O-acetyl-L-homoserine (OAH) is a promising platform compound for the production of L-methionine and other valuable compounds, while its low yield and low conversion rate limit the industrial application. To solve these problems, we constructed a strain for high OAH production with the previously constructed L-homoserine producer Escherichia coli HS33 as the chassis by systematic metabolic engineering. Firstly, PEP accumulation, pyruvate utilization, and OAH synthesis pathway (overexpressing aspB, aspA, and thrA^C1034T) were enhanced to obtain an initial strain accumulating 13.37 g/L OAH. Subsequently, the co-factor synthesis genes were integrated to supply reducing power and energy, which increased the yield to 15.79 g/L. The OAH yield of the engineered strain OAH28 was further increased to 17.49 g/L by strengthening the acetic acid reuse pathway, improving the supply of acetyl-CoA, and regulating the expression of MetX from different sources. Finally, in a 5 L fermenter, OAH28 achieved an OAH titer of 47.12 g/L, with a glucose conversion rate of 32% and productivity of 0.59 g/(L·h). The results lay a foundation for increasing the OAH production by metabolic engineering and give insights into the industrial production of OAH.
Metabolic Engineering/methods* ; Escherichia coli/genetics* ; Homoserine/biosynthesis* ; Fermentation

Synthetic biology is a crucial tool for the development of the bio-industry and bio-economy, representing a significant aspect of new quality productive forces. As a core course for graduate students in bioengineering, Synthetic Biology plays a vital role in ensuring the supply of essential talents for the development of the bio-industry in the new era. To better serve regional economic development and provide high-level talents for China's progress in the bio-industry, we analyzed typical issues encountered in the past teaching activities, set up a multi-disciplinary teaching team, optimized the course contents, adjusted the teaching mode, and mobilized students' learning interest. With the application of scientific research project as the starting point, we guided students to think and discuss deeply through the simulation of application writing and project defense, which improved students' critical thinking and innovative thinking. With industrialization as a focus, we explored a new training model combining production, education, and research through the joint practice base of the university and enterprises introduced typical cases of biomanufacturing to encourage students to engage in scientific research. The teaching reform significantly enhances the comprehensive abilities and national sentiments of graduate students. This paper hopes to serve as a reference for colleagues engaged in teaching in this field.
Synthetic Biology/education* ; Teaching ; China ; Humans

Objective:To examine the therapeutic strategy and its impacting factors by analyzing the perioperative outcomes of total thoracoscopic repeat mitral valve surgery under moderate hypothermia-induced ventricular fibrillation with cardiopulmonary bypass.Methods:This study is a retrospective case series. Totally 63 patients who underwent repeat mitral valve surgery by the same surgeon from January 2021 to December 2023 in Department of Cardiovascular Surgery, the First Medical Center of People′s Liberation Army General Hospital were retrospectively enrolled. There were 28 males and 35 females with an age of (58.3±15.9) years (range: 13 to 84 years). Surgery was performed using a totally thoracoscopic approach under moderate hypothermia-induced ventricular fibrillation. Mitral valvuloplasty was completed in 32 cases and mitral valve replacement in 31 cases. Preoperative baseline data and perioperative outcomes of the patients were collected and Logistic regression was used to analyze independent influencing factors of premature ventricular contractions in the early postoperative period.Results:The intraoperative cardiopulmonary bypass time was (191.5±50.9) minutes (range: 95 to 286 minutes), and the hypothermic ventricular fibrillation time was (99.0±39.8) minutes (range: 34 to 203 minutes). The anal temperature before the start of cardiopulmonary bypass was (36.3±0.5) ℃ (range: 35.2 to 38.0 ℃), the lowest intraoperative anal temperature was (27.3±1.3) ℃(range: 23.7 to 30.1 ℃), and the anal temperature at the time of the cessation of cardiopulmonary bypass was (36.3±0.4) ℃ (range: 35.2 to 37.0 ℃), and excessive rewarming was observed in 33 cases. Six cases applied the artificial heart assist device. Seventeen cases developed premature ventricular contractions in the early postoperative period. Two cases developed neurologic complications. Five cases developed respiratory complications. One case developed urological systemic complications. Six cases were mechanically ventilated for more than 3 days, and the duration of ICU stay in 16 cases was more than 3 days and the postoperative discharge time of ( M(IQR)) 8.0 (3.5) days (range: 3 to 26 days). Two cases died or were discharged voluntarily. Logistic regression results showed that persistent preoperative atrial fibrillation ( OR=11.424, 95% CI: 1.477 to 144.564, P=0.033) and excessive rewarming ( OR=15.249, 95% CI: 1.357 to 279.571, P=0.038) were independent risk factors for the appearance of premature ventricular contractions in the early postoperative period. Conclusions:The technique of total thoracoscopic surgery under induced moderate hypothermic ventricular fibrillation with cardiopulmonary bypass could be applied to repeated mitral valve surgeries with less trauma and faster recovery. Persistent preoperative atrial fibrillation and excessive rewarming are independent risk factors for the occurrence of premature ventricular contractions in the early postoperative period.

