To establish a method of directional differentiation and efficient production of neurons from embryonic stem cells (ES cells)in vitro, based on the 4-/4+ protocol described by Bain, a new method was established to induce ES cells differentiating into neurons by means of three-step differentiation using all-trans retinoic acid (ATRA) combined with astrocyte-conditioned medium (ACM)in Vitro. The totipotency of ES cells was identified by observation of cells morphology and formations of teratoma in immunocompromised mice. The cells differentiation was evaluated continuously by the detection of the specific cellular markers of neural stem cells, neurons and astrocytes, including nestin, NSE and GFAP using immunohistochemistry assay. The NSE positive cells' ratio of the differentiated cells was determined by flow cytometry. It was found that the transparent circular clusters surrounding embryoid bodies induced with combining induction protocol formed just after 24 h and gradually enlarged later. This phenomenon could not be observed in EBs induced only by ATRA. The NSE positive cells' ratio in the cells induced with ATRA and ACM was higher than that of the cells induced by ATRA at different time points of differentiation, and finally reached up to 73.5% among the total differentiated population. It was concluded that ES cells could be induced into neurons with high purity and yield by means of inducing method combining with ATRA and ACM.

To investigate the effects of WIN 55, 212-2 onI_K in cultured rat trigeminal ganglion (TG) neurons, whole-cell patch clamp techniques were used to record theI_K before and after WIN 55,212-2 perfusion at different concentrations. 30 μmol/L WIN 55,212-2 markedly (35.7%±7.3%P<0.01,n=8) inhibitedI_K currents, and the currents were partially recovered after washing. 30 μmol/L WIN 55, 212-2 also induced a significant depolarizing shift in conductance-voltage parameters (control: V_0.5=10.43±4.25 mV, k=16.27±3.86; WIN 55,212-2: V_0.5=24.71±3.91 mV, k=16.69±2.75;n=8,P<0.01 for V_0.5). 0.01 μmol/L WIN 55,212-2 slightly (27.0%±7.9%,P<0.05,n=7) increasedI_K currents, but had no significant change in conductance-voltage parameters (control: V_0.5=10.74±5.27 mV, k=17. 33±2.96; WIN 55, 212-2: V_0.5=11.06±2.05 mV, k=19.69±6.60;n=7,P>0.05 for V_0.5 and k). These results suggested that WIN 55, 212-2 has dual action, which might be through different receptors.

In order to explore whether gene CHFR was inactivated by methylation in leukemia cells, the expression of CHFR was examined before and after treatment with demethylation agent in Molt-4, Jurkat and U937 leukemia cell lines by means of RT-PCR. The methylation of promoter in Molt-4, Jurkat and U937 cells as well as 41 acute leukemia patients was analyzed by MS-PCR. The results showed that methylation of CHFR promoter was inactivated and could be reversed by treatment with a demethylating agent in Molt-4, Jurkat and U937. CHFR promoter methylation was detected in 39% of acute leukemia patients. There was no difference in incidence of CHFR promoter methylation between acute myelocytic leukemia and acute lymphocytic leukemia. In conclusion, CHFR is frequently inactivated in acute leukemia and is a good candidate for the leukemia supper gene. By affecting mitotic checkpoint function, CHFR inactivation likely plays a key role in tumori-genesis in acute leukemia. Moreover, the methylation of gene CHFR appears to be a good index with which to predict the sensitivity of acute leukemia to microtubule inhibitors.

Primary cell culture, techniques of gene transfection, gelatin zymography, and Western blot were used to investigate the effect of hypoxia on the secretion of MMP-2 and MMP-9 in pulmonary artery endothelial cells (PAEC) and smooth muscle cells (PASMC), and the role of HIF-1, Our results showed that (1) after exposure to hypoxia for 24 h, the protein content and activity of MMP-2 in the PAEC medium as well as these of MMP-2 and MMP-9 in PASMC medium (P<0. 01) decreased significantly in contrast to those in normoxic group (P′<0.05); (2) after transfection of wild type EPO3′-enhancer, a HIF-1 decoy, the content and activity of MMP-2 and MMP-9 in hypoxic mediums became higher than those in normoxic group (P<0.01), while transfection of mutant EPO3′-enhancer didn't affect the hypoxia-induced down-regulation. It is concluded that hypoxia could inhibit the secretion and activity of MMP-2 and MMP-9 in PAEC and PASMC, which could be mitigated by the transfection of EPO3′-enhancer and that HIF-1 pathway might contribute to hypoxia-induced down-regulation of MMP-2 and MMP-9.