BACKGROUND:The treatment of distal tibial fractures with soft tissue injury has always been challenging,and the new retrograde tibial nailing is a new choice.Up to now,there were few reports on the biomechanical properties between the new retrograde tibial nailing,anterograde intramedullary nailing and supercutaneous locking plate. OBJECTIVE:To explore the biomechanical stability of new retrograde tibial nailing,antegrade intramedullary nailing and supercutaneous locking plate in the treatment of distal tibial fractures with soft tissue injury using finite element analysis so as to offer a scientific foundation for clinical application. METHODS:The finite element model of transverse distal tibia fracture was established by relevant software utilizing the CT data of the tibia from a 42-year-old healthy male.Retrograde tibial nailing,antegrade intramedullary nailing and supercutaneous locking plate finite element models were assembled under the principle of fracture fixation.Finally,meshing,applying loads,and data processing were accomplished with the ANSYS 2019 software.Moreover,the stress distribution and displacement of the tibia and internal fixation of each model were compared. RESULTS AND CONCLUSION:(1)The displacement of fracture end in the three groups increased with the increase of load.In all mode loads,the average displacement of the fracture end was the least in the retrograde tibial nailing group,followed by the supercutaneous locking plate group,and the highest in the antegrade intramedullary nailing group.At 800 N vertical load,the displacement difference of the fracture end was statistically significant(P<0.05).There was no statistical significance in other load modes.(2)Under different loads,the tibial stress in the three groups was the highest in the middle of the tibia,and gradually decreased to the proximal and distal ends.The stress distribution of the tibial shaft was the highest in the retrograde tibial nailing group,followed by the supercutaneous locking plate group,and the least in the antegrade intramedullary nailing group.(3)Under different loads,the stress of the tibial stress raiser in the three groups was significantly higher in the supercutaneous locking plate group than in the other two groups,with statistical significance(P<0.05).(4)Under different loads,the stress of the fixators in the three groups was the largest in the supercutaneous locking plate group,followed by the retrograde tibial nailing group,and the minimum in the antegrade intramedullary nailing group.There were significant differences in the stress of fixator stress raiser among the three groups under different loading modes(P<0.05).(5)It is indicated that all three fixation methods have the good anti-rotation ability and axial stability.Retrograde tibial nail shows better biomechanical stability.

Objective:To investigate the cognition and learning habits of different types of postgraduates and evaluate learning effect and its potential risk factors on clinical epidemiology in a medical college, so as to provide relevant data for improving the teaching method and learning effect of clinical research methods for postgraduates.Methods:A cross-sectional study design was conducted to enroll all the postgraduates of Grade 2020 in a military medical school. A self-filled questionnaire was adopted to collect data. The discrepancy of cognition and learning habits between different types of postgraduates was evaluated by univariate analysis. Discussion was conducted to clarify the potential risk factors of learning effect. t tests or Mann-Whitney U tests were conducted to test the differences between groups for continuous variables. Chi-squared tests or McNemar tests were applied to evaluate the difference between groups for categorical variables. Results:A total of 652 postgraduate students were enrolled for analysis, including 409 master students (62.7) and 243 doctoral students (37.3). The proportion of doctoral students who have heard of clinical epidemiology ( χ2=19.99, P<0.001), who have learned clinical epidemiology ( χ2=9.20, P=0.002), who are interested in ( χ2=11.41, P=0.001) and think the course is important ( χ2=10.71, P=0.001), who previewed before class( χ2=11.21, P=0.001), reviewed after class ( χ2=3.29, P=0.001) and actively discuss in class ( χ2=11.64, P=0.001) is significantly higher than that of master students, the difference was statistically significance. The average score of all the postgraduates was (5.50±1.62) points before teaching and (7.47±1.90) points after teaching, the difference was statistically significant ( t=-23.49, P<0.001). After teaching, the grades of full-time students improved more than that of part-time graduate students, there was statistical significance in the master group ( t=4.41, P<0.001), while not in the doctor group ( t=0.94, P=0.351). Conclusions:The mastery of key points on clinical epidemiology have significantly improved after teaching among the postgraduates of different types. Different teaching methods and processes should be adopted to the variety of postgraduates according to their knowledge foundations and shortcomings. Besides, standardizing their learning habits are of certain significance to improve the learning effect.

