Promoting C-C coupling for CO2 reduction on Cu2O electrocatalysts with atomically dispersed Rh atoms.

Cu2O doped with atomically dispersed Rh (Rh:Cu2O) is synthesized with a wet chemical method. It shows higher activity and faradaic efficiency at lower overpotential for reduction of CO2 to C2+ products, especially C2H4, than pristine Cu2O. We found that introducing Rh promotes CO2 adsorption, *CO hydrogenation to *CHO and their coupling to O*CCHO intermediates, which contributes to enhanced catalytic performance.

An analysis of the poverty reduction effects on land transfer: Evidence from rural areas in China.

This paper develops a multidimensional poverty index (MPI) evaluation system using multiple measures. We use the China Family Panel Study (CFPS) data to build balanced panel data from 2012 to 2018. Employing the probit model to analyze the impact of land transfer on relative poverty incidence, as well as utilizing the two-way fixed effects model and the logit model, we approach the issue from the perspective of multidimensional relative poverty identification. Our study indicates a decrease in relative poverty among rural households since 2012. Nonetheless, the overall incidence of relative poverty among rural households in China remains high at 20.6%, highlighting the severity of this issue in rural China. Moreover, we examine the heterogeneity of the poverty reduction effects of land transfer-in and land transfer-out. Land transfer can significantly reduce the incidence of relative poverty among rural households, with distinct mechanisms for land transfer-in and land transfer-out. Land transfer-in primarily reduces the relative poverty incidence of rural households through the education, housing, and land dimensions, while land transfer-out focuses on the quality-of-life dimension. Overall, land transfer-out has a more significant poverty reduction effect than land transfer-in. Furthermore, our study reveals that the reduction effect of land transfer on the incidence of relative poverty among rural households persists for at least two years, but by the fourth year, this effect disappears.

Study on the time and scale of mutual aid for aging care under the background of active aging.

Background: China has entered an aging society and will likely become the fastest-aging country in the world. The demand for aging care services has greatly increased. In recent years, the model of mutual aid for aging care has met the needs of older adults, especially those in rural areas. In this case, how much time should be spent on mutual aid for the older adult in terms of time and how much influence the size of the group has in terms of space are two very important questions when studying mutual aid for aging care. Methods: An overlapping generations model is built in this article, which includes representative agents, representative enterprises, the endowment insurance system constructed by the government, and the behavior of representative agents in mutual aid for aging care under the background of active aging. Results: In the base case, the optimal proportion of time to participate in the mutual aid group is 9.31%, and the optimal proportion of time is influenced by the benchmark time of care and the size of the care group. With the increase in the benchmark time of care, the optimal proportion of time increases correspondingly, but the increase is decreasing. With the increase in the size of the care group, the optimal proportion of time decreases, but after the size reaches 4 or 5, the impact becomes very small. When parents' psychological preference coefficient changes from 0.1 to 0.9, that is, when parents change from introverted to extroverted personalities, the optimal proportion of time and parents' utility will also change. Conclusion: For children who usually take care of their parents for a long benchmark time, the optimal time to participate in the mutual aid group based on personal utility maximization is also long. Second, as the size of the group increases, the time for representative agents to participate in the mutual aid group gradually decreases. In addition, the model of mutual aid for aging care is highly correlated with parents' personalities, and extrovert parents benefit more from this model.

Facial fabrication of few-layer functionalized graphene with sole functional group through Diels-Alder reaction by ball milling.

