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)

A simple and accurate method was developed for routine determination of fluoride in foods. Hydrogen fluoride is diffused 20 hr at 50 degrees C from fresh or freeze-dried samples (0.1 g dry wt) in polystyrene petri dishes containing 2 mL 40% HCIO4 and 0.3 g Ag2SO4, and is absorbed on the lids, previously spotted with 0.1 mL 0.5M NaOH. The absorbent layer is dissolved in 2 mL buffer solution, and the fluoride is measured potentiometrically. The method was verified by analysis of NBS Standard Reference Materials; recovery from 28 spiked infant foods (average = 99%, range = 75-135%); and comparison of results with colorimetry results for the same diffusates, after modification to handle 1 g samples. Relative standard deviations varied from 4 to 20% day to day. Detection limits were below 0.05 microgram/g dry weight.
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PMID:Microdiffusion and fluoride-specific electrode determination of fluoride in foods. 52 49

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

The metabolism of neuroblastoma cell glycoproteins was examined using L-E13H]fucose. Incubation of monolayer cultures with [3H]fucose resulted in a rapid uptake of the radioactive precursor and its incorporation into acid-insoluble macromolecules. Less than 3% of the [3H]fucose that was isolated from neuroblastoma cells by trichloroacetic acid precipitation was associated with glycolipids. The metabolism of fucosylated macromolecules was studied in cells which were labelled to a steady state, and then reincubated under conditions which limited reutilization of the radioactive precursor (40 mM unlabelled fucose). During reincubation of the cells, we observed a rapid metabolism (27% by 2 h) of the prelabelled macromolecules which stabilized within a cell generation time to give an overall rate of turnover of 9%. This rapid loss of radioactivity from the cells was not due to exocytosis since less than 4% of the [3H]-fucose was lost into the media as macromolecules during a 5 h reincubation period. The presence of 40 mM fucose in the media did not affect cell growth until after 24 h of incubation or cellular protein synthesis until after 15 h of incubation. When the metabolism of neuroblastoma cell glycoproteins was measured in the presence of 1.8 - 10(-4) M cycloheximide, there appeared to be a less rapid decrease in cell-associated specific activity, and an increased reutilization of [3H]fucose. Although the major proportion of the radioactivity remained as e13H]fucose, extensive incubation of neuroblastoma cells with this radioactive precursor led to increased amounts of tritium associated with other cellular components; However, a rapid rate of glycoprotein metabolism could also be demonstrated with cells incubated with [14C]fucose. This eliminated the possibility that the above results were restricted to the tritiated precursor and merely a reflection of hydrogen-tritium exchange.
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PMID:Rapidly metabolized glycoproteins in a neuroblastoma cell line. 87 78

Most studies of antibody-dependent cellular cytotoxicity (ADCC) by polymorphonuclear leukocytes (PMN) have supported oxidative lytic processes. This may be because the studies used nonhuman or nonneoplastic cells that were highly sensitive to reactive oxygen species or were small enough to be phagocytosed by PMN. We therefore investigated whether oxygen radicals participate in PMN cytotoxicity toward human neuroectodermal solid tumor cells sensitized by 3F8, which is an anti-ganglioside GD2 murine IgG3 monoclonal antibody with documented anticancer activity in humans. A 4-h 51Cr release assay was used to assess tumor cell lysis by hydrogen peroxide, superoxide, and hypochlorite. Nine of 11 GD2(+) human melanoma and neuroblastoma cell lines had equal or greater resistance to these oxidants as compared to a GD2(-) human carcinoma line (SKBr1-III) found by others (and confirmed by us) to be significantly more resistant to oxidative lysis than a murine cell line (P388D1) representative of those commonly used in cytotoxicity assays. To facilitate detection of oxidant-mediated lysis, subsequent studies of 3F8-mediated ADCC used GD2(+) targets that were relatively sensitive and others that were relatively resistant to oxygen radicals. Normal PMN and PMN obtained from children with chronic granulomatous disease, which do not generate reactive oxygen species, were equally effective in ADCC. Granulocyte-macrophage colony-stimulating factor, which primes oxidative responses of normal but not of chronic granulomatous disease PMN, enhanced ADCC by both kinds of PMN. During ADCC of 3F8-sensitized targets, with or without granulocyte-macrophage colony-stimulating factor, GD2(-) "innocent bystander" tumor cells (including P388D1) were not lysed, a finding consistent with unimportant extracellular release of cytotoxic mediators. Finally, antioxidant and antimyeloperoxidase moieties did not block ADCC. We conclude that oxidants are not key factors in 3F8-mediated lysis by PMN of human neuroectodermal tumor cells.
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PMID:Clinically effective monoclonal antibody 3F8 mediates nonoxidative lysis of human neuroectodermal tumor cells by polymorphonuclear leukocytes. 165 2

