Objective:To investigate the risk factors of musculoskeletal disorders(MSDs)in dental postgraduates.Methods:271 dental postgraduates majoring in five different specialties(orthodontics,prosthodontics,endodontics,periodontics and alveolar surgery) with average (2.78 ±1 .57)years of clinical practice were recruited.254 age-matched non-dental postgraduates were served as the controls.The standardized Nordic questionnaire on MSDs and a self-report questionnaire regarding correlative factors were answered. Reliability of the responses was assessed by applying test-retest method.Results:The test-retest method revealed a high reliability of participants'answers with the intraclass correlation coefficient ranging from 0.89 to 0.96.Dental postgraduates had significantly higher incidence (85.6%)of MSDs than the controls(70.4%).In all included dental specialties,high prevalence of MSDs was reported at neck (47.5%-69.8%),followed by shoulders (50.8%-65.1 %),lowerback (27.1 %-51 .2%)and upper back (25.6%-46.5%).Meanwhile,the high prevalence of MSD varied in different specialties.Year of clinical work,clinical hours per week and desk hours per week were found to be the risk factors for MSDs,whereas physical exercise and rest were protective factors.Conclu-sion:MSDs with high prevelence and distinct specialty-related characteristics initiate at the early stage of dental career.Relevant measures to prevent and protect against MSDs should be taken during school-days.

Translationally controlled tumor protein (TCTP)is a small protein highly conserved in a variety of eukaryotic species.TCTP is overexpressed in various tumor cells and has been implicated in the regu-lation of cellular processes including apoptosis,DNA repair and drug resistance.By reviewing the recent pro-gress of TCTP research,TCTP is becoming an important regulator of DNA repair and a new molecular target for tumor therapy.

Objective To explore the effect of cellular inhibitor of apoptosis protein1 (cIAP-1) gene on the radiosensitivity of SMMC-7721 cells.Methods We silenced cIAP-1 expressions by the shRNA technology,and then we detected the changes of cell proliferation,cell cycle and cell apoptosis by CCK8 as-say,Western blot,qRT-PCR and flow cytometry after the radiotherapy.Results The cell proliferation rate of liver cancer SMMC-7721 cells at different radiation doses of 1 Gy,4 Gy,7 Gy and 10 Gy was detected.Comparing with control group (pGCsi-H1-control),the cell proliferation in cIAP-1 silencing group (pGCsiH1-shRNA) was significantly reduced at various radiation doses,and the effect was dose-dependent (P ＜ 0.05).G1/G0 phase arrest was observed after radiation (P ＜0.01),and the proportion of cells in S phase was significantly reduced compared with control (P ＜ 0.01).Compared with control group,G1/G0 phase arrest was detected (P ＜ 0.05),and the percentage of cell apoptosis was increased significantly in cIAP-1 silencing group (P ＜ 0.05).Conclusion cIAP-1 silencing can enhance the radiosensitivity of liver cancer cells,and inhibit cell proliferation by promoting the anti-tumor effect of radiation.

Objective To study the feasibility of DCE-MRI application in the orthotopic transplantation model of gastric cancer in nude mice.Methods Orthotopic transplantation model of gastric cancer in nude mice was established, and 15 models underwent DCE-MRI using the contrast agent of gadopentetate.Subsequently, the tumor was dissected in order to detect the MVD.The MVD was compared between orthotopic transplantation tumor model of gastric cancer and normal gastric mucosa.Results Fifteen nude mice with orthotopic transplantation of gastric cancer successfully underwent DCE-MRI examination.As for the cancer, the values of Ktrans, Kep and Ve were (2.11±0.44) min-1, (4.59±0.93) min-1, and 0.46±0.06, respectively.The MVD in gastric cancer tissues was significantly higher than that in normal gastric mucosa (χ2=16.205, P<0.001).Conclusion DCE-MRI can be used for noninvasively quantitative evaluation of vascular parameters of gastric carcinoma.

Objective To estimate heart function among patients with diabetic foot ulcer,and to investigate the characteristics of heart failure(HF) before and after treatment of ulcer. Methods Items associated with diabetes and some physiological and biochemical indicators were observed in patients with diabetic foot ulcer(162 cases) and with high risk factors of ulcer(75 cases). Heart function was evaluated at patients′ admission, during ulcer related treatment, and prior to discharge. Left ventricular ejection fraction and other cardiac assessment were measured with ultrasonic scan.Results During hospitalization, 23.6%(56/237) patients underwent HF with normal left ventricular ejection fraction, and it was 27.2%(44/162) in patients with foot ulcers. The prevalence of HF was 8.9%(21/237) in all patients studied on admission, and that was 10.5%(17/162) in patients with foot ulcer, more than that without foot ulcer(P＜0.01). More patients with HF were found, being 14.8%(35/237) during 2-7 days after ulcer related treatment initiated, and peak was on the 4th day. There was statistical difference among different Wagner grades(P＜0.05) about the morbidity rate of HF. All patients with HF were improved and tolerant to ulcer related treatment. Conclusion The prevalence of HF with normal left ventricular ejection fraction was relatively high in patients with diabetic foot ulcer, especially after ulcer treatment.

