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Naphthalene-induced oxidative stress in rats and the protective effects of vitamin E succinate.

Quinone metabolites of naphthalene (NAP) are known to produce lipid peroxidation. However, the ability of naphthalene to induce oxidative stress in experimental animals has not been extensively investigated. Furthermore, the effects of vitamin E succinate [(+)-alpha-tocopherol acid succinate; VES] on naphthalene-induced oxidative stress and tissue damage were assessed. Female Sprague-Dawley rats were treated with a single oral dose of 1100 mg naphthalene/kg (0.50 LD50) in corn oil. Vitamin E succinate-treated rats received 100 mg VES/kg/day orally for 3 d before naphthalene treatment, and 40 mg VES/kg/d after NAP administration. Hepatic and brain tissues and urine samples were collected 0, 12, 24, 48, and 72 h after NAP treatment. Naphthalene treatment resulted in a 2.1-fold increase in lipid peroxidation in liver and brain mitochondria at the 24-h time point. Increases in hepatic and brain mitochondrial lipid peroxidation in VES plus NAP-treated rats were 39-46% less than NAP treated rats at 24 h. DNA-single strand breaks increased 3.0-fold in hepatic tissues in NAP treated rats, and increased only 1.6-fold in VES protected rats at the 24-h time point. Glutathione (GSH) decreased by 83 and 49% in hepatic and brain tissues, respectively, in NAP-treated rats at the 24-h time point, while GSH content in VES plus NAP-treated rats decreased 47 and 21% in hepatic and brain tissues, respectively, at this same time point. Microsomal membrane fluidity, a measurement of membrane damage, increased 1.9- and 1.7-fold in liver and brain tissues, respectively, in NAP-treated rats, and only 1.3- and 1.2-fold in NAP plus VES-treated rats at the 24-h time point. The urinary excretion of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT), and acetone (ACON) was determined at 0-96 h after NAP administration. Between 12-24 h after NAP administration maximal excretion of the four urinary lipid metabolites was observed, with increases of 4.5-, 2.7-, 2.3-, and 2.8-fold for MDA, FA, ACT, and ACON, respectively, at the 24-h time point. VES reduced the NAP-induced excretion of these urinary metabolites by 28-49% 24 h after NAP administration. These results support the hypothesis that NAP induces oxidative stress and tissue damage, and that vitamin E succinate provides significant protection.

Animals↗

Associated urological anomalies in children with unilateral renal agenesis.

PURPOSE: Unilateral renal agenesis has been noted in 1:1,000 autopsies. Recently an increased incidence of vesicoureteral reflux was reported in patients with a solitary kidney. We determined the incidence of associated renal abnormalities in children with unilateral renal agenesis. MATERIALS AND METHODS: We retrospectively reviewed 46 consecutive cases of unilateral renal agenesis diagnosed at our hospital between January 1985 and February 1998. Patient age at diagnosis ranged from newborn to 12.5 years (mean 2.8 years). There were 24 boys and 22 girls. The left kidney was absent in 27 patients and the right kidney was absent in the remaining 19. A total of 24 patients were evaluated for urinary tract infection and in the other 22 a solitary kidney was found during examination for congenital malformations, enuresis or abdominal pain. The diagnosis was made in all patients by abdominal ultrasound and confirmed by excretory urography, or diethylenetriaminepentaacetic acid or dimercapto-succinic acid scan. A voiding cystourethrogram was performed in 40 patients (87%). RESULTS: Associated urological anomalies were present in 22 of the 46 patients (48%) with unilateral renal agenesis, including primary vesicoureteral reflux in 13 (28%), ureterovesical junction obstruction in 5 (11%), ureteropelvic junction obstruction in 3 (7%), and ureterovesical and ureteropelvic junction obstruction in 1 (2%). Of the 22 patients 14 (64%) underwent surgical intervention. CONCLUSIONS: Nearly half of the patients with unilateral renal agenesis had associated urological anomalies. Vesicoureteral reflux was the most common associated anomaly and it was usually of high grade. Early recognition and treatment of urological anomalies in a patient with a solitary kidney are imperative to decrease the long-term risk of renal damage.