Because of the important biological functions of peroxidases, there is growing interest in the measurement of their concentrations in various secretions. At present, there is no standard method which allows for comparisons in reported activities. This report describes procedures which can be used to measure peroxidase enzyme concentrations by commonly employed assays. Regression equations have been determined which can be used to calculate concentrations of bovine lactoperoxidase (LPO), human salivary peroxidase (SPO), and human myeloperoxidase (MPO) from activities measured with the following donors: pyrogallol, guaiacol, 2,2'-azinobis(3-ethylbenzylthiazoline-6-sulfonic acid), and thiocyanate (SCN-). The peroxidation rates of these donors depend upon the concentrations of hydrogen peroxide (H2O2) used in the individual assays and thus, for accurate, reproducible results, these concentrations must be carefully controlled. The SCN- normally present in human saliva will reduce observed reaction rates by simple competition kinetics in the ABTS, guaiacol and pyrogallol assays and will increase the rates observed when Cl- is used as a donor in NBS assay for MPO. Therefore, SCN- must be removed from saliva samples prior to peroxidase activity determination by all assays except the thionitrobenzoic acid (NBS) assay. LPO cannot be used as a standard for either SPO or MPO because the specific activities of LPO, SPO, and MPO are significantly different.
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PMID:Quantitative, standardized assays for determining the concentrations of bovine lactoperoxidase, human salivary peroxidase, and human myeloperoxidase. 196 65

Single smooth muscle cells were isolated from the basilar artery of the rat by enzymatic dispersion. The membrane properties of the cells were assessed using the patch-electrode voltage-clamp technique, and cell viability was monitored using fluorescein diacetate uptake. Exposure of the cells to oxyhemoglobin (5 microM) resulted in 1) contraction, 2) the appearance of membrane blebs, 3) an increase in the outward potassium currents, 4) a decrease in the membrane resistance, and 5) cell death. In contrast, no effect of oxyhemoglobin on cultured murine neuroblastoma cells was observed. Methemoglobin (100 microM) had no effects on the smooth muscle cells. Catalase (300 units/ml) or dimethyl sulfoxide (0.5%) protected against the effects of oxyhemoglobin; superoxide dismutase (100-1,000 units/ml) provided only partial protection. Exposure of the cells to superoxide anions generated by xanthine (1 mM) plus xanthine oxidase (10 units/l) or to hydrogen peroxide (500 microM) caused an increase in the outward potassium currents without affecting membrane resistance. Generation of hydroxyl radicals by metal ions plus hydrogen peroxide caused the same effects as oxyhemoglobin, that is, an increase in the potassium currents, followed by a decrease in the membrane resistance and cell death. In conclusion, it appears that oxyhemoglobin exerts its effects on vascular smooth muscle cells by the generation of free radicals, chiefly hydroxyl radicals.
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PMID:Free radicals mediate actions of oxyhemoglobin on cerebrovascular smooth muscle cells. 199 46

The urine level of trace elements has been investigated in some normal adults under different workplace environments in Bangladesh. The samples were collected from 58 subjects, randomly selected from about 500 adults working in 10 different workshops and factories located in Dhaka city. Samples were analyzed by the external beam PIXE method. Proton beams of 2.5 MeV energy and 20 nA intensity were used for sample irradiations. For 40 microC irradiations, the concentration of 14 elements in total (K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr and Mo) in different groups were measured by comparison with a calibration curve obtained from the NBS Orchard Leaf standard (SRM 1571). The results from different workplaces are reported in terms of amount of excretion per unit volume of the sample collected. They, however, do not reflect the total daily excretion level of different subject groups.
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PMID:Urine level of trace elements in some adults in Bangladesh under a workplace environment. 215 44

