BACKGROUND:Bone defects are caused by many factors,such as inflammation,tumor,trauma or bone diseases.Erythropoietin can promote the differentiation of mesenchymal stem cells into osteoblasts and osteoclasts and act on vascular endothelial cells to induce angiogenesis and accelerate the repair of bone and cartilage defects.Erythropoietin is a growth factor with potential application in bone tissue engineering construction. OBJECTIVE:To expound the application and potential mechanism of erythropoietin in bone tissue engineering. METHODS:The first author searched the related articles published in CNKI,WanFang,VIP,and PubMed databases from 2004 to 2022 by computer.Search terms were"erythropoietin,bone defect,bone regeneration,angiogenesis,osteogenesis,osteoblast,osteoclast,bone tissue engineering"in Chinese and English.Finally,64 articles were included for review. RESULTS AND CONCLUSION:(1)Erythropoietin can directly act on osteoblasts and osteoclasts in the bone marrow microenvironment by promoting the differentiation of mesenchymal stem cells into osteoblasts,osteoclasts,adipocytes,nerve cells and stromal cells.The activation of Wnt/β-catenin,hypoxia-inducible factor 1α/vascular endothelial growth factor,p38 MAPK and EphrinB2/EphB4 signaling pathways mediates the osteogenic differentiation of mesenchymal stem cells.(2)Erythropoietin can not only regulate the production of erythrocytes to alter the oxygen-carrying capacity of blood but also stimulate vascular endothelial cells to promote angiogenesis.The new blood vessels can carry oxygen,nutrients,growth factors,and bone progenitor cells necessary for osteogenesis to the osteogenic site,thereby promoting bone formation and fracture healing.(3)Currently,erythropoietin is being used as a growth factor with osteogenic and angiogenic effects in various types of scaffold materials such as chitosan,polycaprolactone,bioceramics,and nanofibers through various drug delivery methods.Erythropoietin,along with other growth factors such as bone morphogenetic protein-2 and bone morphogenetic protein-9,has been applied to the surface of scaffold materials to participate in the repair of bone defects.Erythropoietin has demonstrated excellent practicality in the construction of new tissue-engineered bone and has potential clinical application value.

Objective To compare the efficacy of anterior-posterior and posterior-anterior screw fixation for posterior malleolar fractures surgery.Methods A retrospective analysis of 376 cases of posterior malleolar fractures treated with lag screws from January 2011 to October 2022 with more than 12 months of follow-up period was conducted.The patients were divided into two subgroups based on the thickness of the fracture fragment,with 167 cases in the small fracture subgroup having a fracture fragment thickness＜17 mm(screw thread length)and 209 cases in the large fracture subgroup having a fracture fragment thickness ≥ 17 mm.Each subgroup was further divided into anterior-posterior and posterior-anterior groups based on the direction of screw fixation in the posterior malleolar fracture surgery.In the small fracture subgroups,there were 74 cases in the anterior-posterior group and 93 cases in the posterior-anterior group.In the large fracture subgroup,there were 88 cases in the anterior-posterior group and 121 cases in the posterior-anterior group.The American Orthopaedic Foot and Ankle Society(AOFAS)ankle-hindfoot score was measured at the last follow-up.The displacement of the fracture fragment in the direction of the fracture line(Dn)and perpendicular to the fracture line(Dt)were measured on the first day after surgery and at the last follow-up,and the displacement of the fracture fragment was calculated,which was the difference between Dn+Dt at the last follow-up and Dn+Dt on the first day after surgery.Results On the first day after surgery,X-ray showed no significant difference in Dn and Dt between the anterior-posterior and posterior-anterior groups in both of the small and large fracture subgroups(P＞0.05).The entire group was followed up for 12-85 months,with an average of 19.3 months.In the small fracture subgroup,the displacement of the fracture fragment in the posterior-anterior group[(0.11±0.19)mm]was superior to that in the anterior-posterior group[(0.19±0.21)mm;P=0.011],and the AOFAS score was also superior to that in the anterior-posterior group[(80.2±8.4)points vs.(76.2±8.6)points,P=0.003].In the large fracture subgroup,there was no significant difference in fracture displacement between the posterior-anterior group[(0.11±0.18)mm]and the anterior-posterior group[(0.12±0.19)mm;P=0.630],and there was also no significant difference in AOFAS scores[(84.1±7.8)points vs.(82.8±7.6)points,P=0.246].Conclusions There is no significant difference in the reduction effect between anterior-posterior and posterior-anterior lag screw internal fixation for posterior malleolar fractures in trimalleolar fractures.For patients with fracture thickness＜17 mm,posterior-anterior fixation is superior to anterior-posterior fixation;for patients with fracture thickness ≥17 mm,there is no significant difference in the efficacy between anterior-posterior and posterior-anterior fixation.

