Objective:To establish a stable primary culture method of human gingival epithelial cells, with a higher successful rate and shorter culture time.Methods:Nine patients who received “crown-lengthening surgery”with relatively healthy periodontal conditions were selected (n =9).Gingival sam-ples were collected from the 9 donors during gingivectomy.Gingival epithelial cells were isolated and cul-tured by both an advanced enzyme digestion method and a tissue explant method.In the advanced enzyme digestion culture process,2.5 g/L DispaseⅡwas used to separate the epithelial tissue part from the con-nective tissue part,which lasted for one night.Then the epithelial tissues were digested by 0.025% tryp-sin without EDTA for 10 minutes,and centrifuged by keeping the digested epithelial tissues that re-mained.This advanced method not only decreased the concentration and digesting time of the two above-mentioned enzymes,but also simplified the centrifugel process.The tissue explant method was not changed too much compared with the original method.Growing processes of the primary cells cultured by the two methods were observed and recorded respectively,and indirect immunocytochemical staining was used to identify the type of cultured cells.At the same time,successful rates and cell culture time were also compared between the two methods.Results:Human gingival epithelial cells with typical morpholo-gy could be cultured within a shorter period by the advanced enzyme digestion method with a successful rate of 88.9%,and proliferated rapidly as sheets.After 10 -14 d cells could be passaged,gradually turned to be like fibroblasts when passaged to the third generation,and eventually went to apoptosis.The primary culture time was longer by using the tissue explant method,and approximately after 17 -22 d cells could be passaged,although the successful rate was the same as the enzyme digestion method.Cy-tokeratin staining was both positive by indirect immunocytochemical staining of cells.Conclusion:Pri-mary human gingival epithelial cells cultured by the advanced enzyme digestion method could grow faster and be passaged to the second generation successfully,which could supply a stable origin for cellular ex-periments.

Objective To compare the stress distributions on the anterior horn,body part and posterior horn of menisci between the normal and the injured knees with anterior cruciate ligament (ACL) deficiency using the three-dimensional finite element analysis.Methods A three-dimensional finite element model of tibiofemoral joint was created to simulate the motion states of the normal and ACL-deficiency knees at extension,as well as 15° and 30° flexions.Meanwhile,700N axial load and 134N posterior load were applied to the femur.Then,the stress on the anterior horn,body part and posterior horn of medial and lateral menisci were compared between the normal and ACL-deficient knees.Results With ACL deficiency,when stretching the knees straightly,the stress on the anterior horn of medial meniscus increased to 100.7％ of the normal knees,bigger than that of the affected lateral meniscus (30.7％).At 15° and 30° flexions,the stress on the posterior horn of the medial meniscus in ACL-deficiency knees increased by 36.4％ and 59.7％ respectively when compared to normal knees,while the stress on that of the lateral meniscus did not increase significantly.Apart from the stress on the body part of the lateral meniscus increasing by 39.5％ at extension in ACL-deficiency knees,no obvious changes were observed in the stress on the body part of the medial and lateral menisci.Conclusion ACL deficiency has different effect on the stress of different parts of the meniscus.It mainly increases the stress on the anterior horn of the medial meniscus at extension and that of the posterior horn of the medial meniscus at flexion.

Objective:To solve the problems in intensity-modulated radiation therapy (IMRT) planning, such as large labor cost and high dependence on the experience of physicists and great inconsistency in the quality of plan, and to discuss an unsupervised automatic treatment planning procedure of IMRT.Methods:The eclipse scripting application programming interface (ESAPI) within the Eclipse treatment planning system (TPS) 15.6 and optimization parameters tree search algorithm (OPTSA) were used to emulate and realize the whole planning process. Interacted with the TPS through ESAPI, relevant dosimetric parameters were input and output. The OPTSA evaluated the plan qualities based on dosimetric parameters of the targets and organs at risk (OARs) and iteratively adjusted the optimization objective parameters to achieve a progressively improving IMRT plan. In order to verify the effectiveness of the automatic planning, twenty historical rectum cancer cases were selected from the clinical database, and the dose distribution and specific dosimetric parameters were compared between the plans generated by the OPTSA and the manual plans under the same constraints.Results:All the auto plans have met clinical requirements. Furthermore, 90% and 10% of the auto plans were deemed as clinically improved and equally compared with the manual plans, respectively. The average CI for the PTV was 0.88 and 0.80 for the auto and manual plans respectively. Compared with the manual plans, the mean doses of all the OARs in the auto plans were reduced by 11% in average. The average elapsed time of automatic planning and manual planning was (28.15±3.61) and (36.7±4.6) min, respectively.Conclusions:The plans created by the proposed algorithm have been shown to be at least as good as the manual plans. In addition, this method can shorten the labor time in plan designing while ensuring the plan quality and consistency of the plan.

