ω-transaminase (ω-TA) is a natural biocatalyst that has good application potential in the synthesis of chiral amines. However, the poor stability and low activity of ω-TA in the process of catalyzing unnatural substrates greatly hampers its application. To overcome these shortcomings, the thermostability of (R)-ω-TA (AtTA) from Aspergillus terreus was engineered by combining molecular dynamics simulation assisted computer-aided design with random and combinatorial mutation. An optimal mutant AtTA-E104D/A246V/R266Q (M3) with synchronously enhanced thermostability and activity was obtained. Compared with the wild- type (WT) enzyme, the half-life t_1/2 (35 ℃) of M3 was prolonged by 4.8-time (from 17.8 min to 102.7 min), and the half deactivation temperature (T¹⁰₅₀) was increased from 38.1 ℃ to 40.3 ℃. The catalytic efficiencies toward pyruvate and 1-(R)-phenylethylamine of M3 were 1.59- and 1.56-fold that of WT. Molecular dynamics simulation and molecular docking showed that the reinforced stability of α-helix caused by the increase of hydrogen bond and hydrophobic interaction in molecules was the main reason for the improvement of enzyme thermostability. The enhanced hydrogen bond of substrate with surrounding amino acid residues and the enlarged substrate binding pocket contributed to the increased catalytic efficiency of M3. Substrate spectrum analysis revealed that the catalytic performance of M3 on 11 aromatic ketones were higher than that of WT, which further showed the application potential of M3 in the synthesis of chiral amines.
Transaminases/chemistry* ; Molecular Docking Simulation ; Amines/chemistry* ; Pyruvic Acid/metabolism* ; Enzyme Stability

In unicompartmental replacement surgery, there are a wide variety of commercially available unicompartmental prostheses, and the consistency of the contact surface between the common liner and the femoral prosthesis could impact the stress distribution in the knee after replacement in different ways. Medial tibial plateau fracture and liner dislocation are two common forms of failure after unicompartmental replacement. One of the reasons is the mismatch in the mounting position of the unicompartmental prosthesis in the knee joint, which may lead to failure. Therefore, this paper focuses on the influence of the shape of the contact surface between the liner and the femoral prosthesis and the mounting position of the unicompartmental prosthesis on the stress distribution in the knee joint after replacement. Firstly, a finite element model of the normal human knee joint was established, and the validity of the model was verified by both stress and displacement. Secondly, two different shapes of padded knee prosthesis models (type A and type B) were developed to simulate and analyze the stress distribution in the knee joint under single-leg stance with five internal or external rotation mounting positions of the two pads. The results showed that under a 1 kN axial load, the peak contact pressure of the liner, the peak ACL equivalent force, and the peak contact pressure of the lateral meniscus were smaller for type A than for type B. The liner displacement, peak contact pressure of the liner, peak tibial equivalent force, and peak ACL equivalent force were the smallest for type A at 3° of internal rotation in all five internal or external rotation mounting positions. For unicompartmental replacement, it is recommended that the choice of type A or type B liner for prosthetic internal rotation up to 6° should be combined with other factors of the patient for comprehensive analysis. In conclusion, the results of this paper may reduce the risk of liner dislocation and medial tibial plateau fracture after unicompartmental replacement, providing a biomechanical reference for unicompartmental prosthesis design.
Arthroplasty, Replacement, Knee/methods* ; Biomechanical Phenomena ; Finite Element Analysis ; Humans ; Knee Joint/surgery* ; Knee Prosthesis ; Tibia/surgery*