The widespread use of graphene as a next-generation material in various applications requires developing an environmentally friendly and efficient method for fabricating functionalized graphene. Chemically, graphene can be used as an electron donor or attractor. Here, graphite was successfully exfoliated, and an in situ Diels-Alder reaction (D-A) was carried out to fabricate functionalized graphene with sole functional groups via mechanochemical ball milling. The reactivities of graphene acting as a diene or a dienophile were investigated. Few-layer (≤2 layers) graphene specimens were obtained by wet ball milling, heating in a nitrogen atmosphere, and solvent ultrasonic treatment. The ball-milling method was more effective than heating in a nitrogen atmosphere, and the [2 + 4] D-A of graphene was more dominant than the [4 + 2] D-A in the ball-milling process. The surface tension of functionalized graphene decreased, which provided a theoretical basis for the dispersion and exfoliation of graphite in a suitable solvent. Functionalized graphene still had a high electrical conductivity, which has far-reaching significance for functionalized graphene to be applied in electronic semiconductors and related applications. Meanwhile, functionalized graphene was applied to polymer composite fibers, the tensile strength and the Young's modulus could reach 780 MPa and 19 GPa. The volume resistivity was two orders of magnitude lower than that of pure fiber. Thus, the use of ball milling to efficiently exfoliate and in situ functionalize graphite will help to develop a strategy that can be widely used to manufacture nanomaterials for various application fields.

The Impact of Family Care for the Elderly on Women's Employment from the Perspective of Bargaining Power.

Due to the wishes of the elderly and the traditional family culture in China, family care is the main way of providing for the aged, and women's care is the main way. This is not conducive to the protection of women's employment rights and the realization of self-worth under the background of increasing women's autonomy. Based on the latest data of the China Health and Nutrition Survey Database (CHNS), this paper uses ordinary least squares (OLS) and the instrumental variable method of control endogeneity to analyze the influence of family care activities on the labor participation rate of married women. The innovation of this paper is to introduce family bargaining power into this kind of model for the first time, and further analyze the heterogeneity from the perspective of bargaining power differences. The empirical results show that the family elderly care activities have an obstacle effect on married women's participation in employment, and the family members with strong bargaining power will significantly hinder employment, so this paper puts forward policy recommendations in line with the actual situation, hoping to provide theoretical support for the improvement of the social security system for the elderly.

Generating Assembled MFI Nanocrystals with Reduced b-Axis through Structure-Directing Agent Exchange Induced Recrystallization.

Controlling crystal size and shape of zeolitic materials is an effective way to promote their mass transport and catalytic properties. Herein, we report a single step, Na+ - and porogen- free crystallization of MFI hierarchical architecture made up of aligned nanocrystals with reduced b-axis thickness (5-23 nm) and adjustable Si/Al ratios between 35 to 120, employing the commonly used tetrapropylammonium hydroxide (TPAOH) and tetrabutylammonium hydroxide (TBAOH) as structure-directing agents (SDAs). Homogeneous nucleation driven by both SDAs and subsequent SDA-exchange induced dissolution-recrystallization are responsible for the formation of such structure. The enhanced textural and diffusion properties account for a notable exaggeration of propene selectivity and catalyst lifetime in dimethyl ether-to-olefins (DTO) conversion. This protocol is extendable to the rational synthesis of other hierarchical zeolites through crystallization process control.

Facile preparation of CoO nanoparticles embedded N-doped porous carbon from conjugated microporous polymer for oxygen reduction reaction.

Developing cost-effective approaches for fabricating porous carbon (PC) based catalysts with favourable oxygen reduction reaction (ORR) performance is highly significant for fuel-cell devices. Herein, we reported a precursor controlled, molten salt-templated approach to prepare ultrafine CoO nanoparticles embedded nitrogen-doped PC materials with high surface area (1236 m2 g-1) and large pore volume (0.68 cm3 g-1). This method is simple and feasible, which produce CoO nanoparticles that were uniformly distributed on carbon skeleton with diameters in the range of 5-10 nm. The unexpected collapse of porous structures and agglomeration of metal nanoparticles were suppressed in the synthetic process. The as-made sample not only showed efficient catalytic activity towards ORR in alkaline media with a half wave potential (E1/2) of 0.85 V (vs. RHE), but also exhibited better stability and stronger resistance to methanol than Pt/C.

Does Public Health Insurance Coverage Lead to Better Health Outcomes? Evidence From Chinese Adults.

