Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ultimate purpose of the present study was to evaluate correlations between acute in vivo and in vitro toxicity and log P (P is n-octanol-water partition coefficient). The in vitro toxicity to cloned cells (neuroblastoma N18TG-2 and glioma C6) in culture (ED50) and the in vivo toxicity to mice (LD50) of ethylene glycol ethers were studied in terms of the structure-activity relationship. The test ethers showed a wide range of ED50 values in both cells. LD50 was determined under two conditions: LD50-cont. was estimated in mice pretreated with olive oil and LD50-CCl4 in CCl4-pretreated mice. Multiple regression analyses revealed a significant correlation between log 1/LD50 and log P as follows: log (1/LD50-cont.) = -0.120 (log P)2+0.487log P-1.182, and log (1/LD50-CCl4) = -0.128 (log P)2+0.566log P-1.157. There was no significant correlation either between ED50 and LD50 or between ED50 for N18TG-2 and ED50 for C6. The results suggest that metabolic activation might not occur during acute toxicity from the ethers, and that hydrophobicity, expressed as log P, plays an important role in acute toxicity.
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PMID:Structure-toxicity relationship of ethylene glycol ethers. 161 Mar

This study evaluates the role of intracellular levels of Ca2+ [Ca2+]i in cyclic GMP formation mediated by muscarinic and histamine receptors in the mouse neuroblastoma clone N1E-115. Muscarinic agonists activated the turnover of phosphoinositides with a relative maximal response similar to that observed previously for cyclic GMP formation. Carbamylcholine induced a transient increase in inositol trisphosphate with a time course similar to that of cyclic GMP formation. In cells loaded with the fluorescent Ca2+ probe fura-2/acetoxymethyl ester, carbamylcholine as well as histamine induced a rapid and transient rise in [Ca2+]i. The time course of the changes in [Ca2+]i induced by agonists as well as by ionomycin closely paralleled that of cyclic GMP formation. Chelation of [Ca2+]i by loading of N1E-115 cells with quin 2/acetoxymethyl ester inhibited cyclic GMP formation induced by agonists in a dose-dependent manner. When cyclic GMP formation induced by agonists was assayed after the cells were exposed to 3 mM ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) for 2 min, the formation of cyclic GMP was not inhibited significantly; however, it was completely abolished after 30-min exposure to EGTA. Treatment of cells with phospholipase A2 had no effect on resting [Ca2+]i and only slightly increased cyclic GMP formation, in spite of the induction of a marked release of [3H]arachidonate. Moreover, the formation of cyclic GMP induced by ionomycin was inhibited by the addition of phospholipase A2. Melittin contaminated with phospholipase A2 activity induced a rapid and sustained increase in cyclic GMP formation, as well as unesterified [3H]arachidonate release. However, after inactivation of the phospholipase A2 activity of melittin, its ability to stimulate cyclic GMP formation was enhanced. Our data indicate that receptor agonists stimulate cyclic GMP formation in N1E-115 cells by activating the formation of inositol trisphosphate, which is followed by the release of Ca2+ from intracellular stores. The evidence obtained does not support a major role for arachidonate release in receptor-mediated activation of guanylate cyclase. Conversely, it is consistent with an inhibitory role for arachidonic acid or its metabolites in this process.
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PMID:Role of intracellular Ca2+ mobilization in muscarinic and histamine receptor-mediated activation of guanylate cyclase in N1E-115 neuroblastoma cells: assessment of the arachidonic acid release hypothesis. 197 74

