Objective To determine the time point when porcine pancreatic elastase(PPE)induced abdominal aortic aneurysm(AAA)reaches the regression phase in mice and observe the histological characteristics of AAA in regression phase.Methods AAAs were induced by transient intraluminal infusion of PPE in C57BL/6J mice.The diameters of the mouse abdominal aortas were measured before PPE infusion and sacrifice time,day 14 for AAA progression phase or day 56 for regression phase after PPE infusion,respectively.The histological characteristics of the aneurysm lesion site on day 14 and day 56 after surgery were compared and analyzed.Results The diameters of the abdominal aortas were significantly increased in both day 14 and day 56 after PPE infusion groups(diameter growth rate 147％and 155％,respectively)as compared to the baseline diameters.In the day 14 group,the infused aortas showed typical AAA characteristics,such as elastin break/degradation,medial smooth muscle cells depletion,and inflammatory cell diffused infiltration.In the day 56 group after PPE infusion,although the artery diameter did not change significantly as compared to the day 14 group,histology showed that elastin was partially repaired,new smooth muscle cells were added to the damaged aorta media,the infiltrated inflammatory cells were significantly subsided,and the adventitia neovascularization was reduced,showing a significant feature of the disease regression phase.Conclusion In the PPE-induced mouse AAA model,day 56 after surgery is an appropriate time point for observing aneurysm regression,and the histological characteristics of the regression are obvious.

Population aging in China has led to an increase in the incidence of abdominal aortic aneurysm(AAA).AAA rupture is one of the most severe life-threatening diseases,with high mortality.The main histopathological features of AAA include elastin degradation,smooth muscle cell depletion,extracellular matrix digestion,and mural leukocyte accumulation.Clinically,drug therapy is still lacking,and open/endovascular repair remains the most effective treatment strategy for AAA management.Notably however,the detailed molecular mechanism of AAA remains unclear,representing an important bottleneck affecting the development of potential drug targets.Animal models are the most powerful tools for clarifying the pathogenesis of AAA,and although some medium-to-large laboratory animal models(e.g.,rabbits,guinea pigs,dogs,pigs)have been established for AAA studies,rodent models(mice and rats)are still the main models used in this field.Current method of inducing AAA include intra-infrarenal aortic infusion of elastase,subcutaneous infusion of angiotensin Ⅱ,periaortic calcium chloride painting,and decellularized aortic xenografting;however,AAA tends to stabilize in most models after ceasing pre-induced stimulation(medical or surgical),and there remains a need for ideal animal models that maintain continuous aortic dilation and even rupture.AAA animal models are helpful for elucidating the pathogenesis of AAA,screening new drug targets,and promoting clinical translation.This review aims to discuss the application of current AAA modeling method and their translational relevance.

【Objective】 To study the effect of macrophage mediator 1 (MED1) deficiency on atherosclerosis in female mice. 【Methods】 ApoE knockout (ApoE^-/-), LDLR knockout (LDLR^-/-), MED1^fl/fl, and macrophage MED1 knockout (MED1^△Mac) mice were recruited in the study. Two types of mouse model were constructed:ApoE and macrophage MED1 double knockout (MED1^△Mac/ApoE^-/-) mice and their littermate controls (MED1^fl/fl/ApoE^-/-). ② LDLR knockout (LDLR^-/-) mice receiving bone marrow from MED1^△Mac (MED1^△Mac→LDLR^-/-) or MED1^fl/fl (MED1^fl/fl→LDLR^-/-) mice. Female mice from these two models were fed a Western diet (21% fat and 0.15% cholesterol) for 12 weeks to promote the development of atherosclerosis. Body weight, total cholesterol (TC), and total triglyceride (TG) content in plasma were measured dynamically. After Western diet feeding for 12 weeks, aortic tree and aortic root were collected and hematoxylin-eosin (H&E) and oil red O staining were performed. 【Results】 Plasma TC and TG did not significantly differ between MED1^fl/fl/ApoE^-/- control group and MED1^△Mac/ApoE^-/-experimental group. However, the plaque area in aortic tree and aortic root was significantly increased in MED1^△Mac/ApoE^-/-mice. Moreover, compared with that in MED1^fl/fl→LDLR^-/- control group, the plaque area of aortic tree and aortic root had an increasing trend in MED1^△Mac→LDLR^-/- mice group. 【Conclusion】 MED1 deficiency in macrophages promotes the development of atherosclerosis in female ApoE or LDLR knockout mice.

