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Articles by S. Chen
Total Records ( 8 ) for S. Chen
  Y. G Li , D. F Ji , S Zhong , L. G Shi , G. Y Hu and S. Chen

Aims: The purpose of this study was to investigate the possible mechanism(s) of saponins from Panax japonicus (SPJ) on alcohol-induced hepatic damage in mice. Methods: SPJ were identified by high performance liquid chromatography-evaporative light scattering detection-mass spectrometry (LC–ELSD–MS). Non-toxic concentrations of SPJ were assayed on alcohol-induced hepatic injury in male ICR mice and human hepatic cells. The protective effects were evaluated by biochemical values, histopathological observations and the relative gene expression. Results. In vitro, SPJ showed significant hydroxyl radical scavenging capacity. In vivo, SPJ (50 mg/kg) could rectify the pathological changes of aspartate transaminase, alanine transaminase, malondialdehyde, reduced glutathione (GSH), glutathione peroxidase (GPX), catalase (CAT) and superoxide dismutase (SOD) caused by alcohol metabolism to normal levels except for hepatic GSH and CAT. In hepatic cells, the results were in agreement with foregoing results determined in mice after pretreatment of SPJ (100 µg/ml). RT–PCR results showed that CAT, GPX and SOD mRNA decreased by alcohol metabolism were reversed, in which GPX3, SOD1 and SOD3 could return to a normal level, but CAT, GPX1 and SOD2 mRNA were still evidently lower than the control. Histopathological observations provided supportive evidence for biochemical analyses. Conclusions: SPJ plays an important role in the protection of the structure and function of hepatic mitochondria and karyon by directly scavenging reactive oxygen species/free radicals and up-regulating the expression of antioxidant enzymes (SOD, GPX and CAT), especially to GPX3, SOD1 and SOD3.

  L. S Adams , Y Zhang , N. P Seeram , D Heber and S. Chen

Estrogen stimulates the proliferation of breast cancer cells and the growth of estrogen-responsive tumors. The aromatase enzyme, which converts androgen to estrogen, plays a key role in breast carcinogenesis. The pomegranate fruit, a rich source of ellagitannins (ET), has attracted recent attention due to its anticancer and antiatherosclerotic properties. On consumption, pomegranate ETs hydrolyze, releasing ellagic acid, which is then converted to 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one ("urolithin") derivatives by gut microflora. The purpose of this study was to investigate the antiaromatase activity and inhibition of testosterone-induced breast cancer cell proliferation by ET-derived compounds isolated from pomegranates. A panel of 10 ET-derived compounds including ellagic acid, gallagic acid, and urolithins A and B (and their acetylated, methylated, and sulfated analogues prepared in our laboratory) were examined for their ability to inhibit aromatase activity and testosterone-induced breast cancer cell proliferation. Using a microsomal aromatase assay, we screened the panel of ET-derived compounds and identified six with antiaromatase activity. Among these, urolithin B (UB) was shown to most effectively inhibit aromatase activity in a live cell assay. Kinetic analysis of UB showed mixed inhibition, suggesting more than one inhibitory mechanism. Proliferation assays also determined that UB significantly inhibited testosterone-induced MCF-7aro cell proliferation. The remaining test compounds also exhibited antiproliferative activity, but to a lesser degree than UB. These studies suggest that pomegranate ET–derived compounds have potential for the prevention of estrogen-responsive breast cancers. Cancer Prev Res; 3(1); 108–13

  Q. Fang , S. Chen , Y. Wang , S. Jiang , R. Zhang , C. Hu , C. Wang , F. Liu , K. Xiang and W. Jia
  Aims  Hepatocyte nuclear factor-1α (HNF-1α) regulates the expression of genes encoding proteins involved in glucose metabolism and insulin secretion. Mutations in the HNF-1α gene cause maturity-onset diabetes of the young Type 3. However, the mechanism leading to this disease has not been completely ascertained. Previously, we found a novel mutation in the regulatory element of the human HNF-1α gene in two Chinese diabetes pedigrees. The nucleotide at position -128 T was substituted by G (nt-128 T[RIGHTWARDS ARROW]G). In this study, we analysed the functional defect of nt-128 T[RIGHTWARDS ARROW]G in HNF-1α transcription activity.

