BACKGROUND:The elastic modulus of traditional bone implants is large and does not match the elastic modulus of human bone,which will cause a stress shielding effect and lead to bone resorption.The trabecular scaffold of the triply periodic minimal surface with radial gradient has elastic modulus matching with human cancellous bone,and its yield strength is greater than that of human cortical bone,which provides a new choice for the design of bone scaffold. OBJECTIVE:Triply periodic minimal surface structure with radial gradient was constructed by the implicit surface method.The sample was manufactured by laser selective melting technology,and the quasi-static compression test was carried out to obtain trabecular scaffolds with mechanical properties matching human bones. METHODS:Four types of the trabecular scaffolds of the triply periodic minimal surface with a radial gradient of G,I,P and D were established by the implicit surface method.Samples were manufactured by laser selective melting technology.We observed the surface morphology of the molded sample,evaluated the molding quality,conducted a quasi-static compression test,and evaluated the mechanical properties of the samples. RESULTS AND CONCLUSION:The quasi-static compression test results showed that compared with the four triply periodic minimal surface scaffolds,the platform stress of the G scaffold had less fluctuation and no failure or fracture,indicating that the G scaffold had the best plasticity.The mechanical properties of the G scaffolds with 45%,55%and 65%porosities were analyzed.It was found that the elastic modulus of G scaffolds with 55%porosity was within the range of elastic modulus of human cancellous bone(0.022-3.7 GPa),and the yield strength was close to the maximum yield strength of human cortical bone(187.7-222.3 MPa).In conclusion,G triply periodic minimal surface scaffold with 55%porosity can reduce the stress shielding effect,bear a higher body load,improve the stability of the implant,and prolong the service life of the implant.

BACKGROUND:Scaffold materials serve as platforms that provide space and structure,playing a crucial role in the regeneration of cartilage tissue.Scholars from around the world are exploring different approaches to fabricate more ideal scaffold materials. OBJECTIVE:To review the design principles and preparation methods of cartilage scaffolds,and to further explore the advantages and limitations of various preparation methods. METHODS:Literature searches were conducted on the databases of CNKI,WanFang Data,PubMed,and FMRS from 1998 to 2023.The search terms were"cartilage repair,cartilage tissue engineering,cartilage scaffold materials,preparation"in Chinese and English.A total of 57 articles were ultimately reviewed. RESULTS AND CONCLUSION:(1)The articular cartilage has a unique structure and limited self-repair capacity after injury.Even if self-repair occurs,the newly formed cartilage is typically fibrocartilage,which is far inferior to normal articular cartilage in terms of structure and mechanical properties.It is difficult to maintain normal function and often leads to degenerative changes.Currently,the design and fabrication of scaffold materials for cartilage repair need to consider the following aspects:biocompatibility and biodegradability,suitable pore structure and porosity,appropriate mechanical properties,and bioactivity.(2)Research on the preparation of cartilage scaffolds has made significant progress,continuously introducing new preparation methods and optimization strategies.These methods have their advantages and disadvantages,providing more possibilities for customized preparation and functional design of cartilage scaffolds according to specific requirements.