Child↗

Synthesis and characterisation of poly(D,L-lactic acid)-idoxuridine conjugate.

A new polymeric prodrug was prepared coupling 5-iodo-2'-deoxyuridine (IDU) to poly(d,l-lactic acid) (PLA) via a succinic acid spacer. The PLA-IDU conjugate was characterised by thermal analysis, IR and 1H and 13C NMR spectroscopy. The IDU content (0.024 mequiv.g-1 of PLA) was consistent with the carboxylic acid endgroup present in the polymer sample (0.025 mequiv.g-1 of polymer). The PLA-IDU conjugate was susceptible to degradation in biological environments containing esterase, whereas IDU was not detected by chemical hydrolysis in pH 7.4 phosphate buffer. The conjugate should be used to prepare injectable microspheres and nanospheres containing IDU chemically coupled to the polymer carrier.

Animals↗

Quantification of lanthanides in rocks using succinic acid-derivatized sorbents for on-line SPE-RP-ion-pair HPLC

The use of new poly(norbornene-block-7-oxanorborn-2ene-5,6-dicarboxylic acid)-coated silica-based sorbents as well as of beaded polymers based on poly(norborn-2-ene-5,6-dicarboxylic acid-co-1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene) for the on-line preconcentration of lanthanides from rock digests and their subsequent RP-ion-pair HPLC separation is described. Block co-polymers of norborn-2-ene and 7-oxanorborn-2-ene-5,6-dicarboxylate used for coating were prepared by ring-opening metathesis polymerization (ROMP) and poly(norborn-2-ene-5,6-dicarboxylic acid-co-1,4,4a,5,8,-8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene)-based polymer beads were prepared by ring-opening metathesis precipitation polymerization. Both types of sorbents exhibit an extraordinarily good pH stability, are hydrophilic and therefore easily wetable by water alone, and show high extraction efficiencies for lanthanides within a pH of 3.5-5.5. The rare earth element (REE) content in the investigated rocks varied over 3 orders of magnitude (0.19-108 microg/g). REE concentrations prior to enrichment were typically in the range of 1-25 ng/mL; the total amount of each REE sorbed onto the precolumn was in the range of 8-270 ng. Extraction selectivities of the sorbent may be enhanced by adding 5-sulfosalicylic acid as a masking agent for iron and aluminum as well as methanol as an inhibitor for the precipitation of o-silicic acid. Gradient elution of the lanthanides from the precolumn and their subsequent separation on a RP-C18 column was achieved using hydroxyisobutyric acid (HIBA) and sodium octanesulfonate. Depending on the actual concentration of the lanthanides in the digests and in order to suppress interfering cations, UV detection was carried out with two different postderivatization reagents, 4-(2-pyridylazo)resorcinol (PAR) and arsenazo III. The high selectivity in enrichment as well as the complementary use of post-derivatization reagents allows the fast, quantitative, and highly reproducible quantification of REEs present in rocks by complete removal or suppression of all other interfering components. Thus, recoveries were found to be within a range of 97-103% for most REEs with relative standard deviations of 2-5%.

Journal Article↗

Ototoxicity caused by cisplatin is ameliorated by melatonin and other antioxidants.

