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Phthalate esters (PAEs) can be released into the environment during the dismantling of electronic waste (e-waste), but urinary levels of PAE metabolites (mPAEs) in humans living in e-waste sites have not been documented. In this study, 11 mPAEs were determined in urine samples collected from participants living in e-waste dismantling sites and a reference area in Southern China. The total urinary concentrations of the 11 mPAEs (∑mPAEs) in the e-waste sites (range: 11.1 ng/mL to 3380 ng/mL) were dominated by mono-(2-isobutyl) phthalate and mono-n-butyl phthalate. Participants living in the e-waste sites had significantly higher (p

Liming is a safe and effective remediation practice for Cd contaminated acid paddy soil. The fate of Cd can also be strongly influenced by redox chemistry of sulfur. But it is unclear if, to what extent and how the combination of liming and sulfur mediation could further control Cd uptake by paddy rice. A rice cultivation pot experiment was conducted to evaluate the impact of different sulfur forms (S0 and SO42- in K2SO4) on the solubility, uptake and accumulation of Cd in the soil-paddy rice system and how liming and reducing organic carbon mediate the process. Results showed that under neutral soil circumstances achieved by liming, co-application of K2SO4 and glucose significantly reduced brown rice Cd by 33%, compared to liming alone. They made it more readily for Cd2+ to be precipitated into CdS/CdS2 or co-precipitate with newly formed FeS/FeS2/iron oxides. The higher pH balancing capability of K2SO4 as well as liming kept the newly formed sulfide or iron containing minerals negatively charged to be more prone to adsorb Cd2+, that kept the porewater Cd2+ the lowest among all the treatments. Individual K2SO4 showed significant promoting effect on soil Cd solubility due to SO42- chelation effect. Furthermore, K2SO4 had much weaker inhibiting effect on Cd translocation from root to grain, it showed no significant attenuating effect on brown rice Cd. S0 containing treatments displayed weaker or no attenuating effect on brown rice Cd due to its strong soil acidification effect. On the basis of liming, organic carbon induced sulfur (K2SO4) mediation showed great application potential for safe production on large areas of acid paddy soil contaminated by Cd.

Recently, the nuclear receptor farnesoid X receptor (FXR) has been considered to be a liver tumor suppressor. However, the role of FXR in liver cancer invasion and metastasis remains unclear. The results of the current study demonstrated that FXR suppressed the migratory and invasive capacities of SK-Hep-1 cells in vitro and that FXR overexpression inhibited local invasion and lung metastasis of SK-Hep-1 ×enografts in vivo. Bioinformatics analysis of the gene expression profile of SK-Hep-1 cells with different FXR levels indicated that FXR may regulate the Wnt/β-catenin pathway. Compared with controls, FXR-overexpressing SK-Hep-1 cells exhibited decreased expression of β-catenin target genes and reduced nuclear translocation of β-catenin proteins in vitro and in vivo. In conclusion, these results indicated that FXR may suppress SK-Hep-1 cell invasion and metastasis by suppressing the Wnt/β-catenin signaling pathway. The current study provided novel insight into the diagnosis and treatment of liver cancer.

Exploiting efficient and economical electrocatalysts for hydrogen evolution reaction (HER) is critical for sustainable energy systems. Herein we engineer a novel nanocomposite (RuP/NP-C) comprising ultrafine RuP nanoparticles encapsulated in N, P co-doped porous carbon derived from a well-defined Ru3+ incorporated phytic acid–polyaniline composite. Benefitting from its unique composition and architecture with full exposure of active sites, rapid mass/charge transfer, and improved structural robustness, RuP/NP-C nanocomposite can exhibit respectable HER performance. Significantly, from experimental and theoretical investigations, it is revealed that charge redistribution occurs due to interfacial electronic interaction between RuP and NP-C, leading to electronic modulation of RuP with upshift of the d-band center relative to Fermi level, thereby yielding optimal hydrogen binding strength for HER. This study highlights a promising route to tailor the electronic state of catalyst via interfacial electronic effect for boosted catalytic property.