BACKGROUND:Bone formation is the process by which osteoblasts synthesize and secrete osteoid and promote its mineralization,which generally involves mechanical signal transduction.Osteoblasts are primarily regulated by mechanical factors such as gravity,compressive stress,tensile stress,fluid shear stress,and hydrostatic pressure in vivo,and different mechanical stimuli modulate the proliferation,differentiation,and apoptosis of osteoblasts through various mechanisms,including hormones,cytoskeletal proteins,and microRNAs.By clarifying the effects of biomechanical forces on osteoblasts,it provides ideas and a reference basis for the treatment of osteometabolic diseases involving osteoblasts. OBJECTIVE:To review the effects of different biomechanical forces on the biological characteristics of osteoblasts. METHODS:We conducted a literature search using PubMed,Web of Science,FMRS,CNKI,and WanFang databases for relevant publications published from 2000 to 2023,covering basic research and tissue engineering studies related to the effects of biomechanical forces on osteoblasts.Ultimately,a total of 70 articles were reviewed. RESULTS AND CONCLUSION:Different biomechanical forces have an impact on the biological characteristics of osteoblasts,including proliferation,differentiation,and apoptosis,and these effects are dependent on the intensity and duration of the applied force.Specifically,the effects are as follows:(1)Under microgravity conditions,osteoblast proliferation and differentiation are inhibited,resulting in a decrease in bone density and the development of osteoporosis.(2)Compared to microgravity,hypergravity has a promoting effect on osteoblast proliferation.(3)The effects of compressive stress on osteoblasts are dependent on the loading intensity and time.Appropriate compressive stress can promote osteoblast proliferation and differentiation,which is beneficial for bone tissue formation and repair,while excessive compressive stress can cause osteoblast apoptosis and bone tissue destruction.(4)The biological effects of different types of tensile stress on osteoblasts differ.Studies have shown that a strain rate within the range of 0-12%has a promoting effect on osteoblast proliferation.(5)Fluid shear stress can promote osteoblast proliferation and differentiation and enhance the bone-inducing effect of biomaterials.(6)Static hydrostatic pressure can affect the biological behavior of osteoblasts,including proliferation,differentiation,and apoptosis,and these effects are closely related to the time and intensity of the pressure.Understanding the effects of different biomechanical forces on osteoblasts is of great significance for a deeper understanding of bone growth and maintenance mechanisms.

BACKGROUND:Vertebral compression fracture is a common disease in the current orthopedic field.However,the occurrence of re-fracture in neighboring vertebrae after surgery is a problem that cannot be ignored,which has a serious impact on the normal life of patients. OBJECTIVE:The aim of this study is to establish four postoperative models with different recovery heights using computed tomography images.By using finite element analysis,we derived the stresses on the neighboring vertebrae at different recovery heights and further explored the importance of postoperative recovery of the height of the injured vertebrae. METHODS:A finite element model of the thoracolumbar spine(T11-L3)was established and validated,on the basis of which four postoperative finite element models of L1 with different recovery heights of 100%,80%,60%,and 40%were constructed,in which the cement capacity varied with the recovery height.The specific models are as follows:Model 1 was the postoperative model with normal recovery height,and the cement capacity was 8.3 mL.Model 2 was the postoperative model in which 20%of the anterior height of the L1 was removed and the posterior convexity angle became 10.41°,and the cement capacity was 6.9 mL.Model 3 was the postoperative model in which 40%of the anterior height of the L1 was removed and the posterior convexity angle became 20.17°,and the cement capacity was 4.7 mL.Model 4 was a postoperative model with 60%of the L1 anterior height removed and the posterior convexity angle changed to 28.85°,with a cement capacity of 3.6 mL.For evaluation of the postoperative model,we applied a moment of 7 Nm and an axial force of 500 N.The followings were recorded and analyzed:peak stresses in the L2 upper endplate and T12 lower endplate;peak stresses in the L2 and T12 cancellous bone. RESULTS AND CONCLUSION:(1)The highest peak stresses for each condition of the L2 upper endplate,T12 lower endplate,L2 cancellous bone,and T12 cancellous bone occurred in Model 1 and Model 4.In particular,the T12 lower endplate,except for the posterior extension condition,the anterior flexion,left and right lateral bending,and left and right rotation conditions all reached their highest peak stresses in Model 4,with stresses of 50.3,33.1,44.9,34.3,and 31.9 MPa.(2)Based on the peak stresses in the adjacent vertebral endplates and cancellous bone,after excluding Model 1 and Model 4,the minimum peak stresses for most of the conditions appeared in the Model 2,and the minimum peak stresses appeared in the Model 2 in 66.6%of the cases,especially in the upper endplates of the L2 and cancellous bone except for the posterior extension condition,the minimum peak stresses all appeared on the Model 2.(3)Therefore,controlling the recovery height at about 100%and 40%of the original height was a dangerous recovery height,which had a greater impact on the neighboring vertebrae.Controlling the recovery height at about 80%of the original height may be a more ideal choice.With a recovery height of about 80%of the original height,the adjacent vertebrae are subjected to less stress,thus reducing the risk of re-fracture of the adjacent vertebrae in the patient.

