Estimating the uptake of traffic-derived NO2 from 15N abundance in Norway spruce needles

The 15N ratio of nitrogen oxides (NOx) emitted from vehicles, measured in the air adjacent to a highway in the Swiss Middle Land, was very high [δ15N(NO2) = +5.7‰]. This high 15N abundance was used to estimate long-term NO2 dry deposition into a forest ecosystem by measuring δ15N in the needles and the soil of potted and autochthonous spruce trees [Picea abies (L.) Karst] exposed to NO2 in a transect orthogonal to the highway. δ15N in the current-year needles of potted trees was 2.0‰ higher than that of the control after 4 months of exposure close to the highway, suggesting a 25% contribution to the N-nutrition of these needles. Needle fall into the pots was prevented by grids placed above the soil, while the continuous decomposition of needle litter below the autochthonous trees over previous years has increased δ15N values in the soil, resulting in parallel gradients of δ15N in soil and needles with distance from the highway. Estimates of NO2 uptake into needles obtained from the δ15N data were significantly correlated with the inputs calculated with a shoot gas exchange model based on a parameterisation widely used in deposition modelling. Therefore, we provide an indication of estimated N inputs to forest ecosystems via dry deposition of NO2 at the receptor level under field conditions.

Tissue metabolomics of hepatocellular carcinoma: Tumor energy metabolism and the role of transcriptomic classification

Hepatocellular carcinoma (HCC) is one of the commonest causes of death from cancer. A plethora of metabolomic investigations of HCC have yielded molecules in biofluids that are both up- and down-regulated but no real consensus has emerged regarding exploitable biomarkers for early detection of HCC. We report here a different approach, a combined transcriptomics and metabolomics study of energy metabolism in HCC. A panel of 31 pairs of HCC tumors and corresponding nontumor liver tissues from the same patients was investigated by gas chromatography-mass spectrometry (GCMS)-based metabolomics. HCC was characterized by ∼2-fold depletion of glucose, glycerol 3- and 2-phosphate, malate, alanine, myo-inositol, and linoleic acid. Data are consistent with a metabolic remodeling involving a 4-fold increase in glycolysis over mitochondrial oxidative phosphorylation. A second panel of 59 HCC that had been typed by transcriptomics and classified in G1 to G6 subgroups was also subjected to GCMS tissue metabolomics. No differences in glucose, lactate, alanine, glycerol 3-phosphate, malate, myo-inositol, or stearic acid tissue concentrations were found, suggesting that the Wnt/β-catenin pathway activated by CTNNB1 mutation in subgroups G5 and G6 did not exhibit specific metabolic remodeling. However, subgroup G1 had markedly reduced tissue concentrations of 1-stearoylglycerol, 1-palmitoylglycerol, and palmitic acid, suggesting that the high serum α-fetoprotein phenotype of G1, associated with the known overexpression of lipid catabolic enzymes, could be detected through metabolomics as increased lipid catabolism. Conclusion: Tissue metabolomics yielded precise biochemical information regarding HCC tumor metabolic remodeling from mitochondrial oxidation to aerobic glycolysis and the impact of molecular subtypes on this process.

Oxidation of 3-hydroxyanthranilic acid to the phenoxazinone cinnabarinic acid by peroxyl radicals and by compound I of peroxidases or catalase