This article examines the impacts of public health insurance on the health of adults through use of data from the China Health and Nutrition Survey. We use the endogenous treatment effects model to infer the causal effects of public health insurance on health. We find that public health insurance significantly improves the physical and mental health status of health insurance beneficiaries after controlling for other covariates. Among the 2 types of voluntary public health insurance, the Urban Resident Basic Medical Insurance has the greater impact in improving health than the New Cooperative Medical Scheme. Moreover, the health effect appears to be stronger for middle-aged individuals, the elderly, and those with lower incomes than for their counterparts. The positive health effects may result from few channels, including the increase of health care utilization, the improvement of health-related behaviors, and the fact that individuals with public health insurance are more likely to use higher level care providers. This study provides implications on reforming China's health care system.

Optimization of preparation conditions for calcium pectinate with response surface methodology and its application for cell encapsulation.

The most notable and unique property of pectin is its ability to form gels, which is the foundation of its many functions and applications. To obtain the desired pectin hydrogel beads for tissue engineering or biological applications, the combined effect of the key factors of gel properties of calcium pectinate (CP) beads were investigated by response surface methodology (RSM). The results derived from RSM indicated that the model equation of average size and mechanical stability were significant and could be used to describe the process under a wide range of preparation conditions. The optimum condition for preparing variables were gained graphically. Moreover, the degree of methyl-esterification (DE) of pectin and pectin - calcium concentrates showed significant and combined effort on sphericity factor (SF). The mechanical stability of CP beads was significantly affected by the quadratic contributions of the pectin concentration, the interaction effects between pectin and calcium concentration, and the linear contribution of pectin concentration. The viability and proliferation of cells encapsulated in optimal CP beads demonstrated that the optimal formula results in better gel properties and are more suitable to cell encapsulation.

Kagóme Cobalt(II)-Organic Layers as Robust Scaffolds for Highly Efficient Photocatalytic Oxygen Evolution.

Two Kagóme cobalt(II)-organic layers of [Co3 (µ3 -OH)2 (bdc)2 ]n (1) and [Co3 (µ3 -OH)2 (chdc)2 ]n (2) (bdc=o-benzenedicarboxylate and chdc=1,2-cyclohexanedicarboxylate) that bear bridging OH(-) ligands were explored as water oxidation catalysts (WOCs) for photocatalytic O2 production. The activities of 1 and 2 towards H2 O oxidation were assessed by monitoring the in situ O2 concentration versus time in the reaction medium by utilizing a Clark-type oxygen electrode under photochemical conditions. The oxygen evolution rate (RO2 ) was 24.3 µmol s(-1) g(-1) for 1 and 48.8 µmol s(-1) g(-1) for 2 at pH 8.0. Photocatalytic reaction studies show that 1 and 2 exhibit enhanced activities toward the oxidation of water compared to commercial nanosized Co3 O4 . In scaled-up photoreactions, the pH value of the reaction medium decreased from 8.0 to around 7.0 after 20 min and the O2 production ceased. Based on the amounts of the sacrificial oxidant (K2 S2 O8 ) used, the yield of O2 produced is 49.6 % for 2 and 29.8 % for 1. However, the catalyst can be recycled without a significant loss of catalytic activity. Spectroscopic studies suggest that the structure and composition of recycled 1 and 2 are maintained. In isotope-labeling H2 (18) O (97 % enriched) experiments, the distribution of (16) O(16) O/(16) O(18) O/(18) O(18) O detected was 0:7.55:92.45, which is comparable to the theoretical values of 0.09:5.82:94.09. This work not only provides new catalysts that resemble ligand-protected cobalt oxide materials but also establishes the significance of the existence of OH(-) (or H2 O) binding sites at the metal center in WOCs.

Surface acidity effects of Al-SBA-15 mesoporous materials on adsorptive desulfurization.

