BACKGROUND:Mesenchymal stem cell-derived exosomes may play a crucial role in tissue damage repair,and miRNA is an important component of exosomes for therapeutic effects.Among them,miR-29b-3p has the effect of reducing cell apoptosis,promoting axonal regeneration,and angiogenesis. OBJECTIVE:To study the protective effect of adipose-derived mesenchymal stem cell-derived exosome via miR-29b-3p on a neural cell injury model simulated by H2O2-treated PC12 cells,and explore the relevant mechanisms. METHODS:(1)First,the collagenase digestion method was used to extract rat adipose-derived mesenchymal stem cells.Adipose-derived mesenchymal stem cells were transfected with miR-29b-3p mimics and inhibitors.Exosomes were extracted from the culture supernatant by ultracentrifugation and identified so as to construct adipose-derived mesenchymal stem cell-derived exosomes with high expression and knockdown miR-29b-3p.(2)By constructing a neural cell injury model simulated by PC12 cells treated with H2O2,the relevant mechanisms of the protective effect of adipose-derived mesenchymal stem cell-derived exosome via miR-29b-3p on the simulated neuronal cell injury model were studied. RESULTS AND CONCLUSION:(1)Adipose-derived mesenchymal stem cell-derived exosome had a typical cup-shaped shape and a diameter distribution in the range of 50-140 nm,expressed membrane proteins Alix,CD63,and TSG101,which were specific markers on the surface of exosomes,and could be successfully ingested by PC12 cells.(2)Adipose-derived mesenchymal stem cell-derived exosome pretreatment could reduce cell apoptosis induced by H2O2 treatment in PC12 cells,and this protective effect was enhanced with the increase of miR-29b-3p expression in the exosomes and weakened with the decrease of miR-29b-3p expression in the exosomes.The mechanism of its effect was related to adipose-derived mesenchymal stem cell-derived exosome via miR-29b-3p promoting the expression of anti-apoptotic protein Bcl-2 and inhibiting the expression of apoptotic protein Bax.

Objective:To investigate the occurrence rate and distribution pattern of three-rooted mandibular molars in children using CBCT.Methods:CBCT images of 206 children aged 4-11 years were retrospectively analyzed.The root numbers of the bilateral man-dibular first and second deciduous molars,and the permanent mandibular first molars were recorded.A chi-square test was used to de-tect the gender and side difference.Spearman correlation test was used to analyze the relation between the bilateral homologous teeth and the mandibular first and second deciduous molars on each side.Results:The occurrence rate of three-rooted mandibular first and second deciduous molars and mandibular permanent first molars was 10.9％(19/175),25.1％(46/183)and 28.4％(57/201)for individuals,respectively(x2=18.543,P＜0.01),and 8.7％(32/366),19.0％(73/384)and 23.6％(95/402)for teeth(x2=30.692,P＜0.01),re-spectively.Gender difference was not detected for each tooth type(all P＞0.05),while side differences were detected in mandibular sec-ond deciduous molars and the frequency of three-rooted molar on the right and left side was 23.7％and 14.2％(P＜0.05),respectively.The concurrence rate of bilateral three-rooted mandibular deciduous first and second molars and mandibular permanent first molars was 57.9％(11/19),47.8％(22/46)and 66.7％(38/57),respectively,and the rho was 0.710,0.597 and 0.745,respectively(all P＜0.01);between the three-rooted deciduous first and second molars on the left side,rho=0.188(P＜0.05)and on the right side,rho=0.304(P＜0.01).Conclusion:The occurrence rate of three-rooted mandibular molars in children increases in the following sequence:first deciduous molars＜second deciduous molars＜first permanent molars.They frequently occur bilaterally and exhibit a moderate to high degree of correlation.However,the correlation was very weak between the mandibular deciduous first and second molars.

Objective To compare the root resorption of posterior teeth between fixed orthodontic appliances and clear aligners in adult patients with skeletal Class Ⅲ malocclusion undergoing camouflage treatment by using cone-beam computed tomography(CBCT)measurements.Methods Thirty-two cases of skeletal Class Ⅲ malocclusion patients who had previously undergone camouflage treat-ment were retrospectively selected.Based on the type of orthodontic appliance used,they were divided into two groups(the fixed appli-ance group and the clear aligner group),each comprising 16 cases.CBCT images of the entire dental arch before and after treatment were collected for these patients,and three-dimensional reconstructions of the mandibular central incisors,first premolars,and first molars were generated using Mimics software.Changes in root volume and length of mandibular teeth before and after treatment were measured and compared between the two groups.Results Both groups showed significant reductions in measured root volume of the teeth after orthodontic treatment(P＜0.05).In the clear aligner group,the mean reduction in root length of mandibular central incisors was(0.52±0.60)mm,while in the fixed appliance group,the reduction in root length of mandibular central incisors and first premolars was(0.47±0.38)mm and(0.38±0.25)mm,respectively.These differences were statistically significant(P＜0.05).Except for the sig-nificantly lower reduction in root volume of mandibular central incisors in the clear aligner group compared to the fixed appliance group(P＜0.05),there were no statistically significant differences in other root resorption-related parameters between the two groups(P＞0.05).Conclusion In camouflage treatment of adult skeletal Class Ⅲ malocclusion patients,clear aligners can reduce the amount of root resorption in mandibular anterior teeth to a certain extent compared to fixed orthodontic appliances.However,there is no significant difference between the two appliances in the posterior teeth region.