With rapid development of information technology,blended teaching model has gradually become mainstream teaching model in most colleges and universities.How to evaluate students'learning effect and analyze factors that affect students'per-formance is a key research direction of this teaching model.Taking blended teaching of Medical Immunology course in Xinxiang Medical University as an example,this paper introduces implementation process and evaluation system of blended teaching,analyzes main factors affecting students'performance and learning effect,and focuses on discussing influence of formative evaluation and"flipped classroom"on students'academic performance.

Objective This study aimed to investigate the therapeutic efficacy of Sanjie Quban recipe in a keloid nude mice model and its impact on transforming growth factor-β 1(TGF-β1).Methods Keloid tissue after surgical resection was subcutaneously transplanted into the backs of healthy SPF BALB/C female nude mice,aged 6～8 weeks,and a keloid nude mice model was thus established.The mice were randomly divided into three groups,the Sanjie Quban recipe group,the Asiaticoside tablet group and the control gnup,with five in each group.They were respectively treated with Sanjie Quban recipe,Asiaticoside tablets,or sterile pure water.After 28 days of continuous gavage,the keloid tissue was exfoliated and weighed,and HE staining,Masson staining,and immunohistochemical staining for TGF-β1 were conducted.Differences in keloid weight between the three groups before and after treatment were compared,as were the differences in collagen fiber,fibroblast numbers,and TGF-β1 expression between the three groups after treatment.Results The difference in keloid weight before and after treatment in the Asiaticoside tablet group was greater than that of the control group,and the weight difference before and after treatment keloid treatment was the largest in the Sanjie Quban recipe group(P＜0.01).Compared with the control group,collagen fibers in the Sanjie Quban recipe group were looser and less numerous,and fibroblasts were decreased in number.The expression of TGF-β1 in the Sanjie Quban recipe group was decreased compared with that of the control group(P＜0.01).Conclusions Sanjie Quban recipe has certain therapeutic effects on keloids.The mechanism may involve reducing the expression of TGF-βl in keloid tissue and thereby reducing the proliferation of fibroblasts and the synthesis of extracellular matrix.This study provides experimental and theoretical bases for the clinical treatment of keloids with Chinese medicine.

Background Hand-arm vibration disease is harmful to human body, but there are no effective diagnosis and treatment so far, and current occupational exposure limits underestimate the health damage caused by high-frequency vibration exposure. Objective To evaluate and compare the damage to workers' peripheral circulation and peripheral nerve caused by different frequencies of vibration operation. Methods Drilling workers (n=187) from a mining company in Shandong Province and golf club head grinding workers (n=228) from a sports equipment factory in Guangdong Province were selected as study subjects. Hand symptoms were investigated. SV106 vibration meter was used to measure the target operation-associated vibration frequency spectrum. The 8 h energy-equivalent frequency weighted acceleration, cumulative vibration exposure level (CVEL), and the working age related to causing white finger in 10% of an exposed group were calculated. Result The study subjects were all male. More grinding workers reported hand symptoms than the drilling workers, e.g. peripheral circulation injury (52.6% vs 19.3%), peripheral nerve injury (71.5% vs 23.0%), hand stiffness (64.0% vs 7.0%), and deformed fingers (69.7% vs 4.3%) (all P<0.001). The main vibration frequencies of grinding operation (500-800 Hz) were much higher than those of drilling operation (125~160 Hz). CVEL and working age of vibration exposure showed a linear rising relationship with the cumulative prevalence rate of peripheral circulation and peripheral never injury, the fitting lines all showed good fitting effects (R²=0.812-0.988), and the slope of the fitting line of the grinding workers was larger than that of the drilling workers. The working age of vibration exposure associated with 10% cumulative prevalence of white finger was shorter in the grinding workers than in the drilling workers (6.81 years vs 10.27 years). According to the ISO prediction formula, the working age of vibration exposure was associated with 10% white finger prevalence shorter in the drilling workers than in the grinding workers (3.12 years vs 8.23 years). Conclusion Both the vibration exposure level and the prevalence of hand symptoms are high in two groups of workers with different vibration frequencies, and vibration exposure at a higher frequency tends to have severer damage to workers' hands.