BACKGROUND:The treatment of distal tibial comminuted fractures with soft tissue injury has always been challenging.The new retrograde tibial nailing and supercutaneous locking plate are important treatment methods,but their strain and stress shielding at the fracture end during different periods of fracture healing and different load conditions have not been reported. OBJECTIVE:To explore the biomechanical stability of retrograde tibial nailing and supercutaneous locking plate in different periods of fracture healing by finite element analysis to offer a scientific foundation for clinical application and rehabilitation exercise. METHODS:The finite element model of distal tibial comminuted fracture was established by utilizing the CT data of the tibia from a 40-year-old healthy male.Retrograde tibial nailing,supercutaneous locking plate,and callus models were assembled in accordance with the principle of fracture fixation.The finite element analysis was performed using ANSYS software to compare the displacement of the fracture end,the stress shielding of the tibia,the stress of the callus,and the stress distribution of the tibia and the fixation device during different periods of fracture healing. RESULTS AND CONCLUSION:(1)The relative displacement of the tibial fracture decreased gradually with the healing of the fracture,and the displacement decreased significantly after 3 months.At 0 and 1 months after operation,the vertical displacement and total displacement of the supercutaneous locking plate group were higher than those in the retrograde intramedullary nail group.The Z-axis displacement(horizontal medial and lateral displacement)of the two fixation methods was more obvious than the X-axis and Y-axis,and the Z-axis displacement of supercutaneous locking plate group was the most obvious.The maximum Z-axis displacement of the two fixation methods was located on the outside of the tibia,and the minimum displacement was located on the inside of the tibia.(2)The stress shielding rate at different periods of fracture healing gradually decreased with time.The stress shielding rate of the retrograde intramedullary nail was higher than that of the supercutaneous locking plate at different stages of fracture healing.After 3 months,the stress shielding rate of the supercutaneous locking plate was reduced to about 4%,and the stress shielding rate of the retrograde intramedullary nail was reduced to about 40%.(3)The stress of the stress concentration site of the callus in the two fixation methods increased with the increase of the load,and the stress of the callus in the supercutaneous locking plate group was always greater than that in the retrograde intramedullary nail group.The maximum stress distribution of the callus was approximately equally distributed among the two modes of fixation,both in the lateral portion of the tibia.(4)As the fracture healed,the maximum stress of the tibia in the two groups decreased gradually,and the stress in the supercutaneous locking plate group was always greater than that in the retrograde intramedullary nail group.The average stress of the maximum stress area of the tibia in the supercutaneous locking plate group under 1 500 N load was 285 MPa,while that in the retrograde intramedullary nail group was 26 MPa.(5)As the fracture healed,the stress of the fixation device in the two groups decreased gradually,and the stress in the supercutaneous locking plate group was significantly higher than that in the retrograde intramedullary nail group.After 3 months,the stress of the two fixation devices decreased significantly.(6)It is indicated that in the early stage of fracture healing,the strain on the fracture end in the retrograde intramedullary nail group is small,and the maximum stress of the tibia is moderate,allowing early loaded.The fractured ends in the supercutaneous locking plate group had too large strain and too large maximum stress of the tibia,which needed to be partially loaded under protection and could not be fully loaded.In the middle and late stages of fracture healing,the tibial retrograde intramedullary nail and the supercutaneous locking plate could be completely loaded,and the stress shielding rate of the supercutaneous locking plate was significantly lower than the tibial retrograde intramedullary nail.

The first bite syndrome is a rare maxillofacial pain syndrome easily ignored by clinicians. The pain caused by it not only makes it difficult for patients to eat and delays surgical wound healing, but also rises fear and anxiety of patients while they eat, which would severely reduce their life quality. There are few case reports about the first bite syndrome in China, and clinicians know little about it. Therefore, the early diagnosis and treatment of such a disease are important. In this review, we thoroughly reviewed the etiology and classification, pathogenesis, clinical manifestation, and current treatments of the first bite syndrome, aiming at providing some suggestions for clinicians.

