Evidence for the production of nitric oxide by activated macrophages treated with the antitumor agents flavone-8-acetic acid and xanthenone-4-acetic acid.
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Activated peritoneal macrophages, obtained from mice pretreated with Bacillus Calmette-Guerin, after exposure in vitro to flavone-8-acetic acid (FAA; NSC 347512) at a concentration of 890 microM, produce nitrite (3.7 nmol/10(6) cells), as measured 20 h later by the Griess reaction. Stimulation of nitrite production was inhibited at least 90% by NG-monomethylarginine (125 microM), suggesting that nitrite was formed via nitric oxide as a product of arginine metabolism. Stimulation was only partially inhibited by dexamethasone (0.1 microM). The ability of xanthenone-4-acetic acid (XAA) and three of its analogues to stimulate nitrite production was also investigated. 5,6-Dimethyl-XAA stimulated nitrite production (12.6 nmol/10(6) cells) at an optimal concentration of 80 microM, 8-methyl-XAA was without effect, and XAA and 5-methyl-XAA showed intermediate activity. The optimal in vitro drug concentrations for stimulation by FAA, XAA, and active XAA analogues correlated with the optimal in vivo dose required for the induction of either hemorrhagic necrosis or growth delay of s.c. Colon 38 tumors. These results strongly imply that FAA and active XAA derivatives function as low molecular weight stimulators of nitric oxide formation in macrophages, possibly acting on the same differentiation pathway as do endotoxin and tumor necrosis factor alpha. We suggest that nitric oxide, which is known to be toxic to tumor cells, contributes to the cytotoxic action of FAA and its analogues. (+info)
Adsorption mechanism of copper and cadmium onto defatted waste biomass.
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In this study, the amount of copper or cadmium adsorbed using waste biomass (i.e., coffee grounds (CG) and rice bran (RB)) was investigated. The amount of crude protein in defatted CG (D-CG) or RB (D-RB) was greater than that in CG or RB, respectively. The amount of copper or cadmium adsorbed using CG was greater than that using RB. Additionally, the amount of copper or cadmium adsorbed was not affected by the presence of fat in CG. Adsorption data was fitted to the Freundlich equation, and the correlation coefficients were in the range of 0.794-0.991. The main adsorption mechanism was thought to be monolayer adsorption onto the surface of the waste biomass. The adsorption rate data was fitted to the pseudo-second-order model, and the correlation coefficient average was in the range of 0.891-0.945. This result showed that the rate-limiting step may be chemisorption. Moreover, the amount of copper or cadmium desorbed from CG or RB using 0.01 mol/L or 1.00 mol/L HNO(3) was investigated. Desorption with 0.01 mol/L HNO(3) resulted in the recovery of 86-97% of the copper and cadmium, indicating that copper or cadmium that was adsorbed using waste biomass was recoverable. (+info)
Evidence that enzymes of a novel aerobic 2-amino-benzoate metabolism in denitrifying Pseudomonas are coded on a small plasmid.
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A new pathway for aerobic metabolism of 2-aminobenzoate which proceeds via anthranoyl-CoA has recently been revealed in a Pseudomonas strain KB740. This bacterial strain was found to contain a small 8.1-kbp plasmid pKB740 which appears to harbour the genes encoding for two key enzymes catalyzing the initial reactions of the pathway, 2-aminobenzoate coenzyme A ligase and 2-aminobenzoyl-coenzyme A monooxygenase/reductase. The evidence is as follows: The plasmid content of the culture varied by a factor of ten depending on the growth substrates; it was highest when cells were grown aerobically on 2-aminobenzoate. The plasmid pKB740 could be introduced into Escherichia coli strain JM83 by transformation. Wild-type E. coli and E. coli JM83 are unable to metabolize 2-aminobenzoate whereas the transformed E. coli JM83 cells could grow with this aromatic compound as sole organic substrate and oxidize it completely to CO2. The plasmid recovered from E. coli had the same restriction map as the original plasmid, but was dimerized. The two key enzyme activities were demonstrated in the transformed E. coli in sufficiently high amounts to explain growth. They appear to be regulated on the transcription level by induction; they were formed only during aerobic growth in the presence of 2-aminobenzoate, as in the parent Pseudomonas. The N-terminal amino acid sequence of 2-aminobenzoyl-CoA monooxygenase/reductase was similar to the consensus sequence of the FAD binding site of different flavoenzymes. The data also prove that the enzyme with two flavin functions is a alpha 2 homodimer. Southern blotting of digested chromosomal and plasmid DNA and hybridization against a labelled 15-base oligonucleotide derived from the N-terminal amino acid sequence of 2-aminobenzoyl-CoA monooxygenase/reductase revealed that the gene for this enzyme is coded on the plasmid rather than on the chromosome. The gene was localized on a 3.2-kbp restriction fragment. The formation of 2-aminobenzoyl-CoA monooxygenase/reductase protein in transformed E. coli was demonstrated by Western blotting of proteins of cell extracts separated by SDS/PAGE. The enzyme protein band, which was stained by a procedure based on antibodies against 2-aminobenzoyl-CoA monooxygenase/reductase, was demonstrated in transformed E. coli. (+info)
Parallel-plate wet denuder coupled ion chromatograph for near-real-time detection of trace acidic gases in clean room air.
