| 1. |
- Chen, Baowei, et al.
(författare)
-
Methylation mechanism of tin(II) by methylcobalamin in aquatic systems
- 2007
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 68:3, s. 414-419
-
Tidskriftsartikel (refereegranskat)abstract
- The methylation reaction of tin(II) with methylcobalamin (CH(3)B(12)) in aquatic systems was modeled in the laboratory. The products were detected by a sensitive gas chromatography-flame photometric detector (GC-FPD), and further identified by gas chromatography-mass spectrometry (GC-MS). Both monomethyltin (MMT) and dimethyltin (DMT) were found as methylation products. Three important effecting factors during the methylation reaction, salinity, pH and aerobic or anaerobic, were studied. The results showed that methyl group can be transferred from CH(3)B(12) to tin in aquatic solutions as a radical or carbonium, as well as a carbanion. Two explanations for the pH-dependency of the methylation reaction between tin(II) and CH(3)B(12) were proposed: pH-dependency of the equilibrium states of CH(3)B(12), and pH-dependency of inorganic tin(II) species whose reactivity vary with the redox potential in the solution. Salinity can influence the activity of the methyl donor, which cause changes in the methylation efficiency. Kinetic experiments showed that the methylation reaction was pseudo-first-order for CH(3)B(12).
|
|
| 2. |
- Fu, Jianjie, et al.
(författare)
-
High levels of heavy metals in rice (Oryza sativa L.) from a typical E-waste recycling area in southeast China and its potential risk to human health
- 2008
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 71:7, s. 1269-1275
-
Tidskriftsartikel (refereegranskat)abstract
- Very few studies have investigated the heavy metal contents in rice samples from a typical E-waste recycling area. In this study, 10 heavy metals (As, Ba, Cd, Co, Cr, Cu, Hg, Mn, Ni and Pb) in 13 polished rice and relevant hull samples, six relevant paddy soil samples were investigated. The geometric mean concentrations of Cd, Cu and Hg in soil samples were 1.19, 9.98 and 0.32 microg g(-1), respectively, which were 4.0, 2.0 and 1.1-folds of the maximum allowable concentration (MAC) (0.30, 50.00, 0.30 microg g(-1), respectively) for Chinese agricultural soils. The analyzed metal concentrations were significantly different between rice and relevant hull except for As, Cd and Hg (p<0.05). All metal concentrations, except for Co, in rice hull were higher than those in polished rice. The geometric mean of Pb in polished rice reached 0.69 microg g(-1), which was 3.5-folds higher than the MAC (0.20 microg g(-1)) by the safety criteria for milled rice. Cd contents in 31% of the rice samples exceeded the national MAC (0.20 microg g(-1)), and the arithmetic mean also slightly exceeded national MAC. In addition, Cd and Pb contents in local rice were much higher than commercial rice samples examined in this work and previous studies. Comparing the tolerable daily intakes given by FAO/WHO with the mean estimated daily intakes; Pb daily intake through rice consumption in this area was 3.7 microg day(-1)kg(-1) body weight (bw), which already exceeded the FAO tolerable daily intake, and the Cd daily intake (0.7 microg day(-1)kg(-1) bw) through rice had already taken up 70% of the total tolerable daily intake (1 microg day(-1)kg(-1) bw). The daily intake of Hg and As through rice was much lower than the tolerable daily intakes, but bioaccumulation of Hg through the food chain and intake of As from other food stuff should also be of concern.
|
|
| 3. |
- Li, Hongcheng, et al.
(författare)
-
Effects of waterborne nano-iron on medaka (Oryzias latipes) : antioxidant enzymatic activity, lipid peroxidation and histopathology
- 2009
-
Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513 .- 1090-2414. ; 72:3, s. 684-692
-
Tidskriftsartikel (refereegranskat)abstract
- Toxicity tests were performed to investigate possible harmful effects on medaka exposed to nano-iron. Dose-dependent decreases of superoxide dismutase (SOD) and increases of malondialdehyde (MDA) were induced in the medaka embryo, suggesting that oxidative damage was induced by nano-iron. For adult medaka, the disturbance of antioxidative balance was observed during the early exposure period based on the monitoring of the hepatic and cerebral SOD and reduced glutathione (GSH). No terminal oxidative damage occurred during the whole exposure period, probably due to the high self-recovering capability of the adult fish. Some histopathological and morphological alterations (cell swelling, hyperplasia, and granulomas, etc.) were observed in gill and intestine tissues, which confirmed that deleterious effects occurred as a result of direct contact with nano-iron. It is suggested that further evaluation should be made concerning the risk assessment of waterborne nano-iron on aquatic life.
|
|
| 4. |
- Li, Hongcheng, et al.