Objective:To investigate the performance of W2 plastic scintillator in megavolt photon and electron beams.Methods:The photon and electron beam energy provided by linear accelerator was used to collect data of the W2 scintillator. The parameters include the electrometer reading stability, W2 dose and dose rate linearity, and angular response. And the dose uncertainty of the W2 correction factors was also investigated.Results:The standard deviation of the electrometer reading stability was between 0.03 and 0.47. The linear regression factors of W2 dose were all 1.0; the maximum deviation of the dose rates was 0.61%. The Cerenkov light radiation correction factor(CLR) for 6 and 10 MV were 0.741 and 0.746, respectively, and the CLR for 6, 9, 12 and 15 MeV were 0.750, 0.753, 0.757 and 0.757, respectively. The maximum deviation of dose uncertainty for 15 MeV was 3.15%.Conclusions:The signal obtained by the blue and green channel was no angular dependence, the same as the high-energy electron beam, which verified that the Cerenkov radiation correction factor has good linearity. W2 plastic scintillator can be applied to non-coplanar radiotherapy dosimetry.

Objective To analyze the reasons why patients fail to come to a subsequent visit in outpatient service of Periodontal Department, Peking University School of Stomatology. Measures to reduce the failure rate were explored, so as to perfect the reservation service system. Methods A self-designed questionnaire was handed out to 165 patients who did come to a subsequent visit to the Department of Periodontology during July to December 2013, and 158 were valid. In this questionnaire, factors affecting the patients′ failure to subsequent visit were included, like convenience of registration, satisfaction of the treatment effects, doctors′service attitude and satisfaction of the nurses′ service. Results In our hospital, patients can get registered by queuing on the spot, making a reservation on the consultation desk, 114 telephone reservation and on-line reservation. 89. 23% of queuing registered patients recalled doctors on time, whereas 10. 77% failed to come. For patients who made their initial reservation by consulting the service desk or by 114 phone reservation, 75. 76% came as scheduled, whereas 24. 24% of them failed to come. High rate of failure to come was related to lack of targeted management. Conclusions Differences in ways of getting registered lead to differences in rate of patients′ missing the reservation. This rate can be effectively reduced by perfecting reservation procedure and targeted management.

Objective To investigate the influence of preoperative splenectomy on the prognosis after liver transplantation.Methods The retrospective cohort study was conducted.The clinical data of 95 patients who underwent liver transplantation in the Third Affiliated Hospital of Sun Yat-sen University between January 2004 and January 2014 were collected.Thirty-five patients undergoing preoperative splenectomy and pericardial devascularization and 60 undergoing spleen-preserving liver transplantation were allocated into the study group and control group,respectively.All patients received modified piggyback liver transplantation by the same team.Observation indicators:(1) intra-and post-operative situations;(2) follow-up and survival.The follow-up using telephone interview and outpatient examination was performed once every a week within 3 months postoperatively,once every one month within 6 months postoperatively and once every 3 months after 1 year postoperatively up to January 2016,including routine blood test,plasma-drug concentration of immunosuppressive agent and function of liver and kidney.Ultrasound and abdominal CT were used to monitor the long-term complication and survival.The measurement data with normal distribution were represented as (x)±s,and comparison between groups was done by the t test.Comparison of count data was done by the chi-square test.Results (1) Intra-and post-operative situations:all patients underwent successful liver transplantation.The operation time,volumes of intraoperative blood loss and blood transfusion were (483 ± 136) minutes,(5 683±2 950) mL,(4 887±3 682) mL in the study group and (392± 103)minutes,(3 522± 1 885)mL,(3 455±2 630)mL in the control group,respectively,with statistically significant differences between groups (t=3.683,4.358,2.202,P＜0.05).Six patients in the study group had intraoperative portal vein thrombosis (PVT),including 4 in level 1,1 in level 2 and 1 in level 3,and no patients in the control group,showing a statistically significant difference between groups (x2 =1.979,P＜0.05).Five patients with PVT in level 1 or 2 underwent thrombectomy and then end-to-end anastomosis of PV.One patient with PVT in level 1 had PVT recurrence and was cured by postoperative thrombolytic therapy.One patient with PVT in level 3 received PV reconstruction using artificial blood vessels,and had PVT recurrence and then was cured.There was no PV stenosis between groups.The levels of platelet at 1,3 and 7 days postoperatively were (75±60)× 109/L,(71± 45)×109/L,(111±73)×109/L in the study group and (57±32) ×109/L,(52±46) ×109/L,(87±53)×109/L in the control group,respectively,with statistically significant difference between groups (t =1.909,1.957,1.848,P＜ 0.05).The levels of platelet at 14 and 30 days postoperatively were respectively (230± 152)× 109/L,(310± 140)× 109/L in the study group and (193± 125)× 109/L,(286±62)× 109/L in the control group,with no statistically significant difference between groups (t=1.284,1.199,P＞0.05).The cases with postoperative infection,acute rejection,new-onset PVT in level 1-2 and 3-4 and PV stenosis were respectively 23,0,2,0,2 in the study group and 35,1,2,0,1 in the control group,with no statistically significant difference between groups (x2 =1.171,0.590,0.547,1.184,P＞0.05).Patients with postoperative infection and acute rejection were improved by symptomatic treatment.Two patients in the study group with PVT underwent anticoagulant and thrombolytic therapy,including 1 receiving interventional thrombectomy therapy.Two patients in the control group with new-onset PVT were cured by anticoagulant and thrombolytic therapy.Three patients with PV stenosis underwent percutaneous transhepatic portography (PTA) for balloon dilation,including 1 in the study group with good improvement after stent implantation.(2) Follow-up and survival:95 patients were followed up for 3-24 months,with an average time of 18 months.During the follow-up,the rate of chronic rejection in study and control groups was 5.7％(2/35) and 5.0％(3/60),showing no statistically significant difference between groups (x2 =0.023,P＞0.05).The 1-and 2-year accumulative survival rates were respectively 91.4％ (32/35),82.9％ (29/35) in the study group and 93.3％ (56/60),76.7％(46/60) in the control group,with no statistically significant difference between groups (x2 =0.780,P＞0.05).Conclusion The splenectomy before liver transplantation is easy to form PVT,increase time and difficulty of transplantation surgery,however,it doesn't increase complication risk after transplantation and affect postoperative survival.