Objective:To examine the therapeutic strategy and its impacting factors by analyzing the perioperative outcomes of total thoracoscopic repeat mitral valve surgery under moderate hypothermia-induced ventricular fibrillation with cardiopulmonary bypass.Methods:This study is a retrospective case series. Totally 63 patients who underwent repeat mitral valve surgery by the same surgeon from January 2021 to December 2023 in Department of Cardiovascular Surgery, the First Medical Center of People′s Liberation Army General Hospital were retrospectively enrolled. There were 28 males and 35 females with an age of (58.3±15.9) years (range: 13 to 84 years). Surgery was performed using a totally thoracoscopic approach under moderate hypothermia-induced ventricular fibrillation. Mitral valvuloplasty was completed in 32 cases and mitral valve replacement in 31 cases. Preoperative baseline data and perioperative outcomes of the patients were collected and Logistic regression was used to analyze independent influencing factors of premature ventricular contractions in the early postoperative period.Results:The intraoperative cardiopulmonary bypass time was (191.5±50.9) minutes (range: 95 to 286 minutes), and the hypothermic ventricular fibrillation time was (99.0±39.8) minutes (range: 34 to 203 minutes). The anal temperature before the start of cardiopulmonary bypass was (36.3±0.5) ℃ (range: 35.2 to 38.0 ℃), the lowest intraoperative anal temperature was (27.3±1.3) ℃(range: 23.7 to 30.1 ℃), and the anal temperature at the time of the cessation of cardiopulmonary bypass was (36.3±0.4) ℃ (range: 35.2 to 37.0 ℃), and excessive rewarming was observed in 33 cases. Six cases applied the artificial heart assist device. Seventeen cases developed premature ventricular contractions in the early postoperative period. Two cases developed neurologic complications. Five cases developed respiratory complications. One case developed urological systemic complications. Six cases were mechanically ventilated for more than 3 days, and the duration of ICU stay in 16 cases was more than 3 days and the postoperative discharge time of ( M(IQR)) 8.0 (3.5) days (range: 3 to 26 days). Two cases died or were discharged voluntarily. Logistic regression results showed that persistent preoperative atrial fibrillation ( OR=11.424, 95% CI: 1.477 to 144.564, P=0.033) and excessive rewarming ( OR=15.249, 95% CI: 1.357 to 279.571, P=0.038) were independent risk factors for the appearance of premature ventricular contractions in the early postoperative period. Conclusions:The technique of total thoracoscopic surgery under induced moderate hypothermic ventricular fibrillation with cardiopulmonary bypass could be applied to repeated mitral valve surgeries with less trauma and faster recovery. Persistent preoperative atrial fibrillation and excessive rewarming are independent risk factors for the occurrence of premature ventricular contractions in the early postoperative period.

