AIM: To investigate whether the farnesoid X receptor (FXR) regulates expression of liver cystathionase (CSE), a gene involved in hydrogen sulfi de (H2S) generation. METHODS: The regulation of CSE expression in respons...AIM: To investigate whether the farnesoid X receptor (FXR) regulates expression of liver cystathionase (CSE), a gene involved in hydrogen sulfi de (H2S) generation. METHODS: The regulation of CSE expression in response to FXR ligands was evaluated in HepG2 cells and in wild-type and FXR null mice treated with 6-ethyl chenodeoxycholic acid (6E-CDCA), a synthetic FXR ligand. The analysis demonstrated an FXR responsive element in the 5'-flanking region of the human CSE gene. The function of this site was investigated by luciferase reporter assays, chromatin immunoprecipitation and electrophoretic mobility shift assays. Livers obtained from rats treated with carbon tetrachloride alone, or in combination with 6-ethyl chenodeoxycholic acid, were studied for hydrogen sulphide generation and portal pressure measurement. RESULTS: Liver expression of CSE is regulated by bile acids by means of an FXR-mediated mechanism. Western blotting, qualitative and quantitative polymerase chain reaction, as well as immunohistochemical analysis, showed that expression of CSE in HepG2 cells and in mice is induced by treatment with an FXR ligand. Administration of 6E-CDCA to carbon tetrachloride treated rats protected against the down-regulation of CSE expression, increased H2S generation, reduced portal pressure and attenuated the endothelial dysfunction of isolated and perfused cirrhotic rat livers. CONCLUSION: These results demonstrate that CSE is an FXR-regulated gene and provide a new molecular explanation for the pathophysiology of portal hypertension.展开更多
The effects of chenodeoxycholic acid (CDCA) in a dye solution as a co-adsorbent on the photovoltaic performance of dye-sensitized solar cells (DSSCs) based on two organic dyes containing phenothiazine and triarylamine...The effects of chenodeoxycholic acid (CDCA) in a dye solution as a co-adsorbent on the photovoltaic performance of dye-sensitized solar cells (DSSCs) based on two organic dyes containing phenothiazine and triarylamine segments (P1 and P2) were investigated.It was found that the coadsorption of CDCA can hinder the formation of dye aggregates and improve electron injection yield and thus Jsc.This has also led to a rise in photovoltage,which is attributed to the decrease of charge recombination.The DSSC based on dye P2 showed better photovoltaic performance than P1:a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 89.5%,a short-circuit photocurrent density (Jsc) of 9.57 mA/cm2,an open-circuit photovoltage (Voc) of 697 mV,and a fill factor (FF) of 0.66,corresponding to an overall conversion efficiency of 4.42% under the standard global AM 1.5 solar light condition.The overall conversion efficiency was further improved to 5.31% (Jsc=10.36 mA/cm2,Voc=0.730 V,FF=0.70) upon addition of 10 mM CDCA to the dye solution for TiO2 sensitization.Electrochemical impedance data indicate that the electron lifetime was improved by coadsorption of CDCA,accounting for the significant improvement of Voc.These results suggest that interfacial engineering of the organic dye-sensitized TiO2 electrodes is important for highly efficient photovoltaic performance of the solar cell.展开更多
文摘AIM: To investigate whether the farnesoid X receptor (FXR) regulates expression of liver cystathionase (CSE), a gene involved in hydrogen sulfi de (H2S) generation. METHODS: The regulation of CSE expression in response to FXR ligands was evaluated in HepG2 cells and in wild-type and FXR null mice treated with 6-ethyl chenodeoxycholic acid (6E-CDCA), a synthetic FXR ligand. The analysis demonstrated an FXR responsive element in the 5'-flanking region of the human CSE gene. The function of this site was investigated by luciferase reporter assays, chromatin immunoprecipitation and electrophoretic mobility shift assays. Livers obtained from rats treated with carbon tetrachloride alone, or in combination with 6-ethyl chenodeoxycholic acid, were studied for hydrogen sulphide generation and portal pressure measurement. RESULTS: Liver expression of CSE is regulated by bile acids by means of an FXR-mediated mechanism. Western blotting, qualitative and quantitative polymerase chain reaction, as well as immunohistochemical analysis, showed that expression of CSE in HepG2 cells and in mice is induced by treatment with an FXR ligand. Administration of 6E-CDCA to carbon tetrachloride treated rats protected against the down-regulation of CSE expression, increased H2S generation, reduced portal pressure and attenuated the endothelial dysfunction of isolated and perfused cirrhotic rat livers. CONCLUSION: These results demonstrate that CSE is an FXR-regulated gene and provide a new molecular explanation for the pathophysiology of portal hypertension.
基金supported by the National Natural Science Foundation of China (20772031 & 61006048)National Basic Research Program of China (973 Program) (2006CB806200)+1 种基金the Fundamental Research Funds for the Central Universities (WJ0913001)Scientific Committee of Shanghai (10520709700)
文摘The effects of chenodeoxycholic acid (CDCA) in a dye solution as a co-adsorbent on the photovoltaic performance of dye-sensitized solar cells (DSSCs) based on two organic dyes containing phenothiazine and triarylamine segments (P1 and P2) were investigated.It was found that the coadsorption of CDCA can hinder the formation of dye aggregates and improve electron injection yield and thus Jsc.This has also led to a rise in photovoltage,which is attributed to the decrease of charge recombination.The DSSC based on dye P2 showed better photovoltaic performance than P1:a maximum monochromatic incident photon-to-current conversion efficiency (IPCE) of 89.5%,a short-circuit photocurrent density (Jsc) of 9.57 mA/cm2,an open-circuit photovoltage (Voc) of 697 mV,and a fill factor (FF) of 0.66,corresponding to an overall conversion efficiency of 4.42% under the standard global AM 1.5 solar light condition.The overall conversion efficiency was further improved to 5.31% (Jsc=10.36 mA/cm2,Voc=0.730 V,FF=0.70) upon addition of 10 mM CDCA to the dye solution for TiO2 sensitization.Electrochemical impedance data indicate that the electron lifetime was improved by coadsorption of CDCA,accounting for the significant improvement of Voc.These results suggest that interfacial engineering of the organic dye-sensitized TiO2 electrodes is important for highly efficient photovoltaic performance of the solar cell.