Objective:To evaluate the value of modified gastroscopic laryngeal mask airway (LMA) for airway management under general anesthesia in the patients with liver cirrhosis undergoing endoscopic esophageal variceal ligation (EVL).Methods:Sixty-two American Society of Anesthesiologists physical status Ⅱor Ⅲ patients with liver cirrhosis of either sex, aged 25-64 yr, with body mass index of 18-30 kg/m 2, undergoing endoscopic EVL with general anesthesia, were divided into 2 groups ( n=31 each) using a random number table method: tracheal tube group (group T) and modified gastroscopic LMA group (group L). After induction of anesthesia, a tracheal tube was inserted in group T, and a modified gastroscopic LMA was inserted and the patients were mechanically ventilated to maintain P ETCO 2 at 30-40 mmHg in group L. Successful tracheal intubation or insertion of modified gastroscopic LMA, successful ligator insertion and duration of ligator insertion were recorded.The occurrence of intraoperative hypotension, bradycardia and hypoxemia and consumption of propofol and remifentanil were recorded.At 1 min after tracheal intubation or right placement of LMA (T 1), immediately after the ligator insertion (T 2) and at the end of operation (T 3), Peak (P peak) and mean (P mean) airway pressure were monitored, and airway leak pressure in group L was measured.The extubation time, duration of post-anesthesia care unit stay and bucking during extubation were recorded.The occurrence of sore throat and nausea and vomiting was recorded within 6 h after operation.Postoperative satisfaction scores of endoscopists and patients were also recorded. Results:Sixty-one patients were finally enrolled in the study, with 31 in group T and 30 in group L. Compared with group T, no significant changes were found in the success rate of tracheal intubation or LMA placement, success rate of ligator insertion, P mean at each time point, incidence of postoperative nausea and vomiting, and postoperative satisfaction score of endoscopists ( P>0.05), duration of the ligator insertion was significantly shortened, P peak at each time point was decreased, the incidence of intraoperative hypotension and bradycardia was decreased, the consumption of propofol and remifentanil was reduced, the incidence of bucking during extubation and postoperative sore throat was reduced, and extubation time and duration of post-anesthesia care unit stay was shortened, and satisfaction scores of patients were increased in group L ( P<0.05). No hypoxemia was found in two groups.Airway leak pressure was maintained at 24-26 cmH 2O at each time point in group L. Conclusions:Modified gastroscopic LMA can be safely and effectively used for airway management under general anesthesia in the patients with liver cirrhosis undergoing EVL.

Objective:To investigate the clinical outcomes of patients with intrahepatic cholangiocarcinoma (ICC) undergoing surgical resection.Methods:Patients who undergoing radical surgical resection for ICC from Jan 2015 to Apr 2021 at the Department of General Surgery, the First Affiliated Hospital of Anhui Medical University were included in this retrospective cohort study.Results:There were 67 patients in the final analysis, The median follow-up duration was 14 months (range: 1-60 months). Firty three patients (79.1%) had tumor recurrence, 52 patients (77.6%) died, Among them, 49 patients (73.1%) died from tumor recurrence. The 1-、2-、and 3-year accumulated disease-free and overall survival rate were 35.6%, 19.6%, 16.8% and 53.7%, 32.4%, 20.8%. respectively. The overall survival rate of the group without microvascular invasion was significantly better than those of the group with microvascular invasion ( χ2=5.916, P=0.015). CA19-9≥1 000 U/ml was the only independent risk factor for the disease-free survival. CA19-9≥1 000 U/ml、blood loss≥600 ml、microvascular invasion and tumor recurrence were the independent risk factors for the overall survival. Conclusion:For ICC patients with single tumor, when the tumor diameter is less than 5 cm and has no microvascular invasion, surgical resection is recommended, and a satisfactory prognosis could be achieved.