Renotubular handling of sodium, potassium (K) calcium (Ca), phosphate, hydrogen ions and glucose, and urinary concentrating ability were studied in three children (aged 8, 8.5, 11 years) with renal magnesium (Mg) loss, persisting for more than 2 years after discontinuation of cisplatin treatment for neuroblastoma. A group of healthy children served as controls. Besides renal Mg wasting, a clear-cut tendency towards reduced calciuria associated with normal or slightly elevated plasma Ca was observed. Plasma K tended to be low (3.4-3.7 mmol/l), and plasma chloride was normal. Plasma bicarbonate (HCO3) ranged from 24.9 to 27.8 mmol/l, and urinary pH was always less than 6.0, indicating a renal HCO3 threshold exceeding 24 mmol/l. Plasma creatinine levels, glucosuria and phosphaturia, and urinary concentrating capacity were adequate. Comparable features were found in three children (aged 4.5, 9, 13 years) with primary renotubular hypomagnesaemia-hypokalaemia and hypocalciuria. This study complements the picture of chronic cisplatin tubulopathy in childhood demonstrating that, apart from Mg wasting, a reduced Ca excretion, and a tendency to hypokalaemia and metabolic alkalosis exist. Thus cisplatin may induce renal functional damage identical to that found in primary renotubular hypomagnesaemia--hypokalaemia with hypocalciuria.
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PMID:Chronic renal magnesium loss, hypocalciuria and mild hypokalaemic metabolic alkalosis after cisplatin. 240 Jun 47

The toxicity of single and multiple fire gases is studied to determine whether the toxic effects of the combustion products from materials can be explained by the toxicological interactions (as indicated by lethality) of the primary fire gases or if minor, more obscure gases need to be considered. LC50 values for Fischer-344 rats have been calculated for the individual gases, carbon monoxide (CO), hydrogen cyanide (HCN), or decreased oxygen (O2), for 30-min exposures plus relevant postexposure periods using the NBS Toxicity Test Method. Combination experiments with CO and HCN indicate that they act in an additive manner. Synergistic effects have been found when the animals are exposed to certain combinations of CO and carbon dioxide (CO2). Five percent CO2 raised the threshold for deaths due to hypoxia and decreased the LC50 of HCN. Decreasing the O2 concentration in the presence of various mixtures of the other major fire gases increased the toxicity even further. A comparison of the concentrations of the major combustion products generated from a number of polymeric materials at their LC50 (30-min exposure plus 14-day postexposure) values with the combined pure gas results indicates that, in most cases, the observed toxicity may be explained by the toxicological interactions of the examined primary toxic fire gases. These results provide necessary information for the computer model currently being developed at the Center for Fire Research to predict the toxic hazard that people will experience under various fire scenarios.
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PMID:Effects of exposure to single or multiple combinations of the predominant toxic gases and low oxygen atmospheres produced in fires. 282 Aug 22

The patterns of the cytolytic effects of 6-hydroxydopamine (6-OHDA), with/without ascorbate, on C-1300 and three other cloned mouse neuroblastoma cell lines (N1E-115, NS-20, N-18) were studied in vitro. The sensitivity to 6-OHDA differed and the three cloned cell lines were more sensitive than the wild type C-1300 cell line. Ascorbate synergistically potentiated the cytolytic effect of 6-OHDA to all four cell lines. The 6-OHDA cytotoxicity was eliminated by the addition of exogenous catalase but not by addition of other oxygen free radical scavengers, thereby suggesting that the hydrogen peroxide formed might influence the cells, extracellularly. In addition, the critical time for tumor cell lysis was the first 60 min of the reaction. The cytotoxicity induced by the unmasked cyclophosphamide, 4-hydroperoxycyclophosphamide, was synergistically enhanced in the presence of a nontoxic concentration of 6-OHDA and ascorbate. These data suggest that reactive oxygen intermediates may prove to be a good tool for destroying neuroblastoma cells.
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PMID:Patterns of destruction of mouse neuroblastoma cells by extracellular hydrogen peroxide formed by 6-hydroxydopamine and ascorbate. 308 96


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