Alanine-serine-cysteine transporter 2 (ASCT2) is reported to participate in the progression of tumors and metabolic diseases. It is also considered to play a crucial role in the glutamate-glutamine shuttle of neuroglial network. However, it remains unclear the involvement of ASCT2 in neurological diseases such as Parkinson's disease (PD). In this study, we demonstrated that high expression of ASCT2 in the plasma samples of PD patients and the midbrain of MPTP mouse models is positively correlated with dyskinesia. We further illustrated that ASCT2 expressed in astrocytes rather than neurons significantly upregulated in response to either MPP⁺ or LPS/ATP challenge. Genetic ablation of astrocytic ASCT2 alleviated the neuroinflammation and rescued dopaminergic (DA) neuron damage in PD models in vitro and in vivo. Notably, the binding of ASCT2 to NLRP3 aggravates astrocytic inflammasome-triggered neuroinflammation. Then a panel of 2513 FDA-approved drugs were performed via virtual molecular screening based on the target ASCT2 and we succeed in getting the drug talniflumate. It is validated talniflumate impedes astrocytic inflammation and prevents degeneration of DA neurons in PD models. Collectively, these findings reveal the role of astrocytic ASCT2 in the pathogenesis of PD, broaden the therapeutic strategy and provide a promising candidate drug for PD treatment.

Pulmonary fibrosis is a chronic， progressive and irreversible interstitial lung disease. At present， there is no specific drug for the treatment of pulmonary fibrosis， and many TCM monomers have potential therapeutic value for pulmonary fibrosis， among which flavonoids are the main representative. For example， total flavones of Astragalus memeranaceus and scutellarin can reduce inflammatory cell infiltration， lung injury and extracellular matrix （ECM） deposition by interfering with transforming growth factor-β1/drosophila MAD protein signaling pathway. Total flavonoids of Oxytropis falcata Bunge and salidroside can inhibit lung inflammation by mediating JAK/signal transduction and transcriptional activator signaling pathway， and prevent the epithelial interstitial transition （EMT） process. Quercetin and Ginkgo biloba leaf extract can reduce the apoptosis of macrophages by inhibiting the nuclear factor-κB signaling pathway and play an anti-pulmonary fibrosis role. Urushetin and proanthocyanidins can promote the morphological recovery of myofibroblasts and reduce ECM deposition through the phosphatidylinositol 3-kinase/protein kinase B/mammalian target protein of rapamycin signaling pathway. Naringin and luteolin can inhibit scorch death of macrophage and inflammation response， and improve lung function and lung tissue injury through NOD-like receptor heat protein domain related protein 3 signaling pathway. The ethanol extract of Phyllanthus emblica and calycosin can improve the inflammatory injury and fibrosis of lung tissue by activating the signaling pathway of nuclear transcription factor erythro2-related factor 2/antioxidant response element. Isogliquiritin can inhibit the phenotypic transformation of epithelial cells and reverse EMT progression by inhibiting extracellular signal-regulating kinase signaling pathway. In the future， scholars should consider developing appropriate drug carriers to improve their bioavailability and further study drug targets and pathways， to provide evidence for the development of traditional Chinese medicine monomers of flavonoids into clinical practice.

Depsides and depsidones have attracted attention for biosynthetic studies due to their broad biological activities and structural diversity. Previous structure‒activity relationships indicated that triple halogenated depsidones display the best anti-pathogenic activity. However, the gene cluster and the tailoring steps responsible for halogenated depsidone nornidulin ( 3) remain enigmatic. In this study, we disclosed the complete biosynthetic pathway of the halogenated depsidone through in vivo gene disruption, heterologous expression and in vitro biochemical experiments. We demonstrated an unusual depside skeleton biosynthesis process mediated by both highly-reducing polyketide synthase and non-reducing polyketide synthase, which is distinct from the common depside skeleton biosynthesis. This skeleton was subsequently modified by two in-cluster enzymes DepG and DepF for the ether bond formation and decarboxylation, respectively. In addition, the decarboxylase DepF exhibited substrate promiscuity for different scaffold substrates. Finally, and interestingly, we discovered a halogenase encoded remotely from the biosynthetic gene cluster, which catalyzes triple-halogenation to produce the active end product nornidulin ( 3). These discoveries provide new insights for further understanding the biosynthesis of depsidones and their derivatives.