The mechanism of the ototoxicity caused by cisplatin is based in the generation of reactive oxygen species, which interferes with the antioxidant protection of the organ of Corti. Conversely, the protection of the cochlea with antioxidants ameliorates the ototoxicity by cisplatin. The ototoxicity produced by cisplatin can be reversible or persistent, depending on the age of the patient, cumulative doses, number of chemotherapy cycles, history of noise exposure, and deteriorating renal function. We have obtained in rats an ototoxic chart utilizing cisplatin (10 mg/kg body weight injected intraperitoneally, once only). Together with this treatment, the animals were treated with melatonin in the drinking water (10 mg/L) or injected subcutaneously (250 microg), and with an antioxidant mixture, injected subcutaneously, composed of 0.25 mg alpha-tocopherol acid succinate, 3 mg ascorbic acid, 1 mg glutathione, and 60 mg N-acetylcysteine. The distortion product otoacoustic emissions were determined for a prolonged period of time for each animal. The ototoxicity produced by cisplatin was maximal from days 7 to 10 post-treatment, returning to normal values in a month. When melatonin and the antioxidant mixture were present, the recovery was between days 10 and 15 post-treatment, independent of the means of administration of the pineal product. We conclude that the ototoxicity caused by cisplatin is ameliorated by melatonin and other antioxidants.

Animals↗

Organic acid and potassium accumulation in guard cells during stomatal opening.

Leaflets of Vicia faba L. with either open or closed stomata were quick-frozen and freeze-dried. Individual guard cell pairs and pure samples of palisade parenchyma, spongy parenchyma, and epidermis lacking guard cells were dissected from the leaflets, weighed, and assayed for organic acids or K(+).K(+) was measured by a new enzymatic method. In guard cells of open stomata, as compared to closed stomata, K(+) was 2- to 4-fold higher, malic acid 6-fold higher, and citric acid 3-fold higher. Both aspartic and glutamic acids were also higher, but the amounts present were low compared to malic and citric acids. Isocitric acid was significantly higher in one experiment, but not in another. Glyceric acid was not increased. Succinic acid was too low to detect by the method used; but in guard cells of open stomata the concentration must have been less than 2% of that of malic acid. Malic acid was higher in the palisade parenchyma from the leaflet with open stomata. The ion balance shows that malic and citric acids provide much of the counter ion for the K(+) taken up during stomatal opening.

Journal Article↗

Reaction products of aquatic humic substances with chlorine.

A major concern of the chlorination of aquatic humic materials is the ubiquitous production of trihalomethanes. A large number of other chlorinated organic compounds, however, have been shown to be formed by chlorine's reaction with humic substances. In this study, humic material was concentrated from a coastal North Carolina lake and chlorinated at a chlorine to carbon mole ratio of 1.5 at pH 12. A high pH was necessary for complete dissolution of the humic material and for production of adequate quantities of oxidation and chlorination products for extraction, separation and mass spectrometric identification. After concentration in ether, samples were methylated, separated with a 50-m OV-17 glass capillary column or a 25 m SP-2100 fused-silica column and identified. A Hewlett-Packard 5710A gas chromatograph interfaced to a VG Micromass 7070F double-focusing mass spectrometer was used. Low resolution, accurate mass measurements were made with a combined EI-Cl source. The ability to do low resolution, accurate mass measurements made possible a rapid scan function necessary for capillary column gas chromatography. Accurate mass measurements allowed increased confidence in the identification of compounds, most of which are not available as standards. The products identified in these studies were chlorinated aliphatic straight-chain acids dominated by di- and trichloroacetic acid and the chlorinated dicarboxylic acids: succinic, fumaric and maleic acids. Chlorinated and unchlorinated aliphatic mono- and dicarboxylic acids and unchlorinated polycarboxylic aromatic acids comprise the remaining bulk of the compounds identified.

Chemical Phenomena↗

Photodegradation of hydroxychlorothalonil in aqueous solutions.

