BACKGROUND:Some studies have demonstrated that red blood celllysate added into the bone marrow can increase the efficiency of isolating and purifying mesenchymal stem cells, in order to obtain high-purity and high-quantity bone marrow mesenchymal stem cells.
OBJECTIVE:To isolate and culture bone marrow mesenchymal stem cells of rabbit with red blood celllysis in vitro for exploring proliferation characteristics and performing the biological identification of cells.
METHODS:Bone marrow suspension was col ected by puncturing the tibia with medul o-puncture needle. Red blood celllysis was added to the bone marrow suspension, and bone marrow mesenchymal stem cells were isolated and cultured. Numbers of primary cells were recorded at 4, 7, 10, and 13 days later And Growth curves of the cells at passages 2-5 were drawn for comparison of proliferative characteristics. Inverted phase contrast microscope was used to observe the morphological changes of cells. CD34, CD44 antigens of bone marrow mesenchymal stem cells were identified by flow cytometry and immunity fluorescence.
RESULTS AND CONCLUSION:The adherent bone marrow mesenchymal stem cells mainly showed s spindle shape, with homogeneous nuclei, prominent nucleoli, and rich cytoplasm, which were positive for CD44 antigen and negative for CD34 antigen. The primary cells exhibited an“S”shape. Passage 4 cells had a better proliferative ability, rapider growth and more counting of cells as compared with other generations. These findings indicate that red blood celllysis method is a feasible ways of culturing bone marrow mesenchymal stem cells 0 in vitro, and passage 4 cells have the strongest proliferation capacity.

Objective To determine the detergent-enzymatic cycles and evaluate the biomechanical characteristics as well as extracellular matrix integrity of the decellularized tracheal scaffold in rabbit.Methods Forty tracheal segments were harvested from New Zealand white rabbits.Thirty-five of tracheas were subjected to a detergent-enzymatic method of decellularization for 1/3/5/6/7/8/9 cycles,respectively,and other five were stored in phosphate-buffered saline at 4℃ as a control.Comparative examinations were performed by the macroscopic view,histological view(hematoxylin and eosin stain,Movat Pentachrome stain,4-6-diamidino-2-phenylindole),scanning electron microscope (SEM) and biomechanical properties between decellularized groups and control group.Results After 7 detergent-enzymatic cycles,almost complete decellularized tracheae,retaining the hierarchical and mechanical properties of the native tissues,could be obtained.Histological and molecular biology analysis demonstrated that all cellular components and nuclear material were removed.SEM analysis revealed that the decellularized matrices retained the hierarchical structures of native trachea,and biomechanical tests showed that decellularization approach did not led to any influence on tracheal morphological and mechanical properties.Immunofluorescence analysis show a significant reduction of nuclear material in decellularized tracheas (P ＜ 0.05).Conclusion In conclusion,this work suggests that 7 cycles of the modified DEM generates a bioengineered rabbit tracheal matrix that is structurally and mechanically similar to native trachea which could be a better selection for tracheal reconstruction with tissue engineering method.