SBA-15 and Aluminum-substituted SBA-15 with Si/Al molar ratio 10 (Al-SBA-15(10)) mesoporous materials were directly synthesized by a hydrolysis approach and characterized by a powder X-ray diffraction (XRD), N2 physisorption analysis and Fourier transform infrared (FTIR) etc. The relative number of hydroxyl groups was investigated by in situ FTIR systematically. The acid type and acid strength of the adsorbents were monitord by FTIR at 423 K and 673 K, respectively, utilizing pyridine as a probe. Desulfurization performances of the adsorbents were investigated via static adsorption experiment. Gas chromatography-sulfur chemiluminescence detector (GC-SCD) was employed to detect the sulfur compounds in model fuels before and after treated by the adsorbents. The calcined Al-SBA-15(10) material shows well-ordered hexagonal mesostructure and strong Lewis acid sites (L acid) and weak Brönsted acid sites (B acid). The number of hydroxy on the surface of the Al-SBA-15(10) is more than that of SBA-15, which is beneficial to further modifications such as spontaneous monolayer dispersion. Desulfurization performance of the adsorbents is affected by surface acidity of adsorbents and the constituent of model fuels (olefins, arene, etc.). The thiophene and olefins adsorbed on the B acid site of the adsorbent may occur subsequently alkylation reactions, which may block the pores of the adsorbents and thus cause the reduction of desulfurization capacity.

Preventive action of curcumin in experimental acute pancreatitis in mouse.

BACKGROUND & OBJECTIVES: Curcuma longa (turmeric) has a long history of use in Ayurvedic medicine as a treatment for inflammatory conditions. The purpose of the present study was to investigate the preventive effects of curcumin against acute pancreatitis (AP) induced by caerulein in mouse and to elucidate possible mechanism of curcumin action. METHODS: Curcumin (50 mg/kg/day) was intraperitoneally injected to Kun Ming male mice for 6 days, followed by injection of caerulein to induce AP. GW9662 (0.3 mg/kg), a specific peroxisome proliferator-activated receptor gamma (PPARγ) antagonist, was intravenously injected along with curcumin. Murine macrophage RAW264.7 cells were treated with 100 µmol/l curcumin for 2 h, and then stimulated with 0.1 µ g/ml lipopolysaccharide (LPS). Serum amylase and transaminase levels were measured at 10 h after AP. TNF-α level in mouse serum and cell culture medium were detected by ELISA. Expression of PPARγ and NF-κB were analyzed by RT-PCR and Western blot. RESULTS: Curcumin significantly decreased the pancreas injury and reversed the elevation of serum amylase, ALT and AST activities and TNF-α level in mice with AP. Curcumin treatment inhibited the elevation of NF-κB-p65 in the nucleus of mouse pancreas AP group and RAW264.7 cells, but significantly increased the expression of PPARγ. GW9662 could abolish the effects of curcumin on serum levels of amylase, ALT, AST, TNF-α, and NF-κB level. INTERPRETATION & CONCLUSIONS: Our results suggest that curcumin could attenuate pancreas tissue and other organ injury by inhibiting the release of inflammatory cytokine TNF-α. These effects may involve upregulation of PPARγ and subsequent downregulation of NF-κB.

Interaction of PFOS and BDE-47 co-exposure on thyroid hormone levels and TH-related gene and protein expression in developing rat brains.

Perfluorooctane sulfonate (PFOS) and 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) are two persistent environmental contaminants that are toxic to developing nervous systems, particularly via their disruption of thyroid hormone (TH) function. To investigate whether an interaction existed between PFOS and BDE-47 on TH-mediated pathways, adult female Wistar rats were exposed to 3.2 and 32 mg/kg of PFOS or BDE-47 in their diet and co-exposed to a combination of each chemical (3.2 mg/kg) from gestational day 1 to postnatal day (PND) 14. Serum and brain tissues from both male and female neonates were collected on PNDs 1, 7, and 14 to examine TH-regulated gene and protein expression. The results revealed that (1) a significant accumulation difference occurred between the two chemicals; (2) On a equimolar basis, BDE-47 and PFOS affected serum total triiodothyronine and total thyroxine differently in adults and offspring; (3) there were region-specific and exposure- and time-dependent alterations in TH concentrations and tested gene and protein expression levels; and (4) interaction for the combined chemicals was only observed for brain-derived neurotrophic factor (BDNF), which exhibited a synergistic effect on PND 1 in the cortex and an antagonistic effect on PND 14 in the hippocampus. Our results suggest a complex TH-mediated gene and protein response to BDE-47 and/or PFOS exposure that seems little related to TH homeostasis and that little combined interaction of co-exposures was observed except on BDNF. The underlying mechanisms remain uncertain but seem to involve more actions than just TH-regulated pathway.