Objective:To analyze the clinical features, treatment, and outcomes of fetal/neonatal atrial flutter (AFL) at the onset of the perinatal period to improve the management of this condition.Methods:This retrospective study analyzed the clinical data, treatment, and follow-up results of fetal/neonatal AFL cases transferred to Shanghai Children's Medical Center from November 2013 to August 2021. Clinical characteristics, cardioversion procedures, and outcomes were summarized. Descriptive method was used for statistical analysis.Results:A total of 21 fetuses/neonates presenting with AFL in the perinatal period were involved in this study, including 17 males and four females. Ten of them were born at full term, and 11 were preterms. All of the patients were delivered by cesarean section at 32 to 41 gestational weeks [ (36.6±1.9) weeks] with a birth weight of 2 130 to 4 450g [ (3 059±528) g]. Increased fetal heart rate was all detected after 32 weeks of gestation, and three of them were diagnosed with AFL by fetal echocardiography before being born. The heart rate remained elevated in all cases after birth. All were diagnosed as AFL based on an electrocardiogram on the day of birth, which showed a 2 to 6 over one ratio of atrioventricular conduction. Among the six cases of cardiac insufficiency and low blood pressure complicated by dyspnea and cyanosis, the symptoms were relieved in four cases after mask oxygenation and two cases after ventilation. Among the 21 cases, one was converted spontaneously to normal sinus rhythm and the other 20 recovered after medication or electrical cardioversion. Seven cases were initially treated by drug conversion with a success rate of 5/7 and hospitalized for 23 d (13-25 d). There was one with cardiac insufficiency before treatment and three newly developed cardiac insufficiency during treatment among the seven cases. Thirteen cases were offered electrical cardioversion initially, and the success rate of cardioversion was 12/13. There were five cases of cardiac insufficiency before treatment, while no new cases of cardiac insufficiency was reported during treatment. The duration of hospitalization was 11 d (9-14 d). Apart from one case, the rest 20 infants were followed up from one month to eight years old, and no recurrence was reported.Conclusions:For fetal/neonatal AFL with the onset during the perinatal period, the symptoms mainly manifest in late pregnancy. Its diagnosis depends on fetal echocardiography before birth or electrocardiogram after birth, and electrical cardioversion is a fast and effective measure. While the prognosis of perinatal-onset AFL is generally good.

Objective    To explore the safety and effectiveness of different interventional approaches for the treatment of patent ductus arteriosus (PDA) in children. Methods    The children (≤7 years) who underwent interventional treatment for PDA from 2019 to 2020 in our hospital were retrospectively included. The patients were divided into 3 groups according to the procedures: a conventional arteriovenous approach group, a simple venous approach group, and a retrograde femoral artery approach group. The clinical efficacy of the patients was compared. Results     A total of 220 patients were included. There were 78 males and 142 females, with an average age of 3.21±1.73 years, weight of 14.99±5.35 kg, and height of 96.19±15.77 cm. The average diameter of the PDA was 3.35±1.34 mm. A total of 85 patients received a conventional arteriovenous approach, 104 patients received a simple venous approach, and 31 patients received a retrograde femoral artery approach. The diameter of PDA in the retrograde femoral artery group was smaller than that in the other two groups (3.44±1.43 mm vs. 1.99±0.55 mm; 3.69±1.17 mm vs. 1.99±0.55 mm, P<0.001); the contrast medium usage [40 (30, 50) mL vs. 20 (20, 30) mL; 35 (25, 50) mL vs. 20 (20, 30) mL, P≤0.001] and operation time [32 (26, 44) min vs. 25 (23, 30) min; 29 (25, 38) min vs. 25 (23, 30) min, P<0.05] in the simple venous approach group were significantly less or shorter than those in the other two groups; the length of hospital stay of the conventional arteriovenous group was longer than that in the other two groups [3 (3, 5) d vs. 4 (3, 6) d; 4 (3, 5) d vs. 4 (3, 6) d, P<0.05]. There was no significant difference in postoperative complications. Conclusion    It is safe and effective to close PDA through simple venous approach. The retrograde femoral artery approach has the advantage of simplifying the surgical procedure for PDA with small diameters.

The causes of obstructive azoospermia are complex, mostly permanent, and it is very rare to return to normal without medication or surgery. This article analyzes the changes in the course of a patient with obstructive azoospermia without surgery and medication and the delayed return to normal sperm density. The reasons for its self-recovery: it might be related to asymptomatic epididymitis and ejaculatory duct cysts. The possibility of self-recovery in patients with obstructive azoospermia due to specific etiologies.