BACKGROUND: Thoracolumbar fracture is most common seen in spinal fractures. The paraspinal muscle is subjected to extensive detachment and traction in traditional posterior approach, so the muscular ischemia and denervation lead to muscle atrophy further inducing intractable low back pain. Thereafter, minimally invasive spinal surgery becomes more and more popular.OBJECTIVE: To investigate the clinical efficacy of pedicle screw fixation through Wiltse approach combined with injectable calcium sulfate bone cement for single-level thoracolumbar fracture.METHODS: Clinical data of 52 patients with single-level thoracolumbar fracture without nerve injury were analyzed retrospectively, and were then assigned to observation (n=28) and control groups (n=24) according to the treatment method. The patients in the observation group were treated with pedicle screw fixation through Wiltse approach plus implanted with injectable calcium sulfate bone cement, and those in the control group were subjected to pedicle screw fixation through posterior approach plus implanted with injectable calcium sulfate bone cement. The operation time, blood loss and hospitalization time were compared between two groups. The low back pain was observed at baseline, 1 week and 3 months postoperatively, and the percentage of anterior vertebral height revealed on X-ray was observed at baseline, before ambulation, and during last follow-up. Moreover, the complications, loosening and rupture of the screws were recorded.RESULTS AND CONCLUSION: (1) All patients were followed up, and the follow-up time was 16-24 months. (2) The operation time, blood loss and hospitalization time in the observation group were significantly less than those in the control group (P < 0.05). (3) The postoperative visual analogue scale scores in the two groups were significantly lower than those before surgery, and the scores showed significant differences between two groups (P < 0.05). (4) The percentage of anterior vertebral height before ambulation and during last follow-up in the two groups was significantly improved, and the percentage showed significant difference between two groups at each time point (P < 0.05). (5) These findings suggest that based on strict indications, the pedicle screw fixation through Wiltse approach combined with injectable calcium sulfate bone cement is safe for single-level thoracolumbar fracture, which restores the anterior vertebral height rapidly, alleviates pain and exhibits satisfactory long-term efficacy. Furthermore, it holds shorter operation time and less blood loss than the traditional approach.

BACKGROUND:Percutaneous pedicle screw fixation has been applied in the treatment of thoracolumbar fracture,and has achieved satisfactory clinical efficacy.Injectable calcium sulfate holds good biocompatibility,degradability and fast curing.OBJECTIVE:To explore the clinical efficacy of percutaneous pedicle screw fixation combined with calcium sulfate cement for single-level thoracolumbar fracture.METHODS:Clinical data of 40 patients with single-level thoracolumbar fracture without nerve injury were analyzed retrospectively.All fractured vertebrae were compressed more than 30％ and at least one pedicle was complete.All patients were treated with percutaneous pedicle screw fixation combined with calcium sulfate cement.The Visual Analog Scale and Oswestry Disability Index scores were recorded at baseline,3 months postoperatively and last follow-up;the height of the fractured vertebra body and sagittal Cobb angle were measured on X-ray;the patient's satisfaction and healing rate were recorded.RESULTS AND CONCLUSION:(1) The Oswestry Disability Index at 3 months postoperatively and last follow-up was 16.3％ and 4.4％,respectively.Compared with baseline,the Cobb angle and Visual Analog Scale scores were significantly reduced,and height of the fractured vertebra body was significantly increased after surgery (P ＜ 0.01).(3) The healing rate at last follow-up was 95％,nonunion was not found,and the patients' satisfaction reached 95％.(4) The loss of vertebral height and Cobb angle was found at last follow-up compared with 3 months postoperatively,but had no significant difference (P ＞ 0.05).(5) These results indicate that percutaneous pedicle screw fixation combined with calcium sulfate cement is safe and reliable for single-level thoraclumbar fracture,which not only restores the vertebral height and relieves pain,but also has satisfactory long-term curative efficacy and high healing rate.

Currently,carbon nanoparticle technology is a rapidly developing and emerging technology that has a significant impact in the field of cancer treatment,especially in non-small cell lung cancer.The lymphatic tendency of nano-carbon is used to improve the detection rate of positive lymph nodes,avoiding the leakage of lymph nodes and the crushing and breaking of the lymph nodes to prevent the metastasis of tumorsin non-small cell lung cancer surgery.In addition,carbon nanoparticle has underwent tremendous changes on drug chemical treatment.Its good biocompatibility provides the possibility of serving as a drug carrier,and maintains in vivo drugs at a constant concentration to avoid affecting therapeutic efficacy owning to the half-life of the drug.At the same time,its biological toxicity is lower compared to the traditional drug carrier.This paper focuses on these characteristics of carbon nanoparticle which is applied to the lymphatic target tracking,drug control and release,and elaborates its clinical application prospect in the field of non-small cell lung cancer.