Objective:To investigate the effects of fluoride exposure on proliferation, apoptosis and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in mice.Methods:BMSCs were isolated and cultured from femur bone marrow of C57BL/6 mice (6 - 8 weeks). The cells in passage 3 were used to detect the surface markers of stem cells by flow cytometry. The cells were cultured in media with a final fluoride concentration of 0.0, 0.1, 1.0, 5.0, 10.0, 15.0, 20.0 and 40.0 mg/L, respectively. The effects of different fluoride concentrations on BMSCs cell proliferation (CCK8 method), apoptosis (flow cytometry analysis), osteogenic differentiation ability [alizarin red and alkaline phosphatase (ALP) staining] were detected. Western blot was applied to detect the levels of apoptosis-related proteins [poly ADP-ribose polymerase (PARP)], mitogen-activated protein kinase (MAPK) pathway member proteins [extracellular regulated protein kinase 1/2 (ERK1/2), c-Jun amino-terminal kinase (JNK), p38 and phosphorylated ERK, JNK, p38 (p-ERK, p-JNK, p-p38)], osteogenic differentiation-related protein [Runt-related transcription factor 2 (Runx2), ALP] and Wnt/β-catenin pathway member proteins [glycogen synthase kinase-3β (GSK3β), phosphorylated GSK3β (p-GSK3β) and β-catenin]. Immunocytofluorescense staining was applied to evaluate the expression levels of p-GSK3β and β-catenin. The two pathways (MAPK and Wnt/β-catenin) were blocked by SP600125 and DKK-1, respectively, to testify their involvement in mechanisms of apoptosis and osteogenic differentiation.Results:The mouse BMSCs were successfully isolated and cultured. Flow cytometry analysis showed that the mesenchymal stem cell surface biomarkers (CD73, CD90 and CD105) were positively expressed. The comparison of cell proliferation at three time points (24, 48 and 72 h) in each concentration group was statistically significant ( F = 65.36, 160.04 and 365.32, P < 0.001), and the comparison of early apoptosis (24 h) in each concentration group was statistically significant ( F = 214.04, P < 0.001); compared with the 0.0 mg/L group, the cell proliferation in 15.0, 20.0 and 40.0 mg/L groups decreased, and the early apoptosis rate in 10.0, 15.0 and 20.0 mg/L groups increased ( P < 0.05). When cells were treated with 15.0 mg/L fluoride for 0 - 24 h, the p-JNK/JNK ratio was higher at 2, 4, 8, 12, 18 and 24 h compared with that at 0 min ( P < 0.05); compared with the fluoride group (15.0 mg/L), the early apoptosis rate of cells after SP600125 block decreased ( P < 0.05), and the protein expression levels of PARP and p-JNK decreased ( P < 0.05). After osteogenic induction, compared with the 0.0 mg/L group, in 0.1 and 1.0 mg/L groups ALP staining was enhanced and the number of calcified nodules increased, and the protein expression levels of Runx2 and ALP in the 0.1 and 1.0 mg/L groups were higher ( P < 0.05). After osteogenic induction, compared with the 0.0 mg/L group, the p-GSK3β/GSK3β ratio and β-catenin protein level were significantly higher in the 0.1 and 1.0 mg/L groups ( P < 0.05); and compared with the fluoride group (1.0 mg/L), addition of DKK-1 significantly decreased the protein expression levels of p-GSK3β and β-catenin and reduced the nuclear entry of β-catenin, and ALP staining decreased and the number of calcified nodules decreased. Conclusions:High concentration of fluoride (> 10.0 mg/L) inhibits the proliferation and promotes apoptosis of BMSCs, while low concentration of fluoride (0.1, 1.0 mg/L) promotes osteogenic differentiation. The MAPK/JNK pathway and the classical Wnt pathway are involved in the above cellular processes, respectively.