(författare)
-
Elemental selenium particles at nano-size (Nano-Se) are more toxic to Medaka (Oryzias latipes) as a consequence of hyper-accumulation of selenium : a comparison with sodium selenite
- 2008
-
Ingår i: Aquatic Toxicology. - : Elsevier BV. - 0166-445X .- 1879-1514. ; 89:4, s. 251-256
-
Tidskriftsartikel (refereegranskat)abstract
- Recent studies have shown that elemental selenium particles at nano-size (Nano-Se) exhibited comparable bioavailability and less toxicity in mice and rats when compared to sodium selenite, selenomethinine and methylselenocysteine. However, little is known about the toxicity profile of Nano-Se in aquatic animals. In the present study, toxicities of Nano-Se and selenite in selenium-sufficient Medaka fish were compared. Selenium bioaccumulation and subsequent clearance in fish livers, gills, muscles and whole bodies were examined after 10 days of exposure to Nano-Se and selenite (100 microg Se/L) and again after 7 days of depuration. Both forms of selenium exposure effectively increased selenium concentrations in the investigated tissues. Surprisingly, Nano-Se was found to be more hyper-accumulated in the liver compared to selenite with differences as high as sixfold. Selenium clearance of both Nano-Se and selenite occurred at similar ratios in whole bodies and muscles but was not rapidly cleared from livers and gills. Nano-Se exhibited strong toxicity for Medaka with an approximately fivefold difference in terms of LC(50) compared to selenite. Nano-Se also caused larger effects on oxidative stress, most likely due to more hyper-accumulation of selenium in liver. The present study suggests that toxicity of nanoparticles can largely vary between different species and concludes that the evaluation of nanotoxicology should be carried out on a case-by-case basis.
|
|
| 5. |
- Li, Zhuona, et al.
(författare)
-
Effects of polycyclic musks HHCB and AHTN on steroidogenesis in H295R cells
- 2013
-
Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 90:3, s. 1227-1235
-
Tidskriftsartikel (refereegranskat)abstract
- 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(γ)-2-benzopyran (HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) are widely used in personal care products. Previous studies showed that HHCB and AHTN can be found in various environmental matrices and have potential endocrine disrupting effects. However, the effects on adrenocortical function of HHCB and AHTN are not fully understood. This study evaluated the influences of HHCB and AHTN on seven steroid hormones (progesterone, aldosterone, cortisol, 17α-OH-progesterone, androstenedione, 17β-estradiol, and testosterone) and 10 genes involved in steroidogenic pathways (HMGR, StAR, CYP11A1, 3βHSD2, CYP17, CYP21, CYP11B1, CYP11B2, 17βHSD, and CYP19) using the H295R cell line in the absence and presence of 8-Br-cAMP. MC2R transcription on the cell membrane was also examined to further investigate the effects of HHCB and AHTN on adrenal steroidogenesis. The results demonstrated that HHCB and AHTN could inhibit progesterone and cortisol production mainly by the suppression of 3βHSD2 and CYP21. Meanwhile, high concentrations of AHTN can affect the sensitivity of H295R cells to ACTH by disrupting MC2R transcription. Overall, the results indicate that high concentrations of HHCB and AHTN can affect steroidogenesis in vitro using the H295R cell line.
|
|
| 6. |
- Liao, Chunyang, et al.