Since 3-hydroxyanthranilic acid (3HAA), an oxidation product of tryptophan metabolism, is a powerful radical scavenger [Christen, S., Peterhans, E., ; Stocker, R. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 2506], its reaction with peroxyl radicals was investigated further. Exposure to aqueous peroxyl radicals generated at constant rate under air from the thermolabile radical initiator 2,2'-azobis[2-amid-inopropane] hydrochloride (AAPH) resulted in rapid consumption of 3HAA with initial accumulation of its cyclic dimer, cinnabarinic acid (CA). The initial rate of formation of the phenoxazinone CA accounted for approximately 75% of the initial rate of oxidation of 3HAA, taking into account that 2 mol of 3HAA are required to form 1 mol of CA. Consumption of 3HAA under anaerobic conditions (where alkyl radicals are produced from AAPH) was considerably slower and did not result in detectable formation of CA. Addition of superoxide dismutase enhanced autoxidation of 3HAA as well as the initial rates of peroxyl radical-induced oxidation of 3HAA and formation of CA by approximately 40-50%, whereas inclusion of xanthine/xanthine oxidase decreased the rate of oxidation of 3HAA by approximately 50% and inhibited formation of CA almost completely, suggesting that superoxide anion radical (O2.-) was formed and reacted with reaction intermediate(s) to curtail formation of CA. Formation of CA was also observed when 3HAA was added to performed compound I of horseradish peroxidase (HRPO) or catalytic amounts of either HRPO, myeloperoxidase, or bovine liver catalase together with glucose/glucose oxidase.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficient Oxidation of Cysteine and Glutathione Catalyzed by a Dinuclear Areneruthenium Trithiolato Anticancer Complex

The highly cytotoxic diruthenium complex [(p-MeC(6)H(4)Pr(1))(2)Ru(2)(SC(6)H(4)-p-Me)(3)](+) (1), water-soluble as the chloride salt, is shown to efficiently catalyze oxidation of the thiols cysteine and glutathione to give the corresponding disulfides, which may explain its high in vitro anticancer activity.

Mechanisms of hepatocellular toxicity associated with dronedarone--a comparison to amiodarone

Dronedarone is a new antiarrhythmic drug with an amiodarone-like benzofuran structure. Shortly after its introduction, dronedarone became implicated in causing severe liver injury. Amiodarone is a well-known mitochondrial toxicant. The aim of our study was to investigate mechanisms of hepatotoxicity of dronedarone in vitro and to compare them with amiodarone. We used isolated rat liver mitochondria, primary human hepatocytes, and the human hepatoma cell line HepG2, which were exposed acutely or up to 24h. After exposure of primary hepatocytes or HepG2 cells for 24h, dronedarone and amiodarone caused cytotoxicity and apoptosis starting at 20 and 50 µM, respectively. The cellular ATP content started to decrease at 20 µM for both drugs, suggesting mitochondrial toxicity. Inhibition of the respiratory chain required concentrations of ~10 µM and was caused by an impairment of complexes I and II for both drugs. In parallel, mitochondrial accumulation of reactive oxygen species (ROS) was observed. In isolated rat liver mitochondria, acute treatment with dronedarone decreased the mitochondrial membrane potential, inhibited complex I, and uncoupled the respiratory chain. Furthermore, in acutely treated rat liver mitochondria and in HepG2 cells exposed for 24h, dronedarone started to inhibit mitochondrial β-oxidation at 10 µM and amiodarone at 20 µM. Similar to amiodarone, dronedarone is an uncoupler and an inhibitor of the mitochondrial respiratory chain and of β-oxidation both acutely and after exposure for 24h. Inhibition of mitochondrial function leads to accumulation of ROS and fatty acids, eventually leading to apoptosis and/or necrosis of hepatocytes. Mitochondrial toxicity may be an explanation for hepatotoxicity of dronedarone in vivo.

Capillary electrophoresis contributions to the hydromorphone metabolism in man

CE-ESI multistage IT-MS (CE-MS(n), n < or = 4) and computer simulation of fragmentation are demonstrated to be effective tools to detect and identify phase I and phase II metabolites of hydromorphone (HMOR) in human urine. Using the same CE conditions as previously developed for the analysis of urinary oxycodone and its metabolites, HMOR and its phase I metabolites produced by N-demethylation, 6-keto-reduction and N-oxidation and phase II conjugates of HMOR and its metabolites formed with glucuronic acid, glucose, and sulfuric acid could be detected in urine samples of a patient that were collected during a pharmacotherapy episode with daily ingestion of 48 mg of HMOR chloride. The CE-MS(n) data obtained with the HMOR standard, synthesized hydromorphol and hydromorphone-N-oxide, and CYP3A4 in vitro produced norhydromorphone were employed to identify the metabolites. This approach led to the identification of previously unknown HMOR metabolites, including HMOR-3O-glucide and various N-oxides, structures for which no standard compounds or mass spectra library data were available. Furthermore, the separation of alpha- and beta-hydromorphol, the stereoisomers of 6-keto-reduced HMOR, was achieved by CE in the presence of the single isomer heptakis(2,3-diacetyl-6-sulfato)-beta-CD. The obtained data indicate that the urinary excretion of alpha-hydromorphol is larger than that of beta-hydromorphol.