Photocatalytic degradation of per- and polyfluoroalkyl substances (PFAS) remains insufficient. It is vital to investigate the structure–activity relationship between exposed facets and photocatalytic activity of PFAS. In this study, BiOCl nanosheets with predominantly exposed {0 1 0} or {0 0 1} facets (i.e. {0 1 0}-BiOCl or {0 0 1}-BiOCl) were synthesized via the hydrothermal method and applied for the photodegradation of perfluorooctanoic acid (PFOA). We observed that the degradation rate constant of PFOA via the {0 1 0}-BiOCl (0.0954 min−1) was 2.64-fold better than that of the {0 0 1}-BiOCl (0.0361 min−1) in photocatalytic activity. Density functional theory calculation results revealed that the higher catalytic activity of {0 1 0}-BiOCl was attributed to the in-situ generated surface oxygen vacancies (OVs) and the strong interaction with PFOA molecules via the bidentate adsorption configuration. {0 1 0}-BiOCl nanosheets with OVs exhibited the highest adsorption capacity (55.6 mg g−1h−1) and lowest adsorption energy (-0.399 eV) for PFOA molecules. The electron spin resonance spectroscopy and radical scavenging experiments showed that both photogenerated holes and surface hydroxyl radicals were generated on {0 1 0} facets that contributed to the degradation of PFOA; while only photogenerated holes were formed on {0 0 1} facets. Interestingly, F− ions as the by-products were prone to attaching to the BiOCl facets to block the catalytic sites. To recover the catalytic performance, we adopted a simple chemical precipitation approach to precipitate the F− by using Ca2+ ions. Our findings provide fundamental insights into the interface reactions during the photocatalytic degradation of PFOA.

A nano zerovalent iron activated by persulfate process (nZVI-PS) was applied to degrade 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47), which is representative of the polybrominated diphenyl ethers (PBDEs) found in electronic waste (e-waste) sites. The influences of Cu(II), Zn(II), and Ni(II) ions, which are co-present in electronic wastes were evaluated on the degradation process. Electron paramagnetic resonance (EPR) and quenching studies indicates that sulfate radicals (SO4−) and hydroxyl radicals (HO) were both responsible for the degradation of BDE-47 during the treatment. Zn(II) and Ni(II) inhibited BDE-47 degradation, possibly due to their negative reduction potentials leading to surface adsorption on or complexation with nZVI. Cu(II), however, enhanced the degradation of BDE-47. Characterization of the nZVI surface reveals that the catalytic activity of Cu(II) could be attributed to the synergistic effect of Cu(0)-Cu(III) and Fe(II)-Fe(III) redox pairs, which favored the continuous decomposition of PS and thus BDE-47 degradation. Overall, these findings indicate that nZVI can be used as an effective activator of PS for removal of the lower brominated BDEs (e.g., tetra-BDE) and the role of metal ions cannot be neglected, which provides a significant implication for the use of nZVI-PS system in e-waste contaminated site.

Six parabens and their four metabolites were measured in paired maternal serum (MS) and cord serum (CS) samples collected from 95 pregnant women to elucidate placental transfer of this class of compounds. Matched maternal urine (MU) and amniotic fluid (AF) collected from 13 of 95 pregnant women were also analyzed to examine partition of these chemicals between maternal and fetal tissues. The placental transfer rates (PTRs; concentration ratio of parabens between CS and MS) of methyl- (MeP), ethyl- (EtP), propyl-parabens (PrP) were 0.81, 0.63, and 0.60, respectively. Furthermore, the PTRs of OH-MeP (0.93) and OH-EtP (1.8) were higher than those of their corresponding parent parabens, which suggested that hydroxylation increased placental transfer rates of parabens. Structure-dependent placental transfer mechanisms were observed. A significant negative correlation between molecular weights (or log Kow) of MeP, EtP, PrP, and p-hydroxy benzoic acid (4-HB) and PTRs suggested passive diffusion as a mechanism of placental transfer of these chemicals. Nevertheless, other hydroxylated metabolites (OH-EtP, OH-MeP, and 3,4-dihydroxy benzoic acid (3,4-DHB)) showed a positive correlation between molecular weight (or log Kow) and PTRs, which suggested that the placental transfer is mediated by protein binding of these metabolites. The MU to MS concentration ratios of MeP (MU/MSMeP) and PrP (MU/MSPrP) were 71 and 81, respectively, and MU/MSMeP was two orders of magnitude higher than that found for the metabolite (MU/MSOH-MeP: 0.35), suggesting that hydroxylation metabolite reduced urinary elimination of parabens. To our knowledge, this is the first time to report the occurrence and distribution of parabens and their metabolites in paired maternal-fetal serum, urine, and AF samples in China. Our results provide novel information on placental transfer of parabens and their metabolites.