Objective:To investigate the clinicopathological characteristics and prognostic factors of Siewert Ⅱ and Ⅲ adenocarcinoma of esophagogastric junction (AEG).Methods:The retrospetcive cohort study was conducted. The clinicopathological data of 399 patients with AEG who were admitted to Peking University People′s Hospital from January 1998 to December 2015 were collected. There were 318 males and 81 females, aged 66(range, 19-87)years. Observation indicators: (1) clinicopathological characteristics of Siewert Ⅱ and Ⅲ AEG; (2) follow-up and survival; (3) prognostic factors analysis. Patients were followed up by telephone interview and outpatient examination to detect postoperative survival up to December 2018. Measurement data with normal distribution were represented as Mean±SD, and comparison between groups was conducted using the t test. Measurement data with skewed distribution were represented as M(range), and comparison between groups was conducted using the Mann-Whitney U test. Count data were described as absolute numbers, and comparison between groups was conducted using the chi-square test or Fisher exact probability. Kaplan-Meier method was used to draw survival curves and calculate survival rates. Log-rank test was used for survival analysis. Univariate and multivariate analyses were done using the COX proportional hazard model. Results:(1) Clinicopathological characteristics of Siewert Ⅱ and Ⅲ AEG. Of 399 patients, 198 cases were Siewert Ⅱ AEG and 201 cases were Siewert Ⅲ AEG. There were 130 cases undergoing transthoracic radical AEG surgery, 172 cases undergoing trans-abdominal proximal gastrectomy and 97 cases undergoing transabdominal total gastrectomy. The age, tumor diameter, cases with surgical method as transthoracic radical AEG surgery, transabdo-minal proximal gastrectomy and transabdominal total gastrectomy, the number of positive lymph nodes, cases in tumor TNM stage Ⅰ, Ⅱ, Ⅲ, Ⅳ were (65±10)years, (5.1±2.4)cm, 102, 68, 28, 17(range, 12?22), 20, 57, 117, 4 for patients with Siewert Ⅱ AEG, versus (62±12)years, (6.3±3.2)cm, 28, 104, 69,18(range, 14?27), 16, 41, 134, 10 for patients with Siewert Ⅲ AEG, showing significant differ-ences betweeen them ( t=2.83, ?3.82, χ2=66.97, U=17 407.05, 17 532.00, P<0.05). (2) Follow-up and survival. All 399 patients were followed up for 34(range, 2?160)months. The 5-year overall survival rate was 29.3% for patients with Siewert Ⅱ AEG, versus 37.0% for patients with Siewert Ⅲ AEG, showing no significant difference betweeen them ( χ2=1.46, P>0.05). The median survival time and 5-year overall survival rate were 29.0 months [95% confidence interval ( CI) as 23.4?34.6 months] and 22.9% for patients undergoing transthoracic radical AEG surgery, 43.0 months(95% CI as 33.9?52.1 months) and 34.7% for patients undergoing transabdominal proximal gastrectomy, 54.0 months (95% CI as 37.6?70.4 months)and 44.3% for patients undergoing transabdominal total gastrectomy, showing a significant difference in the survival among the 3 groups ( χ2=13.81, P<0.05). Of the 198 Siewert Ⅱ AEG patients, the 5-year overall survival rate was 24.6% for the 96 patients undergoing transabdominal surgery, versus 35.4% for the 102 patients undergoing transthoracic surgery, showing no significant difference in the survival between them ( χ2=3.10, P>0.05). Of the 201 Siewert Ⅲ AEG patients, the 5-year overall survival rate was 40.0% for the 173 patients undergoing transabdominal surgery, versus 16.1% for the 28 patients undergoing transthoracic surgery, showing a significant difference between them ( χ2=11.32, P<0.05). (3) Prognostic factors analysis. Results of univariate analysis showed that surgical method, pathological N staging, patholgical M staging were related factors for prognosis of Siewert Ⅱ and Ⅲ AEG ( hazard ratio=0.68, 1.25, 2.18, 95% CI as 0.54?0.86, 1.15?1.36, 1.28?3.73, P<0.05). Results of multivariate analysis showed that transthoracic approach, pathological stage N2?N3 and pathological stage M1 were independent risk factors for prognosis of Siewert Ⅱ and Ⅲ AEG ( hazard ratio=0.64, 1.25, 2.18, 95% CI as 0.51?0.80, 1.16?1.35, 1.28?3.70, P<0.05). Conclusions:Compared with Siewert Ⅲ AEG, Siewert Ⅱ AEG has a smaller tumor diameter, less positive lymph nodes, poorer prognosis. Transthoracic approach is preffered for the Siewert Ⅱ AEG. Transthoracic approach, pathological stage N2?N3 and pathological stage M1 are independent risk factors for prognosis of Siewert Ⅱ and Ⅲ AEG.