An intracellular (ATP + Mg2+)-dependent Ca2+ pumping mechanism has been identified and characterized within the cultured clonal neuroblastoma cell line N1E-115. Using cell suspensions treated with 0.005% saponin which selectively permeabilizes the plasma membrane in 95-98% of the cells, it was possible to show clearly that the intracellular Ca2+ pump mechanism is of non-plasma membrane origin and therefore can be compared directly with the Ca2+ pump characterized in detail in synaptosomal membrane vesicles (Gill, D. L., Grollman, E. F., and Kohn, L. D. (1981) J. Biol. Chem. 256, 184-192; Gill, D. L., Chueh, S. H., and Whitlow, C. L. (1984) J. Biol. Chem. 259, 10807-10813) which was proven by flux reversal studies to be derived from the neural plasma membrane (Gill, D. L. (1982) J. Biol. Chem. 257, 10986-10990). The intracellular Ca2+ pump in N1E-115 cells is distinct from mitochondrial Ca2+ accumulation and is increased up to 8-fold higher as cells reach confluency. In similarity to the neural plasma membrane pump, the intracellular Ca2+ pump within N1E-115 cells has high affinity for Ca2+ (Km = 0.28 microM), is dependent on both ATP (Km = 26 microM) and either Mg2+ or Mn2+ which half-maximally activate Ca2+ pumping at 0.35 mM and 0.32 mM, respectively, and shows similar specificity for Sr2+ and Ba2+ which half-maximally inhibit Ca2+ transport at 50 microM and 1.5 mM, respectively. In contrast to the neural plasma membrane pump, the intracellular Ca2+ pump displays approximately 40-fold higher sensitivity to La3+ (IC50 = 5 microM) and an apparent 400-fold lower sensitivity to VO4(3-) (IC50 = 185 microM), although the inhibitory effectiveness of VO4(3-) is increased 37-fold by a 15-min preincubation of the permeabilized cells with VO4(3-) in the absence of ATP (apparent IC50 = 5 microM). In further contrast to the neural plasma membrane Ca2+ pump, the intracellular pump within N1E-115 cells is stimulated more than 20-fold by oxalate (giving prolonged linear Ca2+ accumulation), is resistant to low saponin concentrations, and is not modified by calmodulin even after extensive treatment with ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid and/or calmodulin antagonist drugs. However, calmidazolium is effective in inhibiting the intracellular Ca2+ pump with an IC50 of approximately 2 microM.
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PMID:An intracellular (ATP + Mg2+)-dependent calcium pump within the N1E-115 neuronal cell line. 316 Jun 97

The incorporation of methionine, lysine, and leucine into protein was studied in Ca2+-depleted and Ca2+-restored preparations of C-6 glial tumor cells in minimal medium. Although incorporation proceeded at linear rates in both preparations for more than 1 h and into the same spectrum of proteins, Ca2+-restored cells incorporated amino acid 5- to 10-fold more rapidly than Ca2+-depleted cells. Addition of approximately 200 microM Ca2+ in excess of chelator was required to achieve maximal rates of incorporation in Ca2+-depleted preparations. Stimulation by Ca2+ was rapid in onset (several minutes) and slowly reversible by chelator. Ca2+ was uniquely potent and specific among physiologically occurring cations in conferring such stimulation. Stimulation of amino acid incorporation by Ca2+ occurred over a broad range of pH and osmolarities and was facilitated by Mg2+. The effects of Ca2+ in stimulating amino acid incorporation were not traceable to changes in cAMP metabolism, amino acid uptake, protein catabolism, cell ATP or GTP content, or aminoacylation of transfer RNA. Actinomycin D (1 microgram/ml) did not block the stimulatory effects of Ca2+ although puromycin and cycloheximide did. The stimulatory effects of Ca2+ on protein synthesis were not restricted to C-6 in minimal medium. Protein synthesis was reduced by ethylene glycol bis(B-aminoethyl ether)-N,N,N',N'-tetraacetic acid 40 to 75% in C-6 glioma, GH3 pituitary tumor, PC-12 adrenal tumor, N2A neuroblastoma, and HeLa cells incubated under simulated growth conditions with various enriched media and sera. Ca2+-depleted S49 lymphoma, CHO ovarian tumor, and normal, dispersed chicken embryo cells in enriched medium responded to Ca2+ restoration with increased rates of protein synthesis as did collagenase-dispersed normal rat liver cells in minimal medium. Protein synthesis in rabbit reticulocyte lysates was also inhibited by Ca2+-selective chelators or by Ca2+ removal by parvalbumin affinity chromatography and the inhibition was reversed by Ca2+. These findings are consistent with the existence of a Ca2+ requirement in the translational phase of protein synthesis in eukaryotic cells.
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PMID:Identification of a Ca2+ requirement for protein synthesis in eukaryotic cells. 631 27