Perfluorooctane sulfonate increased hepatic expression of OAPT2 and MRP2 in rats.

The toxicity of perfluorooctane sulfonate (PFOS), a persistent organic compound, is of great concern. Several studies have reported that PFOS decreases circulating thyroid hormone (TH) concentrations. However, the mechanisms involved remain to be determined. Female rats were exposed to (1) vehicle; (2) PFOS (0.2, 1.0, and 3.0 mg/kg); (3) propylthiouracil (PTU, 10 mg/kg); or (4) PTU (10 mg/kg) + PFOS (3.0 mg/kg) by gavage once a day for 5 consecutive days. Parameters including contents of total T4 (TT4) and total T3 (TT3) in both serum and bile, serum concentrations of transthyretin and thyroglobulin, as well as transcripts of transporters involved in hepatic uptake and efflux of T4 were determined in control and PFOS-exposed groups. TT4 and TT3 were also analyzed in PTU and PTU + PFOS groups in order to reflect the different hormone effects between PFOS, PTU, and PFOS + PTU. Results showed that serum TT4 and TT3 decreased, while bile TT4 and TT3 remained stable following PFOS exposure. Exposure to 3.0 mg/kg of PFOS significantly enhanced hepatic organic anion transporter OATP2 mRNA expression (1.43 times of control). Treatment with PFOS increased hepatic expression of multidrug resistance--associated protein MRP2, approximately 1.80 and 1.69 times of control in 1.0 and 3.0 mg/kg groups, respectively. Spearman's correlation coefficients revealed that MRP2 mRNA expression correlated well with serum TT4 level (r = -0.528, P = 0.012). Serum thyroglobulin and transthyretin levels remained stable. Serum TT3, bile TT4, and bile TT3 were significantly different between PFOS and PTU groups. No significant differences of TT4 and TT3 in both serum and bile were observed between PTU and PTU + PFOS (P > 0.05). In conclusion, PFOS increased hepatic expression of OAPT2, which could possibly enhance hepatic uptake and metabolism of T4 in rats. PFOS-induced TT4 deficiency is mainly due to the extrathyroidal metabolism of T4, which is probably different from the classic goitrogen, PTU.

Transcriptional effects of prenatal and neonatal exposure to PFOS in developing rat brain.

Perfluorooctane sulfonate (PFOS), a persistent and bioaccumulative compound, is widely distributed in the environment. To explore the molecular mechanism of neonatal neurotoxic effects, we evaluated the transcriptional effects of prenatal and neonatal exposure to PFOS in developing rat brain by performing gene expression profiling in the cerebral cortex. Dams received 3.2 mg/kg PFOS in their feed from gestational day 1 (GD1) to weaning (PND 21). Pups then had free access to treated feed until PND 35. Six Illumina RatRef-12 Expression BeadChips were used to identify gene expression changes on postnatal days (PNDs) 1, 7, and 35. Significantly affected genes (P < 0.05) were involved in neuroactive ligand-receptor interaction, calcium signaling pathways, cell communication, long-term potentiation/depression, the cell cycle, and peroxisome proliferator-activated receptor (PPAR) signaling. To compare prenatal and lactational exposure contributions to transcriptional effects, a subset of altered genes obtained from the gene-profile study that represented neurobiological functions was analyzed using RT-PCR in a follow-up cross-foster study lasting from PND1 to 21. Prenatal and postnatal exposure to PFOS caused potential neurotoxicity as demonstrated by developmentally different global transcriptional changes. Prenatal exposure was more effective in altering expression of several genes. Also, transcriptional effects of PFOS exposure on neurodevelopment occurred primarily by disrupting the neuroendocrine system.

Effects of subchronic perfluorooctane sulfonate exposure of rats on calcium-dependent signaling molecules in the brain tissue.

