Finite element analysis of the stability of Mason type Ⅲ radial head fracture fixed with three cross-bridge headless compression screw and locking plate / 中国骨伤

OBJECTIVE@#To compare the biomechanical stability of three cross-bridge headless compression screws and locking plates in the fixation of Mason type Ⅲ radial head fractures by finite element method.@*METHODS@#Using reverse modeling technology, the radial CT data and internal fixation data of a healthy 25-year-old male were imported into the relevant software. Three-dimensional finite element model of 3 cross-bridge headless compression screws and locking plates for MasonⅢ radial head fractures were established, and the radial head was loaded with 100 N axial loading. The maximum displacement, maximum Von Mises stress and stress distribution of the two groups were compared.@*RESULTS@#The maximum displacements of the three cross-bridge screws group and locking plate group were 0.069 mm and 0.087 mm respectively, and the Von Mises stress peaks were 18.59 MPa and 31.85 MPa respectively. The stress distribution of the three screws group was more uniform.@*CONCLUSION@#Both internal fixation methods can provide good fixation effect. CoMPared with the locking plate fixation method, the 3 cross-bridge headless compression screws fixation is more stable and the stress distribution is more uniform.

Hydroxyapatite-polyvinyl alcohol/collagen-chitosan-gelatin composite hydrogel for repairing rabbit osteochondral defect / 中国组织工程研究

BACKGROUND:Osteochondral defect of the joint is a difficult problem faced by orthopedic surgeons,and traditional repair methods are difficult to obtain satisfactory curative effects.Hydroxyapatite-polyvinyl alcohol-based composite hydrogel material is a direction of current research. OBJECTIVE:To prepare hydroxyapatite-polyvinyl alcohol/collagen-chitosan-gelatin composite hydrogel material and characterize its physical characteristics,to verify its histocompatibility and cell adhesion and proliferation ability after implantation in vivo,and explore its repair effect on rabbit osteochondral defects. METHODS:The cylindrical porous poly(lactic acid)scaffold was prepared by 3D printing technology(the pore sizes were 1.2,1.4,1.6 and 1.8 mm,respectively).The poly(lactic acid)scaffold was injected with polyvinyl alcohol and hydroxyapatite mixed emulsion.After freezing thawing and dichloromethane dissolution,hydroxyapatite-polyvinyl alcohol hydrogel was prepared.Then,the collagen-chitosan-gelatin mixture was injected into the hydroxyapatite-polyvinyl alcohol hydrogel and crosslinked with genipin.Finally,the hydroxyapatite-polyvinyl alcohol/collagen-chitosan-gelatin composite hydrogel was prepared by alcohol cleaning and freeze-drying.The physical characteristics of the four groups of hydrogels were characterized,and the hydrogels with the best performance were screened for follow-up experiments.Hydroxyapatite-polyvinyl alcohol hydrogel and collagen-chitosan-gelatin composite hydrogel were implanted subcutaneously in SD rats.Hematoxylin-eosin staining and Masson staining were used to observe the adhesion growth of cells on the material surface.Osteochondral defect(diameter:5 mm,depth:6 mm)models were made in the femoral trochlea of bilateral knee joints of 15 rabbits.The composite hydrogel was implanted on the left side(experimental group),while no material was implanted on the right side(control group).Micro-CT and histology were used to evaluate the repair effect of osteochondral defects. RESULTS AND CONCLUSION:(1)Based on the results of porosity,water content,mechanical testing and scanning electron microscopy,it was concluded that the hydroxyapatite-polyvinyl alcohol/collagen-chitosan-gelatin composite hydrogel with a pore size of 1.2 mm was more consistent with the general characteristics of natural cartilage,which was used for subsequent experiments.(2)Hematoxylin-eosin staining and Masson staining exhibited that with the extension of subcutaneous implantation time of the materials,the adhesion of cells around the two materials increased significantly,and the proliferation of cells after the implantation of collagen-chitosan-gelatin was better,a large number of cells could be seen growing into the formed network structure,and the network structure was gradually degraded.(3)In the rabbit osteochondral defect experiment,8 weeks after surgery,Micro-CT examination demonstrated that the material implanted in the experimental group had good integration with the surrounding bone-cartilage,with some bone growth on the surface and inside,while the cartilage and subcartilage in the control group still had obvious defects,without effective repair.Hematoxylin-eosin staining and toluidine blue staining displayed that the composite hydrogel in the experimental group integrated with the surrounding articular cartilage 4-8 weeks after implantation.With the extension of time,new cartilage gradually formed on the surface of the material.At 12 weeks,most of the defect was covered by new cartilage,and good bone growth was also observed in the subcartilage.In the control group,the deep bone defects were mostly repaired and the superficial cartilage and subchondral bone defects were also repaired to a certain extent,but they were mainly replaced by fibrous tissue and part of fibrocartilage 12 weeks after surgery.(4)In conclusion,hydroxyapatite-polyvinyl alcohol/collagen-chitosan-gelatin composite hydrogel material can mimic the structure and function of natural cartilage,and can effectively repair osteochondral defects in animal experiments.

