Femoral neck fractures in pediatric fractures account for less than 1% which is very rare, and its mechanism is commonly caused by high-energy trauma. If children with femoral neck fracture cannot receive timely and effective treatment, they are at high risk of avascular necrosis of the femoral head (AVN), coxa vara, bone nonunion, premature physeal closure, leg length discrepancy and other complications. Surgical treatment is currently preferred over conservative treatment, which has a higher complication rate. Among them, AVN is one of the most common and the most difficult complications to manage. So far, no effective treatment measures and reliable predictors have been reported, and the related factors affecting the occurrence of AVN have also been controversial. Once femoral head necrosis occurs in children, the prognosis is not ideal due to the lack of appropriate treatment methods. Therefore, this paper reviews the research progress on the related factors of AVN after femoral neck fracture in children based on the literature reports in the past decade.

Objective To investigate epidemiological characteristics of animal plague in Microtus brandti plague foci in China from 2005-2013,and to found the reason for cross epidemic of Microtus brandti and Mongolian gerbil plague.Methods Totally 135 Yesinia pestis (Y.pestis) were isolated in Microtus brandti plague foci from 2005 to 2013.According to the typing method of Y.pestis and The Criteria of Plague Natural Foci and Animal Plague Epidemic(GB 16883-1997),bacteria type was identified using biochemical tests and sugar alcohols glycolysis test.Monitoring reports of the plague epidemic situation in Abag Banner,Xilinhot,Sonid left Banner,Xi Ujimqin Banner,Dong Ujimqin Banner,Inner Mongolia were collected.The epidemiological distribution of animal plague in Microtus brandti plague foci was analyzed.Results In 135 strains tested which were isolated from 2005-2007 and 2010,128 strains were fermented farinose,unfermented rhamnose; and 7 strains were fermented rhamnose,unfermented arabinose in 2008.According to the types of Microtus brandti Y.pestis (fermented rhamnose,unfermented arainose) and Mongolian gerbil Y.pestis (fermented arainose,unfermented rhamnose),Microtus brandti plague was identified in the epidemic in Xilinhot and Dong Ujimqin Banner in 2008.The Mongolian gerbil plague was epidemic in Abag Banner,Xilinhot and Xi Ujimqin Banner in2005-2007 and 2010.Conclusions In 2005,Mongolian gerbil type of Y.pestis is first isolated in Abag Banner,Xilinhot and Xi Ujimqin Banner.It is confirmed a newly discovered Mongolian gerbil plague foci.Abag Banner,Xilinhot,Sonid left Banner,Xi Ujimqin Banner and Dong Ujimqin Banner are Microtus brandti plague foci,only Dong Ujimqin Banner is Microtus brandti plague foci,others are two types of Microtus brandti and Mongolian gerbil plague foci.Since 2005,new epidemic situation is found,the Microtus brandti plague foci is becoming complex.It is a serious threat to human being.We must further strengthen the research and prevention in future.

Objective To investigate the teaching effect of applying idea of ‘ integrating world with specialty' in teaching ward - round.Methods Totally 112 undergraduates from department of anesthesiology in Chongqing medical university were randomly divided into 2 groups:group C and group T.The students in group C and group T were received traditional method and teaching ward-round applying idea of ‘integrating world with specialty' respectively.The teching effects were compared.Results Constituent ratio of performance of written test and defence of case analysis in group C and group T were respectively as follow,excellent ( 12％,19％) vs.(31％,37％),good (25％,19％ ) vs.(50％,44％ ),middle (54％,50％ ) vs.( 19％,13％ ),bad (9％,12％ ) vs.(0,6％ ),and there were statistically differences between the two groups.Conclusion Teaching ward-round applying idea of ‘ integrating world with specialty' integrates medical knowledge with social skills and common sense of life,making it easier for medical students to understand and master professional knowledge,as a result of improving the students' ability of problem analysing and solving.