Methods  Luciferase reporter gene assays were carried out to examine the functional characteristics of this mutant. Electrophoretic mobility shift assays and chromatin immunoprecipitation were performed to confirm the binding of nuclear proteins to oligonucleotides.

Results  The variant construct (nt-128 T[RIGHTWARDS ARROW]G) had a 1.65-fold increase in promoter activity compared with that of the wild-type construct in HepG2 cells and a 1.33-fold increase in MIN6 cells, respectively. The variant resided at a FOXA/HNF-3 binding site identified by a series of competitive electrophoretic mobility shift assays and antibody supershift analyses. The assays showed a differential binding affinity in the wild-type and the nt-128 T[RIGHTWARDS ARROW]G mutant fragments by FOXA/HNF-3. Chromatin immunoprecipitation indicated that FOXA/HNF-3 bound to this region in vivo. One nucleotide substitution in the FOXA/HNF-3 site in the human HNF-1α regulatory element caused an increase of HNF-1α transcriptional activity.

Conclusions  Our data suggested that this substitution in the promoter region affects DNA-protein interaction and HNF-1α gene transcription. The mutant may contribute to the development of diabetes in these two nt-128 T[RIGHTWARDS ARROW]G pedigrees of Chinese.

  J.S. Chen , R.F. Zhu , Y.X. Zhang , S. Chen , C. Gao and D.G. Li
  A defoliation experiment was conducted on a Leymus chinensis-dominated steppe to provide guidelines of grazing management and restoration of degraded grasslands. There were five defoliation treatments: CK (non-defoliation as control); LD (Light Defoliation, cut 12 cm aboveground level); MD (Medium Defoliation, 8 cm); HD (Hard Defoliation, 4 cm) and SD (Severe Defoliation, 2 cm). Results showed that HD and SD defoliation significantly decreased the belowground biomass. Defoliation increased plant species diversity but decreased biomass of L. chinensis significantly. The biomass of L. chinensis under LD was lower than that in control indicating L. chinensis was highly sensitive to defoliation. It is necessary in this area that grazing should be restricted to a level of light defoliation to prevent loss of plant productivity.
  S. Chen , Q. Song , Y. Cheng and L. Chen
  Nowadays, the inventory misplacement is a significant issue in the supply chain management. This study analyzes how the managers consider using Radio Frequency Identification (RFID) to effectively eliminate misplacement problems and to improve profitability. A mean-risk framework is carried out to portray this issue and a central semi-deviation model is proposed for risk measurement to analyze the impact of risk attitude on RFID adoption. Both risk neutral and risk aversion cases are discussed in this study. By considering both fixed setup cost and the tag cost, it is proved that retailers do not always benefit more from implementing RFID, unless the level of available products and tag cost are both low enough. Under the risk analysis, it is found that a risk aversion manager will be more unwilling than a risk neutral manager to invest RFID technology. Moreover, the manager will be more unwilling to invest RFID if the manager is more risk-averse.
  J.L. Yang , H.J. Hao , B. Zhang , Y.X. Liu , S. Chen and Y.Q. Na
  Measurement of soluble CD30 (sCD30) levels may predict acute rejection episodes (ARE). To explore the value of sCD30 after transplantation, we tested serum sCD30 levels in 58 kidney transplant cases at 1 day before and 7 and 28 days after transplantation by enzyme-linked immunosorbent assay (ELISA). The incidences of ARE after kidney transplantation were recorded simultaneously. Meanwhile, 31 healthy individuals were selected as a control group. The results showed a relationship between sCD30 level in serum before kidney transplantation and the incidence of ARE. However, the relationship was more significant between serum sCD30 levels at day 7 after kidney transplantation and the incidence of ARE. There was no obvious relationship between serum sCD30 levels at day 28 after kidney transplantation and the incidence of ARE. These results suggested that the level of sCD30 at day 7 posttransplantation provides valuable data to predict ARE.
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