Objective: This study aimed to evaluate the validity and predictive value of different methods for myopia screening, and to provide the most effective method of myopia screening. Methods: A total of 7 441 students of grade 1-12 selected from 36 primary and middle schools in 12 counties in Jiangsu Province were enrolled in this study for ophthalmological examination, and uncorrected visual acuity (UCVA, Plan A), noncycloplegic autorefraction (NCAR, Plan B) and combination of UCVA and NCAR (Plan C) were included in the examination. Receiver operating characteristics (ROC) curve was performed to determine the cut-off values (The gold standard is cycloplegic refraction: SE≤0.5 D), and positive predictive value, sensitivities, specificities and other indicators of three screening tests were compared and calculated. Results: The AUC of the combination test for uncorrected visual acuity(UCVA) and noncycloplegic autorefraction (NCAR) was nearly 1(0.91, 95%CI=0.90-0.92), and the sensitivity, specificity, Yoden index, diagnostic coincidence rate, positive predictive value and negative predictive value were 92.4%，89.5%，0.82，91.1%，91.3%，90.8%, respectively, but the index of the younger pupils in primary schools was relatively low. The result of screening plan A for students of middle and high school students was the closest to that of myopia diagnosis. Conclusion Combination test, which was recommended by China National Health Commission, can be a practical solution for school students for myopic screening. Under the condition of no mydriatic refraction, Plan A could be considered for myopia screening especially for middle and high school students. For the younger pupils, it is suggested to use the internationally recommended myopia screening strategy, that is, SE ≤ 0.50D after mydriasis.

Objective: The purpose of the current study was to determinate the prevalence of dating violence perpetration and victimization and to examine its relationship with childhood abuse among medical college students. Methods: Cluster sampling survey was carried out among 3 727 freshmen and sophomores in two medical colleges from Anhui Province. Information with general demographic variables, childhood abuse and dating violence was obtained. Logistic regression was used to identify the relationship of different types of childhood abuse and dating violence after controlled for confounding factors. Results: The rate of dating violence perpetration and victimization was 37.8% and 27.8%, respectively. Female students had higher childhood emotional abuse experience (61.9%) than male students (51.6%), while male students had higher childhood physical and sexual abuse (28.2% and 19.4%) than females (24.3% and 10.5%) (χ2=33.84，6.33，52.97，P<0.01). Results showed that increased dating violence perpetration [OR(95%CI)=1.71(1.48-1.98),1.55(1.33-1.82),1.75(1.43-2.15)]and victimization [OR(95%CI)=1.84(1.43-2.16),1.59(1.34-1.87),1.62(1.32-2.00)](P<0.01) among individuals with physical, emotional and sexual abuse after controlling for confounding variables. No gender difference was found within other groups in the relationship between childhood abuse and dating violence(P>0.05). Conclusion Childhood abuse experiences are associated with higher risk of dating violence perpetration and victimization among college students. Reducing childhood abuse is beneficial to the prevention and control of dating violence among medical college students.

Objective: To investigate the current status of screen time in preschoolers during the outbreak of Corona Virus Disease 2019 (COVID-19), and the influences of parent-child active play and school online education on screen time. Methods: A total of 2 370 preschoolers were chosen through clustering sampling from 7 kindergartens in Wuxi urban areas. Questionnaire survey was administered to parents for child screen time, active play, online education as well as characteristics information. Results: A total of 1 428(60.3%) preschoolers reported more than 1 hour screen time a day, and 1 915(80.8%) preschoolers reported more than 20 minutes consecutive screen time. Compared with the weekend before the COVID-19 outbreak, 1 551(65.4%) preschoolers reported an increase of 10 minutes in screen time perday, and 1 444(60.9%) reported an increase of 5 minutes for one sersion. Logistic regression analysis showed that after controlling for confounding factors, high frequency of parent-child active play, parents’ exercise habits, online education from kindergartens and children’s active participation in the online education were negatively associated with preschoolers’ excessive and increased screen time during this period(OR=0.39-0.79, P<0.05). Conclusion During the COVID-19 outbreak, preschoolers’ media use in Wuxi city is worrisome. Parent-child active play, parents’ exercise and online education from kindergartens may play a positive role in reducing preschoolers’ media use.

