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Heavy metal pollution is a major concern in environ- mental treatment. In this paper, immobilization mechanisms of Cu2+ in an acidic solution by brucite were investigated. The final pHs of brucite suspensions with initial pHs of 2.0 and 1.6 rose to 6.8 and 6.03, respectively, after an agitation of 48 hours, which indicates that brucite has a good neutralization capacity for acidic media. When ionic strength of the suspension rose from 0.05 mol/L to 0.8 mol/L, final pH and Cu2+ adsorption on brucite increased from 5.82 and 21.45% to 6.17 and 27.78%, respectively, which suggests that Cu2+ shows chemisorption reaction on brucite. The immobilization of Cu2+ in a brucite suspension is attributed to the synergism of neutralization and the adsorption capacities of brucite. Brucite samples adsorbing Cu2+ at a final pH of 5.8 were characterized by X-ray photoelectron spectroscopy (XPS), which indicates that there are two copper species on brucite surface. One species bonds with oxygen to form a structure of bulk brucite-O-Cu-OH, and another species is CuCO3 precipitate as a result of Cu2+ carbonation. [ABSTRACT FROM AUTHOR]

Objective To observe the effects of fenvalerate on calcium homeostasis in rat ovary. Methods Female Sprague-Dawley rats were orally given fenvalerate at daily doses of 0.00, 1.91, 9.55, and 31.80 mg/kg for four weeks. The ovary ultrastucture was observed by electron microscopy. Serum free calcium concentration was measured by atomic absorption spectrophotometry. The activities of phosphorylase a in rat ovary were evaluated by the chromatometry. The total content of calmodulin in ovary was estimated by ELISA at each stage of estrous cycle. Radioimmunoassay (RIA) was used to evaluate the level of serum progesterone. Results Histopathologically, damages of ovarian corpus luteum cells were observed. An increase in serum free calcium concentration was observed in rats treated with 31.80mg/kg fenvalerate. The activities of phosphorylase a enhanced in all treated groups, and fenvalerate increased the total content of calmodulin significantly in estrus period. Serum progesterone levels declined in fenvalerate exposed rats in diestrus. Conclusion Fenvalerate interferes with calcium homeostasis in rat ovary. Also, the inhibitory effects of fenvalerate on serum progesterone levels may be mediated partly through calcium signals. [ABSTRACT FROM AUTHOR]

Objective To investgate the metabolism of terephthalic acid (TPA) in rats and its mechanism. Methods Metabolism was evaluated by incubating sodium terephthalate (NaTPA) with rat normal liver microsomes, or with microsomes pretreated by phenobarbital sodium, or with 3-methycholanthrene, or with diet control following a NADPH-generating system. The determination was performed by high performance liquid chromatography (HPLC), and the mutagenic activation was analyzed by umu tester strain Salmonella typhimurium NM2009. Expression of CYP4B 1 mRNA was detected by RT-PCR. Results The amount of NaTPA (12.5–200 μmo1·L-1 detected by HPLC did not decrease in microsomes induced by NADPH-generating system. Incubation of TPA (0.025–0.1 mmol·L-1) with induced or noninduced liver microsomes in an NM2009 umu response system did not show any mutagenic activation. TPA exposure increased the expression of CYP4B1 mRNA in rat liver, kidney, and bladder. Conclusion Lack of metabolism of TPA in liver and negative genotoxic data from NM2009 study are consistent with other previous short-term tests, suggesting that the carcinogenesis in TPA feeding animals is not directly interfered with TPA itself and/or its metabolites. [ABSTRACT FROM AUTHOR]

Objective This study was designed to examine the in vitro effects of fenvalerate on steroid production and steroidogenic enzymes mRNA expression level in rat granulosa cells. Methods Using primary cultured rat granulosa cells (rGCs) as model, fenvalerate of various concentrations (0, 1, 5, 25, 125, 625 μmol/L) was added to the medium for 24 h. In some cases, optimal concentrations of 22(R)-hydroxycholesterol (25 μmol/L), Follicle stimulating hormone (FSH, 2 mg/L), or 8-Bromo-cAMP (1 mmol/L) were provided. Concentrations of 17β-estradiol(E2) and progesterone (P4) in the medium from the same culture wells were measured by RIA and the steroidogenic enzyme mRNA level was quantified by semi-quantitative RT-PCR. Results Fenvalerate decreased both P4 and E2 production in a dose-dependent manner while it could significantly stimulate rGCs proliferation. This inhibition was stronger in the presence of FSH. Furthermore, it could not be reversed by 22(R)-hydroxycholesterol or 8-Bromo-cAMP. RT-PCR revealed that fenvalerate had no significant effect on 3β-HSD, but could increase the P450scc mRNA level. In addition, 17β-HSD mRNA level was dramatically reduced with the increase of fenvalerate dose after 24 h treatment. Conclusion Fenvalerate inhibits both P4 and E2 production in rGCs. These results support the view that fenvalerate is considered as a kind of endocrine-disrupting chemicals. The mechanism of its disruption may involve the effects on steroidogenesis signaling cascades and/or steroidogenic enzyme's activity. [ABSTRACT FROM AUTHOR]