Objective To evaluate the clinical effects of short-term (3-6 months) and long-term (12 months) dual antiplatelet therapy (DAPT) after the implantation of coronary drug-eluting stents (DES). Methods The eligibilities of the patients included stable angina, acute coronary syndrome and silent ischemia. The lesions were in a native coronary vessel. The clinical observation endpoints were all-cause death, cardiogenic death, myocardial infarction, stroke, stent thrombosis, target lesion revascularization, severe bleeding, and true adverse clinical events. The clinical observation endpoints were all-cause death, cardiogenic death, myocardial infarction, stroke, stent thrombosis, target lesion revascularization, severe bleeding, and true adverse clinical events. By searching Pubmed, Chinese biomedical literature and other Chinese and English databases and manual search, qualified randomized controlled studies were evaluated and data were extracted for meta-analysis. Results A total of 12 randomized controlled studies were conducted. Detsky scores were all greater than 5 points. There were a total of 25949 patients in the study with a follow-up rate of 97.9%. There were no significantly different in all cause death (OR = 0.86，95%CI 0.71-1.05，P = 0.14), cardiac death (OR = 0.94，95% CI 0.70-1.25，P = 0.67), stent thrombosis (OR = 1.36，95%CI 0.94-1.98，P = 0.11), stroke (OR = 1.01，95%CI 0.71-1.42，P = 0.98), target lesion revascularization (OR = 0.121，95%CI 0.94-1.55，P = 0.14),and true adverse clinical events (OR = 0.98，95%CI 0.83-1.14，P = 0.75). The incident rate of myocardial infarction during the follow-up period was higher in the short-term group than in the long-term group (OR = 1.27, 95% CI 1.02-1.59, P = 0.04). The proportion of severe bleeding in the long-term group increased significantly (OR = 0.69, 95% CI 0.50-0.95, P = 0.02). Asian population studies showed that all-cause mortality was higher in the long-term treatment group than in the short-term group (OR = 0.72, 95% CI 0.53-0.97, P = 0.03), and there was no significant difference in severe bleeding between the two groups. Conclusion According to the defined clinical observation endpoints, the short-term dual antiplatelet effect is not inferior to the long-term group. Seven asian group studies have shown that the long-term group has high all-cause mortality. It can not rule out the deviation and/or population caused by the small sample size or individual variation. The results need to be further verified. This result can be used as a clinical warning to adjust the dual antiplatelet cycle based on the individualized risk of bleeding and coronary lesions.

Since December 2019, novel coronavirus pneumonia (NCP) has been reported in Wuhan, Hubei Province, and spreads rapidly to all through Hubei Province and even to the whole country. The virus is 2019 novel coronavirus (2019-nCoV), never been seen previously in human, but all the population is generally susceptible. The virus spreads through many ways and is highly infectious, which brings great difficulties to the prevention and control of NCP. Based on the needs of orthopedic trauma patients for emergency surgery and review of the latest NCP diagnosis and treatment strategy and the latest principles and principles of evidence-based medicine in traumatic orthopedics, the authors put forward this expert consensus to systematically standardize the clinical pathway and protective measures of emergency surgery for orthopedic trauma patients during prevention and control of NCP and provide reference for the emergency surgical treatment of orthopedic trauma patients in hospitals at all levels.

Glutamate decarboxylase, a unique pyridoxal 5'-phosphate-dependent enzyme, catalyzes α-decarboxylation of L-glutamate to γ-aminobutyrate. However, glutamate decarboxylase from different sources has the common problem of poor thermostability that affects its application in industry. In this study, proline was introduced at 13 different positions in glutamate decarboxylase by using the design strategy of homologous sequence alignment between Thermococcus kodakarensis and Lactobacillus brevis CGMCC No.1306. A mutant enzyme G364P with higher thermostability was obtained. Compared to the wild type, thermostability of the mutant G364P was significantly improved, the half-life time (t1/2) at 55 °C and the semi-inactivation temperature (T₅₀ ¹⁵) of the mutant G364P increased 19.4 min and 5.3 °C, respectively, while kcat/Km of the mutant enzyme remained nearly unchanged. Further analysis of their thermostability by molecular dynamics simulations were performed. The root mean square deviation of G364P and root mean square fluctuation in the loop region including G364 were lower than the wild type at 313 K for 10 ns, and G364P increased one hydrophobic interaction in the loop region. It proves that mutation of flexible 364-Gly to rigid proline endows glutamate decarboxylase with enhanced thermostability.
Glutamate Decarboxylase ; Glutamic Acid ; Lactobacillus brevis ; Molecular Dynamics Simulation ; Proline

