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

The adsorptive endocytosis of conjugates of the marker enzyme horseradish peroxidase (HRP) with lectins and cholera toxin was studied in cultured neurons, neuroblastoma cells, and, in vivo, in the rat, by electron microscopic cytochemical (HRP), quantitative autoradiographic, morphometric, and biochemical techniques. The uptake of ricin-HRP by cultured neuroblastoma cells is 100 to 200 times greater than free HRP; furthermore, ricin does not stimulate the fluid phase endocytosis of HRP. Conjugates of wheat germ agglutinin and cholera toxin with HRP are 10 to 40 times more sensitive than free HRP in tracing retrograde connections in the rat central and peripheral nervous system. Conjugates of various ligands with HRP undergo endocytosis into the cisternae of the Golgi apparatus (or Golgi-Endoplasmic-Reticulum-Lysosome-GERL) and in residual bodies of cultured neurons and in vivo, while free HRP is found only in residual bodies. We conclude that: 1) various ligands with affinities to plasma membrane moieties are more sensitive, and probably more reliable, markers of "membrane" flow than free HRP, and 2) the pathway involved in the adsorptive endocytosis of ligands is different from the pathway of fluid phase uptake of HRP. These findings are consistent with the view that, in addition to its established role in the centrifugal traffic of various moieties, the neuronal Golgi apparatus is also involved in a centripetal vesicular membrane traffic. We spectulate that the neuronal Golgi apparatus, and probably the Golgi apparatus of other cells, is at the "crossroads" of a vesicular membrane traffic, and may thus exert significant controls on biologic membrane equilibria.
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PMID:Presidential address. The role of neuronal golgi apparatus in a centripetal membrane vesicular traffic. 705 89

To investigate further the selectivity of retrograde axonal transport of horseradish peroxidase (HRP) isoenzymes previously observed in the rat central visual pathways, cultured mouse neuroblastoma cells (clone N18) were examined for selectivity of endocytosis of peroxidases and cationized ferritin in vitro. Differentiating N18 cells were incubated with proteins in various timing and pulse-chase experiments, and examined for the ultrastructural localization of endocytosed protein using cytochemical techniques. Semi-quantitative morphometry was performed on some of the samples. Major findings were as follows. (1) The protein was internalized into vesicles (coated and uncoated), short tubules and occasional small cup-shaped bodies within the first few minutes, and transferred via tubules and uncoated vesicles to secondary lysosome-like organelles (vacuoles, multivesicular bodies and dense bodies) from 5 to 15 min, with dense bodies representing the final site of protein accumulation. All the proteins tested were endocytosed through the same pathways in the soma and neurite of the cell. (2) There was no indication of a net orthograde or retrograde neuritic transport proteins. (3) There were induced increases in both vesicle and tubule formation as a result of protein endocytosis, with HRP isoenzyme C showing the greatest effect. (4) The apparent rate of internalization of HRP isoenzyme C into vesicles during the initial 5 min was significantly greater than for other peroxidases amd cationized ferritim. (5) Relatively more tubules than vesicles were involved in the uptake of protein as endocytosis was prolonged from 5 min to 8 h, with HRP isoenzyme C showing the largest effect. (6) There were indications of preferential compartmentation of endocytosed protein into certain organelles.
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PMID:Endocytosis and compartmentation of peroxidases and cationized ferritin in neuroblastoma cells. 744 Dec 98

The endocytosis of ricin, horseradish peroxidase (HRP), and a conjugate of ricin-HRP by monolayer cultures of murine neuroblastoma was studied using morphological and biochemical techniques. The binding of (125)I-ricin and (125)I-ricin-HRP to cells at 4 degrees C, as a function of ligand concentration, was a saturable process. The apparent affinity constants, determined at equilibrium, were 2.8 X 10(6) M(-1) for ricin and 1 x 10(6) M(-1) for ricin-HRP. The number of binding sites per cell was 8 x 10(7) and 3 x 10(7) for the lectin and the conjugate, respectively. The binding of (125)I-ricin to monolayers as not proportional to cell density. We found reduced binding at higher cell concentrations, suggesting a decrease in the accessibility of the ligand for the receptor site or fewer sites with increasing cell population. Neuroblastoma cells have an acid-phosphatase-positive network of cisternae and vesicles near the Golgi apparatus (GERL). Ricin-HRP undergoes endocytosis in vesicles and cisternae corresponding to GERL, and in residual bodies (dense bodies). The cellular uptake of ricin-HRP was 100-200 times greater than free HRP and there was no stimulation of fluid phase endocytosis by ricin. When monolayers were exposed to concentrations of native HRP 100-fold that of the conjugate, cellular uptake of peroxidase was comparable, but HRP was localized only in residual bodies and never in elements of GERL. These results support the conclusion that GERL is involved in the adsorptive endocytosis of ricin-HRP, while residual bodies are involved in the bulk uptake of HRP. In addition, the binding, uptake, and possible recycling of (125)I- subunit B (the binding subunit) of ricin and of (125)I-ricin was examined by quantitative electron microscope autoradiography. Both ricin and its binding subunit displayed similar autoradiographic grain distributions at 4 degrees C, and there was no evidence of their breakdown or recycling to the plasma membrane during endocytosis for 2 h.
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PMID:Pathways involved in fluid phase and adsorptive endocytosis in neuroblastoma. 746 17