Objective To investigate the anatomical classification of left intrahepatic bile duct (LHD) and the pattern of bile duct reconstruction during pediatric split liver transplantation and their relationship with postoperative biliary complications. Methods Clinical data of 75 pediatric recipients undergoing split liver transplantation were analyzed retrospectively. Before splitting the donor liver, iopromide injection was used for retrograde cholangiography through the common bile duct. According to the patterns of intrahepatic bile ducts in the second, third and fourth segments, the anatomical classification of LHD of the donor liver was determined. The biliary reconstruction regimens for different classification types of LHD were summarized. The incidence and treatment of biliary complications after pediatric split liver transplantation were analyzed. Results Among 75 donor livers, the anatomical classification of LHD included 57 cases (76%) of type Ⅰ, 9 cases (12%) of type Ⅱ, 4 cases (5%) of type Ⅲ and 5 cases (7%) of type Ⅳ LHD, respectively. Among 75 pediatric recipients, 69 cases (53 cases of type Ⅰ, 8 type Ⅱ, 4 type Ⅲ and 4 type Ⅳ) underwent the left hepatic duct-jejunum Roux-en-Y anastomosis, 1 case received common bile duct-jejunum Roux-en-Y anastomosis (type Ⅳ), and 5 cases underwent the left hepatic duct-common bile duct end-to-end anastomosis (4 cases of type Ⅰ and 1 type Ⅱ). Postoperative biliary complications occurred in 6 cases (8%), including 3 cases of biliary anastomotic stenosis, 2 cases of biliary anastomotic leakage and 1 case of bile leakage on the hepatic resection surface. Among 6 recipients, 4 cases were classified as type Ⅰ and 2 cases of type Ⅲ LHD. No significant difference was observed in the incidence of biliary complications between typical type and anatomical variant type of LHD (all P > 0.05). Among 3 recipients with biliary anastomotic stenosis, 2 cases underwent percutaneous transhepatic cholangial and drainage (PTCD) and 1 case repeatedly received biliary-intestinal anastomosis. Two cases of biliary anastomotic leakage underwent PTCD and 1 case of bile leakage on the hepatic resection surface received local drainage. All 6 children survived after treatment. Conclusions Anatomical variation of LHD can be observed in 24% of donor livers, and type Ⅱ accounts for the highest proportion of 12%. Prior to donor liver splitting, routine cholangiography and fine biliary anastomosis may effectively lower the incidence of biliary complications. The incidence of postoperative biliary complications is not significantly associated with the anatomical classification of LHD.

