Xu-Dong Feng

Publications (3)11.87 Total impact

• Article: Gadolinium triggers unfolded protein responses (UPRs) in primary cultured rat cortical astrocytes via promotion of an influx of extracellular Ca2+.

  Xu-Dong Feng, Qing Xia, Lan Yuan, Hai-Feng Huang, Xiao-Da Yang, Kui Wang
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  ABSTRACT: Gadolinium (Gd) and its complexes are utilized widely in industrial and clinical diagnoses. As a rare earth metal ion, free gadolinium (Gd(3+)) in the human body poses neurotoxic risks during its in vivo release and retention. In the central nervous system, astrocytes play a pivotal role in processing toxic metal ions. The present study evaluates the effects of Gd on cellular calcium homeostasis, a common mechanism that causes cell death, and on unfolded protein responses (UPRs), a mechanism for cell survival in response to toxic stimuli in mammalian cells. The experimental results indicate that the influx of extracellular Ca(2+) increases greatly after the exposure of astrocytes to Gd; however, no cell deaths were observed. Further evidence suggests the up-regulated expression of the endoplasmic reticulum (ER)-resident chaperone protein GRP78 by ER stress-mediated signal transductions, specifically the activation of ATF6, eIF2a, and IRE1. These results suggest that Gd promotes Ca(2+) influx, thus triggering UPRs, which can be closely associated to the resistance of astrocytes to Gd-induced cytotoxicity.
  Cell Biology and Toxicology 04/2010; 27(1):1-12. · 2.51 Impact Factor
• Article: Synthesis, biocompatibility and cell labeling of L-arginine-functional beta-cyclodextrin-modified quantum dot probes.

  Mei-Xia Zhao, Qing Xia, Xu-Dong Feng, Xu-Hui Zhu, Zong-Wan Mao, Liang-Nian Ji, Kui Wang
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  ABSTRACT: A series of quantum dots (QDs), CdSe, CdSe/CdS and CdSe/ZnSe, coated with L-arginine-modified beta-cyclodextrin (beta-CD-L-Arg) were prepared in a solution of H2O and hexane by ultrasonic method and characterized using PL, UV-vis, TEM, EDX and FTIR techniques. We observed that beta-CD-L-Arg-coated QDs are water-soluble and stable with high colloidal properties in water. Their photophysical properties are similar to those of trioctylphosphine oxide (TOPO)-coated nanocrystals. The quantum yield (QY) of beta-CD-L-Arg/CdSe/ZnSe QDs in water is 68%, which is much higher than those of beta-CD-L-Arg/CdSe/CdS (26%) and beta-CD-L-Arg/CdSe (13%). The in vitro cytotoxicity of these QDs was evaluated in ECV-304, SH-SY5Y and Hela cells and low cytotoxicity was observed. In particular, the beta-CD-L-Arg/CdSe/ZnSe QDs presented lower cytotoxicity to these cells (CC(50) value is 173 microg/mL in ECV-304 cells for 48h). This may be due to the presence of the ZnSe and beta-CD-L-Arg outlayer, which may improve the biocompatibility of QDs. The QDs were further investigated for biological labeling in ECV-304 cells using confocal laser scanning fluorescence microscopy. We found that these QDs were capable of localing to the cytoplasm of cells. These results demonstrate that the beta-CD-L-Arg-coated QDs could be used as a potential photoluminescent nanocrystal probing agent with good biocompatibility.
  Biomaterials 02/2010; 31(15):4401-8. · 7.40 Impact Factor
• Article: High doses of bifendate elevate serum and hepatic triglyceride levels in rabbits and mice: animal models of acute hypertriglyceridemia.

  Si-Yuan Pan, Rong Yang, Yi-Fan Han, Hang Dong, Xu-Dong Feng, Na Li, Wei Geng, Kam-Ming Ko
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  ABSTRACT: To investigate the effects of bifendate on serum and hepatic lipids level in rabbits and mice. Animals were administered bifendate [powdered pill suspended in 0.5% sodium carboxymethylcellulose (CMC)] at increasing doses (0.25-1 g/kg, ig). Blood lipid and apolipoprotein levels were measured using commercially available assay kits. The treatment of rabbits with a single dose of bifendate (0.3 g/kg) caused a time-dependent and biphasic change in serum triglyceride (TG) levels, with the value reaching a maximum (3-fold increase compared to the baseline value) between 24 and 36 h post-dosing. When mice were orally treated with bifendate (0.25-1 g/kg), serum TG levels increased by 39%-76% and 14%-39% at 24 and 48 h post-dosing, respectively. When given at daily doses of 0.25 and 1 g/kg for 4 d, bifendate increased serum TG levels (56%-79%), with concomitant elevations in apolipoprotein A-I and apolipoprotein B levels at 24 h after the last dosing. TG levels were also increased (11%-43%) in liver samples of mice receiving single or multiple doses of bifendate. However, bifendate treatment caused slight reductions in serum and hepatic total cholesterol levels (9%-13%). The hypertriglyceridemia induced by bifendate was ameliorated by fenofibrate but not inositol nicotinate treatment in mice. The findings suggest that bifendate treatment at high oral doses can cause an acute elevation in serum and hepatic TG levels.
  Acta Pharmacologica Sinica 07/2006; 27(6):673-8. · 1.95 Impact Factor