(författare)
-
Changes in synaptic transmission, calcium current, and neurite growth by perfluorinated compounds are dependent on the chain length and functional group
- 2009
-
Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 43:6, s. 2099-2104
-
Tidskriftsartikel (refereegranskat)abstract
- Scientific and public concerns on perfluorinated compounds (PFCs) are increasingly growing because of their environmental persistency, bioaccumulation, and extensive distribution throughout the world. Little is known about the effects of PFCs on neural function and the underlying mechanisms. Recent evidence suggests that the toxicological effects of PFCs are closely correlated with their carbon chain lengths. In this present work, the actions of PFCs with varying chain length on cultured rat hippocampal neurons and possible action patterns were examined. Increases in the frequencies of spontaneous miniature postsynaptic current (mPSC) were commonly found in cultured neurons when perfused with PFCs. The increase of mPSC frequency was in proportion to the carbon chain length, and the potency of perfluorinated carboxylates was less pronounced than that of perfluorinated sulfonates. A comparable but less perceptible trend was also found for the amplitudes of voltage-dependent calcium current (ICa). No regular change in pattern was observed for the effects of PFCs on activation and inactivation kinetics of ICa. Furthermore, prolonged treatment of PFCs inhibited the neurite growth of neuronsto various degrees. Comparisons between nonfluorinated and perfluorinated analogues demonstrated thatthefluorination in alkyl chain exerts stronger actions on neurons as compared to the surfactant activity. This study shows that PFCs exhibit adverse effects on cultured neurons to various extents, which is dependent on the carbon chain length and functional group attached to the fully fluorinated alkyl chain.
|
|
| 7. |
- Sun, Zhendong, et al.
(författare)
-
4-Hexylphenol influences adipogenic differentiation and hepatic lipid accumulation in vitro
- 2021
-
Ingår i: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 268:Part A
-
Tidskriftsartikel (refereegranskat)abstract
- Finding the potential environmental obesogens is crucial to explain the prevalence of obesity and the related pathologies. Increasing evidence has showed that many chemicals with endocrine disrupting effects can disturb lipid metabolism. Whether 4-hexylphenol (4-HP), a widely-used surfactant and a potential endocrine disrupting chemical (EDC), is associated to influence adipogenesis and hepatic lipid accumulation remained to be elucidated. In this study, both the 3T3-L1 differentiation model and oleic acid (OA)-treated HepG2 cells were used to investigate the effects of 4-HP on lipid metabolism, and the underlying estrogen receptor (ER)-involved mechanism was explored using MVLN assay, molecular docking simulation and the antagonist test. The results based on lipid droplet staining and triglyceride accumulation assay showed that 4-HP treatment promoted the adipogenic differentiation of 3T3-L1 cells and increased hepatic cellular OA accumulation in exposure concentration-dependent manners. The study on the elaborated transcription networks indicated that 4-HP activated peroxisome proliferator-activated receptor γ (PPARγ) as well as the subsequent adipogenic gene program in 3T3-L1 cells. This chemical also induced the increase of OA uptake and decreases of de novo lipogenesis and fatty acid oxidation in HepG2 cells. The agonistic activity of 4-HP in triggering ER-mediated pathway was shown to correlate with its perturbation in lipid metabolism, as evidenced by the enhanced development of mature lipid-laden adipocytes and suppression of excessive hepatic lipid accumulation upon its co-treatment with ER antagonist. Altogether, these findings provide new insights into the potential health impacts of 4-HP exposure as it may relate to obesity and nonalcoholic fatty liver disease.
|
|
| 8. |
- Sun, Zhendong, et al.
(författare)
-
Butylated hydroxyanisole isomers induce distinct adipogenesis in 3T3-L1 cells
- 2019
-
Ingår i: Journal of Hazardous Materials. - : Elsevier. - 0304-3894 .- 1873-3336. ; 379
-
Tidskriftsartikel (refereegranskat)abstract
- Butylated hydroxyanisole (BHA) isomers, as the widely used anthropogenic antioxidants in food, have been revealed to induce endocrine disrupting effects, while the mechanism how BHA isomers regulate the lipogenic differentiation remains to be elucidated. Using 3T3-L1 differentiation model, the effects of BHA isomers, including 2-tert-butyl-4-hydroxyanisole (2-BHA), 3-tert-butyl-4-hydroxyanisole (3-BHA) and their mixture (BHA), on adipogenesis were tested. The results showed that 3-BHA and BHA promoted adipocyte differentiation and enhanced the cellular lipid accumulation through the regulation of the transcriptional and protein levels of the adipogenetic biomarkers, while 2-BHA had no effect. The effective window for 3-BHA induced lipogenesis was the first four days during 3T3-L1 differentiation. BHA isomers showed no binding affinities for peroxisome proliferator activated receptor gamma (PPAR gamma). Instead, the upstream of PPAR gamma signaling pathway, i.e. the phosphorylation of cAMP-response element binding protein (CREB), upregulation of CAAT/enhancer-binding proteins beta (C/EBP beta) and elevated cell proliferation during postconfluent mitosis stage were induced by 3-BHA exposure. Altogether, this study revealed the adipogenic effect of 3-BHA through interference with the upstream events of the PPAR gamma signaling pathway. The authorized usage of BHA as food additives and its occurrence in human sera can potentially contribute to the incidence of obesity, which is of high concern.