OBJECTIVE: To investigate the effect of down-regulation of miR-205-5p on 3-bromopyruvate-induced apoptosis in human nasopharyngeal carcinoma CNE2Z cells. METHODS: Nasopharyngeal carcinoma CNE2Z cells were transfected with miR- 205-5p-mimic or miR-205-5p-inhibitor, treated with 80 μmol/L 3-bromopyruvate alone, or exposed to both of the treatments. The proliferation of the treated cells was examined with MTT assay, and early apoptosis of the cells was detected using a mitochondrial membrane potential detection kit (JC-1). DAPI fluorescence staining was used to detect morphological changes of the cell nuclei and late cell apoptosis; Annexin V-FITC/PI double staining was employed to detect the cell apoptosis rate. Western blotting was used to detect the expressions of Bcl-2, Bax, Mcl-1 and Bak proteins. RESULTS: Exposure to 3-bromopyruvate significantly inhibited the proliferation of CNE2Z cells, and increasing the drug concentration and extending the treatment time produced stronger inhibitory effects. Treatment with 80 μmol/L 3-bromopyruvate for 24, 48 and 72 h resulted in inhibition rates of (45.7±1.21)%, (64.4±2.02)% and (78.3±1.55)% in non-transfected CNE2Z cells, respectively; the inhibition rates were (27.7±1.04)%, (34.8±2.10)% and (44.3±1.57)% in the cells transfected with miR-205-5p-mimic, and were (80.5 ± 0.94)%, (87.9 ± 0.50)% and (93.8 ± 1.16)% in cells transfected with miR-205-5p-inhibitor, respectively. The results of mitochondrial membrane potential detection showed that the relative proportion of red and green fluorescence decreased significantly in miR-205-5p-inhibitor-transfected cells with 3-bromopyruvate treatment. Combined treatment of the cells with 3-bromopyruvate and miR-205-5p-inhibitor transfection obviously increased nuclear fragmentation and nuclear pyknosis and significantly increased cell apoptotic rate as compared with the two treatments alone ( < 0.01), causing also decreased expressions of Bcl-2 and Mcl-1 proteins and increased expressions of Bax and Bak proteins. CONCLUSIONS Inhibition of miR-205-5p enhances the proapototic effect of 3-bromopyruvate in CNE2Z cells possibly in relation to the down-regulation of Mcl-1 and Bcl-2 and the up-regulation of Bak and Bax proteins.

Chiral amines are important building blocks for the synthesis of pharmaceutical products and fine chemicals. Highly stereoselective synthesis of chiral amines compounds through asymmetric amination has attracted more and more attention. ω-transaminases (ω-TAs) are a promising class of natural biocatalysts which provide an efficient and environment-friendly access to production of chiral amines with stringent enantioselectivity and excellent catalytic efficiency. Compared with (S)-ω-TA, the research focused on (R)-ω-TA was relatively less. However, increasing demand for chiral (R)-amines as pharmaceutical intermediates has rendered industrial applications of (R)-ω-TA more attractive. Improving the thermostability of (R)-ω-TA with potential biotechnological application will facilitate the preparation of chiral amines. In this study, the dynamic surface loop with higher B-factor from Aspergillus terreus (R)-ω-TA was predicted by two computer softwares (PyMOL and YASARA). Then mutant enzymes were obtained by deleting amino acid residues of a dynamic surface loop using site-directed mutagenesis. The results showed that the best two mutants R131del and P132-E133del improved thermostability by 2.6 ℃ and 0.9 ℃ in T₅₀¹⁰ (41.1 ℃ and 39.4 ℃, respectively), and 2.2-fold and 1.5-fold in half-life (t1/2) at 40 ℃ (15.0 min and 10.0 min, respectively), compared to that of wild type. Furtherly, the thermostability mechanism of the mutant enzymes was investigated by molecular dynamics (MD) simulation and intermolecular interaction analysis. R131del in the loop region has lower root mean square fluctuation (RMSF) than the wild type at 400 K for 10 ns, and mutant enzyme P132-E133del increases four hydrogen bonds in the loop region. In this study, we obtain two stability-increased mutants of (R)-ω-TA from A. terreus by deleting its dynamic surface loop and also provide methodological guidance for the use of rational design to enhance the thermal stability of other enzymes.