Hydroxychlorothalonil is the principal degradation product of the fungicide chlorothalonil in soil, and it is routinely detected in leachate from golf course greens at concentrations as high as 2 ppm. However, it is not detected in receiving waters of shallow ponds. Irradiation with simulated sunlight degraded hydroxychlorothalonil in distilled-deionized water, phosphate buffer, and pond water with half-lives of approximately 30 min. Slower degradation was observed in solutions of NaCl and NaCN, suggesting photonucleophilic substitution reactions may be responsible for the degradation. Hydroxylated products resulting from the displacement of chlorine and cyano groups were detected within the first hour of irradiation but were subsequently degraded to small aliphatic acids (succinic, oxalic, and malonic acid) within 96 h. Simulations of aquatic dissipation of the chemical using the U.S. Environmental Protection Agency standard pond scenario in the exposure analysis modeling system indicate that the 30-min half-life measured in the laboratory would equate to a half-life of 2.6 d in a 2-m-deep pond and as much as 3.4 d in seawater. Although hydroxychlorothalonil is moderately stable and mobile in soil, these data suggest that, in surface water, it should be rapidly degraded by sunlight to small aliphatic acids on transport into aquatic systems.

Fungicides, Industrial↗

[Studies on the chemical constituents of the leaves from Artabotrys hexapetalus].

Artabotrys hexapetalus (annonaceae) is distributed in southern China. As a Chinese folk herb medicine, its root and fruits are used to treat malaria and scrofula, respectively. Two new flavonol glycosides, artabotryside-A (1), -B (2), three known flavonoids: taxifolin (3), 7-O-glucoluteolin (4), apigenin-7-O-apiosyl(1-->2) glycoside (5), and two organic acid: succinic (6) and fumaric acid (7) have been isolated from the leaves of A. hexapetalus. The structures of 1 and 2 were elucidated as quercetin-3-O-alpha-L-rhamnopyranosyl (1-->2)-alpha-L-arabinofuranoside (1) and kaempferol-3-O-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinofuranoside (2), respectively, on the basis of spectral analysis. The compounds 3 through 7 were found from A. hexapetalus for the first time.

Annonaceae↗

Inhibition of etoposide-induced DNA damage and cytotoxicity in L1210 cells by dehydrogenase inhibitors and other agents.

The mechanism of action of 4'-demethylepipodophyllotoxin-9-(4,6-O-ethylidene-beta-D-glucopyra noside) (VP-16), an important antitumor agent, is unclear. There is evidence that DNA may be the target of action because VP-16 causes single-strand and double-strand breaks in DNA and produces cytotoxicity over a similar dose range. We have hypothesized that an enzyme system, such as dehydrogenase, catalyzes an oxidation-reduction reaction involving the pendant phenolic group which forms an active metabolite that causes the DNA damage and cytotoxicity. To test our hypothesis, we investigated the effect of disulfiram, an aldehyde dehydrogenase inhibitor, and its metabolite, diethyldithiocarbamate, on VP-16-induced DNA damage in L1210 cells. Using the alkaline elution technique to assay DNA damage, we found that disulfiram and diethyldithiocerbamate inhibited VP-16-induced single-strand breaks. Both compounds were also capable of significantly reducing VP-16-induced cytotoxicity. Oxalic acid, pyrophosphate, and malonic acid, competitive inhibitors of succinate dehydrogenase, and the naturally occurring dehydrogenase substrates, succinic acid, beta-glycerophosphate, and isocitric acid, also blocked the effects of VP-16. Free-radical scavengers were also studied. While sodium benzoate was particularly effective in preventing drug-induced DNA damage and cytotoxicity, a number of other scavengers were not. Our data are consistent with the hypothesis that VP-16 is activated by an enzyme such as a dehydrogenase which transforms it into an active intermediate resulting in DNA damage and, consequently, cell death.

Aldehyde Dehydrogenase↗

Effect of organic acids and nitrogen source on alcoholic fermentation: study of their buffering capacity.

The effect of tartaric acid and other organic acids on alcoholic fermentation was studied. Organic acids in media with high sugar concentrations and ammonium as the sole nitrogen source had an enormous impact on Saccharomyces cerevisiae metabolism during alcoholic fermentation. The main effect on yeast metabolism was the quick acidification of the media in the absence of organic acids. All of the organic acids used in this study (tartaric, malic, citric, and succinic acids) showed a buffering capacity, but not all of the acids had the same one. However, the results suggested that buffering should not be considered the only effect of organic acids on yeast metabolism. Nitrogen source also had a great influence on media pH. Ammonium consumption by yeasts produced a greater acidification of the media than when amino acids were used.