|
|
| 9. |
- Sun, Zhendong, et al.
(författare)
-
Perturbation of 3-tert-butyl-4-hydroxyanisole in adipogenesis of male mice with normal and high fat diets
- 2020
-
Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 703
-
Tidskriftsartikel (refereegranskat)abstract
- As one of the widely used anthropogenic food additives, 3-tert-butyl-4-hydroxyanisole (3-BHA) has been found to perturb adipogenesis in vitro and induce lipid accumulation in some strains of oleaginous microalgae. The impact of this chemical on adipocyte development and lipid metabolism in mammals remains to be elucidated. In this study, we performed 18-week oral administration of 3-BHA to male C57BL/6J mice with normal diet (ND) or high-fat diet (HFD) and investigated its impacts on adipogenesis and lipid accumulation in vivo. The results indicated that long-term exposure to 3-BHA impacted the mouse body weight gain, white adipose tissue accumulation, and plasma lipids through transcriptional regulation of adipogenesis, lipid metabolism, and adipocyte endocrine function, while glucose metabolism and insulin sensitivity remained unaffected. HFD-fed mice responded to 3-BHA stimulation differently from ND-fed animals, suggesting potential risks for the human burden of 3-BHA in lean and obese subjects. The findings herein validate 3-BHA as an environmental obesogen, and more caution is recommended for its authorized use as a food antioxidant against lipid rancidity.
|
|
| 10. |
- Wang, Thanh, 1979-, et al.
(författare)
-
The in vitro estrogenic activities of polyfluorinated iodine alkanes
- 2012
-
Ingår i: Journal of Environmental Health Perspectives. - USA : National Institute of Environmental Health Sciences (NIEHS). - 0091-6765 .- 1552-9924. ; 120:1, s. 119-125
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Polyfluorinated iodine alkanes (PFIs) are important intermediates in the synthesis of organic fluoride products. Recently, PFIs have been detected in fluoropolymers as residual raw materials, as well as in the ambient environment.OBJECTIVES: High production volumes and potential environmental releases of PFIs might become a concern, but the exposure risk and toxicity of these chemicals are still unclear. In this study, we investigated the potential estrogenic effects of PFIs.METHODS: We studied the estrogenic effects of fluorinated iodine alkanes (FIAs), fluorinated telomer iodides (FTIs), and fluorinated diiodine alkanes (FDIAs) using the E-screen and MVLN assays and the evaluation of estrogen-responsive genes in MCF-7 cells.RESULTS: FIAs have an iodine atom at one end of the perfluorinated carbon chain. 1-Iodoperfluorohexane (PFHxI) and 1-iodoperfluorooctane (PFOI) promoted the proliferation of MCF-7 cells, induced luciferase activity in MVLN cells, and up-regulated the expression of TFF1 and EGR3. In these assays, other FIAs gave negative responses. FDIAs have an iodine atom at each end of the perfluorinated carbon chain, and all the FDIAs showed estrogenic effects. The estrogenic potencies of FIAs and FDIAs correlate well with the carbon chain length of the chemicals. The optimum chain length for estrogenic effects is six carbons, and then eight and four carbons. All FTIs have a single iodine atom at the end of a partially fluorinated carbon chain. None of the FTIs showed estrogenic effects in the tests.CONCLUSIONS: The estrogenic effects of PFIs are dependent on the structural features of iodine substitution and chain length. This research will be helpful in further understanding the estrogenic effects of perfluorinated compounds.
|
|