Intramyocellular lipid stores increase markedly in athletes after 1.5 days lipid supplementation and are utilized during exercise in proportion to their content

Intramyocellular lipids (IMCL) and muscle glycogen provide local energy during exercise (EX). The objective of this study was to clarify the role of high versus low IMCL levels at equal initial muscle glycogen on fuel selection during EX. After 3 h of depleting exercise, 11 endurance-trained males consumed in a crossover design a high-carbohydrate (7 g kg(-1) day(-1)) low-fat (0.5 g kg(-1) day(-1)) diet (HC) for 2.5 days or the same diet with 3 g kg(-1) day(-1) more fat provided during the last 1.5 days of diet (four meals; HCF). Respiratory exchange, thigh muscle substrate breakdown by magnetic resonance spectroscopy, and plasma FFA oxidation ([1-(13)C]palmitate) were measured during EX (3 h, 50% W (max)). Pre-EX IMCL concentrations were 55% higher after HCF. IMCL utilization during EX in HCF was threefold greater compared with HC (P < 0.001) and was correlated with aerobic power and highly correlated (P < 0.001) with initial content. Glycogen values and decrements during EX were similar. Whole-body fat oxidation (Fat(ox)) was similar overall and plasma FFA oxidation smaller (P < 0.05) during the first EX hour after HCF. Myocellular fuels contributed 8% more to whole-body energy demands after HCF (P < 0.05) due to IMCL breakdown (27% Fat(ox)). After EX, when both IMCL and glycogen concentrations were again similar across trials, a simulated 20-km time-trial showed no difference in performance between diets. In conclusion, IMCL concentrations can be increased during a glycogen loading diet by consuming additional fat for the last 1.5 days. During subsequent exercise, IMCL decrease in proportion to their initial content, partly in exchange for peripheral fatty acids.

Gamma-tocopherol supplementation inhibits protein nitration and ascorbate oxidation in rats with inflammation

Gamma-tocopherol (gammaT) complements alpha-tocopherol (alphaT) by trapping reactive nitrogen oxides to form a stable adduct, 5-nitro-gammaT [Christen et al., PNAS 94:3217-3222; 1997]. This observation led to the current investigation in which we studied the effects of gammaT supplementation on plasma and tissue vitamin C, vitamin E, and protein nitration before and after zymosan-induced acute peritonitis. Male Fischer 344 rats were fed for 4 weeks with either a normal chow diet with basal 32 mg alphaT/kg, or the same diet supplemented with approximately 90 mg d-gammaT/kg. Supplementation resulted in significantly higher levels of gammaT in plasma, liver, and kidney of control animals without affecting alphaT, total alphaT+gammaT or vitamin C. Intraperitoneal injection of zymosan caused a marked increase in 3-nitrotyrosine and a profound decline in vitamin C in all tissues examined. Supplementation with gammaT significantly inhibited protein nitration and ascorbate oxidation in the kidney, as indicated by the 29% and 56% reduction of kidney 3-nitrotyrosine and dehydroascorbate, respectively. Supplementation significantly attenuated inflammation-induced loss of vitamin C in the plasma (38%) and kidney (20%). Zymosan-treated animals had significantly higher plasma and tissue gammaT than nontreated pair-fed controls, and the elevation of gammaT was strongly accentuated by the supplementation. In contrast, alphaT did not significantly change in response to zymosan treatment. In untreated control animals, gammaT supplementation lowered basal levels of 3-nitrotyrosine in the kidney and buffered the starvation-induced changes in vitamin C in all tissues examined. Our study provides the first in vivo evidence that in rats with high basal amounts of alphaT, a moderate gammaT supplementation attenuates inflammation-mediated damage, and spares vitamin C during starvation-induced stress without affecting alphaT.