Amino Acids↗

Influence of acidic eluent for retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography on a weakly acidic cation-exchange resin in the H+ -form.

Influence of acidic eluent on retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography (ion-exclusion/CEC) were investigated on a weakly acidic cation-exchange resin in the H(+)-form with conductivity. Sensitivities of analyte ions, especially weak acid anions (F(-) and HCOO(-)), were affected with degree of background conductivity level with pK(a1) (first dissociation constant) of acid in eluent. The retention behaviors of anions and cations were related to that of elution dip induced after eluting acid to separation column and injecting analyte sample. These results were largely dependent on the natures of acid as eluent. Through this study, succinic acid as the eluent was suitable for simultaneous separation of strong acid anions (SO(4)(2-), Cl(-), NO(3)(-) and I(-)), weak acid anions (F(-), HCOO(-) and CH(3)COO(-)), and cations (Na(+), K(+), NH(4)(+), Mg(2+) and Ca(2+)). The separation was achieved in 20 min under the optimum eluent condition, 20 mM succinic acid/2 mM 18-crown-6. Detection limits at S/N=3 ranged from 0.10 to 0.51 microM for strong acid anions, 0.20 to 5.04 microM for weak acid anions and 0.75 to 1.72 microM for cations. The relative standard deviations of peak areas in the repeated chromatographic runs (n=10) were in the range of 1.1-2.9% for anions and 1.8-4.5% for cations. This method was successfully applied to hot spring water containing strong acid anions, weak acid anions and cations, with satisfactory results.

Anions↗

Modulation of TCDD-induced fetotoxicity and oxidative stress in embryonic and placental tissues of C57BL/6J mice by vitamin E succinate and ellagic acid.

The ability of vitamin E succinate and ellagic acid to modulate 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced developmental toxicity and oxidative damage in embryonic/fetal and placental tissues was studied in C57BL/6J mice. Vitamin E succinate (100 mg/kg per day) and ellagic acid(6 mg/kg per day) were administered by gavage to groups of pregnant mice on days 10, 11 and 12 of gestation and 40 mg vitamin E succinate/kg or 3 mg ellagic acid/kg on day 13 of gestation. A number of animals from the vitamin E succinate and ellagic acid treated groups also received 30 microg TCDD/kg on day 12 of gestation, 2 h prior to vitamin E succinate or ellagic acid treatment. Groups of treated animals were terminated on day 14 of gestation, and the biomarkers of oxidative stress, including superoxide anion production and the induction of lipid peroxidation and DNA-single strand breaks (SSB), were determined in whole embryonic and placental tissues homogenates. Groups of treated animals were also killed on day 18 of gestation for investigation of the fetotoxic and teratogenic effects as well as effects on the placentae. Vitamin E succinate and ellagic acid significantly decreased TCDD-induced fetal growth retardation fetal death and placental weight reduction, with no significant ameliorating effects on TCDD-induced malformations including cleft palate and hydronephrosis. Vitamin E succinate treatment resulted in decreases of 77-88%, 70-87%, and 21-47% in the production of superoxide anion, lipid peroxidation and DNA-SSB, respectively, in embryonic and placental tissues, while ellagic acid caused 47-98%, 79-93%, and 37-53% decreases, respectively, in these parameters. These results indicate that TCDD-induced fetal death and fetal and placental weight reductions in C57BL/6J mice may be due to oxidative damage induced by TCDD, and ellagic acid and vitamin E succinate provide protection against those effects. Ellagic acid provided better protection than vitamin E succinate against TCDD-induced fetal growth retardation and increases in lipid peroxidation in embryonic and placental tissues.

Animals↗