Advances in therapeutic drug monitoring methods based on liquid chromatography-tandem mass spectrometry / 中华检验医学杂志

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology has the characteristics of high specificity and high throughput, making it rapidly applied and developed in the field of clinical testing. Its application in the monitoring of therapeutic drugs can effectively improve the quantitative accuracy and sensitivity, and formulate a personalized and optimal dosing plan for patients. However, this technology still faces some challenges, and automation, quality control, and quantitative traceability will be the future development direction.

Toxicity and Mechanism of Di-(2-ethylhexyl) Phthalate on Testis / 生物化学与生物物理进展

Di-(2-ethylhexyl) phthalate (DEHP) is currently one of the most widely used plasticizers, widely found in all kinds of items, such as children’s toys and food packaging materials, but also added to wallpaper, cable protective agents and other building decoration materials. DEHP is toxic and absorbed by the human body through respiratory tract, digestive tract and skin contact, which can cause damage to multiple systems, especially the male reproductive system, and testis is an important target organ. Oxidative stress injury is the core mechanism of spermatogenesis disorder caused by DEHP. DEHP exposure can cause oxidative stress or reactive oxygen species (ROS) increase in germ cells, and on this basis, promote cell apoptosis or cause excessive autophagy. The toxicity of DEHP to Leydig cells is mainly to interfere with the synthesis of steroid hormones. For Sertoli cells, ferroptosis and destruction of the blood-testis barrier are common injury mechanisms. In addition, gene methylation caused by DEHP not only affects the spermatogenic process, but also has epigenetic effects on offspring. In this paper, we reviewed the pathological damage, germ cell toxicity and epigenetic effects of DEHP on testis, and focused on the damage and molecular mechanism on testicular spermatogenic cells, Leydig cells and Sertoli cells. Future research is required to elucidate the body’s clearance mechanism and treatment plan after exposure to DEHP and whether DEHP will damage the function of myoid cells. It is hoped that this can provide new ideas for prevention and treatment of male reproductive disorders resulting from long-term exposure to plastic products.

Advances in the structure and function of chitosanase / 生物工程学报

Chitosanases represent a class of glycoside hydrolases with high catalytic activity on chitosan but nearly no activity on chitin. Chitosanases can convert high molecular weight chitosan into functional chitooligosaccharides with low molecular weight. In recent years, remarkable progress has been made in the research on chitosanases. This review summarizes and discusses its biochemical properties, crystal structures, catalytic mechanisms, and protein engineering, highlighting the preparation of pure chitooligosaccharides by enzymatic hydrolysis. This review may advance the understandings on the mechanism of chitosanases and promote its industrial applications.

