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 NIST has produced and is in the process of certifying two new leaf CRMs, SRM1515 Apple Leaves and SRM 1547 Peach Leaves, as replacements for the no longer available NBS Orchard Leaves and the almost depleted Citrus Leaves. These two new materials have been processed and are being thoroughly evaluated and should provide the most advanced natural matrix botanical trace-element reference materials available. Caution should be used in determining a basis weight (drying) for these CRMs because of their very fine particle size. Homogeneity has been established by instrumental neutron activation analysis on both leaf materials for five elements, to date, to better than 1.5% (1 s) for 100-mg sample sizes.
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PMID:Homogeneity and evaluation of the new NIST leaf certified reference materials. 170 64

A study was undertaken to determine the average values for elements in normal human brain (11 individuals, age group 65-75). Twelve brain parts were selected from both hemispheres. Determinations were carried out by NAA and ICP-AES. The main elements (Na, K, Mg, Ca, Fe, P, S) and trace elements (Al, B, Co, Cr, Cu, Mn, Ni, Pb, Zn) were investigated. Quality control was ensured by using NBS Bovine Liver SRM. The results obtained with independent methods were compared, and the data show a good correlation. On the basis of these investigations, the regional distribution of elements can be given.
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PMID:Determination of main and trace element contents in human brain by NAA and ICP-AES methods. 170 77

Instrumental neutron activation analysis (INAA) has been applied to multielemental determinations of medicinal extracts obtained from the plants. Cordia Verbenacea DC, Folidago Microglossa DC, and Petiveria Alliacea. Concentrations of the elements Al, Br, Ca, Cl, Co, Cs, Fe, K, La, Mg, Mn, Na, Rb, Sb, and Zn have been determined in dried extracts of these herbs by short and long irradiations under a thermal neutron flux of 10(11)-10(13) n/cm2s in the IEA-R1 nuclear reactor. The NBS Tea Leaves (1572) and NIES Pepperbush (1) reference materials were analyzed simultaneously with the plant extracts. The results obtained in these analyses have shown a good accuracy and reproducibility of the method. The relative errors and the relative standard deviations were less than 10% for most of the elements analyzed.
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PMID:Determination of inorganic components in Brazilian medicinal plants by neutron activation analysis. 170 83

The elemental compositions of 18 biological reference materials have been processed, for 14 stepped combinations of irradiation/decay/counting times, by the INAA Advance Prediction Computer Program. The 18 materials studied include 11 plant materials, 5 animal materials, and 2 other biological materials. Of these 18 materials, 14 are NBS Standard Reference Materials and four are IAEA reference materials. Overall, the results show that a mean of 52% of the input elements can be determined to a relative standard deviation of +/- 10% or better by reactor flux (thermal plus epithermal) INAA.
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PMID:Instrumental neutron activation analysis of biological samples. 170 88

Several food crops were analyzed for residues of ethylenethiourea (ETU), a suspect thyroid and liver carcinogen present in EBDC fungicides, using a commercial particle beam (PB) LC/MS method. The PB/LC/MS detection limits for ETU in crops (5 ppb, 1.25 ng) are comparable to those obtained by LC with electrochemical detection. Spectra obtained from crop samples containing as little as 5 ng of ETU were matched with the NBS library reference EI spectrum. Isotopically labeled ETU was used as an internal standard for quantitation and determination of recoveries. No enhancement of molecular ion signal intensity from unlabeled ETU was observed upon coelution with the isotopically labeled variant. This MS method permits detection of ETU with increased selectivity without compromising sensitivity.
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PMID:Determination of ethylenethiourea in crops using particle beam liquid chromatography/mass spectrometry. 175 Jul 1