Perfluorooctane sulfonate (PFOS) is a persistent and bio-accumulative pollutant ubiquitous in wildlife and humans, which receives many concerns on the fate, transport, distribution, and toxicity. Studies have shown that PFOS-induced neurotoxicity in experimental animals; however, little is known about the potential mechanism of PFOS exposure on the central nervous system (CNS). Ca(2+)/calmodulin-dependent protein kinase IIalpha (CaMKIIalpha), cAMP-response element binding protein (CREB), c-fos, and c-jun, which are important down-stream molecules of calcium signaling in describing neuron cells structure and function in the CNS, were examined in the paper with the purpose to evaluate the effect of PFOS exposure on brain and approach the molecular mechanisms involved in the neurotoxicity induced by PFOS. Adult male Sprague-Dawley rats were administered with PFOS at dosages of 1.7, 5.0, and 15.0 mg/L in drinking water for 91 consecutive days. LC/MS was used for PFOS analysis in brain tissues, and western blot was employed to determine the expression of CaMKIIalpha and pCREB in the isolated cortex and hippocampus. The expression of c-fos and c-jun was detected by real-time reverse transcription polymerase chain reaction. The results showed that the expression of CaMKIIalpha and pCREB exhibits a significant increase in cortex and hippocampus after treatment with PFOS, compared with the control. The transcription factor c-fos was up-regulated in hippocampus, and c-jun was elevated both in cortex and hippocampus in PFOS-treated groups. These results indicated that, at least in part, the neurotoxic effect induced by PFOS is mediated by the Ca(2+)-dependent molecules in calcium signaling.

Combination of curcumin and green tea catechins prevents dimethylhydrazine-induced colon carcinogenesis.

The chemopreventive effects of curcumin and green tea catechins individually and in combination on 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis were studied in male Wister rats following 32 weeks of dietary treatment. The incidence, number and size of colorectal cancer were measured. Colorectal aberrant crypt foci (ACF) were analyzed by methylene blue staining. Proliferation indices and apoptotic indices were determined by PCNA immunostaining and TUNEL assay, respectively. The results showed that dietary curcumin, catechins and combination administration significantly inhibited the total number of ACF per rat. The combination treatment displayed the most potent inhibitory effect, while there was no difference of inhibition between curcumin and catechins-treated groups. The incidence of colorectal cancer in the treated groups was significantly lower than that of positive control group. Compared with the positive control group, the proliferation index was significantly decreased and the apoptotic index was significantly increased in all treatment groups, while the effect of the combination was the greatest among the treated groups. Our findings suggest that the combination of curcumin and catechins may produce a synergistic colon cancer-preventative effect that would be more potent than each of the compounds alone.

Effect of gestational and lactational exposure to perfluorooctanesulfonate on calcium-dependent signaling molecules gene expression in rats' hippocampus.

Perfluorooctanesulfonate (PFOS) is an environmental contaminant found in human and animal tissues worldwide. The developing nervous system is thought to be particularly sensitive to PFOS by the fact that PFOS can cross blood-brain and placental barriers. Effect of gestational and lactational exposure to PFOS on central nervous system (CNS) in Wistar rats was investigated by the cross-foster model built with PFOS at 0 or 3.2 mg/kg food. Real-time reverse transcription-polymerase chain reaction was employed to evaluate the gene expression of calcium-dependent signaling molecules in rats' hippocampus which are critical to the function of CNS. The expression of calcium-related signaling molecules, such as N-methyl-D-aspartate receptor subtype-2B (NR2B), calmodulin (CaM), Ca2+/calmodulin-dependent kinase II alpha (CaMKIIalpha) and cAMP-response element-binding (CREB) were increased in the PFOS exposure group at postnatal day 1 (PND 1). The decreased NR2B in the prenatal PFOS exposure group, the decreased CaM in the pre-/postnatal PFOS exposure group, the increased CaMKIIalpha in the whole-life PFOS exposure group and the increased CREB in the prenatal/whole-life PFOS exposure group was observed at PND 7. At PND 35, rats exhibited the decreased NR2B in the pre-/postnatal and the whole-life PFOS exposure group, and the decreased CaM in the postnatal PFOS group. The results indicate that perinatal exposure to PFOS during the critical period of development of the brain may have neurotoxic effect on CNS by mediating the molecules of calcium signaling pathway.