Background Long-term exposure to hand-transmitted vibration can lead to hand-arm vibration syndrome, one manifestation of which is impaired peripheral blood circulation in the arms. Altered expressions of prostacyclin I₂ (PGI₂) and thromboxane A₂ (TXA₂) in blood may be one of the important mechanisms of vibration-induced hand-arm vibration syndrome. Objective To reveal the effects of rat tail vibration on the expressions of PGI₂ and TXA₂ in plasma, and to establish the correlation between the change of rat plasma PGI₂ to TXA₂ ratio and rat tail vibration. Methods Fifty SPF-grade male SD rats were randomly divided into five groups: control group, 1 d exposure group, 3 d exposure group, 7 d exposure group, and 14 d exposure group, with 10 rats in each group. The rats were placed in rat immobilizes on a immobilization table, and the rats' tails were connected to a shaker and fixed with medical tape. There was no overlap between the immobilizes and between the rats' tails by no contact between the immobilization table and the shaker. The exposure dose was 125 Hz, 5.9 m·s⁻², 4 h·d⁻¹, and the vibration direction was linear vertical vibration. Abdominal aortic blood was taken at the end of vibration exposure, and the expressions of PGI₂, TXA₂, and their hydrolysates 6-keto-prostaglandin F_1α (6-keto-PGF_1α) and thromboxane B₂ (TXB₂) were measured by enzyme-linked immunosorbent assay, and the 6-keto-PGF_1α/TXB₂ values were calculated. Spearman rank correlation was used to analyze whether the expression of vascular factors correlated with the accumulated time of vibration. Results The expression levels of plasma 6-keto-PGF_1α were (896.12±124.37), (1068.13±119.41), (1215.26±122.64), and (1317.94±106.54) ng·L⁻¹ in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, which were higher than that in the control group, (830.60±109.47) ng·L⁻¹ (P<0.001). The PGI₂ expression levels were (86.49±2.40), (107.90±2.65), (114.02±2.16), and (126.95±1.94) ng·L⁻¹ in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, all higher than (60.09±2.11) ng·L⁻¹ in the control group (P＜0.001). The expression levels of TXB₂ were (132.14±4.10), (145.52±4.09), (179.91±4.98), and (204.10±3.22) ng·L⁻¹ in the 1 d, 3 d, 7 d, and 14 d groups of rats, respectively, which were higher than that in the control group, (106.08±3.26) ng·L⁻¹ (P<0.001). The expression levels of plasma TXA₂ were (211.99±3.24), (236.33±3.88), and (245.45±4.23) ng·L⁻¹ in rats in the 3 d, 7 d, and 14 d groups, respectively, which were all elevated compared with (174.79±4.19) ng·L⁻¹ in the control group (P<0.001). Compared with the control group, the 6-keto-PGF_1α/TXB₂ values were decreased in the 7 d and 14 d groups (P<0.05). The 6-keto-PGF_1α, PGI₂, TXB₂, and TXA₂ expressions were positively correlated with vibration accumulation time (r=0.84, 0.84, 0.80, 0.84, P<0.001) and the 6-keto-PGF_1α/TXB₂ values were negatively correlated with vibration accumulation time (r=-0.24, P=0.003). Conclusion Local exposure of rat tail to vibration could increase the expressions of PGI₂ and TXA₂ in blood, and the elevated expressions show a dose-effect relationship with the duration of vibration exposure, but the PGI₂/TXA₂ tends to decrease with the accumulation of vibration exposure.

