BACKGROUND:At present,there is still controversy in clinical practice about the choice of internal fixation of Pauwels type Ⅲ femoral neck fracture,and the selection of internal fixation that provides stable fixation strength is the key basis for achieving Pauwels type Ⅲ fracture fixation. OBJECTIVE:The three-dimensional finite element analysis method was used to test the difference in biomechanical strength of three types of internal fixation in Pauwels type Ⅲ femoral neck fracture,which provided a reference for its clinical treatment. METHODS:Using the CT data of the left femur of a healthy male volunteer,a complete femur and its cancellous bone were reconstructed in Mimics software,and Geomagic studio software was used for reverse modeling.Cannulated compression screw,dynamic hip screw,and femoral neck system were created in UG-NX software.Three kinds of internal fixation models were assembled on the femur model,and Pauwels type Ⅲ femoral neck fracture was simulated by Hypermesh software.Finally,Abaqus software was used to carry out finite element experimental analysis to analyze and compare the stress distribution,stress peak,strain,and displacement distribution caused by fixed femoral neck fracture of different internal fixation systems. RESULTS AND CONCLUSION:(1)The stress of the proximal femur bone mass was mainly distributed in the area below the femoral neck near the fracture end,with the highest stress peak in the dynamic hip screw group and the smallest in the femoral neck system group.(2)The stress distribution of the internal fixation device was mainly concentrated on the screw surface near the fracture line,with the highest stress peak in the femoral neck system group and the smallest in the dynamic hip screw group.(3)The main strain field of the proximal femur bone mass was distributed in the upper surface area where the bone and screw contacted,and the yield strain was the smallest in the femoral neck system group and the largest in the cannulated compression screw group.(4)The main strain field of the internal fixation device model was distributed on the upper surface of the femoral neck screw,with the yield strain being the smallest in the femoral neck system group and the largest in the cannulated compression screw group.(5)The displacement distribution values of femur,proximal bone mass,distal bone block,internal fixation device and internal fixation with the femur as a whole in the three femoral neck fracture internal fixation models decreased gradually from proximal to distal,and the peak displacement of the femoral neck system group was the largest and the lowest in the dynamic hip screw group.(6)The results showed that when the Pauwels type Ⅲ femoral neck fracture was fixed,the stress distribution of femoral neck system was more uniform,the mechanical conduction characteristics were better,and it was subjected to lower yield strain,higher stress and higher displacement.It has relatively better biomechanical stability and can provide a superior mechanical environment for fracture healing.

Objective:To investigate the influence of low-dose ionizing radiation on the expression level of serum insulin-like growth factor binding protein-3 (IGFBP-3) in radiation workers in hospitals.Methods:183 radiation workers were randomly selected and grouped by work type including interventional radiology ( n=37), nuclear medicine ( n=43), radiotherapy ( n=48), and diagnostic radiology ( n=55). The content of IGFBP-3 in the serum of radiation workers was detected by ELISA assay. Results:It was observed that the expression level of serum IGFBP-3 in the four groups had significant differences ( F=6.056, P<0.05), and the content of serum IGFBP-3 in the interventional radiology group was significantly higher than that of nuclear medicine, radiotherapy, and diagnostic radiology groups ( t= 2.815, 3.611, 3.936, P<0.05). The concentration of IGFBP-3 in the serum of radiation workers among different annual effective dose groups was statistically different ( F=8.380, P<0.05), which gradually increased with the increase of annual effective dose and length of service ( rs=0.202, 0.151, P<0.05). Conclusions:The expression level of serum IGFBP-3 has the potential to be used as a biomarker to reflect the cumulative exposure of long-term chronic low-dose ionizing radiation.

Objective:To observe multiple locus variable-number tandem repeat analysis (MLVA) typing of Brucella isolated from Himalayan marmot in Qinghai-Tibet Plateau of Qinghai Province, and to explore the relationship between the strains and strains previous isolated from Qinghai Province. Methods:Blood samples of Himalayan marmot were collected in Qinghai-Tibet Plateau of Qinghai Province from March 2019 to October 2020. Pathogens were isolated and cultured from Brucella antibody positive samples identified by using the rose bengal test (RBT). Conventional biological methods and molecular biological methods (BCSP31-PCR and AMOS-PCR) were used for strain identification. At the same time, MLVA method was used to genotype the isolated strains, and cluster analysis was used to analyze the genetic relationships between the strains based on the genotype of 70 Brucella isolated from different hosts in Qinghai Province. Results:A total of 1 466 blood samples of Himalayan marmot were collected from Qinghai-Tibet Plateau. Two strains of Brucella were isolated and cultured from 64 RBT-positive samples, named QH2013054 and QH2013062, respectively. They were identified as Brucella ovis biotype Ⅲ by conventional and molecular biological methods. The MLVA genotyping results showed that QH2013054 and QH2013062 were different at the Bru16 locus, indicating different MLVA genotypes. Cluster analysis showed that strain QH2013054 had the same MLVA genotype as 7 strains, among which 6 strains were from 3 farmers and 3 sheep from the same family in Gonghe County, and 1 strain was from a farmer in Menyuan Hui Autonomous County. The strain QH2013062 had the same MLVA genotype as 4 strains, including 3 strains from 3 farmers in Menyuan Hui Autonomous County and 1 strain from a farmer in Tu Autonomous County of Huzhu. Conclusions:The strains of Brucella isolated from Himalayan marmot in Qinghai-Tibet Plateau of Qinghai Province have the same MLVA genotype as some strains of Brucella isolated from humans and sheep in Qinghai Province. It is speculated that the host humans, sheep and Himalayan marmot in Qinghai-Tibet Plateau may have a common source of infection.

Birth defects is one of the most important problems of human society. External birth defect is one of the major research fields of plastic surgery. This kind of disorders damages the body image of patients in mild or severe way, affects severely the social confidence of the patients themselves and their families. we summarized the research progress of the common external birth defects (the incidence top 10) from the aspects of pathogenesis, prevention, treatments and so on, in order to provide reference materials to the prevention and treatment of them.