The endocytotic uptake and intracellular decay of horseradish peroxidase isoenzymes C and A by cultured mouse neuroblastoma cells were analyzed quantitatively by a direct spectrophotometric assay. At concentrations below 1 mg/ml, the rate of uptake of the isoenzyme C was more than three times as much as the isoenzyme A. This differential uptake suggests that previous claims of horseradish peroxidase being endocytosed only in the nonselective fluid phase are oversimplified. The implication of this selectivity in the biological significance of retrograde axonal transport of proteins by neuronal systems is discussed.
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PMID:Differential uptake of horseradish peroxidase isoenzymes by cultured neuroblastoma cells. 746 60

Neuro-2a neuroblastoma cells can be stimulated to extend neurites with a number of agents, one of which, neuraminidase, induces terminal differentiation by a mechanism involving enhanced Ca2+ influx. Permeabilization of such differentiated cells with saponin and treatment with cholera toxin B subunit linked to horseradish peroxidase revealed intense staining of the nuclear membrane, indicating the presence of GM1 ganglioside. Unstimulated cells had barely detectable levels of nuclear GM1. Nuclei isolated by sucrose density gradient centrifugation similarly showed intense staining with fluorescently labeled cholera toxin B subunit, in contrast to nuclei from undifferentiated controls. Treatment with chloroform-methanol removed most of the fluorogenic material. Chemical analysis of such nuclei from neuraminidase-treated cells confirmed significant elevation of GM1 above control levels, along with virtual absence of markers for plasma membrane and Golgi apparatus. Cerebellar granule cells from neonatal rats revealed a similar phenomenon following spontaneous neurite outgrowth in culture.
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PMID:Induced and spontaneous neuritogenesis are associated with enhanced expression of ganglioside GM1 in the nuclear membrane. 775 42

We report the detection of endogenous intracellular glutathionyl (GS.) radicals in the intact neuroblastoma cell line NCB-20 under oxidative stress. Spin-trapping and electron paramagnetic resonance (EPR) spectroscopic methods were used for monitoring the radicals. The cells incubated with the spin trap 5,5-dimethyl-1-pyrroline 1-oxide (DMPO) were challenged with H2O2 generated by the enzymic reaction of glucose/glucose oxidase. These cells exhibit the EPR spectrum of the GS. radical adduct of DMPO (DMPO-.SG) without exogenous reduced glutathione (GSH). The identity of this radical adduct was confirmed by observing hyperfine coupling constants identical to previously reported values in in vitro studies, which utilized known enzymic reactions, such as horseradish peroxidase and Cu/Zn superoxide dismutase, with GSH and H2O2 as substrates. The formation of the GS. radicals required viable cells and continuous biosynthesis of GSH. No significant effect on the resonance amplitude by the addition of a membrane-impermeable paramagnetic broadening agent indicated that these radicals were located inside the intact cell. N-Acetyl-L-cysteine (NAC)-treated cells produced NAC-derived free radicals (NAC.) in place of GS. radicals. The time course studies showed that DMPO-.SG formation exhibited a large increase in its concentration after a lag period, whereas DMPO-NAC. formation from NAC-treated cells did not show this sudden increase. These results were discussed in terms of the limit of antioxidant enzyme defenses in cells and the potential role of the GS. radical burst in activation of the transcription nuclear factor NF-kappa B in response to oxidative stress.
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PMID:Endogenous intracellular glutathionyl radicals are generated in neuroblastoma cells under hydrogen peroxide oxidative stress. 775 47

A sensitive peroxidase-dependent luminol-enhanced chemiluminescence (ECL) assay for determination of hydrogen peroxide (H2O2) generation by tumour cells was established. This test system allows determination of H2O2 in concentrations as low as 25 pmol (50 nmol/L) and yields results which are comparable to those obtained using a less sensitive photometric method and a previously described scopoletin fluorescence assay. After 3 h incubation time 10(4) SK-N-SH neuroblastoma cells released 60 +/- 5 pmol H2O2 in the supernatant and this level was significantly (p < 0.025) increased by about 70% in the presence of 5 pmol (100 ng/mL) recombinant tumour necrosis factor alpha (TNF alpha). In contrast, H2O2 production was slightly reduced by TNF alpha at a very low concentration of 0.5 fmol (0.01 ng/mL).
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PMID:Measurement of endogenous and TNF alpha-mediated H2O2 production in supernatants of SK-N-SH neuroblastoma cells with an enhanced chemiluminescence assay. 798 27