Background The metabolites and metabolic pathways of hand-arm vibration syndrome have not yet been elucidated. Objective To investigate the effect of local vibration on endogenous metabolites in rat serum by metabolomic analysis, to preliminarily explore the potential metabolic pathway of endogenous metabolites, so as to provide evidence for further research on the mechanism of hand-arm vibration syndrome. Methods Thirty-two SPF male SD rats, (211.3±11.1) g, 7−8 weeks of age, were selected and randomly divided into three groups: control group (14 rats, without vibration), 7 d vibration group (9 rats, continuously vibration for 7 d), and 14 d vibration group (9 rats, continuous vibration for 14 d). The vibration rats were vibrated every day for 4 h, the frequency weighted acceleration was 4.9 m·s⁻², the vibration frequency was 125 Hz, and the vibration direction was one-way vertical vibration. The control group had the same conditions except not contacting vibration. After the vibration exposure, the blood samples taken from the abnormal aorta of rats were collected, and the changes of rat serum metabolome were analyzed by ultra-performance liquid chromatography-tandem time-of-flight mass spectrometry. Principal components analysis (PCA) was used to explore changes in rat serum metabolic profile, and orthogonal partial least squares-discriminant analysis (OPLS-DA) was used to screen out differential metabolites. Combined with online databases, a metabolic pathway enrichment analysis of differential metabolites was performed. Results The PCA analysis showed that compared with the control group, the rat serum metabolic profiles in the 7 d group and the 14 d group were clearly differentiated, and the rat serum metabolic profiles in the 7 d group and the 14 d group partially overlapped. The OPLS-DA analysis showed significant differences between groups. The main parameters were: model interpretation rate R²Y=0.914, model predictive ability Q²=0.58. The OPLS-DA analysis screened out 26 and 119 differential metabolites from the 7 d group and the 14 d group respectively, and there were 24 common differential metabolites between the 7 d group and the 14 d group. The metabolomic pathway analysis showed that local vibration-induced changes in rat serum metabolism were mainly related to arachidonic acid metabolism in the 14 d group, among which the metabolites with significant effects were arachidonic acid, prostaglandin E₂, and prostaglandin D₂. Conclusion Local vibration could affect the normal metabolism in rats, and the metabolic pathway with significant influence is arachidonic acid metabolism after a 14 d exposure and the involved metabolites are arachidonic acid, prostaglandin E₂, and prostaglandin D₂.

Objective:To analyze the changes in T lymphocyte subsets, B lymphocytes and NK cells in children with active tuberculosis (TB) and their clinical significance.Methods:T lymphocyte subsets, B lymphocytes and NK cells in peripheral blood samples of 106 patients with acute TB (TB group) and 106 healthy children (healthy control group) were detected by flow cytometry and compared between different groups.Results:The percentages of CD3 + T, CD4 + T and NK cells as well as the CD4 +/CD8 + T cell ratio were significantly lower in the TB group than in the healthy control group ( Z=-3.783, P=0.000; Z=-5.401, P=0.000; Z=-3.434, P=0.001; Z=-2.014, P=0.044). The percentages of double negative T (DNT) and B cells in the TB group were significantly higher than those in the healthy control group ( Z=2.765, P=0.006; Z=6.880, P=0.000). No significant difference in the percentage of CD8 + T or double positive T (DPT) cells was observed between the two groups ( P>0.05). The expression of peripheral lymphocyte subsets varied in TB children of different age groups (0-<3, 3-<6, 6-<10 and 10-<16 years old). There were significant differences in CD3 + T, DNT and B cells among the four age groups ( H=10.081, P=0.018; H=14.583, P=0.002; H=8.498, P=0.037). The percentage of CD4 + T cells was significantly lower in children with extrapulmonary TB than in those with pulmonary TB ( Z=-3.068, P=0.002). No statistically significant difference in other lymphocyte subsets was found between children with extrapulmonary and pulmonary TB ( P>0.05). Conclusions:Tuberculosis could lead to immune dysfunction in children. Dynamic monitoring of the changes in peripheral lymphocyte subsets in children with TB could be conducive to better assessment of immune status and providing personalized treatment.