Objective To investigate the effect of Danhuangsan on high glucose-induced vascular endothelial cell injury based on PINK 1/Parkin signaling pathway,and to explore its specific mechanism.Methods Human um-bilical vein endothelial cells were cultured in vitro and randomly divided into control group,growth factor group,Danhuangsan group,high glucose group,high glucose+growth factor group,high glucose+Danhuangsan group,with 3 cases in each group,treated for 48 hours.Cell scratch test was used to detect cell migration rate,and Transwell test was used to detect cell invasion rate.Immunofluorescence was used to detect the expression of anti-apoptotic protein Bcl-2,Beclin-1 and pro-apoptotic protein Bax.Western blot was used to detect the protein expression levels of PINK 1,Parkin and LC 3-Ⅱ.Results Cell scratch test and Transwell test showed that under normal environment and high glucose treatment,Danhuangsan could reduce the cell migration and invasion rate(P＜0.05).Immunofluorescence assay showed that under normal environment and high glucose treatment,Danhuang-san up-regulated the expression levels of Bcl-2 and Beclin-1 protein in cells(P＜0.05).Western blot results showed that under normal environment and high glucose treatment,Danhuangsan increased the protein expression levels of PINK 1,Parkin and LC 3-Ⅱ in cells and down-regulated the expression levels of Bax protein(P＜0.05),and the effects of Danhuang powder were significantly better than those of blank serum and growth factor(P＜0.05).Conclusion Danhuangsan can alleviate high glucose-induced endothelial cell injury by activating PINK 1/Parkin pathway,and the mechanism may be related to promoting mitophagy and enhancing the repair of damage.

Objective:To summarize the experience of surgical treatment of prosthetic valve dysfunction and evaluate the safety of operation.Methods:The clinical data of 142 patients admitted by the same cardiovascular surgeon from January 2015 to December 2019 at the first medical center of Chinese People's Liberation Army General Hospital. The clinical data were retrospectively analyzed, including 60 males (42.25%) and 82 females (57.75%), with an average age of 59.4 years old. Inclusion criteria: patients received redo-valvuloplasty or valve replacement after valvuloplasty or replacement, excluding mitral balloon dilatation and tricuspid valvuloplasty without implantation of annuloplasty ring.Results:The reasons of redo heart valve surgery in the same valve position including: bioprosthetic valve failure, mechanical prosthetic valve dysfunction, valve dysfunction after valvuloplasty, prosthetic valve infectious endocarditis, perivalvular leakage. There was 2 death in 142 cases, and the operative mortality rate was 1.41%. The reasons of the perioperative period death include cerebral hemorrhage, coagulation dfsfunction; perioperative complications include low cardiac output syndrome (LCOS), hypoxic-ischemic encephalopathy, respiratory failure, tracheal re-intubation, re-thoratomy for hemaostsis.Conclusion:There are many reasons for reoperation of prosthetic valve dysfunction, and the reoperation surgery is a difficult procedure. However, choosing the suitable surgical option, strengthening the perioperative management of such patients can effectively reduce the incidence of postoperative mortality and complications, minimally invasive surgery can reduce the mortality and complications.