【Objective】 To compare the histological characteristics of porcine pancreatic elastase （PPE） induced abdominal aortic aneurysms （AAA） and angiotensin Ⅱ （AngⅡ） induced AAA in mice. 【Methods】 In the PPE group， the mouse abdominal aorta segment from the infrarenal abdominal aorta to the iliac artery was isolated and its branch arteries were ligated to avoid leakage during PPE perfusion. We perfused the isolated aorta segment with a PPE solution at a concentration of 1.5 U/mL for 5 min and then closed the abdominal cavity. The diameter of the abdominal aorta was measured before and 14 days after the surgery， and the perfusion segment of the arteries was collected at day 14 after the surgery. The histological characteristics of the aneurysm were analyzed and graded by histological and immunohistochemical methods. In the AngⅡ group， ten apolipoprotein E knockout mice were prepared， and AngⅡ [1 000 ng/(kg·min)] was infused with osmotic pumps for 28 days. The aorta was separated and the aneurysm aorta segment was analyzed. The wild type mice were used as normal health controls. 【Results】 In the PPE group， the diameter of the PPE perfused aorta segments increased and was significantly larger than the basal diameter ［（0.52±0.02） mm vs. （1.23±0.11） mm］ at day 14 after surgery. All the ten mice developed AAA after PPE application. The histological results showed typical pathological features of AAA in PPE perfused mice， such as elastic fiber breakage， smooth muscle exhaustion， and increased inflammation. Six of the ten mice developed aneurysms after AngⅡ infusion （6/10）. The aneurysms/dilatations were mostly in the suprarenal abdominal aorta， but also in the thoracic aorta and aortic arch. The histology analysis showed that the formation of arterial dissection was common after AngⅡ infusion， and the typical vascular “false lumen” was found. The breakage of elastic fibers， the exhaustion of smooth muscle damage， and the inflammatory response were not as typical as the PPE model in AngⅡ perfused animals. 【Conclusion】 The histological characteristics of PPE induced AAA are very typical and well present the inflammatory process in the development of aneurysm. The AngⅡ model is suitable for the study of aneurysms combined with aortic dissection. Both models have their own advantages and can complement each other.

Objective:To explore the morphological characteristics, treatment strategies and clinical results of complex hyperextension tibial plateau fractures.Methods:From October 2017 to January 2019, data of 27 patients with complex hyperextension tibial plateau fractures were retrospectively analyzed. There were 19 males and 8 females with an average age of 43.4 years (range, 23-68 years). According to Schatzker classification of tibial plateau fractures: there are 8 cases of type IV, 5 of type V, and 14 of type VI; according to the three-column theory classification: there are 8 cases of two-column fracture and 19 cases of three-column fracture. Bicondylar fractures were treated with medial Tomofix locking plate and anterolateral L-shaped locking plate through medial and anterolateral approach; tibialmedial condylar fractures was treated with T-shaped plate and posteromedial locking plate through extended medial approach. Patients with anterior tibial fractures were treated with horizontal strip plate through modified anterior median approach. Combined soft tissue or bone injury was repaired. The fracture healing and reduction were evaluated by X-ray and CT scan. The reduction of tibial plateau fracture was evaluated by Rasmussen radiology standard, and the knee joint function was evaluated 12 months after the operation by the score of American hospital for special surgery (HSS).Results:All the 27 surgeries were performedsuccessfully. The operation time was 130-350 minutes, with an average time of 165 minutes. Twenty-seven cases were followed up for 12-24 months, with an average period of 15.8 months. All fractures were healed. The average clinical healing time was 13.5 weeks (range, 10-18 weeks). Twelve months after operation, Rasmussen's radiology score was 13-18, with an average of 16.7 points, among them there were 19 excellent and 8 good. Twelve months after the operation, the score of HSS knee joint was 82-98, with an average score of 93.2 points, and there were 22 cases excellent, 4 cases good and 1 case fair. The excellent and good rate was 96.2% (26/27).Conclusion:Complex hyperextension tibial plateau fractures often combined with tibial bicondylar, medial tibial condyle or anterior tibial fractures. According to the morphological characteristics of complex hyperextension tibial plateau fractures, using appropriate surgical approach and internal fixation, repairing ligament soft tissue structure and reconstructing knee joint stability can achieve satisfactory results.

【Objective】 To generate secreted frizzled-related protein 4 (SFRP4) transgenic mice and analyze their biological properties. 【Methods】 We generated SFRP4 transgenic mice by DNA microinjection and detected the expression of SFRP4 by qRT-PCR and Western blotting. 【Results】 SFRP4 transgenic mice were successfully generated by DNA microinjection. The expression of SFRP4 was dramatically increased in transgenic mice liver compared with that of wide type. 【Conclusion】 The transgenic mice model of SFRP4 was successfully established by DNA microinjection. It provides a good model for studying the function of SFRP4 and the mechanism of participating in metabolic diseases.