Objective:To compare the short-term outcomes of femoral neck system (FNS) and dynamic hip screw (DHS) in the treatment of femoral neck fractures.Methods:A retrospective analysis was performed of the 105 patients with fresh femoral neck fracture who had been treated by FNS fixation from September 2019 to October 2020 or by DHS fixation from January 2018 to October 2020 at Department of Orthopaedics, The Third Hospital Affiliated to Peking University. In the FNS group of 54 cases, there were 18 males and 36 females with a mean age of (60.7±15.2) years; in the DHS group of 51 cases, there were 14 males and 37 females with a mean age of (63.3±13.2) years. The 2 groups were compared in terms of hospital stay, operation time, intraoperative blood loss, incision length, intraoperative fluoroscopy frequency, qualify of reduction, and femoral neck shortening length, Harris hip score and complications at the last follow-up.Results:The 2 groups were comparable due to insignificant differences in their preoperative general data or follow-up time ( P>0.05). In the FNS group, the median operation time [45.0 (40.0, 59.0) min], intraoperative blood loss [30.0 (20.0, 50.0) mL], incision length [4.0 (4.0, 5.0) cm], intraoperative fluoroscopy frequency [10.5 (9.0, 12.0) times] and hospital stay [2.0 (2.0, 4.0) d] were significantly superior to those in the DHS group [72.0 (55.0, 89.0) min, 50.0 (30.0, 50.0) mL, 7.0 (6.0, 8.0) cm, 18.0 (15.0, 19.0) times, and 3.0 (3.0, 6.0) d] (all P<0.05). There were no statistical differences between the 2 groups in quality of reduction, length of femoral neck shortening, failure rate of internal fixation or Harris hip score at the last follow-up ( P>0.05). There were no such surgical complications as deep infection or femoral head necrosis in either of the 2 groups. Conclusions:In the fixation of femoral neck fractures, both FNS and DHS may lead to fine short-term outcomes. However, compared with DHS, FNS exhibits advantages of simplicity, minimal invasion, less surgical trauma and intraoperative fluoroscopy frequency, and reduced operation time and hospital stay.

Objective: To identify the risk factors for failure of internal fixation with proximal femoral nail antirotation (PFNA) for reverse intertrochanteric hip fractures. Methods: A retrospective study was conducted of the 45 patients with reverse intertrochanteric hip fracture who had been treated with PFNA fixation from January 2006 through January 2018 at the Department of Traumatic Orthopaedics, The Third Affiliated Hospital to Peking University. They were 19 males and 26 females, aged from 19 to 97 years (average, 71.9 years). According to the AO/OTA classification, there were 7 cases of type 31-A3.1, 4 cases of type 31-A3.2 and 34 cases of type 31-A3.3. Fracture healing was judged according to the X-ray at the time of last follow-up. The patients were assigned into a healed group and a failed group. The 2 groups were compared in terms of gender, age, body mass index (BMI), mechanism of injury, AO classification, type of main fracture line, reduction method, reduction quality, status of lateral femoral wall and tip-apex distance. A multivariate logistic regression model was designed to analyse the dependent variable 'implant failure’ with a set of independent variables as risk factors. Results: The 45 patients were followed up for 12 to 62 months (average, 28.4 months). Implant failure was observed in a total of 6 patients (13.3%), 3 of whom had helical blade perforation, 2 main screw breakage, and one cut-out of helical blade. The single factor analysis revealed significant differences in reduction quality and type of main fracture line between the patients with successful fixation and those with failed fixation (P<0.05). The multiple logistic regression analysis identified poor reduction quality (OR=30.809, 95%CI: 1.052~902.298, P=0.047) and a transverse fracture line (OR=25.639, 95%CI: 1.636~401.917, P=0.021) as risk factors for implant failure. Conclusion Poor reduction quality and a transverse fracture line may be predictors of implant failure in reverse intertrochanteric hip fractures treated with PFNA fixation.