Development and validation of prognostic nomogram for malignant pleural mesothelioma / 中华肿瘤杂志

Objective: To development the prognostic nomogram for malignant pleural mesothelioma (MPM). Methods: Two hundred and ten patients pathologically confirmed as MPM were enrolled in this retrospective study from 2007 to 2020 in the People's Hospital of Chuxiong Yi Autonomous Prefecture, the First and Third Affiliated Hospital of Kunming Medical University, and divided into training (n=112) and test (n=98) sets according to the admission time. The observation factors included demography, symptoms, history, clinical score and stage, blood cell and biochemistry, tumor markers, pathology and treatment. The Cox proportional risk model was used to analyze the prognostic factors of 112 patients in the training set. According to the results of multivariate Cox regression analysis, the prognostic prediction nomogram was established. C-Index and calibration curve were used to evaluate the model's discrimination and consistency in raining and test sets, respectively. Patients were stratified according to the median risk score of nomogram in the training set. Log rank test was performed to compare the survival differences between the high and low risk groups in the two sets. Results: The median overall survival (OS) of 210 MPM patients was 384 days (IQR=472 days), and the 6-month, 1-year, 2-year, and 3-year survival rates were 75.7%, 52.6%, 19.7%, and 13.0%, respectively. Cox multivariate regression analysis showed that residence (HR=2.127, 95% CI: 1.154-3.920), serum albumin (HR=1.583, 95% CI: 1.017-2.464), clinical stage (stage Ⅳ: HR=3.073, 95% CI: 1.366-6.910) and the chemotherapy (HR=0.476, 95% CI: 0.292-0.777) were independent prognostic factors for MPM patients. The C-index of the nomogram established based on the results of Cox multivariate regression analysis in the training and test sets were 0.662 and 0.613, respectively. Calibration curves for both the training and test sets showed moderate consistency between the predicted and actual survival probabilities of MPM patients at 6 months, 1 year, and 2 years. The low-risk group had better outcomes than the high-risk group in both training (P=0.001) and test (P=0.003) sets. Conclusion: The survival prediction nomogram established based on routine clinical indicators of MPM patients provides a reliable tool for prognostic prediction and risk stratification.

Shoulder arthroscopic treatment of avulsion fracture of humeral greater tuberosity with double-row suture bridge / 中华创伤骨科杂志

Objective:To evaluate the shoulder arthroscopic treatment of avulsion fracture of humeral greater tuberosity with double-row suture bridge.Methods:Retrospectively analyzed were the 13 avulsion fractures of humeral greater tuberosity which had been treated by shoulder arthroscopic double-row suture bridge at Bone and Joint Department, Guangzhou Liwan District Orthopedic Hospital from March, 2018 to March, 2020. There were 6 males and 7 females, with an average ages of 52.3 years (from 35 to 69 years). According to the Mutch classification, all the fractures of humeral greater tuberosity were attributed to the avulsion type. Of them, 3 were simple avulsion fractures of humeral greater tuberosity and 10 were complicated with shoulder anterior dislocation which was reduced manually before operation. There were 3 obsolete avulsion fractures of humeral greater tuberosity. Regular clinic and X-ray follow-ups were carried out. At the final follow-up, the pain, range of motion (ROM) and stability of the shoulder joint were assessed using visual analogue scale (VAS), American shoulder elbow scores (ASES), and Korean shoulder scores (KSS).Results:All the patients were followed up for an average of 12.3 months (from 10 to 16 months) postoperatively. No infection or shoulder instability was observed. At the final follow-up, the abduction and elevation averaged 164.6° (from 135° to 180°), the lateral external rotation 62.7° (from 40° to 80°), the internal rotation touch back test T10 level (from L2 to T6), the VAS 0.65 (from 0 to 2.5), the ASES 90.5 (from 78 to 100), and the KSS 91.5 (from 84 to 100).Conclusion:Shoulder arthroscopic treatment of avulsion fracture of humeral greater tuberosity with double-row suture bridge is minimally invasive and allows for repair of combined injury, leading to quick postoperative recovery.

Fixation with a retrograde pubic ramus intramedullary nail for anterior pelvic ring fractures / 中华创伤骨科杂志

