| Cementum is a highly reactivity mineralized tissue. It is the important physiological structure contributing to the attachment between periodontal ligaments and teeth, also the stabilization of the teeth in the alveolar cavity, supporting and transferring the occlusal forces. The periapical and periodontal diseases are usually with different degrees of cementum lesion. The restore of the periapical diseases includes the inflammation controlling and the rebuilding of the periapical bone, periodontal ligaments and cementum. The regeneration of the periodontal tissue needs the formation of the new connective tissue and alveolar bone, but the most important is the re-attachment between the connective tissue and the surface of the teeth roots. Cementum is just the key structure of the re-attachment above. The researches in recent years have revealed that the cementum attachment protein (CAP) playedimportant roles during the processes of the cementum regeneration, aggradation, and the formation of the attachment between the perio -dontal ligaments and the surface of the teeth roots. Nowadays, the researches on the CAP are focusing in its biological effects on the attachment, spreading and the mitosis activity of the perio -dontal ligament cells, gingival fibroblasts and the alveolar bone cells. In this study, we evaluated the simpler method of isolation and purification of the CAP, also we determined the biological activity of the bovine CAP we obtained. Then we analysed the N-terminal amino acid sequence of the bovine CAP by the Edman method and the degenerate primers were desidned and synthesized based on the fifteen N-terminal amino acid sequence of the bovine CAP, we carried out a polit study on the cDNA infor -mation of the bovine CAP by RT-PCR and degenerate-PCR, it provided some theoretic data to the recombination and expression of the CAP. At the same time, we studied the biological effects of the CAP on the human dental follicle cells in vitro, enhanced the understanding of the CAP. Our study established the foundation to the further researches on the structure and fuctions of the CAP, also our study contributed to the new methods of the treatments to periapical and periodontal diseases, the improvements on surfaces of the implants, and the reimplantation teeth. This paper includes following three parts: 1. Isolation,purification and identification of the bovine CAP The teeth were collected from the two-year-old calves immediately after slaughter, root surfaces were cleaned of adhering connective tissue, and cementum was harvested with a curette. The cementum was extracted in acetic acid containing proteinase inhibitors then with guanidine HC1. After dialysis and ultrafiltration centrifuga-tion, the protein content of the two extracts were assayed by sodium dodecyl sulfide-polyacrylamide gel electrophoresis (SDS-PAGE), protein band of the guanidine extract migrating with Mr55,000 was excised with clean razor blades. CAP was obtained after elution with isopropanol and concentrated with tri-chlorine acetic acid, and then lyophilized. The SDS-PAGE and the isoelectric focusing electrophoresis of the purified bovine CAP resulted in the single bands. The isoelectric point of the bovine CAP was between 7.35 and 8.15.In order to determine the purity of the bovine CAP, peptide mass spectrometry analysis and PSl protein database search was estimat -ed. As the results, the molecular weight of the bovine CAP was Mr5 5,261, the purity of CAP was above 95%, and no protein in the PS1 protein database matched the CAP completely.The attachment activity of the CAP to the human periodontal ligament cells (HPDLC) was evaluated by the MTT and solid -phase binding assay. The CAP we obtained promoted the HPDLC attachment obviously, but the activity was not in a concentration -dependent manner. Optimal attachment occurred at 1.0-2.5mg/L concentration, the peak attachment occurred at 2.5mg/L concentra -tion, at 5.0mg/L concentration, the attachment droped. The results of this assay was similar to the previous study, it meane...
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