Inhibition by interferon-gamma of human mononuclear cell-mediated low density lipoprotein oxidation. Participation of tryptophan metabolism along the kynurenine pathway

In this study we examined the potential inhibition by interferon-gamma (IFN gamma) of the early stages of low density lipoprotein (LDL) oxidation mediated by human peripheral blood mononuclear cells (PBMC) and monocyte-derived macrophages (MDM) in Ham's F-10 medium supplemented with physiological amounts of L-tryptophan (Trp). We assessed LDL oxidation by measuring the consumption of LDL's major antioxidant (i.e., alpha-tocopherol) and targets for oxidation (cholesteryllinoleate and cholesterylarachidonate), together with the accumulation of cholesterylester hydroperoxides and the increase in relative electrophoretic mobility of the lipoprotein particle. Exposure of PBMC or MDM to IFN gamma induced the degradation of extracellular Trp with concomitant accumulation of kynurenine, anthranilic and 3-hydroxyanthranilic acid (3HAA) in the culture medium. Formation of 3HAA, but neither Trp degradation nor formation of kynurenine and anthranilic acid, was inhibited by low amounts of diphenylene iodonium (DPI) in a concentration-dependent manner. In contrast to oxidative Trp metabolism, exposure of human PBMC or MDM to IFN gamma failed to induce degradation of arginine, and nitrite was not detected in the cell supernatant, indicating that nitric oxide synthase was not induced under these conditions. Incubation of LDL in Trp-supplemented F-10 medium resulted in a time-dependent oxidation of the lipoprotein that was accelerated in the presence of PBMC or MDM but inhibited strongly in the presence of both cells and IFN gamma, i.e., when Trp degradation and formation of 3HAA were induced. In contrast, when IFN gamma was added to PBMC or MDM in F-10 medium that was virtually devoid of Trp, inhibition of cell-accelerated LDL oxidation was not observed. Exogenous 3HAA added to PBMC or purified monocytes in the absence of IFN gamma also strongly and in a concentration-dependent manner inhibited LDL oxidation. Selective inhibition of IFN gamma-induced formation of 3HAA by DPI caused reversion of the inhibitory action of this cytokine on both PBMC- and MDM-mediated LDL oxidation. These results show that IFN gamma treatment of human PBMC or MDM in vitro attenuates the extent of LDL oxidation caused by these cells, and indicate that Trp degradation with formation of 3HAA is a major contributing factor to this inhibitory activity.

Supported Cu(II) polymer catalysts for aqueous phenol oxidation

Supported Cu(II) polymer catalysts were used for the catalytic oxidation of phenol at 30 degrees C and atmospheric pressure using air and H(2)O(2) as oxidants. Heterogenisation of homogeneous Cu(II) catalysts was achieved by adsorption of Cu(II) salts onto polymeric matrices (poly(4-vinylpyridine), Chitosan). The catalytic active sites were represented by Cu(II) ions and showed to conserve their oxidative activity in heterogeneous catalysis as well as in homogeneous systems. The catalytic deactivation was evaluated by quantifying released Cu(II) ions in solution during oxidation, from where Cu-PVP(25) showed the best leaching levels no more than 5 mg L(-1). Results also indicated that Cu-PVP(25) had a catalytic activity (56% of phenol conversion when initial Cu(II) catalytic content was 200 mg L(Reaction)(-1)) comparable to that of commercial catalysts (59% of phenol conversion). Finally, the balance between activity and copper leaching was better represented by Cu-PVP(25) due to the heterogeneous catalytic activity had 86% performance in the heterogeneous phase, and the rest on the homogeneous phase, while Cu-PVP(2) had 59% and CuO/gamma-Al(2)O(3) 68%.