Objective:To evaluate the effects of comprehensive reform of clinical education on cultivating the clinical thinking ability of medical students in internal medicine.Methods:A total of 44 clinical interns on medicine rotation were included in this study and divided into experimental group and control group, and a series of measures for clinical teaching reform, which included undergraduate tutorial system, team-based learning (TBL) mode, combination of electronic medical record and handwritten medical record, as well as formative assessment, were applied to fully promote clinical thinking ability of medical students. SPSS 17.0 software was used to compare the scores of final academic tests of rotation and competition of medical record writing between the control and the experiment groups. Self-designed questionnaires on undergraduate tutors and clinical interns were applied to comprehensively evaluate the effects of this education reform.Results:Independent-sample t tests showed there were statistically significant difference ( P<0.01) in the scores of final academic tests of rotation and competition of medical record writing between the two groups, and the mean score of the experiment group was higher than that of the control group. Questionnaire survey showed that tutors and clinical interns both fully affirmed the positive effects of the education reform on cultivating clinical thinking ability of medical students in internal medicine. Conclusion:Application of comprehensive education reform in clinical teaching of internal medicine, which based on introduction of undergraduate tutorial system and TBL mode, could effectively promote the clinical thinking ability of medical students and the teaching quality.

Objective : To study the anatomical characteristics of the root and root canal system of the mandibular second permanent molar in the Uygur people and provide a reference for clinical practice. Methods : A total of 125 mandibular second permanent molars were extracted from Uygur patients in hospitals in the Xinjiang Uygur Autonomous Region. Three-dimensional reconstruction was performed after micro-CT scanning. The number of root canals, the root canal type (Weine classification and Fan′s C-shaped canal classification) and the occurrence of lateral accessory canals were observed. Results : A sex difference was not detected in the root number or root form (χ2 = 1.277, P = 0.259). The incidence of 2-rooted molars was 70.4% (n = 88); type 2-1 canals were most common in the mesial root, with an incidence of 29.5%, followed by type 1-1 and 2-2 canals (each with an incidence of 26.1%), and the distal root mostly had a type 1-1 canal (96.6%). The incidence of single-rooted molars was 28.8%, and the frequency of C-shaped (n = 28) and non-C-shaped (n = 8) single-rooted molars was 22.4% and 6.4%, respectively. A three-rooted molar was detected in one case. The incidence of accessory canals was 65.2%. Conclusion Uygur mandibular second molars are mainly composed of two roots, and the incidence of a single root and root canal fusion is low (including C-shaped canals). Two-rooted molars frequently have two mesial canals and one distal canal.

Objective To explore the clinical value of portal exposure in laparoscopic treatment of children with type Ⅲ biliary atresia (BA).Methods From June 2013 to October 2017,30 infants with type Ⅲ BA who treated with laparoscopic portoenterostomy in Huai'an Women and Children's Hospital were selected.A percutaneous suture was used to snare the round ligament and retract the liver,other percutaneous stay sutures were then introduced and fundus and neck of gallbladder were sutured to elevate the liver to expose the portal hepatis.The fibro cord and hepatic vessels were mobilized,and then two rubber bands were put around the left and right portal veins and hepatic arteries.The portal hepatis was exposed by laterally stretching the two elastic rubber bands.The fibro cord was removed and then laparoscopic portoenterostomy was accomplished.In 20 cases,the liver was enlarged,part of hepatic lobus quadratus was removed laparoscopiclly for exposure of the portal hepatis.Results There were 30 cases in this group,2 cases were converted to open surgery by a micro transverse incision.There was no surgical death.Time of laparoscopic procedure varied from 210 to 280 min.All cases survived the surgery without any intraoperative complications.Blood loss during operation was minimal,without necessity for blood transfusion.One case died of respiratory failure one week after surgery.Two cases were lost follow-up.Twenty-five cases were followed up for 3～51 months(mean 22.4 months).Three cases died because of repeated cholangitis and liver failure at 10,16,35 months postoperatively.Nineteen patients' total bilirubin had dropped to normal,three others' bilirubin levels dropped significantly after surgery.Conclusion The technique of laparoscopic hepatic porta exposure can help to complete hepatic portoenterostomy successfully,reduce the conversion rate of laparoscopic surgery,and improve the surgical effect.

Objective: To investigate the dental anatomy of C57BL/6 mice strain. Methods: The skulls and alveolar bones of 16 C57BL/6 mice were scanned by a micro-CT scanner. After 3D reconstruction,the internal and external anatomy of each tooth type was examined. Results: The upper incisors were more curved (mean radius: 2. 37 mm vs. 6. 31 mm) and shorter (mean tooth length: 8. 63 mm vs. 11. 19 mm) than the lower incisors. The palatal roots of the upper 2nd molars (3-rooted),the mesial roots of the lower first molars(double-rooted) and the mesial and distal roots of the lower 2nd molars (double-rooted) had type 1-2 canal form,and all the other roots had a single canal. The mesiodistal diameter of the crown,as well as the numbers of the cusps and developing grooves decreased from the 1st to the 3rd molars. The external tooth shape was very similar as the morphology of the pulp cavity. Conclusion: The C57BL/6 mouse have strong incisors. The tooth size and the anatomic complexity decrease from the 1st to the 3rd molars,which reflects a trend of degradation.