Objective:To assess the three-dimensional dose distribution in radiotherapy plans using the structural similarity index(SSIM), compare the performance of SSIM with commonly used quality assessment indices, and develop a SSIM-based quality assessment method of multiple prescribed doses.Methods:The SSIM was introduced to providea quality score of various voxels by comparing actual and ideal three-dimensional dose data and combining the spatial location information of the voxels. Then the average value in a region of interest (ROI) was calculated as the quality score of the region. Fifty-three cases of cervical cancer were selected to analyze the correlation of the SSIM with the uniformity index (HI), conformity index (CI) of the dose distribution in various ROIs and to explore the capability of the SSIM to reflect the uniformity and conformity of dose distribution.Two types of quality defects were individually introduced into two of 53 radiotherapy plans. Then the two plans were compared with normal plans to characterize the response of the SSIM.Results:There was no correlation between HI and SSIM in positive lymph nodes(PGTVnd) due to the decrease in the HI sensitivity, while there was a significant negative correlation between them in regions where PGTVnd was removed from the planning target volume(PTV, R=-0.86, P<0.01). Meanwhile, there was a significant positive correlation between CI and SSIM in PGTVnd ( R=0.83, P<0.01). Therefore, the SSIM can be used to identify the artificial design defects in plans by determining abnormal dose gradients. Conclusions:Apart from reducing the defects of previous assessment parameters, the SSIM has the capability to assess the quality of radiotherapy plans by combining the uniformity and conformity of dose distribution and can provide accurate feedback on the spatial locations of quality defects.

Objective:To develope an automatic volumetric modulated arc therapy (VMAT) planning for rectal cancer based on a dose-prediction model for organs at risk(OARs) and an iterative optimization algorithm for objective parameter optimization.Methods:Totally 165 VMAT plans of rectal cancer patients treated in Peking University Cancer Hospital & Institute from June 2018 to January 2021 were selected to establish automatic VMAT planning. Among them, 145 cases were used for training the deep-learning model and 20 for evaluating the feasibility of the model by comparing the automatic planning with manual plans. The deep learning model was used to predict the essential dose-volume histogram (DVH) index as initial objective parameters(IOPs) and the iterative optimization algorithm can automatically modify the objective parameters according to the result of protocol-based automatic iterative optimization(PBAIO). With the predicted IOPs, the automatic planning model based on the iterative optimization algorithm was achieved using a program mable interface.Results:The IOPs of OARs of 20 cases were effectively predicted using the deep learning model, with no significantly statistical difference in the conformity index(CI) for planning target volume(PTV)and planning gross tumor volume(PGTV)between automatic and manual plans( P>0.05). The homogeneity index (HI) of PGTV in automatic and manual plans was 0.06 and 0.05, respectively( t=-6.92, P< 0.05). Compared with manual plans, the automatic plans significantly decreased the V30 for urinary bladder by 2.7% and decreased the V20 for femoral head sand auxiliary structure(avoidance)by 8.37% and 15.95%, respectively ( t=5.65, 11.24, P< 0.05). Meanwhile, the average doses to bladder, femoral heads, and avoidance decreased by 1.91, 4.01, and 3.88 Gy, respectively( t=9.29, 2.80, 10.23, P< 0.05) using the automatic plans. The time of automatic VMAT planning was (71.49±25.48)min in 20 cases. Conclusions:The proposed automatic planning based on dose prediction and an iterative optimization algorithm is feasible and has great potential for sparing OARs and improving the utilization rate of clinical resources.

Objective To study the application of laser speckle contrast algorithm in high-frequency ultrasound blood flow imaging. Methods The laser speckle contrast algorithm was extended to the field of high-frequency ultrasound blood flow imaging. The high-frequency ultrasound structure images were processed by using the classic laser speckle temporal contrast algorithm to suppress the static tissue signals, enhance the dynamic blood flow signals, and obtain the high-frequency ultrasound blood flow images. The simulation experiments on flow phantoms were conducted to verify the effectiveness of the algorithm, and then human skin tissue in vivo experiments were performed to verify the applicability of the algorithm. The performances of blood flow images which obtained from ultrasound structure images with different frames by laser speckle contrast algorithm were compared and analyzed. Results The blood flow information in a tube was clearly visible in the flow phantoms experiments. The static skin tissue signals were significantly suppressed, dynamic blood flow signals were strengthened in the human skin tissue in vivo experiments, and high-frequency ultrasound blood flow images were obtained. By comparing and analyzing the performances of blood flow images, the results showed that the best blood flow images could be obtained when the number of frame was set to 10 frames. Conclusions The speckle contrast algorithm is feasible and has good application prospects in high-frequency ultrasound blood flow imaging.