Objective:To explore the clinical efficacy of a retrograde pubic ramus intramedullary nail (RPRIN) in the treatment of anterior pelvic ring fractures.Methods:A retrospective study was conducted to analyze the 14 patients with anterior pelvic ring fracture who had been treated and followed up at Department of Traumatic Surgery, Tongji Hospital From June 2020 to February 2021. There were 10 males and 4 females with an age of (44.8±12.5) years. By the AO/OTA classification for pelvic fractures, 5 cases were type 61-A, 4 cases 61-B, and 5 cases type 61-C; by the Nakatani classification, 1 case belonged to unilateral zone Ⅰ fracture, 5 cases to unilateral zone Ⅱ fracture, 2 cases to unilateral zone Ⅲ fracture, 3 cases to right zone Ⅱ and left zone Ⅲ fracture, 2 cases to zone Ⅲ fracture on both left and right sides, and 1 case to zone Ⅱ fracture on both sides. The time from injury to operation was (7.8±1.8) days. All the anterior pelvic ring fractures were fixated with a RPRIN. The time and fluoroscopic frequency for placement of every single RPRIN, quality of fracture reduction, and pelvic function and incidence of postoperative complications at the last follow-up were recorded.Results:A total of 18 RPRINs were placed in the 14 patients. For placement of each RPRIN, the time was (35.9±8.6) min, and the fluoroscopic frequency (22.8±1.9) times. No complications such as infection occurred at any surgical incision after RPRIN placement. According to the Matta scoring, the quality of postoperative fracture reduction was assessed as excellent in 7 cases, as good in 5 cases and as fair in 2 cases. The 14 patients were followed up for (18.1+1.5) months. Their X-ray and CT images of the pelvis at the last follow-up showed that the fractures healed well and the intramedullary nails were placed in the cortical bone of the anterior ring of the pelvis. According to the Majeed scoring at the last follow-up, the pelvic function was assessed as excellent in 10 cases, as good in 3 cases and as fair in 1 case. One patient reported discomfort during squatting 2 months after operation but the symptom improved 3 months later without any special treatment. No patient experienced such complications as displacement or slippage of RPRIN, or pain at the insertion site.Conclusion:RPRIN is effective in the treatment of anterior pelvic ring fractures, showing advantages of small surgical incision, limited intraoperative fluoroscopy and short operation time.

Application of our self-made Kirschner wire connecting rod in difficult extraction of intramedullary implants / 中华创伤骨科杂志

Objective:To report the application of our self-made Kirschner wire connecting rod combined with a conventional intramedullary nail extractor in difficult extraction of intramedullary devices.Methods:From January 2012 to August 2017, 10 patients with a hard-to-remove intramedullary device were treated at Department of Orthopaedics, The Fifth Hospital Affiliated to Xinjiang Medical University. They were 7 males and 3 females with a mean age of (40.0±9.0) years. In cases where no relevant extractor was available for the intramedullary device or it was impossible to connect the extractor connecting rod to the tail of the intramedullary device, the Kirschner wire was bent and pulled through the screw hole or the hole newly drilled at the tail of the intramedullary device to be tied or fixed with a conventional extractor connecting rod to form an effective connection. Next, our self-made Kirschner wire connecting rod was used to pull out the intramedullary device. In this cohort, 7 intramedullary nails in the tibia, 1 femoral intramedullary nail, 1 humeral intramedullary nail, and 1 tibial elastic nail were removed. The difficult extraction was due to "cold welding" of the tail cap of the intramedullary nail in 3 cases, mismatch between the screw rod of the extractor and the tail screw hole of the intramedullary nail in 4 cases, and unavailability of relevant removal tools in 3 cases. The time for intramedullary device removal, blood loss and postoperative adverse reactions were recorded.Results:Of this cohort, 9 patients underwent simple removal of the intramedullary device and 1 patient replacement of the intramedullary device. The total time for removal of an intramedullary device was (2.3±0.8) h, ranging from 1.0 to 3.2 h. The amount of blood loss was (159.0±61.0) mL, ranging from 80 to 250 mL. The follow-up was (14.5±2.2) months, ranging from 11 to 18 months. There was no infection or fracture associated with implant removal.Conclusion:Application of our self-made Kirschner wire connecting rod in combination with a conventional intramedullary nail extractor is an easy operation to successfully extract hard-to-remove intramedullary implants, requiring no more special instruments.

Hydrogen Sulfide Regulates the Response to Oxidative Stress in Plants / 中国生物化学与分子生物学报

Oxidative stress is a state of redox imbalance, and it easily leads to oxidative damage in an organism. The main mechanism of oxidative stress is to regulate the redox balance by activating the antioxidant system. As an important signaling molecule, hydrogen sulfide(H