Twenty-four advanced (surgical stage III and IV) ovarian carcinomas and 15 borderline ovarian tumours were studied for the overexpression of nm23 and HER-2/neu (c-erb-B2) by means of immunohistochemistry on sections from routinely processed, paraffin-embedded, archival tumour blocks, using the NCL-nm23 and the NCL-CB11 monoclonal antibodies and the streptavidin-biotin-peroxidase technique. Significantly more advanced ovarian carcinomas (p = 0.034) expressed high levels of nm23 when compared to borderline tumours. HER-2/neu (c-erb-B2) expression, as could be expected, was also significantly more frequent in advanced ovarian carcinomas (p = 0.006). We were not able to find the previously reported association between nm23 and HER-2/neu overexpression in our tumours. Our results on nm23 overexpression in ovarian cancer are coincident with those previously reported using nm23-mRNA measurements on fresh ovarian tissues. Thus, ovarian carcinoma seems to belong to the group of tumours, like colon carcinoma and neuroblastoma, in which nm23 overexpression is associated with a more malignant phenotype. Immunohistochemistry performed on archival samples from ovarian carcinomas seems adequate for the demonstration of nm23 overexpression in ovarian cancer. This opens the possibility for larger studies on series of patients with a closed follow-up, which could help to establish the role of this gene in this kind of tumour.
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PMID:nm23 expression in advanced and borderline ovarian carcinoma. 870 36

We have established an enzyme immunoassay for phosphoneuroprotein 14 (PNP 14) which is mainly localized in the cytoplasmic matrix in presynaptic axon terminals and which is phosphorylated in vivo, as well as in vitro. Fab' prepared from rabbit IgG antibodies against bovine PNP 14 was conjugated with maleimide-horseradish peroxidase. The enzyme-conjugated Fab' was used as a second antibody in a sandwich enzyme immunoassay. This assay was able accurately to quantify 0.5-100 ng of rat PNP 14, as well as bovine PNP 14, and it was used for the determination of concentrations of PNP 14 in various rat tissues, neuroblastoma cells, and brains of other vertebrates. The concentrations of PNP 14 in the rat cerebrum, cerebellum, and testis were 1.1, 1.0, and 0.28 micrograms/mg of protein, respectively, and those in other tissues examined were less than 0.1 microgram/mg of protein. PNP 14 was also found in cultured cells, such as rat pheochromocytoma PC12 cells, NG108-15 cells, which are a hybrid between a mouse neuroblastoma and a rat glioma, mouse neuroblastoma Neuro-2a cells, and human neuroblastoma IMR32 cells. Furthermore, PNP 14-specific immunoreactivity was evaluated in the brains of various vertebrates, such as fish, frog, snake and chicken by immunoblot and enzyme immunoassay. The results revealed the immunoreactivity in the brains of all vertebrates examined and the levels were determined to be 0.6-2.1 micrograms bovine PNP 14 equivalents per mg of protein, suggesting that PNP 14 might be an essential component of the central nervous systems of vertebrates.
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PMID:Distribution of phosphoneuroprotein 14 (PNP 14) in vertebrates: its levels as determined by enzyme immunoassay. 900 21

We report the effects of meta-iodobenzylguanidine (MIBG), a neuroblastoma-seeking agent, on cell proliferation and several oxidative stress-related parameters in the human neuroblastoma cell line SK-N-BE(2c). MIBG inhibited the proliferation of this cell line in micromolar concentrations. Measurements of the malondialdehyde (MDA) concentrations (a measure of the extent of lipid peroxidation) of cells treated with MIBG showed that increasing concentrations of MIBG led to an increase in MDA levels of the cells. This effect was most pronounced after one day of cellular exposure to MIBG and disappeared after 3 days. Disappearance of the elevated MDA levels caused by MIBG is probably the result of increased activity of the H2O2 detoxifying enzymes, catalase and glutathion peroxidase (GPx). The catalase- and GPx-enzyme activity of cells exposed to MIBG steadily increased with time, reaching a maximum after 4 days. Oxidative stress caused by MIBG thus at first leads to cellular damage (lipid peroxidation) but over a longer period does not lead to decreased proliferation rate of the cells, most likely because of cellular adaptation to increased oxidative stress by up-regulation of the H2O2 detoxifying enzymes catalase and GPx.
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PMID:MIBG causes oxidative stress and up-regulation of anti-oxidant enzymes in the human neuroblastoma cell line SK-N-BE(2c). 924 93


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