Notexin from Notechis scutatus scutatus snake venom was subjected to tyrosine modification with p-nitrobenzenesulphonyl fluoride (NBSF), and four modified derivatives were separated by h.p.l.c. The results of amino acid analysis and sequence determination revealed that only Tyr-7, Tyr-70 and Tyr-77 were modified in notexin. Modification of Tyr-7 resulted in decreases in lethal toxicity and enzymic activity by 70.2% and 22.7% respectively. Conversely, modification of Tyr-77 caused a 1.8-fold increase in enzymic activity, in contrast with the loss of 52.5% of lethality. A drastic decrease in lethal toxicity was observed when both Tyr-7 and Tyr-70 were modified, whereas the enzymic activity decreased by only 35.8%. Likewise, the derivative in which Tyr-7 and Tyr-77 were modified retained 44.4% of enzymic activity, but showed a marked decrease in lethal toxicity. It is obvious that modification of tyrosine residues causes a decrease in lethal toxicity of notexin, which does not directly correlate with the change in enzymic activity. On the other hand, the antigenicity of NBS derivatives remained unchanged. The modified derivatives retained their affinity for Ca2+, indicating that the modified tyrosine residues did not participate in Ca2+ binding. These results indicate that modification of tyrosine residues can differentially influence the enzymic activity and lethal toxicity of notexin, and suggest that notexin might possess two functional sites, one being responsible for the catalytic activity and the other associated with its lethal effect.
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PMID:Dissociation of lethal toxicity and enzymic activity of notexin from Notechis scutatus scutatus (Australian-tiger-snake) venom by modification of tyrosine residues. 176 38

Analogues of 4-([2-(1H-imidazol-1-yl)-1-(4-substituted-phenyl)ethoxy]methyl)benz oic acids were synthesized for searching of more potent and selective thromboxane synthetase inhibitors. All title compounds are first reported. Results of preliminary pharmacological tests showed that all title compounds have activity against thromboxane synthetase, i.e. inhibiting platelet aggregation induced by AA in vitro with rabbit. Compound 15 is the most potent. Its activity is 55.6% of that of Dazoxiben in comparison of IC50. The change of group substituted on benzene would affect inhibitory activity to thromboxane synthetase. Esters are more potent than the parent acids. This is probably due to the greater platelet permeability of the more lipophilic ester prior to intraplatelet deesterification. NBS was applied to the preparation of p-bromoethylbenzoic ester. This method increased the yield and simplified operating process.
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PMID:[Synthesis and platelet aggregation inhibitory activity of analogues of 4-([2-(1H-imidazol-1-yl)-1-(4-substituted-phenyl)ethoxy]methyl)benzoic acids]. 182 15

The effects of changes in pH on the binding of agonists and antagonists to the human platelet thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptor were determined. Competition binding studies were performed with the TXA2/PGH2 mimetic [1S-1 alpha,2 beta (5Z), 3 alpha(1E,3R*),4 alpha)]-7-[3-(3-hydroxy-4'-iodophenoxy)-1-buteny) 7-oxabicyclo-[2.2.1]-heptan-2-yl]-5-heptenoic acid ([125I]BOP). The pH optimum for binding of [125I] BOP to washed human platelets was broad with a range of pH 4-6 in contrast to that of the TXA2/PGH2 receptor antagonist 9,11-dimethyl-methano-11,12-methano-16-(3-iodo-4-hydroxyl)-13-aza-15 alpha,beta-omega-tetranorthromboxane A2 ([125I]PTA-OH) which was 7.4. Scatchard analysis of [125I]BOP binding in washed platelets at pH 7.4, 6.0, and 5.0 revealed an increase in affinity (Kd = 1.16 +/- 0.06, 0.64 +/- 0.09, and 0.48 +/- 0.05 nM, respectively) and an increase in the number of receptors (Bmax = 2807 +/- 415, 5397 +/- 636, and 7265 +/- 753 sites/platelet, respectively). The potency of I-BOP to induce shape change in washed platelets at pH 6.0 was also significantly increased from an EC50 value of 0.34 +/- 0.016 nM at pH 7.4 to 0.174 +/- 0.014 nM at pH 6.0 (n = 6, p less than 0.05). In contrast, the EC50 value for thrombin was unaffected by the change in pH. In competition binding studies with [125I]BOP, the affinity of the agonists U46619 and ONO11113 were increased at pH 6.0 compared to 7.4. In contrast, the affinity of the TXA2/PGH2 receptor antagonists I-PTA-OH, SQ29548, and L657925 were either decreased or unchanged at pH 6.0 compared to 7.4. Diethyl pyrocarbonate and N-bromosuccinimide, reagents used to modify histidine residues, reversed the increase in affinity of [125I]BOP at pH 6.0 to values equivalent to those at pH 7.4. In solubilized platelet membranes, the effects of NBS were blocked by coincubation with the TXA2/PGH2 mimetic U46619. The results suggest that agonist and antagonist binding characteristics are different for the TXA2/PGH2 receptor and that histidine residue(s) may play an important role in the binding of TXA2/PGH2 ligands to the receptor.
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PMID:Differential effect of pH on thromboxane A2/prostaglandin H2 receptor agonist and antagonist binding in human platelets. 183 Mar 8