Objective:To explore the effect of tumor deposit (TD) on the prognosis of patients with stage Ⅲ colon cancer after radical resection.Methods:The clinicopathological data of patients with stage Ⅲ colon cancer after radical surgery at the Department of Gastrointestinal Surgery, Peking University People's Hospital from Jan to Dec 2015 were analyzed collected. Clinicopathological characteristics such as tumor location, degree of differentiation, mismatch repair status, lymphatic and venous invasion, and preoperative CEA and CA19-9 levels were used to study the effect of TD on the postoperative survival of patients.Results:Among the 155 patients with stage Ⅲ colon cancer, 37 (23.9%) had tumor deposits. The incidence of tumor deposits was higher in patients with intravascular tumor thrombus and preoperative serum CA19-9 elevation ( χ2=9.567, P=0.002; χ2=11.561, P=0.003); Patients with tumor deposits had worse overall survival and disease-free survival than those without cancer nodules (OS: P=0.029, DFS: P=0.025). Multivariate COX analysis found that tumor deposit was an independent risk factor for postoperative overall survival and disease-free survival ( HR=1.990, 95% CI: 1.032-3.835, P=0.040; HR=2.416, 95% CI : 1.205-3.820, P=0.009). Conclusions:Tumor deposit is an independent risk factor affecting postoperative overall survival and disease-free survival in patients with stage Ⅲ colon cancer. For patients with lymph node metastasis, incorporating TD into TNM staging can more accurately predict the postoperative prognosis.

【Objective】 To understand the current situation of blood components distribution in domestic prefecture-level blood stations through analyzing the components distribution data of 24 prefecture-level blood stations in China. 【Methods】 The data of components distribution of 24 blood stations from 2017 to 2020 as well as the data of blood deployment of 24 blood stations from 2019 to 2020 were collected and analyzed. 【Results】 From 2017 to 2020, positive annual growth in red blood cells, plasma and cryoprecipitate was observed in 22, 19 and 15 out of the 24 blood stations, and the annual growth median rate of above three components was 5.24%, 3.80% and 3.25%, respectively. Among the 24 prefecture-level blood stations, 23 carried out the preparation of cryoprecipitate. 【Conclusion】 The distribution of red blood cells, cryoprecipitate and plasma in prefecture-level blood stations is increasing year by year. However, there is a overstock of plasma, and most blood stations need blood employment.

Objective:To observe the clinical characteristics of esophageal reflux after total gastrectomy (ERATG), and to explore the mechanism of occurrence.Methods:Fourteen gastric cancer patients who underwent total gastrectomy were prospectively enrolled in this study. The postoperative symptoms were observed and recorded and 24 h MII-pH with pH monitoring was performed to investigate the characteristics of postoperative reflux.Results:After total gastrectomy patients were with different degrees of ERATG as heartburn, appetite loss, chest tightness and belching. The overall nature of ERATG is mainly weak acid, with a pH between 4 and 7. ERATG involved esophageal-jejunal anastomosis and a length of esophagus 7 cm above the anastomosis. Patients with typical reflux symptoms had a lower pH minimum in the upright position than those without typical symptoms[(4.76±0.71) vs.(5.68±0.37), t=2.866, P<0.05]. Patients with typical reflux symptoms had a higher frequency of reflux of mixed liquid and liquid-air reflux than those without typical symptoms[liquid(31.25±29.76) vs.(4.50±9.14), t=0.011, P<0.05; liquid-air(19.50±12.99) vs.(2.00±2.61), t=0.004, P<0.05]. Conclusion:ERATG is mainly a upward reflux of weakly acidic gas, with typical symptoms of heartburn, appetite loss, chest tightness and belching. Patients with typical symptoms usually have lower pH in the upright position.

Objective To investigate the influence of mismatch repair status on clinicopathological characteristics and prognosis in patients with colon cancer.Methods Patients who underwent radical excision for colon cancer between Nov 2012 and Mar 2016 at Peking University People's Hospital were enrolled.Clinicopathological data and prognosis were collected.Multivariate analysis were used to identify independent characteristics of MMR-deficient colon cancer.The influence of MMR-deficient on prognosis of colon cancer were analyzed through Kaplan-Meier curve.Results The overall rate of MMR-deficient in colon cancer was 17.1％ (51/299).Multivariate logistic regression analysis showed that low differentiation (OR =3.555,95％ CI:1.685-7.640,P ＜ 0.001),right-sided colon cancer (OR =5.645,95％ CI:2.483-14.715,P ＜ 0.001) and UICC Stage Ⅰ-Ⅱ (OR =4.099,95％ CI:1.863-9.840,P ＜0.001) were associated with MMR-deficient colon cancer.Conclusion Low differentiation,right-sided colon cancer and UICC Stage Ⅰ-Ⅱ were more common in MMR-deficient colon cancer.