AIK is a novel cationic peptide with potential antitumor activity. In order to construct the AIK expression vector by Gateway technology, and establish an optimal expression and purification method for recombinant AIK, a set of primers containing AttB sites were designed and used to create the AttB-TEV-FLAG-AIR fusion gene by overlapping PCR. The resulting fusion gene was cloned into the donor vector pDONR223 by attB and attP mediated recombination (BP reaction), then, transferred into the destination vector pDESTl 5 by attL and attR mediated recombination (LR reaction). All the cloning was verified by both colony PCR and DNA sequencing. The BL21 F. coli transformed by the GST-AIR expression plasmid was used to express the GST-AIK fusion protein with IPTG induction and the induction conditions were optimized. GST-AIR fusion protein was purified by glutathione magnetic beads, followed by rTEV cleavage to remove GST tag and MTS assay to test the growth inhibition activity of the recombinant AIR on human leukemia HL-60 cells. We found that a high level of soluble expression of GST-AIK protein (more than 30% out of the total bacterial proteins) was achieved upon 0.1 mmol/L ITPG induction for 4 h at 37 °C in the transformed BL21 F. coli with starting OD₆₀₀ at 1.0. Through GST affinity purification and rTEV cleavage, the purity of the resulting recombinant AIK was greater than 95%. And the MTS assays on HL-60 cells confirmed that the recombinant AIK retains an antitumor activity at a level similar to the chemically synthesized AIK. Taken together, we have established a method for expression and purification of recombinant AIK with a potent activity against tumor cells, which will be beneficial for the large-scale production and application of recombinant AIK in the future.
Antimicrobial Cationic Peptides ; biosynthesis ; Antineoplastic Agents ; metabolism ; Escherichia coli ; metabolism ; Genetic Vectors ; HL-60 Cells ; Humans ; Polymerase Chain Reaction ; Recombinant Proteins ; biosynthesis ; Sequence Analysis, DNA

Objective To investigate the effect from circumferential distribution angle of forwards wedge vortex generators on aerodynamic drag reduction during flow around a cylinder, so as to provide theoretical evidences for low drag sprint garment design. Methods Forwards wedge vortex generators were reconstructed based on the NIKE’s AeroBalde. Given that the individual parts of an athlete body can be treated as multiple cylinders with varied dimensions and positions, 48 forwards wedge vortex generators were distributed as four columns on windward side of the cylinder, which were symmetrical with the YOZ plane. When the air flowed through the cylinder at the speed of 32 km/h, large eddy simulation was carried out on the computational domains which were properly meshed with polyhedral mesh to investigate the drag force, flow filed and pressure distributions. Results It was effective for drag reduction of the cylinder induced by airflow when two columns of forwards wedge vortex generators were circumferential distributed in the range of 55°-75°and the circumferential internal angle between two columns was in the range of 10° or 15°. The pressure distribution on leeward side of the cylinder was apparently changed after surface modification, which minimized the pressure drag dominant in aerodynamic drag. The drag reduction mechanism was that micro-vortices were generated downstream after flow through the forwards wedge vortex generators, which resulted in an early transition to critical flow with low drag force. Conclusions Effective aerodynamic drag reduction is achieved if forwards wedge vortex generators are properly distributed. The research findings can provide guidance for wind tunnel test and low drag sprint garment design.