With the phase out of perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), the composition profiles of poly- and perfluoroalkyl substance (PFAS) in our living environment are unclear. In this study, 25 PFASs were analyzed in indoor dust samples collected from urban, industrial, and e-waste dismantling areas in China. PFOS alternatives, including 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) (median: 5.52 ng/g) and 8:2 chlorinated polyfluorinated ether sulfonate (8:2 Cl-PFESA) (1.81 ng/g), were frequently detected. By contrast, PFOA alternatives, such as hexafluoropropylene oxide dimer acid (HPFO-DA, Gen-X) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA), were not found in any of the dust samples. As expected, all legacy PFASs were widely observed in indoor dust, and 4 PFAS precursors were also detected. Dust concentrations of 6:2 Cl-PFESA were strongly correlated (p 0.05) with those of 8:2 Cl-PFESA regardless of sampling sites. 6:2 Cl-PFESA was also significantly associated with that of PFOS in industrial and e-waste (p 0.01) areas. Association analysis suggested that the sources of PFOS and its alternatives are common or related. Although ∑Cl-PFESA concentration was lower than that of PFOS (17.4 ng/g), industrial areas had the highest 6:2 Cl-PFESA/PFOS ratio (0.63). Composition profiles of PFASs in the industrial area showed the forefront of fluorine change. Thus, the present findings suggested that Cl-PFESAs are widely used as PFOS alternatives in China, and high levels of human Cl-PFESA exposure are expected in the future. Short-chain PFASs (C4-C7) were the predominant PFASs found in dust samples, contributing to over 40% of ∑total PFASs. Furthermore, perfluoro-1-butanesulfonate/PFOS and perfluoro-n-butanoic acid (PFBA)/PFOA ratios were 2.8 and 0.72, respectively. These findings suggested shifting to the short-chain PFASs in the environment in China. To the authors knowledge this is the first study to document the levels of 6:2 Cl-PFESA, 8:2 Cl-PFESA in indoor dust.

Novel alternatives of perfluorooctane sulfonate (PFOS), chlorinated polyfluorinated ether sulfonates (Cl-PFAESs) are increasingly being detected in the aquatic and terrestrial environment. Previous studies mainly focused on aquatic biota; however, the knowledge about the ecotoxicological risk they pose to terrestrial plants was still lacking. In this study, the accumulation of two Cl-PFAES (6:2 and 8:2 Cl-PFAES) and PFOS in wheat seedlings at environmentally relevant levels (50 and 100 μg L−1) was investigated. Concentrations of Cl-PFAESs in the roots were an order of magnitude higher than those in shoots, indicating that they were primarily accumulated in the roots. The values of root and shoot bioconcentration factor was comparable between 6:2 Cl-PFAES and PFOS. However, these indexes of 8:2 Cl-PFAES were 42–91% higher and 70–76% lower than PFOS, respectively. As a result, 6:2 Cl-PFAES had a similar accumulation pattern as PFOS, whereas 8:2 Cl-PFAES was predominantly restricted to the roots, which might be attributed to their hydrophobicity and carbon chain length. In addition, at 250 mg L−1 of Cl-PFAESs, plant biomass and pigment content were 24–30% and 0.4–18%, respectively, which were lower than those of PFOS. As compared with PFOS, Cl-PFAESs induced higher levels of root membrane permeability, reactive oxygen species and malondialdehyde content, as well as reduced the activities of antioxidant enzymes and glutathione content. These suggested the occurrence of a severer oxidative damage and the breakdown of the antioxidant defence system in wheat cells. Therefore, we conclude that Cl-PFAESs might pose a higher potential threat to the environment than PFOS.