Objective: To investigate the effects of p38 mitogen-activated protein kinases (p38 MAPK) inhibitor (SB203580) on airway inflammation in a mouse model of asthma. Methods: Forty-eight female BALB/c mice were randomly divided into four groups (n=12): control group, asthma group, dexamethasone group (2 mg/kg) and SB203580 group (5 mg/kg). Within 24 hours after the last ovalbumin (OVA) challenge, airway responsiveness was measured by lung resistance (RL) and dynamic compliance (Cdyn). Bronchoalveolar lavage fluid (BALF) was collected for counting total cells, eosinophils, lymphocytes, neutrophils and macrophages. IgE and OVA-specific IgE in serum and IL-4, IL-5, IL-13 and IFN-γ in BALF were detected by ELISA. Lung tissues were stained with hematoxylin and eosin (HE) and alcian blue-periodic acid-Schiff (AB-PAS) to observe histopathological changes. Expression of p38 MAPK and phosphorylated p38 (p-p38) MAPK was detected by immunohistochemical staining and Western blot, respectively. Results: (1) The mice in the asthma group showed typical symptoms of acute asthma after inhaling aerosolized OVA, while the symptoms were alleviated in those treated with dexamethasone or SB203580. (2) When challenged with the methacholine at the doses of 0.050 mg/kg, 0.100 mg/kg and 0.200 mg/kg, asthmatic mice treated with dexamethasone or SB203580 showed significantly decreased RL and increased Cdyn as compared with those in the asthma group (all P<0.05). (3) The concentrations of total IgE and OVA-specific IgE in serum in both dexamethasone and SB203580 groups were lower than those in the asthma group (all P<0.05). (4) Compared with the asthma group, the numbers of the total cells, eosinophil, lymphocytes and neutrophils in BALF were decreased in dexamethasone and SB203580 groups (all P<0.05). (5) Compared with the asthma group, the dexamethasone and SB203580 groups showed lower levels of IL-4, IL-5 and IL-13, but higher levels of IFN-γ in BALF (all P<0.05). (6) Dexamethasone or SB203580 significantly decreased the hyperemia and edema in airway mucosa, reduced the infiltration of inflammatory cells in the peribronchial areas and alleviated the tracheal epithelium goblet cell metaplasia in asthmatic mice. (7) Treatment with dexamethasone or SB203580 inhibited OVA-induced phosphorylation of p38 MAPK in asthmatic mice as revealed by immunohistochemical staining (both P<0.05). No significant difference in the expression of p38 MAPK was observed among the four groups (all P>0.05). (8) Expression of p-p38 MAPK at protein level in both dexamethasone and SB203580 groups was lower than that in asthma group (both P<0.05). Conclusion SB203580 regulated the Th1/Th2 balance through inhibiting the activation of p38 MAPK signaling pathway to alleviate OVA-induced airway inflammation.

Objective: To analyze the trend of lung cancer incidence rate among rural residents in Feicheng city between the years 2000 and 2012,and predict the incidence rate between the years 2013 and 2018,and subsequently provide baseline data for lung can-cer control and prevention.Methods:With the cancer registration data in Feicheng rural areas,the time trend of lung cancer inci-dence rate and the annual percentage change(APC)were calculated by the Joinpoint model,while the incidence of lung cancer from 2013 to 2018 were predicted by the ARIMA(p,d,q)model.Results:A total of 3,908 new cases of lung cancer were diagnosed be-tween 2000 to 2012.The incidence rate was 40.77/105,the age-specific cancer incidence rate in the Chinese population(ASRC)and world population(ASRW)were 32.95/105 and 32.97/105,respectively.The incidence was 2.14 times higher among males than females (P<0.001).The incidence of lung cancer which apparently rose from 25.13/105to 64.92/105 with an APC value of 9.74%(P<0.001),was increasing every year.The change in the trend of lung cancer with respect to age could be divided into three segments,the incidence rate in the 0 to 59 years group showed a rapid upward trend(APC=113.38,P<0.001),which was lower in the 60 to 79 years group (APC=20.39,P<0.05)and began to decline in the 80 years or older group(APC=-21.20,P>0.05).The incidence of lung cancer was also observed to be increasing yearly from 2013 to 2018,and with an average annual growth rate of 4.92%,was predicted to reach 87.92/105 in 2018.Conclusions:The occurrence of lung cancer was closely related to population aging,unhealthy habits,and environmental risk factors.Due to the increasing aging population,the incidence of lung cancer will continue to increase.In order to formulate specif-ic strategies,the control and prevention of lung cancer must be based on its incidence features.