Objective:To establish the normal values of water-perfused high resolution esophageal manometry (HREM)(GAP-36A) at resting period, water swallowing, semisolid swallowing and solid swallowing in Chinese population.Methods:From September 1, 2019 to June 30, 2020, 91 healthy volunteers receiving water-perfused HREM (GAP-36A) at resting period, water swallowing, semisolid swallowing and solid swallowing were selected from 9 hospitals (Union Hospital, Tongji Medical College, Huazhong University of Science and Technology; the First Affiliated Hospital of Dalian Medical University; the Second Hospital of Hebei Medical University; the Second Affiliated Hospital, Naval Medical University; the First Affiliated Hospital, Sun Yat-sen University; the First Affiliated Hospital, University of Science and Technology of China; Aviation General Hospital of China Medical University; the Affiliated Hospital of Medical School of Nanjing University and the First People′s Hospital of Yichang). Parameters included the position of the upper and lower edges of the upper esophageal sphincter (UES) and lower esophageal sphincter (LES), the length of the LES and UES, the position of the pressure inversion point (PIP), the resting pressure of UES and LES and swallow-related parameters such as the distal contraction integral (DCI), 4 s integrated relaxation pressure (IRP), distal latency (DL) and UES residual pressure. One-way analysis of variance, post-hoc test and sum rank test were used for statistical analysis.Results:A total of 87 healthy volunteers were enrolled, including 40 males and 47 females, aged (38.5±14.2) years old (ranged from 19 to 65 years old). The position of the upper and lower edges of the LES was (42.7±2.8) and (45.6±2.8) cm, respectively, the length of the LES was (2.9±0.4) cm, and the position of PIP was (43.3±2.8) cm. The position of the upper and lower edges of the UES was (18.1±3.0) and (22.6±2.0) cm, respectively, and the length of the UES was (4.8±1.0) cm. The resting pressure of LES and UES was (17.4±10.7) and (84.1±61.1) mmHg (1 mmHg=0.133 kPa), respectively. The DCI value at solid swallowing was higher than those at water swallowing and semisolid swallowing ((2 512.4±1 448.0) mmHg·s·cm vs. (2 183.2±1 441.2) and (2 150.8±1 244.8) mmHg·s·cm), and the differences were statistically significant ( t=-4.30 and -3.74, both P<0.001). The values of 4 s IRP at semisolid swallowing and solid swallowing were lower than that at water swallowing ((4.6±4.1) and (4.9±3.9) mmHg vs. (5.4±3.9) mmHg), and the differences were statistically significant ( t=3.38 and 2.09, P=0.001 and 0.037). The DL at water swallowing was shorter than those at semisolid swallowing and solid swallowing ((8.5±1.8) s vs. (9.8±2.2) and (10.6±2.8) s), and the DL at semisolid swallowing was shorter than that at solid swallowing, and the differences were statistically significant ( t=-10.21, -13.91 and -4.68, all P<0.001). The UES residual pressure at water swallowing was higher than those at semisolid swallowing and solid swallowing (9.5 mmHg, 6.5 to 12.3 mmHg vs. 8.0 mmHg, 4.5 to 11.7 mmHg and 5.5 mmHg, 2.0 to 9.3 mmHg), and the UES residual pressure at semisolid swallowing was higher than that at solid swallowing, and the differences were statistically significant ( t=3.48, 10.30 and 6.35, all P<0.001). Conclusions:The normal values of water-perfused HREM (GAP-36A) in Chinese population at resting period, water swallowing, semisolid swallowing and solid swallowing can provide a reference basis for clinical diagnosis and treatment for patients receiving water-perfused HREM examination.

Objective:To prepare hydroxyapatite(HA)coating on polyether ether ketone(PEEK)surface by magnetron sputtering technique and to study its biosafety.Methods:Sulfonated PEEK was used to increase the binding area and HA coating was constructed on it using magnetron sputtering technology.SEM and energy dispersive spectroscopy(EDAX)were used to detect the construction effect.Cell adhesion assay,cytoskeletal fluorescence staining and SEM validation were used to assess cytologrcal safety.In vivo safety tests were conducted in SD rats and golden hamsters.Results:HA coating with gradient morphology was successfully constructed on the PEEK surface using above technique.The coating promoted cell adhesion,extension and proliferation.No systemic toxicity and no sig-nificant influence in HE staining of the main infernal organs samples were observed.The coating alleviated the oral mucosal irritation caused by simple sulfonation to a certain extent.Conclusion:HA coating can be prepared stably with magnetron sputtering technology and can meet the biosafety needs for clinical applications.

Objective: To investigate the diagnosis, treatment and prognosis of nonodontogenic periapical lesions and to provide a reference for clinical diagnosis and treatment. Methods: A case of a patient with right upper molar pulp with apical penetration and local occlusion admitted to the West China Stomatological Hospital of Sichuan University was retrospectively analyzed, and the curative effect of microapical surgery and pith preservation was also analyzed. Results : The imaging features of tooth 16 showed periradicular radiolucency combined with local radiopaque lesions around the distal buccal apical area. Endodontic microsurgery was performed under local anesthesia. Soft tissue coverage was observed in the distal buccal apical area during the surgery, and no radiopaque tissue was detected. The distal buccal root apex was cut by 3 mm, and mineral trioxide aggregate was used for root-end backfilling. The postoperative pathological results revealed fibrous connective tissue. One-week recall X-ray examination showed tight root-end backfilling and no periradicular radiolucency; an electrical test of pulp vitality showed positive results. The four-year follow-up showed that there was no discoloration in tooth 16 and no significant difference in thermal and electrical tests of pulp vitality compared with control teeth. Combining the clinical manifestations, imaging features, surgical exploration results and pathological reports, the case was most likely to be cemental hypoplasia. Through the literature review, the treatment and healthy pulp preservation of such cases by endodontic microsurgery under the premise of preserving teeth has not been reported. Conclusion For maxillary posterior teeth with periapical lesions but healthy pulp, accurate estimation of pulp status, endodontic microsurgical exploration and application of bioactive materials can achieve vital pulp preservation while removing the lesions.