Human nerve growth factor (NGF) is a nerve cell growth regulation factor, which can provide nutrition for the neurons and promote the neurites outgrowth. In order to produce large-scale recombinant human nerve growth factor (rh-beta-NGF), we constructed a plasmid vector, which can stably express the rh-beta-NGF in the HEK293 cell lines. First, the plasmid of pCMV-beta-NGF-IRES-dhfr was constructed and transformed into HEK293 cells. Then MTX pressurized filter and limiting dilution methods were used to obtain monoclonal HEK293 cell lines. After stepwise reducing serum in culture media, the cells eventually adapted to serum-free medium and secreted rh-beta-NGF. SDS-PAGE analysis revealed that the expression product owned a molecular weight of about 13 kDa and a purity of more than 50%. The peptide mapping sequencing analysis demonstrated the sequences of rh-beta-NGF matched with the theoretical ones. Later we purified this protein by ion exchange and molecular sieve chromatograph. Finally, our experimental results exhibited that the recombinant cell lines can stably express rh-beta-NGF with a high efficiency of more than 20 pg/cell x day. In addition, this protein could successfully induce differentiation of PC12 cells. In summary, our recombinant HEK293 cells can express bio-active rh-beta-NGF with great efficiency and stability, which supply a valid basis to large-scale production of rh-beta-NGF.
Cell Differentiation ; Genetic Vectors ; HEK293 Cells ; Humans ; Nerve Growth Factor ; biosynthesis ; Plasmids ; Recombinant Proteins ; biosynthesis

Objective To analyze and evaluate the application of indirect hemagglutination test (IHA) method in the epidemic area of Meriones unguiculatus in Inner Mongolia.Methods The plague monitoring summary and epidemic analysis reports of each year in Inner Mongolia from 1996 to 2016 were collected.The serum results of the IHA method were analyzed,including the time,region and the distribution of host animals.Results From 1996 to 2016,a total of 38 096 serum samples were detected from various host animals,and 172 positive samples were detected,with a positive rate of 0.45％.In the 21 years,except 2001 and 2015,the occurrence and prevalence of plague were judged by the IHA method for the remaining 19 years.There were 10 counties detected positive sera by IHA method;the positive results were detected by IHA method in 6 kinds of host animals,including 5 rodents and 1 carnivorous,and the positive rate of Rhombomys opimus was up to 6.17％ (91/1 475),the highest titer of the seropositive host animals was as high as 1:10 240.Conclusions The IHA method is easy to operate and economical.It plays a huge role in the timely detection of the epidemic in systematic monitoring of the Meriones unguiculatus in Inner Mongolia.

Objective To investigate the characteristics,clinical indicators and risk factors of levofloxacin-induced arrhythmias in large hospitalized populations.Methods Using the"Adverse Event Active Monitoring and Intelligent Assessment Alert System-Ⅱ"(ADE-ASAS-Ⅱ),the electronic medical record of inpatients using levofloxacin in 2019 was monitored to obtain relevant data for patients with arrhythmias.Patients without arrhythmia were selected by propensity score matching,and the risk factors of levofloxacin-induced arrhythmias were analyzed by univariate and multivariate conditional logistic regression.Results The incidence of levofloxacin-induced arrhythmias was 1.64％in 12 879 people who used levofloxacin.The incidence in people over 65 years was 3.22％.The main manifestations of levofloxacin-induced arrhythmias were extrasystole(0.84％),tachycardia(0.63％),QT interval prolongation(0.44％),and no severe arrhythmias such as torsades de pointes and ventricular fibrillation.Multivariate Logistic regression analysis showed that the course of administration(OR=1.030,95％CI 1.009 to 1.050,P=0.004)and intravenous administration(OR=2.392,95％CI 1.478 to 3.870,P＜0.001)independent risk factors for levofloxacin-induced arrhythmias.Conclusion Arrhythmias caused by levofloxacin are common and have various types,among which the occurrence of QT interval prolongation is occasional.We should pay more attention to elderly patients who receive intravenous levofloxacin and try to avoid long courses of medication.