Objective:To discuss how to make the surgical strategy for tibial tubercle fracture associated with bicondylar tibial plateau fracture.Methods:Data of thirty-five patients of tibial tubercle fractures associated with bicondylar tibial plateau fractures who were treated from October 2014 to May 2018 were retrospectively analyzed. There were 26 males and 9 females with an average age of 37.6 years (range, 21-68 years). According to Schatzker classification in tibial plateau fracture, 16 cases were type V and 19 cases were type VI. According to the integrity of tibial tubercle fracture and cortical bone of the proximal tibia in bicondylar tibial plateau fracture, they were divided into four types: type A, tibial tubercle fracture fragment and cortical bone of the proximal tibia are both complete; type B, tibial tubercle fracture fragment is complete but cortical bone of the proximal tibia is comminuted; type C, tibial tubercle fracture fragment is comminuted but cortical bone of the proximal tibia is complete; type D, both of them are comminuted. The surgical approaches and fixation methods of all the tibial tubercle fractures were according to the four different types. There were 22 cases with type A and B that were treated via an anterolateral and a medial incision, 13 cases with type C and D were treated via an anterior midline and a medial incision. There were 4 cases belonging to type A fixed with lag screws singly, 18 cases with type B fixed with 1/4 tubular plates, 7 cases with type C and 6 cases with type D fixed by 1/4 tubular plates combined with lag screws.Results:Thirty-five patients were followed up for 16.8 months (range, 12-24 months). All fractures healed with an average time of 4.7 months (range, 3-6 months). Loss of reduction didn’t occur in 34 cases except one. According to Rasmussen radiographic evaluation, the average score was 14.1 (range, 10-18) and clinical outcomes were rated with excellent in 11 cases, good in 19, fair in 5. The excellent and good rate was 85.7% (30/35) . The mean Hospital for Special Surgery (HSS) scores of all cases were 86.8 (range, 64-98) and the functional scores were excellent in 22 cases, good in 10 cases and fair in 3 cases with the excellent and good rate of 91.4% (32/35) . Surgical complications included fat liquefaction in 2 cases, superficial wound infection in 1, loosening of implant in 1and traumatic arthritis in 1.Conclusion:This kind of tibial tubercle fracture associated with bicondylar tibial plateau fracture is rare and special. Therefore, the preoperative plan should be made by considering the morphological features of the tibial tubercle fragments and the cortical bone of the proximal tibia. The middle longitude approach is the best way to expose tibial tubercle fragments which should be fixed with 1/4 tubularplate and/or lag screws.

Objective: To explore the clinical features and treatment strategies of tibial plateau fractures sustained with hyperextension varus. Methods: Data of 11 patients of tibial plateau fractures with hyperextension varus treated from January 2008 to November 2017 were retrospectively analyzed. There were 7 males and 4 females with an average age of 41.2 years old (range, 25-67 years). Injuries were caused by falling down in 7 cases, traffic accident in 3 cases, and falling from height in 1 case, respectively. On the basis of Luo's three columns classification in tibial plateau, there were 9 cases of medial column fracture and 2 cases of medial combined with posterior column fracture. Six cases were concomitant with fibular head fracture and 2 cases with the injury of common peroneal nerve. Preoperative magnetic resonance imaging showed that there were anterior cruciate ligament injury in 3 cases, posterior cruciate ligament injury in 4 cases, medial meniscus injury in 5 cases, lateral meniscus injury in 3 cases, medial collateral ligament injury in 6 cases, iliotibial band injury in 2 cases and posterolateral complex injury of the knee joint in 9 cases, respectively. All tibial plateau fractures were treated firstly by open reduction and internal fixation via medial approach of the knee. The medial meniscuses and collateral ligaments were explored, in which of them there were 2 medial meniscuses with the marginal tear been sutured simultaneously. Then the knee joints which were still unstable after the examination of stable tests in 6 cases with posterolateral complex injuries were repaired surgically via lateral approach. Fibular head fractures were fixed with anchor nails or cannulated screws in 6 cases. The ruptured posterior cruciate ligaments in 2 cases were reconstructed with autologous tendon transplantation under endoscopy. Results: All the patients were followed up for an average period of 16.2 months (range, 12-22 months). All fractures were healed in 10-20 weeks with an average time of 16.5 weeks. The range of extension of the affected knee joint in all patients was 0° and the average flexion was 135° (range, 120°-145°) one year after surgery. The average flexion of affected knee in 4 cases which were only treated with the tibial plateau fracture without the mild ligament injuries was 137° (range, 132°-145°) and the average flexion of affected knee in 7 cases who were treated with tibial plateau fracture and severe posterolateral complex included posterior cruciate ligaments completely broken with reconstruction was 132° (range, 120°-140°). According to Rasmussen radiographic evaluation, the average score of all patients was 16.3 (range, 14 to 18) and clinical outcomes were rated with excellent in 10 cases and good in 1. The excellent and good rate was 100% (11/11). The mean of the hospital for special surgery (HSS) score was 86.7 (range, 79-96) and the functional scores were excellent in 9 cases, good in 2 cases thus the excellent and good rate was 100% (11/11). Both varus stress test 30° and dial test were positive in one case considered for the ligament laxity postoperatively who didn’t accept further treatment and the stabilization tests were negative in the other 10 cases. There were no intraoperative complications in all patients such as neurovascular injury. No incision infection, failure of the implants and fracture nonunion occurred postoperatively. Traumatic arthritis of the affected knee occurred one year after surgery in 1 case who had no obvious pain after treated with oral medicine. Conclusion The hyperextension varus injuries of the knee are rare clinically. The posterolateral complex should be evaluated thoroughly for this injury pattern. If it's necessary, the posterolateral structures must be repaired surgically after the tibial plateau fractures are fixed.

