Dissolved organic carbon diminishes manganese oxide-driven oxidation of chromium.

Oxidation of chromium (Cr)-bearing minerals by manganese (Mn) oxides is viewed as the dominant mechanism controlling geogenic production of Cr(VI) and its contamination of groundwater. This process may be modulated by other chemical constituents found in the natural environment, but such confounding factors have not been quantified. Here, we evaluated the mechanism of Cr(III) oxidation by mixed-valence Mn oxide in the presence of citric and gallic acids, two natural organic matter (NOM) constituents commonly found in the soil environment. Incubation experiments showed that each organic acid enhanced solubilization of Cr(III) and Mn over controls without organic addition but increasing organic acid concentration decreased production of Cr(VI), with approximately 8.5 times less Cr(VI) produced in the citric acid than gallic acid experiments. X-ray absorption spectroscopy showed that negligible Cr(VI) was present in solid-phase reaction products, regardless of treatment. Geochemical modeling revealed that in the citric acid experiments, unprotonated Cr(III)-citrate was the dominant organo-metallic complex in solution, while (CrOH)2+ distribution positively correlated with concentrations of Cr(VI) produced. Collectively, these results illustrate how NOM can modify expected chemical pathways driving Cr cycling, and such mechanistic information should be better integrated into models predicting Cr redox dynamics and availability in the environment.

Antioxidant and hepatoprotective activities of Dicoma anomala Sond. aqueous root extract against carbon tetrachloride-induced liver damage in Wistar rats.

OBJECTIVE: To evaluates the antioxidant and hepatoprotective potentials of Dicoma anomala Sond. (Asteraceae) on body weight, feed and water intake, biochemical parameters and organ histology. METHODS: Various concentrations (1.56-25 µg/mL) were used in the in vitro assays 1,1-diphenyl-2-picryl hydrazyl (DPPH, superoxide anion, hydroxyl radicals, etc.). The effects of treatment with 125, 250 and 250 mg/mL Dicoma anomala aqueous roots extract (DARE) was investigated in vivo in the CCl4-induced hepatotoxic rats during the 15 days study. RESULTS: Water extract exhibited the best activity (IC50: 15.20 ± 0.03, 11.70 ± 0.10, and 0.84 ± 0.05 µg/ mL) in vitro in DPPH, hydroxyl and superoxide anion radicals, respectively, when compared with standards. Pre-treatment and treatment with different concentrations of DARE significantly (P < 0.05) attenuated the elevated serum activities of aspartate transaminase, alanine transaminase levels while increasing the activities of superoxide dismutase, catalase and glutathione peroxidase. The histopathological evaluations revealed extensive liver damage characterized by severe vacuolar and cytoplasmic degeneration, hepatic necrosis, and cellular infilteration in pre-treated groups while in the treated groups; such liver damages were not observed most especially at 500 mg/kg dose. CONCLUSION: The results proved the hepatoprotective potential of DARE against CCl4-induced oxidative stress. Moreover, histopathological examinations revealed better therapeutic advantage of DARE than prophylactic use.

Right ampullary ectopic pregnancy following bilateral tubal ligation using spring clips.

Pregnancy is unlikely to occur in women who have undergone sterilization. However when it occurs, there is a substantial risk that it will be an ectopic pregnancy. We report a case of right unruptured ampullary ectopic gestation following tubal sterilization with spring clips 6 years prior to presentation. The likely aetiology may be spontaneous reanastomosis.