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This paper describes the performance of our automated acidic (CH(3)COOH, HCOOH, HCl, HNO(2), SO(2), and HNO(3)) gases monitor utilizing a parallel-plate wet denuder (PPWD). The PPWD quantitatively collects gaseous contaminants at a high sample flow rate ( approximately 8 dm(3) min(-1)) compared to the conventional methods used in a clean room. Rapid response to any variability in the sample concentration enables near-real-time monitoring. In the developed monitor, the analyte collected with the PPWD is pumped into one of two preconcentration columns for 15 min, and determined by means of ion chromatography. While one preconcentration column is used for chromatographic separation, the other is used for loading the sample solution. The system allows continuous monitoring of the common acidic gases in an advanced semiconductor manufacturing clean room. (+info)
Separation of -amino acids using a series of zwitterionic sulfobetaine exchangers.
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A set of five new covalently bond sulfobetaine exchangers with inner quaternary amines and outer sulfonic acids have been prepared by attachment of a series of zwitterionic precursors to hyperporous divinylbenzene polymers using a grafting reaction. The series of zwitterionic exchangers have the same backbone and identical spacers to the polymeric backbone, as well as comparable capacities. The only difference is the chain length for one to five methylene groups between the charged functional groups. Chromatographic properties are examined by separation of alpha-amino acids using sodium acetate and nitric acid eluents. The separation mechanism is explored by varying eluent ionic strength and eluent pH, resulting in the conclusion that amino acids are separated due to cation exchange interactions. This is a behavior never before observed using zwitterionic exchangers. It contradicts the fact that sulfobetaine-type materials used in zwitterionic ion chromatography (ZIC) usually are well suited for anion separation and only poorly for cation separation. Contrary to anion separations using the identical set of exchangers, the materials with three and four methylene groups between the charges give the highest retention factors. Materials showing the high potential in ZIC separations of inorganic anions give low retention factors for amino acids and vice versa. (+info)
Probucol attenuates oxidative stress, energy starvation, and nitric acid production following transient forebrain ischemia in the rat hippocampus.
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Multivariate approach in the optimization procedures for the direct determination of manganese in serum samples by graphite furnace atomic absorption spectrometry.
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A method for direct determination of manganese (Mn) in human serum by graphite furnace atomic absorption spectrometry (GFAAS) was proposed in this work. The samples were only diluted 1:4 with nitric acid 1% (v/v) and Triton((R)) X-100 0.1% (v/v). The optimization of the instrumental conditions was made using multivariate approach. A factorial design (2(3)) was employed to investigate the tendency of the most intense absorbance signal. The pyrolysis and atomization temperatures and the use of modifier were available and only the parameter modifier use did not have a significant effect on the response. A Center Composed Design (CCD) presented best temperatures of 430 degrees C and 2568 degrees C for pyrolysis and atomization, respectively. The method allowed the determination of manganese with a curve varying from 0.7 to 3.3 mug/L. Recovery studies in three concentration levels (n=7 for each level) presented results from 98 +/- 5 to 102 +/- 7 %. The detection limit was 0.2 mug/L, the quantifying limit was 0.7 mug/L, and the characteristic mass, 1.3 +/- 0.2 pg. Intra- and interassay studies showed coefficients of variation of 4.7-7.0% (n=21) and 6-8%(n=63), respectively. The method was applied for the determination of manganese in 53 samples obtaining concentrations from 3.9 to 13.7 mug/L. (+info)