The overall goal of our research is to develop effective new photosensitizers for tumor-selective photodynamic therapy. Phenoxazine dyes, including several Nile blue analogues, are known to localize selectively in animal tumors. Structural modifications yielded several series of analogues with substantially higher 1O2 yields and different photochemical and physicochemical properties. This study examined the photosensitization potency, cellular uptake, and retention of these derivatives in human bladder carcinoma cells (MGH-U1) in culture. Nile blue derivatives containing halogens and/or sulfur substitutes were selected to exhibit different 1O2 yields, pKa values, and hydrophobicities. The effectiveness of these derivatives in mediating photokilling of tumor cells in vitro corresponded well with the 1O2 yields of these compounds, indicating that structural modifications which resulted in increased 1O2 yields enhanced potency in mediating photocytotoxicity in vitro. Using derivatives (sat-NBS and sat-NBS-61) with the highest 1O2 quantum yield (0.35 and 0.821), over 90% cell kill was achieved at a sensitizer concentration of 5 x 10(-8) M, about 3 orders of magnitude more effective than hematoporphyrin derivative, the only sensitizer currently available clinically. This result suggests that some of the oxazine derivatives could potentially be effective photosensitizers. The correspondence between 1O2 yield and photosensitizing potency, together with results showing enhanced photocytotoxicity in the presence of D2O and reduced photocytotoxicity under hypoxic conditions, strongly suggests that the generation of 1O2 is a major mechanism mediating the photocytotoxic effect. The uptake of Nile blue derivatives by cells in culture exhibited a pattern of rapid initial uptake followed by a gradual increase in cellular dye contents. The uptake does not correlate directly with the individual pKa values or hydrophobicities of the derivatives, indicating that the structural modifications that increased 1O2 yields did not significantly alter the uptake and retention of Nile blue derivatives. The highly concentrative uptake by and slow efflux from dye-loaded cells were consistent with an active mechanism for the cellular accumulation of these dyes. On the other hand, the retention of the compounds was directly proportional to dye concentration in the medium over a 1000-fold range of concentrations, and the uptake could proceed at temperatures below 2 degrees C; these observations excluded endocytosis or a carrier-mediated mechanism for the uptake. The uptake was also unaffected by the presence of serum in the medium. Based on these results, we hypothesize that Nile blue derivatives transport across the cell membrane possibly as deprotonated forms and, upon entering the cell, either partition into lipophilic areas of the cell membranes and/or become sequestered in certain intracellular organelles.
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PMID:Photosensitization, uptake, and retention of phenoxazine Nile blue derivatives in human bladder carcinoma cells. 184 56

A technique is described which enables one to obtain detailed dose characteristics of 90Sr beta-ray ophthalmic applicators. A radiochromic radiation detector which is a solid-state solution of hexahydroxyethyl pararosaniline cyanide in a nylon polymer (i.e., thin foil), has been used to determine the surface dose rate and dose distribution of these sources. The detectors are rugged, easily handled, have an equivalent response (optical density per unit absorbed dose) to photons and electrons, and produce high-resolution images. They have been found useful for this application due to the high surface dose rates [0.10-1.0 Gy (H2O)/s] and their low sensitivity (approximately 10(4) Gy for an optical density of 1.0). The foils have been evaluated on a He-Ne scanning laser densitometer with a resolution of 0.3 mum. Comparison with NIST (formerly NBS) extrapolation ionization chamber measurements indicates surface dose-rate agreement within 6%. Spectral dosimetric characteristics are presented and discussed.
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PMID:A new method for characterizing beta-ray ophthalmic applicator sources. 187 Apr 89


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