Objective To evaluate the reliability of colony PCR in identifying the recombinant clones selected from phage antibody libraries. Methods The digested pComb3 vector and Lc fragments, Lc library plasmid, and Fd fragments were ligated successively. The ligation product was transformed into Escherichia Coli strain XL 1-blue bacilli by electroporation and thus murine Fab phage antibody library was constructed.The transformed recombinant clones selected randomly from libraries were identified simultaneously by colony PCR, plasmid PCR and restriction enzyme digestion. The identification consistency was analyzed. The interference was excluded by control PCR using the relevant constituents as template. Results The educed library content of Lc library was 1.175?10 6 CFU and the content of Fab antibody library was 1.02?10 6 CFU. Different recombinant percentages were obtained through three different identification methods (the Lc positive recombinant percentages by colony PCR, plasmid PCR and enzyme digestion were 100%, 78% and 78%, respectively; the Fd positive recombinant percentages by three methods were 90%, 66% and 66%, respectively; the dual positive recombinant (Fd and Lc insert simultaneously) percentages by three methods were 90%, 50% and 50%, respectively). A high frequency of false-positives appeared in colony PCR identification. Nonspecific amplification of control PCR was presumably induced by some intracellular components in XL 1-blue bacilli. Conclusion The identification of the recombinant clones selected from phage antibody libraries by colony PCR remains ambiguous. So it is our assertion that the traditional identification methods such as plasmid PCR or enzyme digestion are more accurate and will less false positive results.

Objective: To clone Fd and light chain genes of monoclonal antibody HAb18 against human hepatoma and verify their accuracy and liability. Methods: Total RNA was extracted from hybridoma cell line secreting MAb HAb18, and Fd and light chain genes were amplified by RT-PCR. After PCR products were ligated into pMD18T vector, positive clones were screened and DNA sequences were tested and analysed by relative softwares. Then, light chain and Fd genes were sequential cloned into phage display vector pComb3. After recombinant vector was transformed into E.coli XL1-blue, recombinant vector was rescued by helper phage M13K07 and the specificity of phages to antigen was detected by indirect ELISA. Results: The size of amplified Fd and light chain genes was separately 665 bp and 668 bp. The results of sequence analysis showed that both VL and VH contained 2 characteristic cystines and CH1 was IgG1 classes and CL was ?. ELISA result identified that expressed Fab antibody could specially bind to corresponding antigen. Conclusion: Fd and light chain genes of MAb HAb18 were successfully cloned, which lay a good foundation for constructing a diversity of engineering antibody.

A foot trajectory control method is proposed for biomimetic robot.Compared with traditional methods,the method uses a single CPG neuron to directly apply the foot trajectory generated by the oscillator to the hexapod robot.The joint angles is solved reversely for realizing the rhythmic foot swing,thereby achieving lateral walking.The step distance and step amplitude in foot trajectory,and the forward and backward swing trajectories during the swing phase can be adjusted by setting the load factor,period,amplitude and other parameters in the CPG oscillator.The feasibility of applying the improved Hopf model to foot trajectory is verified through the joint simulation using Matlab and Coppeliasim.Compared with traditional methods,the improved model has high flexibility in parameter adjustment and performs well in concurrency processing.

Biological central pattern generator(CPG)is of great research significance to the gait control for hexapod robot.Therefore,a Kimura neural oscillator based CPG gait control strategy for hexapod robot is proposed.The mechanical structure of hexapod robot is designed with the spider as the bionic object,and its kinematics is solved.An oscillator model is established based on Kimura neural oscillator,and its parameters are adjusted.The CPG network model is designed according to the phase relation of the 6 legs of the robot.Gait experiments are conducted with computer simulation tools and prototypes.The results demonstrate that the output signal amplitude and phase difference of the CPG network model generated based on Kimura neural oscillator are stable,meeting the gait control requirements of hexapod robot.The study provides a feasible gait control strategy for hexapod robot.