Objective: The study aims to examine the prospective association and sex differences of pubertal timing and tempo with behavior problems. Methods: Participants from two primary schools in grade 1-3 were selected through clustering convenience sampling method in Bengbu, Anhui Province was established since 2013 (T1), with informed consent, 2 084 students were recruited, and follow-up surveys were conducted in 2015 (T2), 2017 (T3) and 2019 (T4) respectively. Demographic information, non-suicidal self-injury (NSSI), suicidal ideation, suicide plan, suicide attempt and externalizing symptoms were collected through questionnaire investigation, and pubertal development in boys and girls were evaluated by secondary sexual development (testicular volume for boys and breast development for girls). At T4, externalizing symptoms were evaluated by MacArthur Health & Behavior Questionnaire-Child (HBQ-C). Using SAS PROC NLMIXED to fit nonlinear growth model to estimate pubertal timimg and tempo. Puberty timing was classified into early, on-time, and delayed groups; and the puberty tempo into fast, average, and slow groups. Multivariable logistic regression model was used to analyze the predictive effects of modeling pubertal timing and tempo on multi-disciplinary behavior problems in adolescence boys and girls. Results: There were 1 909 people with complete baseline and follow-up questionnaires and puberty development information. Reported rates of externalizing symptoms, NSSI, suicidal ideation, suicide plan, suicide attempt and were 13.9% (265), 24.4% (466), 14.2% (271), 4.6% (88) and 2.3% (43) respectively. Logistic regression analysis results show that fast pubertal tempo increases the risk of externalization [OR(95%CI)=2.85(1.53-5.31) and NSSI [OR(95%CI)=2.11(1.22-3.65)] for boys, and the risk of suicide attempt [OR(95%CI)=2.99(1.07-8.35)] for girls. Slow tempo can reduce the risk of suicidal ideation and suicide plan for boys [OR(95%CI)=0.40(0.18-0.87), 0.07(0.01-0.67)], the externalizing symptoms and suicidal ideation for girls [OR(95%CI)=0.33(0.13-0.81)，0.38(0.17-0.85)]. Early pubertal timing will increase the risk of suicide plan for boys [OR(95%CI)=3.60(1.04-12.43)], meanwhile late timing can reduce the risk of NSSI in girls [OR(95%CI)=0.39(0.19-0.80)]. Conclusion The tempo of pubertal development may be a useful predictor of adolescent behavioral problems.

Objective: To examine pubertal timing across body mass index (BMI) trajectory under polygenic susceptibility in boys and girls,and to provide a reference basis for children’s adolescent development deviation form early intervention strategies. Methods: All the participants were recruited from 1 to 3 grade in 2016 from 2 Bengbu primary school and were followed up for 3 consecutive years. The study comprised 997 children (418 boys) with available data for height, weight, BMI, breast Tanner stages and testicular volume annually. The polygenic risk score (PRS) was computed based on 17 SNPs derived from published genome-wide association studies for early pubertal timing. Group-based trajectory model (GBTM) was used to identified BMI trajectory in children. Accelerated failure time model (AFT) was used to examine associations of different BMI trajectory and polygenic risk with pubertal development in boys and girls. Results: Classes of BMI trajectory were persistently healthy weight, persistently overweight and persistently obesity. Adjusted concomitant variables, boys with persistently obesity exhibited 6.10-mo delay of testicular volume in low polygenic risk group (adjusted TR=1.05，P=0.04). Compared with the girls in persistently healthy weight group, the girls with low PRS were persistently overweight or obesity, which was associated with thelarche age 3.42 and 6.84-mo earlier, respectively (adjusted TR=0.97，0.94,P<0.01). Persistently overweight or obesity in girls with moderate PRS was associated with an earlier age of thelarche timing of 6.72 and 8.96-mo, respectively (adjusted TR=0.94，0.92, P<0.01). At high PRS groups, the persistently obese girls were found to have a more advanced age (10.80 and 12.96-mo, respectively) of thelarche (adjusted TR=0.90，0.88, P<0.01). Conclusion Persistently overweight and obesity is associated with early thelarche in girls, but persistently obesity may increase delayed puberty risk in boys with low polygenic risk.