Objective: To design and confirm the cleavage activity of ribozyme Rz217 to oncogene ki-rasG12V messenger RNA and search for a new method for gene therapy targeting oncogene ki-ras. Methods: According to Symon' s principle,design an ribozyme specific for ki-rasc12v mRNA, both the constructs for transcription in vitro of ribozyme Rz217 and ki-ras exonl and the mammalian expression constructs of ribozyme Rz217 were constructed by DNA recombinant technique,ribozyme Rz217 and ki-ras exonl mRNA was obtained by transcription in vitro with T7 and SP6 RNA polymerase. Pancre atic carcinoma cell line PaTu8988 and human hepatocellular carcinomacell line BEL7404 were transfected with Rz217 mammalian expression constructs and the level of endogenous ki-rasG12V mRNA or ki-ras mRNA was determined by semiquantitative RT-PCR. Results: Not only in vitro but also in vivo, ribozyme Rz217 can cleave the mRNA of oncogene ki-ras (G12V) in site-specific manner and can not cleave the mRNA of wild-type ki-ras. Conclusion: Ribozyme Rz217 can cleave oncogene ki-rasc12v mRNA and the cleveage is specific for ki-rasG12V mRNA.

Objective To explore the way and technique to gain adequate seed cells for skin tissue engineering sufficiently. Methods Human telomerase reverse transcriptase (hTERT) gene was introduced into rabbit keratinocytes by eukaryotic vector. The positive clones were selected and cultured in microcarrier-RCCS. The growth of immortalized keratinocytes was observed, and the metabolic rate and pan-cytokeratins (AE1/AE3) expression of immortalized keratinocytes in experimental groups were detected and compared with those in the control group. Results The immortalized keratinocytes in the experimental groups grew rapidly and had a high metabolic rate and shorter population doubling time (PD) (P