1. In order to elucidate the structure-function relation of a glucoamylase [EC 3.2.1.3, alpha-D-(1 leads to 4) glucan glucohydrolase] from Aspergillus saitoi (Gluc M1), the reaction of Gluc M1 with NBS was studied. 2. The tryptophan residues in Glu M1 were oxidized at various NBS/Gluc M1 ratios. The enzymatic activity decreased to about 80% of that of the native Gluc M1 with the oxidation of the first 2 tryptophan residues. The oxidation of these 2 tryptophan residues occurred within 0.2-0.5 s. On further oxidation of ca. 4-5 more tryptophan residues of Glu M1, the enzymatic activity of Gluc M1 decreased to almost zero (NBS/Gluc M1 = 20). Thus, the most essential tryptophan residue(s) is amongst these 4-5 tryptophan residues. 3. 7.5 tryptophan residues were found to be eventually oxidized with increasing concentrations of NBS up to NBS/Gluc M1 = 50. This value is comparable to the number of tryptophan residues which are located on the surface of the enzyme as judged from the solvent perturbation difference spectrum with ethylene glycol as perturbant. 4. In the presence of 10% soluble starch, about 5 tryptophan residues in Gluc M1 were oxidized at an NBS/Gluc M1 ratio of 20. The remaining activity of Glu M1 at this stage of oxidation was about 76%. On further oxidation, after removal of soluble starch, the enzymatic activity decreased to zero with the concomitant oxidation of 2 tryptophan residues. The results indicated that the essential tryptophan residue(s) is amongst these 2 tryptophans. 5. The UV difference spectrum induced by addition of maltose and maltitol to Gluc M1 showed 4 troughs at 281, 289, 297, and 303 nm. The latter 3 troughs were probably due to tryptophan residues of Gluc M1 and decreased with NBS oxidation.
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PMID:N-bromosuccinimide oxidation of a glucoamylase from Aspergillus saitoi. 680 73

Tryptophan residues in ribonuclease from a Rhizopus sp. (RNase Rh) were modified by NBS, H2O2-dioxane, o-nitrophenylsulfenyl chloride (NPS-Cl) and the relation between the extent of modification and enzymatic activity was studied in each case. By extrapolation of the modified tryptophan residue-enzymatic activity curve to a completely inactive state, it was found that modification of 1-2 tryptophan residues is responsible for loss of enzymatic activity. RNase Rh was partly protected from modification by H2O2-dioxane (pH 8.4) and NPS-Cl (pH 3.5) when in the presence of 2'-AMP and the fluorescence emission spectrum of RNase Rh was quenched by adding 2'-AMP. It seems, therefore, that 1 or 2 tryptophan residues are involved in the active site of RNase Rh or are located near the active site. The solvent perturbation difference spectra of RNase Rh were measured using ethylene glycol and D2O as perturbants. The results indicated that 1.2 tryptophan residues for D2O and 1.9 tryptophan residues for ethylene glycol were exposed to the solvents. These data show that about 1.2-1.9 tryptophan residues are exposed to the solvent and their modification causes loss in enzymatic activity.
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PMID:Chemical modification of tryptophan residues in ribonuclease from a Rhizopus sp. 739 Sep 80

We have developed a method for promoting cell aggregation with bifunctional macromolecules synthesized by coupling cell-binding peptides to an inert, water-soluble polymer. The peptides Arg-Gly-Asp (RGD) and Tyr-Ile-Gly-Ser-Arg (YIGSR) were conjugated through their amino termini to both ends of linear poly(ethylene glycol) (PEG), producing bifunctional hybrid polymers: RGD-PEG-RGD and YIGSR-PEG-YIGSR. RGD-PEG-RGD promoted aggregation of mechanically-dissociated fetal brain cells, pheochromocytoma cells (PC12), and neuroblastoma cells maintained in rotation culture at 37 degrees C. Enhanced aggregation was noticeable within 10 minutes and became more pronounced over the next several hours: after 7-9 hours, the mean aggregate volume was up to 10 times larger than the mean volume produced in suspensions containing unmodified PEG. Similar results were obtained with YIGSR-PEG-YIGSR and PC12 cells. Enhancement in aggregation correlated with the ability of soluble RGD or YIGSR to inhibit cell adhesion to surfaces coated with laminin or fibronectin. This method for promoting aggregation may be useful for large scale culture of anchorage dependent cells, eliminating the need for microcarriers. In addition, aggregates formed by this method may be suitable for use in artificial organs or as cell transplants for tissue regeneration.
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PMID:Cell-binding peptides conjugated to poly(ethylene glycol) promote neural cell aggregation. 776 20

