Biomedical subjects

Xiao-Chen Zhao

Publications and source records attributed to Xiao-Chen Zhao.

4 recordsLinked to original sources

PubMed2003

The antihyperglycaemic activity of berberine arises from a decrease of glucose absorption.

The mechanism of action of berberine as an antihyperglycaemic agent was investigated in the Caco-2 cell line. Berberine was found to effectively inhibit the activity of disaccharidases in Caco-2 cells. It also decreased sucrase activity after preincubation with Caco-2 cells for 72 hours. However gluconeogenesis and glucose consumption of Caco-2 cells were not influenced. 2-Deoxyglucose transporting through Caco-2 cell monolayers was decreased by berberine but the effect was not statistically significant. These results suggest that the antihyperglycaemic activity of berberine is at least partly due to its ability to inhibit alpha-glucosidase and decrease glucose transport through the intestinal epithelium.

Berberine↗

PubMed2003

Changes of biological functions of dipeptide transporter (PepT1) and hormonal regulation in severe scald rats.

AIM: To determine the regulatory effects of recombinant human growth hormone (rhGH) on dipeptide transport (PepT1) in normal and severe scald rats. METHODS: Male Sprague-Dawley rats with 30% total body surface area (TBSA) III degree scald were employed as the model. In this study rhGH was used at the dose of 2 IU/kg(-1)d(-1). An everted sleeve of intestine 4 cm long obtained from mid-jejunum was securely incubated in Kreb's solution with radioactive dipeptide (3H-glycylsarcosine, 3H-Gly-Sar, 10 microCi/ml) at 37 degrees C for 15 min to measure the effects of uptake and transport of PepT1 of small intestinal epithelial cells in normal and severe scald rats. RESULTS: Abundant blood supply to intestine and mesentery was observed in normal and scald rats administered rhGH, while less supply of blood to intestine and mesentery was observed in rats without rhGH. Compared with controls, the transport of dipeptide in normal rats with injection of rhGH was not significantly increased (P=0.1926), while the uptake was significantly increased (P=0.0253). The effects of transport and uptake of PepT1 in scald rats with injection of rhGH were significantly increased (P=0.0082, 0.0391). CONCLUSION: Blood supply to intestine and mesentery of rats was increased following injection of rhGH. The effects of uptake and transport of dipeptide transporters in small intestinal epithelial cells of rats with severe scald were markedly up-regulated by rhGH.

Animals↗

PubMed2003

Hormonal regulation of dipeptide transporter (PepT1) in Caco-2 cells with normal and anoxia/reoxygenation management.

AIM: To determine the regulation effects of recombinant human growth hormone (rhGH) on dipeptide transporter(PepT1) in Caco-2 cells with normal culture and anoxia/reoxygenation injury. METHODS: A human intestinal cell monolayer (Caco-2) was used as the in vitro model of human small intestine and cephalexin as the model substrate for dipeptide transporter (PepT1). Caco-2 cells grown on Transwell membrane filters were preincubated in the presence of rhGH in the culture medium for 4 d, serum was withdrawn from monolayers for 24 h before each experiment. The transport experiments of cephalexin across apical membromes were then conducted; Caco-2 cells grown on multiple well dishes (24 pore) with normal culture or anoxia/reoxygenation injury were preincubated with rhGH as above and uptake of cephalexin was then measured. RESULTS: The transport and uptake of cephelaxin across apical membranes of Caco-2 cells after preincubation with rhGH were significantly increased compared with controls (P=0.045, 0.0223). Also, addition of rhGH at physiological concentration (34 nM) to incubation medium greatly stimulates cephalexin uptake by anoxia/reoxygenation injuried Caco-2 cells (P=0.0116), while the biological functions of PepT1 in injured Caco-2 cells without rhGH were markedly downregulated. Northern blot analysis showed that the level of PepT1 mRNA of rhGH-treated injured Caco-2 cells was greatly increased compared to controls. CONCLUSION: The present results of rhGH stimulating the uptake and transport of cephalexin indicated that rhGH greatly upregulates the physiological effects of dipeptide transporters of Caco-2 cells. The alteration in the gene expression may be a mechanism of regulation of PepT1. In addition, Caco-2 cells take up cephalexin by the Proton-dependent dipeptide transporters that closely resembles the transporters present in the intestine. Caco-2 cells represent an ideal cellular model for future studies of the dipeptide transporter.

Base Sequence↗

PubMed2002

Adeno-associated virus mediated expression of human erythropoietin in vitro.

AIM: To investigate the expression of human erythropoietin (hEpo) in 293 cell line using adeno-associated virus (AAV) vector, and provide information for its potential application in human gene therapy. METHODS: The human Epo cDNA was inserted into the AAV cassettes, and recombinant adeno-associated virus (rAAV-EPO) vectors were generated by cotransfection methods without helper virus. The expression of hEpo was detected by RT-PCR and ELISA methods. RESULTS: A recombinant adeno-associated virus expressing hEpo was constructed and generated successfully. Positive signal of mRNA was detected from 293 cells transduced with rAAV-EPO, and the hEpo level in supernatant reached 500 U/L. CONCLUSION: rAAV-EPO expressed biologically active hEpo effectively, suggesting that it is a suitable gene expression tool for further study in vivo experiments.

Cell Line↗