Objective To explore the guiding significance of posterior tibial plateau partition for the selection of surgical approach in treatment for posterior column fracture.Methods From June 2008 to May 2015,46 patients with posterior column fractures of tibial plateaus treated were retrospectively analyzed.There were 31 males and 15 females with an average age of 35.1±12.8 years old (range,19-62 years).Nineteen patients were left side and twenty-seven patients were right side.Injury was caused by traffic accident in 27 cases,falling from bicycle in 12 cases and falling from height in 7 cases.On the basis of the posterior condyle with anatomical structure in tibia1 plateau,the posterior column was divided into four parts.All fractures were treated via the optimal approach based on the location of them.The posteromedial approach was used with fractures in zone 1 and 2,posterolateral approach used in zone 3,lateral approach via the fibular head osteotomy was used in zone 4 and combined approaches were used in multiple zones.All the fractures involved the posterior column were treated by anatomical reduction and fixation with plates and screws under direct vision.Results All the patients were followed up with an average of 15.5±3.7 months (range from 12 to 24 months).The healing time of all patients was 11-18 weeks,with an average time of 14.6±2.3 weeks.According to Rasmussen radiographic evaluation,the average score was 15.1 (range from 11 to 18) and clinical outcomes were rated with "excellent" in 17 cases,"good" in 24 cases,"fair" in 5 cases.The excellent and good rate was 89.1％ (41/46).The mean HSS (the Hospital for Special Surgery) score of all patients at 12 months operatively were 86.7±8.6 (range from 67 to 98) and the functional scores were excellent in 25 cases,good in 17 cases and fair in 4 cases with the excellent and good rate was 91.3％ (42/46).The average range of motion in affected knee was 118°±13.7° (range from 0° to 135°) in 17 cases via posterolateral approach,123°±15.6° (range from 0° to 135°) in 18 cases via posteromedial approach,115°±16.7° (range from 0° to 130°) in 18 cases via combined posteromedial and posterolateral approaches and 124°±7.4° (range from 0° to 130°) in 4 cases via the fibular head osteotomy lateral approach.Complications included fat liquefaction in 1 case,anterior tibial artery spasm in 1 case and traumatic arthritis in 1 case.Conclusion The partition of posterior tibial plateau can be used to guide the surgical approach to the posterior column simply and accurately.For the fractures of isolated posterior column and posterior column mainly involved,the partition has a certain guiding significance.

Objective:To investigate the clinical application value of ultrasound in the diagnosis and differential diagnosis of Takayasu arteritis (TA ). Methods: A total of 39 suspected TA patients were examined by ultrasonography,erythrocyte sedimentation rate (ESR),C reactive protein (CRP)and CT angiography (CTA), and the ultrasound examination results were compared and analyzed with the final chinical diagnosis results. Results:Of the 39 cases of suspected TA patients which had been examined by ultrasound,33 cases were diagnosed as TA,2 cases were diagnosed as atherosclerosis (AS),2 cases were diagnosed as fibromuscular dysplasia (FMD) and 2 cases were diagnosed as thromboangiitis obliterans (TAO).Compared with final chinical diagnosis results, 1 FMD patient was misdiagnosed as TA,and the rest of the diagnostic results were consistent with the final chinical diagnosis results.Conclusion:Ultrasound examination can provide objective and accurate basis for the diagnosis and differential diagnosis of TA,and it is an effective method of imaging examination.