Chitinase has been purified from the extract of cabbage stems with roots through successive steps of ammonium sulfate fractionation, Sephadex G-75 gel filtration, chromatofocusing and Sephacryl S-200 HR gel filtration. By these steps, the purity of the enzyme increased by 63 fold and the recovery of the enzyme activity was 18%. The purified enzyme was homogeneous when analyzed by SDS-PAGE. It showed an optimal pH of 6 and optimal temperature of 60 degrees C for hydrolysis of ethylene glycol chitin (EGC). The molecular mass of the enzyme was 41 kDa, as determined by SDS-PAGE. Heavy metal ions (1.5 mM) Ag+, Hg2+ and Fe2+, and chemical modification agents NAI (1 mM), NBS (0.5 mM) and CHD (0.5 mM) significantly or completely inhibited the activity of the enzyme. Substrate EGC at high concentrations also inhibited the activity. BSA (0.05%), Triton X-100 (0.5%) and glycerol (50%) provided significant protection of the enzyme from freezing inactivation.
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PMID:Purification and properties of chitinase from cabbage stems with roots. 889 65

The ability of angiotensin II (AII) to regulate [Ca++]i in human neuroblastoma (SH-SY5Y) cells stably expressing recombinant rat AT1A receptors was investigated using microfluorimetric methods, and compared to responses obtained by stimulation of native muscarinic receptors. Applications of AII or carbachol produced biphasic rises of [Ca++]i, but in Ca++-free solutions (containing 1 mM ethylene glycol-bis (beta-aminoethyl ether)N,N,N,'N'-tetraacetic acid), both agonists produced only transient monophasic rises of [Ca++]i, and second applications were without effect. Application of Ca++(o) (2.5 mM) to cells after exposure to either agonist produced a Ni2+-sensitive rise of [Ca++]i in the absence of agonist ("capacitative Ca++ influx"). After removal of Ca++(o), both AII and carbachol elicited a second rise of [Ca++]i. Thapsigargin (1 microM) prevented these second rises of [Ca++]i. During capacitative Ca++ influx, application of AII failed to produce a further rise of [Ca++]i. In contrast, carbachol produced a further rise of [Ca++]i, attributable to activation of both nicotinic and muscarinic receptors, because it was reduced (but not abolished) by mecamylamine (1 microM) and was observed when muscarine was used as the agonist. Thus, activation of recombinant AT1A and muscarinic receptors in SH-SY5Y cells leads to mobilization of Ca++ from a common intracellular pool, and stimulates capacitative Ca++ influx. Muscarinic (but not AII) receptor occupancy is capable of stimulating an additional Ca++ influx pathway.
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PMID:Regulation of [Ca++]i in human neuroblastoma (SH-SY5Y) cells expressing recombinant rat angiotensin1A receptors by angiotensin II and carbachol. 919 Aug 61

Extensive necrotic death of MSN neuroblastoma cells could be induced after incubation with the calcium ionophore, A23187. The reaction was concentration-dependent and time course-dependent. Levels of the 66 kd/alpha-internexin neurofilament protein (NF-66) and the cognate heat shock protein 70 (Hsc 70) decreased during the Ca2+-activated cell death. Addition of the calcium chelator, ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) restored the normal level of NF-66 and partially that of the Hsc 70. Use of either calpain I or calpain II inhibitor could alleviate the reduction of 66 kd protein during the ionophore treatment whereas only calpain I inhibitor treatment was effective in restoring the normal level of the Hsc 70. Neither of these calpain inhibitors could block the ionophore triggered cell death. EGTA was toxic to cells in a wide range of concentration suggesting a calcium-independent activation of cell death mechanism.
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PMID:Calcium ionophore-induced degradation of neurofilament and cell death in MSN neuroblastoma cells. 948 52


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