Objective:To compare the difference of LLD (leg length discrepancy) between robot-assisted and conventional methods of total hip arthroplasty (THA).Methods:Data of 38 patients who had THA performed by robot-assisted or conventional methods from January 2019 to May 2020 were retrospectively analyzed. There were 38 cases (54 hips) in robot-assisted THA group (robot group) with 18 males and 20 females (age 53.5±13.6 years, BMI 26.2±3.4 kg/m 2), and there were 21 cases (32 hips) with osteonecrosis of the femoral head, 17 cases (22 hips) with Crown typeⅠandⅡdevelopmental dysplasia of the hip. There were 38 cases (54 hips) in conventional THA group (conventional group), with 19 males and 19 females, (age 52.3±14.7 years old, BMI 25.7±2.9 kg/m 2), and there were 19 cases (30 hips) with developmental dysplasia of the hip, and 19 cases (24 hips) with osteonecrosis of the femoral head. The operative time, postoperative LLD, Harris score, forgotten joint score-12 (FJS-12) and the difference between preoperative and postoperative LLD between the two groups were compared, and the correlation between surgical methods and the change of hip length was also evaluated. Results:The operation time of the robot group was 73.3±14.1 min and which was 59.3±12.6 min in conventional THA group ( t=2.732, P=0.003). In the robot group, the postoperative LLD was 2.3±3.4 mm, which was less than that of the conventional group 6.7±5.4 mm ( t=3.521, P < 0.001). When the absolute value of LLD was larger than 5 mm as an abnormal value, it was 2.6% (1/38) in the robot group and 47.3% (18/38) in the conventional group. The difference of hip length (HL) in planning and post-operation in the robot group was 2.8±2.2 mm, which was smaller than that in the conventional THA group 7.9±5.3 mm ( t=2.357, P < 0.001). In addition, there was a correlation between the change of hip length results and the postoperative measurement of hip length in the robot group ( r=0.983, P < 0.001). At the last follow-up, Harris score and FJS-12 were recorded in the robot group and coventional group. The scores were 83.1±5.3 and 32.5±4.9 respectively in the robot group, 82.9±7.2 and 31.9±6.7 in the conventional group, respectively. There was no significant difference between the two groups ( t=0.221, 0.356; P=0.819, 0.731). Postoperative bleeding occurred in 1 case in the robot group with postoperative suture healed well. The fracture of the posterior wall of the acetabulum was found in the conventional group and the patient avoids weight bearing 4 weeks after operation. The postoperative recovery was good and no other related complications were found. Conclusion:Robot-assisted THA can accurately restore the length of both legs and reduce LLD compared with conventional THA. The real-time monitoring of LLD during robot operation can give the operator an accurate reference.

Objective To construct the prokaryotic expression vector of human autophagy-related LC3B gene,obtain the GST-LC3B recombinant plasmid , purify the GST-LC3B fusion protein and identify its activity in vitro.Methods Human LC3B coding region was amplified from the human mammary gland cDNA by PCR and inserted into the prokaryotic expres -sion vector pGEX-KG.The recombinant plasmid pGEX-KG-LC3B was transformed into E.coli Rossate.The expressed product was purified by GST-Sepharose 4B beads and identified by SDS-PAGE and Western blot analysis .The function of the purified protein GST-LC3B was detected by GST pull-down assay.Results About 400 bp of the LC3B coding region was successfully amplified from the mammary gland library by PCR and inserted into pGEX -KG.The result of double diges-tion and sequencing showed that the GST-LC3B recombinant plasmid was successfully obtained .The GST-LC3B fusion pro-tein of about 40 000 (Mr) was successfully purified and identified by SDS-PAGE and Western blotting analysis.GST pull-down assay showed that GST-LC3B could interact with Atg4B, which identified its known function .Conclusion The pro-karyotic expression vector of GST-LC3B is constructed successfully , which will facilitate further research on the function of LC3B in autophagy.

Objective To construct the eukaryotic expression vector of cyclin-dependent kinase ( CDK) 7 labeled with Myc tag, obtain the expressed product , and identify its interaction with FLAG-P53 at the protein level .Methods Human CDK7 coding gene region amplified from the mammary cDNA library by PCR was inserted into the pXJ -40 vector.The recombinant plasmid Myc-CDK7 transfected into human 293T cell lines was investigated and examined by SDS-PAGE and Western blotting.In addition,assay was applied to determine the interaction between Myc-CDK7 and FLAG-p53.Results The coding region of CDK7 was successfully amplified by PCR and cloned into pXJ-40 vector, which was identified by double enzyme digestion and gene sequencing .Myc-CDK7 was successfully expressed in human 293T cell lines according to SDS-PAGE and Western blotting assay indicated that Myc-CDK7 could interact with P53 protein, which verified its known function .Conclusion The eukaryotic expression vector Myc-CDK7 is successfully obtained , which will contribute to further research on CDK 7-mediated cell cycle regulation .