Objective To understand the epidemiological characteristics of recent brucellosis in Hohhot.Methods Clinical data of patients with brucellosis in Hohhot City were retrospectively analyzed,and the patients were diagnosed in the outpatient clinic of Comprehensive Center for Disease Prevention and Control of Inner Mongolia Autonomous Region from 2014 to 2017.To analyze the patient's area,age,gender,occupation and time distribution of the disease.Results A total of 1 940 patients with brucellosis were diagnosed in Hohhot from 2014 to 2017,with an average age of 50.8 years old.There were 1 464 males with an average age of 50.4 years old and 476 females with an average age of 51.9 years old;the male-female ratio was 3:1.The number of cases of brucellosis in 2014-2017 was 612,649,402,and 277,respectively.Brucellosis was mainly distributed in three districts including Horinger County (937 cases),Tumd Left Banner (236 cases) and Tuoketuo County (191 cases),accounting for 70.31％ (1 364/1 940) of the total number of cases in the city.The age of onset was at least 1 year old,the oldest age was 86 years old,and most cases were in the 45-＜ 65 age group,the total number of cases was 1 046,accounting for 53.92％ (1 046/1 940) of the total number of cases in the city;the occupational distribution was mainly farmers (1 795 cases),herders (13 cases) and veterinarians (17 cases),with a total of 1 825 cases,accounting for 94.07％ (1 825/1 940).The time distribution was mainly concentrated in March-July,and the number of cases was 1 157 cases.Conclusions The number of brucellosis cases in Hohhot area of Inner Mongolia is mainly from Horinger County,Tumd Left Banner and Tuoketuo County;the cases occur frequently in Spring and Summer;the age of onset is mainly between 45-＜ 65 years old,they are mainly male farmers.

Objective To compare the biomechanical effects of n-HA/PA66 vertebral body cage and percutaneous vertebroplasty for treating osteoporotic vertebral fracture, so as to provide theoretical foundations for clinically choosing operative approach and numbers of n-HA/PA66 cage. Methods Based on finite element models of normal vertebral T11-L3, four finite element models of vertebral T11-L3 with n-HA/PA66 cage implanted by different approaches (transversus approach A, B and psoas major muscle approach A, B) were established. Two controlled models without intertransverse ligaments were also built. Besides, two finite element models of osteoporotic vertebral T11-L3 with injection of 1.8 mL or 3.6 mL bone cement were built, respectively. The loads of 500 N and force torque of 7 N·m from different directions were applied on nine models, to calculate and analyze the displacement and stress of the osteoporotic vertebrae during standing, extension, anteflexion, lateral bending, and rotation, and to investigate the biomechanical effects from two kinds of osteoporotic vertebral fracture treatment on vertebral body. Results Under the same loading, bone cement could lead to a larger stress increase while a smaller displacement decrease in vertebral body compared with n-HA/PA66 cage. The model with n-HA/PA66 cage implanted by psoas major muscle approach A (namely, a cage was implanted through psoas major muscle) had the minimal increase in vertebral stress while the maximum decrease in displacement. Conclusions In order to reduce the risk of the additional fracture due to stress increment and recover the stiffness of osteoporotic vertebrae, clinicians are suggested to implant one n-HA/PA66 cage through psoas major to treat the osteoporotic vertebral fractures.

Objective To explore the biomechanical effect from different volumes of bone cement on osteoporotic spine T11-L3 at different levels of osteoporosis in vertebroplasty by the finite element method, so as to offer theoretical foundation for the selection of cement volume before vertebroplasty. Methods Based on CT scan images, the finite element models of spine T11-L3 were built and validated. Twelve models of osteoporotic spine T11-L3 without bone cement were developed as the control models. The spine L1 was injected with 1.8 mL and 3.6 mL bone cement, respectively, to strengthen the spine and build 24 models of spine T11-L3 at different levels of osteoporosis. The vertical load (500 N) and the torque (7 N·m) were applied on superior face of the spine T11 to calculate and analyze vertebral stress and displacement under the working conditions of standing, backward extension, anteflexion, lateral bending and rotation, respectively. Results After injection of bone cement, the changes in vertebral stress and displacement under torsional loads were the maximum. For the models with injection of 1.8 mL bone cement, as the levels of osteoporosis increased, the stress of spine L1 increased from 55.0% to 87.7%, and the displacement decreased from 6.5% to 32.0% under torsional loads. The torsional stress of spine T12 and L1 at the highest level of osteoporosis increased by 3.6% and 5.7%, respectively. For the models with injection of 1.8 mL bone cement, as the level of osteoporosis increased, the stress of spine L1 increased from 288.5% to 313.8%, and the displacement decreased from 8.9% to 44.7% under torsional loads. The torsional stress of spine T12 and L1 at the highest level of osteoporosis increased by 7.3% and 7.6%, respectively. Conclusions The deterioration in osteoporosis and the increase in cement volume will lead to the increase in vertebral stress. The vertebral stress and displacement will increase most under torsional loads. Therefore, for patients with vertebral fracture at high level of osteoporosis, low-dosage bone cement should be considered in order to avoid a large increase in stress, and torsional movement of the patients should be restricted.