Fe(II)-catalyzed peroxymonosulfate (PMS) activation process was able to degrade persistent organic pollutants, such as polybrominated diphenyl ethers (PBDEs), but the slow transformation rate from the generated Fe(III) to Fe(II) restricted the efficiency of this process. In this study, we found that the addition of small quantities of gallic acid (GA), a model compound of natural polyphenols, in the Fe(III)/PMS process (namely GA/Fe(III)/PMS process) could exert a long-term influence on Fe(II) recycle and accelerated the degradation of 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) over 72 h. Under conditions of 20.3 µM GA, 13.6 µM Fe(III) and 400 µM PMS, the degradation efficiency of BDE47 reached 85%, which was 9.4 times higher than that in the Fe(III)/PMS process. The degradation kinetics can be divided into an initial “fast stage” (kobs1 = 0.298 h−1) and a second “slow stage” (kobs2 = 0.021 h−1). Aromatic radicals such as hydroxycyclohexadienyl radical (poly-HCD ) produced by the attack of SO4 −/HO on GA was proposed to be responsible for Fe(II) recycle in the first stage, while ring-opened products following SO4 −/HO attack of GA-quinone mainly initiated Fe(III) reduction in the second stage. Owing to the multiple Fe(III) reduction pathways, PMS would be continuously activated by Fe(II) to form SO4 − and HO , which were the dominant reactive species for BDE47 degradation. Finally, natural polyphenols extracted from green tea were proven effective in enhancing BDE47 degradation in Fe(III)/PMS process. This study not only provides a new way to propagate Fe(II)-activated persulfate chain reactions for the degradation of refractory organic contaminants, like PBDEs, but also sheds new insight into the reactivity of organic byproducts toward Fe in PMS-based oxidation system.

In the present study, concentrations of bisphenol A (BPA) and its six alternatives were quantified in serum samples collected from elder population living around an e-waste recycling facilities as well as an reference area in China. BPA, bisphenol AF (BPAF), and bisphenol F (BPF) were frequently detected (detection rates:65%) in serum samples collected from residents living near e-waste dismantling facilities, with geometric mean (GM) concentrations of 3.2, 0.0074, and 0.062 ng/mL, respectively. The detection frequencies of other four bisphenols (BPs) in serum samples were lower than 25%, regardless of the sampling areas. Significant difference (Mann-Whitney U-test, p 0.05) was observed in the serum concentration of BPA, but not BPAF and BPF, between the e-waste recycling and reference areas. This finding indicated e-waste dismantling activities are correlated with human BPA exposure. Significant higher (p 0.05) detection rates of donors who had abnormal fasting blood glucose (FBG) levels were found in e-waste recycling areas (45%) than those found in reference area. Our results suggested BPA and BPAF exposure might associated with abnormal FBG in participants living in e-waste sites. To our knowledge, this study is first determination of BPs in serum samples and assessment of health risk of elderly people from BPs exposure in e-waste dismantling area.

Uptake and accumulation by plants is a significant pathway in the migration and transformation of phthalate esters (PAEs) in the environment. However, limited information is available on the mechanisms of PAE metabolism in plants. Here, we investigated the metabolism of di-n-butyl phthalate (DnBP), one of the most frequently detected PAEs, in pumpkin (Cucurbita moschata) seedlings via a series of hydroponic experiments with an initial concentration of 10 mg L-1. DnBP hydrolysis occurred primarily in the root, and two of its metabolites, mono-n-butyl phthalate (MnBP) and phthalic acid (PA), were detected in all plant tissues. The MnBP concentration was an order of magnitude higher than that of PA in shoots, which indicated MnBP was more readily transported to the shoot than was PA because of the former's dual hydrophilic and lipophilic characteristics. More than 80% of MnBP and PA were located in the cell water-soluble component except that 96% of MnBP was distributed into the two solid cellular fractions (i.e., cell wall and organelles) at 96 h. A 13-20% and 29-54% increase of carboxylesterase (CXE) activity shown in time-dependent and concentration-dependent experiments, respectively, indicated the involvement of CXEs in plant metabolism of DnBP. The level of CXE activity in root subcellular fractions was in the order: the cell water-soluble component (88-94%) >> cell wall (3-7%) > cell organelles (3-4%), suggesting that the cell water-soluble component is the dominant locus of CXE activity and also the domain of CXE-catalyzed hydrolysis of DnBP. The addition of triphenyl phosphate, a CXE inhibitor, led to 43-56% inhibition of CXE activity and 16-25% increase of DnBP content, which demonstrated the involvement of CXEs in plant metabolism of DnBP. This study contributes to our understanding of enzymitic mechanisms of PAE transformation in plants.

