AIM: To study the recombinant plasmid pDL121 and its expression product in E.coli. METHODS: pDL121 was analysed by using 6 different restriction endonucleases and dot blotting, and the isolated 23 kDa protein band was cut and injected twice into rabbits to raise anti - 23 kDa serum. RESULTS: The restriction map of pDL121 was quite different from other leptospiral genes reported and digoxin labeled recombinant DNA probe of pDL121 could detect the pathogenic leptospires, whereas, not the nonpathogenic leptospires. The anti - 23 kDa serum could recognize the sonicated antigen of L. interrogans serovar lai strain 017 and 23 kDa protein expressed in pDL121 and the titer of the antiserum were very high, approximately 1/12 800. Injection of the E. coli lysate of pDL121 with Freund's adjuvant into guinea pigs resulted in some protection of the animal against the challenge with strain 017. CONCLUSION: It indicated that 23 kDa protein had good imunogenicity and could serve as a candidate for protective antigen of L. interrogans and the inserted fragment of pDL121 could be a new gene .

AIM: To study the recombinant plasmid pDL121 and its expression product in E.coli. METHODS: pDL121 was analysed by using 6 different restriction endonucleases and dot blotting, and the isolated 23 kDa protein band was cut and injected twice into rabbits to raise anti-23 kDa serum. RESULTS: The restriction map of pDL121 was quite different from other leptospiral genes reported and digoxin labeled recombinant DNA probe of pDL121 could detect the pathogenic leptospires, whereas, not the nonpathogenic leptospires. The anti-23 kDa serum could recognize the sonicated antigen of L.interrogans serovar lai strain 017 and 23 kDa protein expressed in pDL121 and the titer of the antiserum were very high, approximately 1/12 800. Injection of the E.coli lysate of pDL121 with Freund's adjuvant into guinea pigs resulted in some protection of the animal against the challenge with strain 017. CONCLUSION: It indicated that 23 kDa protein had good imunogenicity and could serve as a candidate for protective antigen of L.interrogans and the inserted fragment of pDL121 could be a new gene .

This study was conducted to investigate the biomechannical properties of tissue-engineering cartilage. The compressive modulus of the collagen-chondrocyte constructs that had been cultured in vivo for 16 weeks and the centrifuge-tube-cultured cartilage in vitro were measured with 5% strain. The results showed that the compressive moduli of the centrifuge-tube-cultured cartilage at the 4th, 8th, 12th and 16th weeks were 0.352MPa, 0.653MPa,0.233MPa and 0.262MPa respectively. The top modulus among them was at the 8th week. The compressive modulus of the neocartilage engineered by the collagen-chondrocyte constructs in vivo for 16 weeks was 10.668 MPa and reached the same order of magnitude as human fetal articular cartilage, but it is still under that of the human fetal articular cartilage actually. The culture methods should be developed further though the dynamic alteration of the compressive modulus of the centrifuge-tube-cultured neocartilage is in accord with that of the GAG/DNA content ratio of the neocartilage.