Objective To assess the clinical curative effect of accordion technique in the treatment of tibial delayed union or nonunion.Methods From February 2016 to December 2017,data of 11 patients with tibial delayed union (n=8) or non-union (n=3) who had been treated by accordion technique with an Ilizarov ring external fixator were retrospectively analyzed.10 males and 1 female were included in our study,with an average age of 41.9 years (range,21-63 years).There were 5 cases of docking site delayed union after Ilizarov transport for chronic tibial osteomyelitis.There were 3 cases of fracture site delayed union after external fixation for open tibia comminuted fracture.There were 3 cases of nonunion after tibia closed fracture,including 2 cases who had hybrid external fixation treatment,and 1 case who had conservative treatment.All the cases received accordion technique using Ilizarov ring external fixators.First,gradual compression at the fracture site was conducted until the bony contact was seen on a radiograph.After bony contact,compression was continued at a rate of 0.85 mm/d for a week,followed by distraction of 0.85 mm/d for 2-3 weeks.Afterward,a second compression was conducted using same rate and time with the distraction procedure.And there was a 7-day latent period between compression and distraction.One or two cycles of compression-distraction were needed before union was present radiographically.Results Bony union was obtained in all 11 patients after a mean time of 5.4 months (from 3 to 9 months).The mean follow-up for the 11 patients was 15.2 months (from 11 to 29 months).The mean duration of the accordion technique treatment was 50.2 d (range,35-67 d).The accordion technique was used 1 time for 8 patients,and 2 times for 3 patients.The mean duration of bone consolidation was 114.9 d (range,64-239 d).According to Paley evaluation criteria,osseous results were excellent in 8 cases,good in 3 cases,with a good to excellent rate of 100％(11/11);functional results were excellent in 7 cases,and good in 4 cases,with a good to excellent rate of 100％(11/11).Conclusion The accordion technique is a minimal invasive,safe and reliable treatment program for tibial delayed union or nonunion.

Objective:To investigate the effect of lateral tibial periosteum distraction on diabetic foot and vasculitis foot.Methods:A retrospective analysis of 13 patients (16 feet) who received lateral tibial periosteal distraction between June 2019 and May 2020 were included in the study. 9 males and 4 females; aged 39-77 years (average 66 years); left foot 7 cases, right foot 9 cases. 5 cases were patients with diabetic foot, 1 case was diabetic foot with arteriosclerosis obliterans, 2 cases were thromboembolic vasculitis, and 5 cases were arteriosclerosis obliterans. The tibial periosteum was dissected and a distraction device was placed. In the 3 patients with foot ulcers, tibial periosteum distraction devices were placed on the severer side. The periosteal distraction began on the third day after surgery, about 0.75 mm/d, the adjustment was done usually in two weeks. Two weeks later, the stretch plate was removed surgically. The followings were evaluated: visual analogue scale (VAS) pain score, foot peripheral oxygen saturation, foot capillary filling test, lower extremity arterial CT angiography (CTA), etc.Results:All 13 patients were followed up for 2-12 weeks, with an average of 3.85 weeks. VAS pain score: the average pain score of 13 patients with preoperative foot pain was 5.31±1.84 (range, 2-9) points, and 2 weeks after surgery, the average value was 2.46±1.39 (range, 1-6) points with statistical significance ( t=6.124, P<0.001) ; peripheral foot oxygen saturation: the average preoperative blood oxygen saturation of 12 patients was 87.83%±14.83% (range, 50%-98%), 1 patient was not detected before surgery, and 2 weeks after operation, the average blood oxygen saturation was 92.33%±7.91% (range, 75%-99%). There was no significant difference between them ( t=1.124, P=0.285). The foot skin temperature of 10 patients was 35.68±0.85 ℃ (range, 34.00-36.60 ℃) before surgery and 36.23±0.46 ℃ (range, 35.50-36.90 ℃) after surgery, and the difference was statistically significant ( t=3.197, P=0.008) . Capillary filling test: 2 weeks after operation, the capillary filling response was significantly improved. All 13 patients had improved CTA of both lower extremity arteries before operation, and 11 patients had CTA taken back after two weeks of operation. Compared with preoperative CTA, new vascular network was found in the operation limb. In addition to 1 patient with thromboangiitis obliterans (mainly suffering from foot pain, no wound symptoms), 2 of 12 patients with heart failure, renal failure and other basic diseases did not heal, and the wounds of the other 10 patients had improved significantly 1 month later. Conclusion:Lateral tibia periosteum distraction can be used to treat chronic ischemic diseases of lower extremities with satisfactory postoperative results.