The nuclear receptor farnesoid X receptor (FXR) acts as a liver protector by regulating normal liver homeostasis. Spontaneously developed liver tumors have been found in FXR-null mice. However, the role of FXR in the tumorigenesis of human hepatocellular carcinoma (HCC) is still poorly understood. In this study, we measured the expression of FXR and its primary target gene, small heterodimer partner, and analyzed the clinical significance of FXR expression in HCC patients. A lentiviral vector that selectively overexpresses FXR was used to investigate the function of FXR in HCC cell proliferation both in vitro and in vivo . Our data showed that in human HCC, FXR expression was significantly reduced and was positively correlated with multiple malignant clinicopathological characteristics. Lentivirus-mediated exogenous FXR expression resulted in a marked increase of small heterodimer partner expression, significant repression of liver cancer cell proliferation, and tumor growth in nude mice. These results suggest that FXR may be of clinical and pharmacological importance as a promising biomarker of HCC.

Soil washing is one of the few permanent treatment alternatives for removing metal contaminants. Ethylenediaminetetraacetic acid and its salts (EDTA) is very effective at removing cationic metals and has been utilized globally. However it is ineffective for anionic metal contaminants or metals bound to soil organic matter. The simultaneous removal of cationic and anionic metal contaminants by soil washing is difficult due to differences in their properties. The present study evaluated the potential of a washing process using two synthesized EDTA-derivatives, C 6 HEDTA (2,2′-((2-((carboxymethyl)(2-(hexanoyloxy)ethyl)amino)ethyl)azanediyl)diacetic acid) and C 12 HEDTA (2,2′-((2-((carboxymethyl) (2-(dodecanoyloxy)ethyl)amino)ethyl)azanediyl)diacetic acid), which consist of a hydrophilic polycarboxylic moiety and a hydrophobic moiety with a monoalkyl ester group. A series of equilibrium batch experiments at room temperature were conducted to investigate the efficacy of C 6 HEDTA and C 12 HEDTA as extractants for both oxyanion Cr(VI) and cationic Cu(II). Results showed that either C 6 HEDTA or C 12 HEDTA can extract both Cr(VI) and Cu(II) from humic acid simultaneously. However, C 6 HEDTA was less effective for Cr(VI) probably because it has no surface activities to increase solubility of humic acid, like C 12 HEDTA. Extraction of Cr(VI) was mainly attributed to the decreased surface tension and enhanced solubility of organic matter. Extraction of Cu(II) was attributed to both the Cu(II) chelation and enhanced solubility of humic acid. It was demonstrated that the hydrophilic polycarboxylic moiety of C 12 HEDTA chelates cations while the monoalkyl ester group produces surface active properties that enhance the solubility of humic acid.

Cholesterol 7alpha-hydroxylase (CYP7a1) is the rate-limiting enzyme in the classic pathway of bile acid synthesis. Expression of CYP7a1 is regulated by a negative feedback pathway of bile acid signaling. Previous studies have suggested that bile acid signaling is also required for normal liver regeneration, and CYP7a1 expression is strongly repressed after 70% partial hepatectomy (PH). Both the effect of CYP7a1 suppression on liver regrowth and the mechanism by which 70% PH suppresses CYP7a1 expression are unknown. Here we show that liver-specific overexpression of an exogenous CYP7a1 gene impaired liver regeneration after 70% PH, which was accompanied by increased hepatocyte apoptosis and liver injury. CYP7a1 expression was initially suppressed after 70% PH in an farnesoid X receptor/ small heterodimer partner-independent manner; however, both farnesoid X receptor and small heterodimer partner were required to regulate CYP7a1 expression at the later stage of liver regeneration. c-Jun N-terminus kinase and hepatocyte growth factor signaling pathways are activated during the acute phase of liver regeneration. We determined that hepatocyte growth factor and c-Jun N-terminus kinase pathways were involved in the suppressing of the CYP7a1 expression in the acute phase of live regeneration. Taken together, our results provide the significance that CYP7a1 suppression is required for liver protection after 70% PH and there are two distinct phases of CYP7a1 gene regulation during liver regeneration.

