mV. Kinetic and equilibrium experiments indicate that yohimbine is a competitive inhibitor of the action of batrachotoxin. These results support the conclusion that yohimbine inhibitis the sodium flux by acting on the channel gating mechanism rather than by occluding the channels.
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PMID:Interaction between batrachotoxin and yohimbine. 68 61

Intracisternal type A particles were isolated from MOPC-104E myeloma grown subcutaneously and from N 4 neuroblastoma cells in culture. Polyadenylated RNA was prepared from the particles and tested in a cell-free translation system derived from rabbit reticulocytes. RNA from the two sources directed the synthesis of multiple polypeptides with similar distributions of electrophoretic mobilities in sodium dodecyl sulfate-containing polyacrylamide gels, including one conponent of the same size as the major A-particle structural protein (73,000 daltons). Analysis of the RNAs by electrophoresis in methyl mercury-containing agarose gels revealed a 35S component common to A-particles from both cell types. This was a major component of the N4 preparations, whereas a 28S species predominated in the case of MOPC-104E. These two RNAs (35S from N4 cells and 28S from MOPC-104E), when isolated on isokinetic sucrose gradients, each directed the synthesis of a 73,000-molecular-weight polypeptide that comigrated on gels with authentic A-particle structural protein. Idnetity of the cell-free product was confirmed by two-dimensional analysis of the [35S]methionine-labeled tryptic peptides. The N4 RNA preparations also contained a major32S component which did not code effectively for the A-particle structural protein.
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PMID:RNA associated with murine intracisternal type A particles codes for the main particle protein. 69 Nov 7

A method for determining As and Se in beef offal and fish was developed. The sample was digested by heating with a mixture of nitric, perchloric, and sulfuric acids. No pre-reduction of As and Se was necessary. Using a simplified generator, the metal hydrides were evolved by reduction with sodium borohydride pellets from sulfuric and hydrochloric acid media. The hydrides were swept by a flow of nitrogen into a nitrogen-hydrogen-entrained air flame. Absolute detection limit of the method was about 6 ng for As and 4 ng for Se, and absolute sensitivity for both metals was estimated to be 5 ng. Effects of the presence of several cations and anions in the matrix were investigated and some were found to have a suppressive effect on the atomic absorption signal. The analytical results obtained for samples of NBS No. 1571 Orchard Leaves and NBS No. 1577 Bovine Liver agreed well with certified values.
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PMID:Atomic absorption spectrometric determination of arsenic and selenium in offal and fish by hydride generation. 72 42

Mouse neuroblastoma clone N18, rat glioma clone C6, and rat striated muscle clone L6 were grown in a serum-free Dulbecco's modified Eagle's medium. Their doubling times were 48 hours, 40 hours, and 4 days, respectively. Morphologic features were similar to the original parent cell lines. Membrane components of N18 and C6 grown in serum-free medium were compared with the original parent cell lines. Defects of several membrane proteins were found with sodium dodecyl sulfate--polyacrylamide gel electrophoresis.
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PMID:Establishment of mouse neuroblastoma clone N18, rat glioma clone C6, and rat striated muscle clone L6 in serum-free, chemically defined medium. 74 55


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