Objective: To evaluate the elastic modulus of Beagle's periodontal ligament(PDL) by means of nanoindentation, and to help build constitutive model of PDL precisely. Methods: 24 cross sections were obtained from the tooth root of lower first molars of beagle dog. With nanoindentation, intrusion and unloading to PDL sites on different planes of long axial and in different directions on the same plane of tooth root were achieved, and the load-displacement curves were obtained, from which the elastic modulus was calculated and analyzed. Results: The elastic modulus of the beagle's periodontal ligament varied from 0. 452-1. 542 Mpa. There was no significant difference in elastic modulus of the beagle's lower first premolar PDL in relation to different planes of long axial, while significant difference was found in different directions (buccal/lingual sides and mesial/distal sides) on the same plane of tooth root(P＜ 0. 05). Conclusion: There was a difference in the elastic modulus of periodontal ligament in buccal/lingual sides and mesial/distal sides of the same tooth root.

Objective To systematically evaluate the relation between prognostic nutrition index (PNI) and prognosis of bladder cancer (BC) patients treated with radical cystectomy (RC). Methods We searched the literatures about the relation between PNI and the prognosis of patients treated with radical cystectomy published from the inception to January 30, 2021 in PubMed, Embase, Web of Science, CNKI, Wanfang, VIP and Chinese Medical Journal Database, and used RevMan5.3 software for Meta analysis. Results We included six literatures which comprise a total of 1273 patients. The results showed that there was a significant correlation between low PNI and OS of BC patients treated with RC (HR=2.0, 95%CI: 1.56-2.56), and there was a significant difference in RFS, PFS and DSS between low PNI and BC patients treated with RC (HR=1.93, 95%CI: 1.51-2.48). In the subgroup analysis, there were statistical differences in PNI and the prognosis of BC patients treated with RC between the Chinese group (HR=2.13, 95%CI: 1.62-2.81) and the Japanese group (HR=1.78, 95%CI: 1.08-2.94), and the PNI cutoff value had a good predictive effect on the prognosis of patients in the range of 46.08-51.30. Conclusion There is a significant relation between the level of PNI and OS of bladder cancer patients treated with radical cystectomy. Low PNI can be used as an effective marker to predict the prognosis of patients.