Prenatal and postnatal impact of perfluorooctane sulfonate (PFOS) on rat development: a cross-foster study on chemical burden and thyroid hormone system.

Perfluorooctane sulfonate (PFOS), an environmentally persistent organic pollutant, has been reported to be transferred to the developing organisms via both placenta and breast milk. A cross-foster model was used to determine whether prenatal or postnatal exposure to PFOS alone can disturb the TH homeostasis in rat pups, and if so, which kind of exposure is a major cause of TH level alteration. Pregnant rats were fed standard laboratory rodent diet containing 0 (control) or 3.2 mg PFOS/kg throughout gestation and lactation period. On the day of birth, litters born to treated and control dams were cross-fostered, resulting in the following groups: unexposed control (CC), pups exposed only prenatally (TC), only postnatally (CT) or both prenatally and postnatally (TT). Serum and liver PFOS concentrations, serum total thyroxine (T4), total triiodothyronine (T3), reverse T3 (rT3) levels, and hepatic expression of genes involved in TH transport, metabolism, and receptors were evaluated in pups at the age of postnatal days (PNDs) 0, 7, 14, 21, or 35. PFOS body burden level in pups in group CT increased, while those in group TC dropped as they aged. Neither total T3 nor rT3 in pups was affected by PFOS exposure. Gestational exposure to PFOS alone (TC) significantly (p < 0.05) decreased T4 level in pups on PNDs 21 and 35, 20.3 and 19.4% lower than the control on the same PND, respectively. Postnatal exposure to PFOS alone (CT) also induced T4 depression on PNDs 21 and 35, 28.6 and 35.9% lower than controls, respectively. No significant difference in T4 level (p > 0.05) was observed between TC and CT on these two time points. None of the selected TH related transcripts was affected by PFOS in pups on PND 0. Only transcript level of transthyretin, TH binding protein, in group TT significantly increased to 150% of the control on PND 21. The results showed that prenatal PFOS exposure and postnatal PFOS exposure induced hypothyroxinemia in rat pups to a similar extent, which suggested that in utero PFOS exposure and postnatal PFOS accumulation, especially though maternal milk, are matters of great concern.

Effects of perfluorooctane sulfonate on rat thyroid hormone biosynthesis and metabolism.

The potential toxicity of perfluorooctane sulfonate (PFOS), an environmentally persistent organic pollutant, is of great concern. The present study examines the ability of PFOS to disturb thyroid function and the possible mechanisms involved in PFOS-induced thyroid hormone alteration. Male Sprague-Dawley rats were exposed to 1.7, 5.0, and 15.0 mg/L of PFOS in drinking water for 91 consecutive days. Serum was collected for analysis of total and free thyroxine (T4), total triiodothyronine (T3), and thyrotrophin (TSH). Thyroid and liver were removed for the measurement of endpoints closely related to thyroid hormone biosynthesis and metabolism following PFOS exposure. Determined endpoints were the messenger RNA (mRNA) levels for two isoforms of uridine diphosphoglucuronosyl transferases (UGT1A6 and UGT1A1) and type 1 deiodinase (DIO1) in liver, sodium iodide symporter (NIS), TSH receptor (TSHR), and DIO1 in thyroid as well as the activity of thyroid peroxidase (TPO). Serum total T4 level decreased significantly at all applied dosages, whereas total T3 level increased markedly only at 1.7 mg/L of PFOS. No statistically significant toxic effects of PFOS on serum TSH were observed. Hepatic UGTIA1, but not UGT1A6, mRNA was up-regulated at 5.0 and 15.0 mg/L of PFOS. Treatment with PFOS lowered hepatic DIO1 mRNA at 15.0 mg/L but increased thyroidal DIO1 mRNA dose dependently. The activity of TPO, NIS, and TSHR mRNA in thyroid were unaffected by PFOS treatment. These results indicate that increased hepatic T4 glucuronidation via UGT1A1 and increased thyroidal conversion of T4 to T3 via DIO1 were responsible in part for PFOS-induced hypothyroxinemia in rats.