Objective: To investigate the clinicopathologic and molecular features of the rare cribriform morular variant of papillary thyroid carcinoma (CMV-PTC). Methods: The clinicopathologic data of 10 patients with CMV-PTC were retrospectively reviewed. Immunohistochemical (IHC) staining was done using LSAB method. DNA sequencing for APC were applied using Sanger method. BRAF V600E mutation was examined using ARMS method. The cytological, morphological, IHC and molecular features were analyzed. Results: All patients were female at an average age of 27 years old. The tumors were mostly located in the right lobe of thyroid. Fine needle aspiration cytology was performed in three patients; two were diagnosed as suspicious for PTC and one as PTC. Nine tumors presented as solitary nodule and two as multiple nodules in both lobes. Infiltration was demonstrated in three cases. The average size was 2.6 cm. The neoplastic cells were arranged in papillary, cribriform, solid and glandular patterns, with rare or without colloid inside the lumen. The number of morula varied, ranging from zero to many. The neoplastic cells were variably enlarged, showing round, oval or spindle shape. Nuclear irregularity was identified as irregular membrane, nuclear grooves or pseudoinclusion, but no typical ground glass feature. Peculiar nuclear clearing could be observed in the morular cells. IHC staining showed the neoplastic cells were negative for thyroglobulin and p63, but positive for TTF1, cytokeratin 19 and estrogen receptor. Diffuse staining with cytokeratin was seen in the neoplastic cells and the morula. Specific cytoplasmic and nuclear staining of β-catenin was seen in the neoplastic cells but not the morula. Ki-67 proliferation index was 1%-30%. No recurrence or metastasis was observed. One patient was demonstrated to harbor both somatic and germline mutations of the APC gene, who was found to have adenomatous polyposis and her mother died of colonic carcinoma. No BRAF V600E mutation was detected. Conclusions CMV-PTC is rare and shows atypical cytological and clinicopathological features, and it is easily misdiagnosed.TG, TTF1, ER and β-catenin are specific IHC markers for CMV-PTC. The morula is negative for cytokeratin 19, in contrast to squamous metaplasia. Although CMV-PTC has indolent clinical behavior, a definite diagnosis is necessary to rule out the possibility of APC gene mutation and related extra-thyroidal neoplasm, such as FAP and Gardner syndrome.

OBJECTIVETo evaluate the effect of individualized scalp acupuncture base on location of brain function for motor dysfunction in stroke patients.

METHODSA total of 180 patients were randomly assigned into an individualized scalp acupuncture (ISA) group, a conventional scalp acupuncture (CSA) group and a rehabilitation group, 60 cases in each one. In the ISA group, we stimulated Sishencong (EX-HN 1), motor area and balance area, matched with pre-motor area for higher muscle tension, application area and's three-needle for involuntary motion, application area for poor motor coordination, forehead five-needle for cognitive disorder, sensory area for sensory disturbance. In the CSA group, the affected Dingnieqianxiexian (MS 6), Dingniehouxiexian (MS 7) and Zhenxiapangxian (MS 14) were selected. Rehabilitation was used during needle retained in the two groups. Simple rehabilitation was used in the rehabilitation group. All the treatment was given from Monday to Friday for 4 weeks, once a day for 20 times. Eight-week follow-up was applied. The Fugl-Meyer assessment (FMA) for motor function, modified Barthel Index (MBI) were used to evaluate clinical effect.

RESULTSAfter treatment and at follow-up, FMA and MBI scores increased compared with those before treatment in the three groups（all<0.01）, with significant differences among the three groups (all<0.000 1) and better results in the ISA group compared with those in the other two groups (<0.05,<0.01) at the two time points. The FMA and MBI scores in the CSA group were higher than those in the rehabilitation group after treatment and at follow-up (all<0.05).

CONCLUSIONThe individualized scalp acupuncture can improve motor dysfunction and self-care ability of daily life for stroke patients.