Liver mass depends on one or more unidentified humoral signals that drive regeneration when liver functional capacity is diminished. Bile acids are important liver products, and their levels are tightly regulated. Here, we identify a role for nuclear receptor–dependent bile acid signaling in normal liver regeneration. Elevated bile acid levels accelerate regeneration, and decreased levels inhibit liver regrowth, as does the absence of the primary nuclear bile acid receptor FXR. We propose that FXR activation by increased bile acid flux is a signal of decreased functional capacity of the liver. FXR, and possibly other nuclear receptors, may promote homeostasis not only by regulating expression of appropriate metabolic target genes but also by driving homeotrophic liver growth.

The farnesoid X receptor (FXR) is a key metabolic regulator in the liver by maintaining the homeostasis of liver metabolites. Recent findings suggest that FXR may have a much broader function in liver physiology and pathology. In the present work, we identify a novel role of FXR in protecting liver cell from apoptosis induced by nutritional withdrawal including serum deprivation in vitro or starvation in vivo. Two FXR ligands, chenodeoxycholic acid (CDCA) and GW4064, rescued HepG2 cells from serum deprivation-induced apoptosis in a dose-dependent manner. This effect of FXR on apoptotic suppression was compromised when FXR was knocked down by short interfering RNA. Similarly, the effects of both CDCA and GW4064 were abolished after inhibition of the MAPK pathway by a specific inhibitor of MAPK kinase 1/2. Immunoblotting results indicated that FXR activation by CDCA and GW4064 induced ERK1/2 phosphorylation, which was attenuated by serum deprivation. In vivo, FXR−/− mice exhibited an exacerbated liver apoptosis and lower levels of phosphorylated-ERK1/2 compared to wild-type mice after starvation. In conclusion, our results suggest a novel role of FXR in modulating liver cell apoptosis.

Farnesoid X receptor (FXR, NR1H4) is a member of the nuclear hormone receptor superfamily, which plays an essential role in regulating bile acid, lipid, and glucose homeostasis. Both male and female FXR−/− mice spontaneously developed liver tumors; however, no other tumors were developed after 15 months of age. In contrast, no liver tumors were observed in wild-type mice of the same age. Histologic analyses confirm that tumors were hepatocellular adenoma and carcinoma. Although there was no obvious tumor at ages 9 to 12 months, FXR−/− livers displayed prominent liver injury and inflammation. Strong labeling of apoptotic hepatocytes and liver damage–induced compensatory regeneration were observed. Deregulation of genes involved in bile acid homeostasis in FXR−/− mice was consistent with abnormal levels of bile acids presented in serum and liver. Genes involved in inflammation and cell cycle were up-regulated in aging FXR−/− mice but not in wild-type controls. Increasing the bile acid levels by feeding mice with a 0.2% cholic acid diet strongly promoted N-nitrosodiethylamine–initiated liver tumorigenesis, whereas lowering bile acid pool in FXR−/− mice by a 2% cholestyramine feeding significantly reduced the malignant lesions. Our results suggest an intriguing link between metabolic regulation and hepatocarcinogenesis. [Cancer Res 2007;67(3):863–7]

Human nerve growth factor (hNGF) gene was proliferated with human leucocyte DNA as template by PCR. Then a fusion gene coding hNGF and luciferase (Luc) cDNAs was inserted into transfer vector pSXIVVI+X3/3 with the control of Syn XIV promoter. Luc and hNGF were simultaneously synthesized in Spodoptera larvae upon infection with a recombinant baculovirus, TnNPV-Luc-NGF-OCC+. Densitometric scanning of SDS-PAGE revealed that ∼18% of the total Coomassie blue-stainable protein of the infected larvae was represented by Luc protein, while the hNGF level was ∼8%. Both proteins were similar to their authentic counterparts in terms of immunoreactivity.