Objective:The aim of this study was to compare the perioperative outcomes of a totally thoracoscopic repeat mitral valve surgery under hypothermic ventricular fibrillation with those of a conventional median sternotomy approach for repeat mitral valve surgery and to explore the safety of the totally thoracoscopic repeat mitral valve surgery under hypothermic ventricular fibrillation.Methods:Patients requiring repeat mitral valve surgery admitted by the same surgeon at Cardiovascular Surgery, First Medical Center, Chinese PLA General Hospital from January 2018 to January 2022 were retrospectively enrolled. The patients were divided into the totally thoracoscopic group under hypothermic ventricular fibrillation and the conventional median sternotomy group according to the procedure, and the preoperative baseline data and perioperative outcomes were collected and statistically analyzed using SPSS 22.0.Results:A total of 91 patients matched the criteria for study enrollment, 25 in the totally thoracoscopic group and 66 in the median sternotomy group. There was no statistical difference in the preoperative baseline data between the two groups. The totally thoracoscopic group has advantages in mitral valvuloplasty rate(32.0% vs. 7.6%, P=0.008), transfusion rate(72.0% vs. 98.5%, P<0.001), mechanical ventilation time [(19.0±27.8)h vs.(43.3±58.3)h, P=0.009], chest drainage tube time [(2.2±1.9)days vs.(3.7±2.4)days, P=0.004], postoperative chest drainage volume [(489.6±319.1)ml vs.(913.6±568.4)ml, P=0.001], postoperative discharge time[(8.0±2.7)days vs.(13.9±12.8)days, P=0.026]. The totally thoracoscopic group had a longer cardiopulmonary bypass time [(180.8±41.7)min vs.(143.2±39.7)min, P<0.001], and it had an intraoperative ventricular fibrillation time of(100.2±42.5)min. There were no statistically significant differences in the postoperative complication rate(12.0% vs. 21.2%, P=0.481) and mortality(4.0% vs. 4.5%, P=1.000) between the two groups. Conclusion:The totally thoracoscopic approach has the characteristics of less invasion and faster recovery compared with the median sternotomy approach. Hypothermic ventricular fibrillation simplifies the procedure at the ascending aorta while reducing myocardial injury than conventional occlusion of the ascending aorta. Totally thoracoscopic mitral valve surgery under hypothermic ventricular fibrillation is a safe minimally invasive technique.

Objective:To summarize the clinical data of mitral valve surgery completed in a single surgical team in one year, to discuss the etiologic characteristics, methods, results and early postoperative outcomes of mitral valvuloplasty surgeries, and to analyze the epidemiologic trends of mitral valve diseases admitted to the hospital.Methods:A total of 209 mitral valve surgeries completed by the same surgeon in the single surgical team at the Cardiovascular Surgery, First Medical Center, Chinese PLA General Hospital, from January 2021 to December 2021 were retrospectively analyzed. Mitral valve surgery accounted for 53.6% of all surgeries in this team during the same period. There were 100 cases(47.8%) in males and 109 cases(52.2%) in females, aged 11-85 years old, with a mean of(53.5±15.2) years old. There were 121 cases(57.9%) of NYHA class Ⅱ and 88 cases(42.1%) of class Ⅲ/Ⅳ.Results:Of the 152 mitral valvuloplasty surgeries, 117(77%) were performed with a totally Thoracoscopic approach. Annuloplasty rings were applied in 145 cases(95.4%), including semi-rigid closed Physio II annuloplasty rings in 118 cases(81.4%), Gore-Tex artificial chordae were applied in 89 cases(58.6%) for a total of 145, leaflet repair in 15 cases(9.9%), edge-to-edge repair in 2 cases(1.3%), commissure suture in 34 cases(22.4%), and chordae tendineae and papillary muscle splitting in 15 cases(9.9%). The repair rate of degenerative mitral valve disease was 100%, and the repair rate of rheumatic mitral valve disease was 48.1%. The echocardiogram was received about one week after surgery, and there was no or trace regurgitation in 91 cases(59.9%), mild in 58 cases(38.2%), and moderate in 3 cases(2.0%). There were 2 cases(1.3%) of all-cause death.Conclusion:Degenerative mitral valve disease have become the leading cause of mitral valve disease in our center, and the proportion of rheumatic mitral valve disease has decreased. Degenerative mitral valve disease has a very high repair rate, and rheumatic mitral valve disease has a relatively low repair rate due to its special pathologic and anatomic characteristics. Most mitral valvuloplasty procedure can be performed in a totally thoracoscopic approach. The application of a mitral valvuloplasty ring combined with Gore-Tex artificial chordae by an experienced surgeon can achieve reliable repair results.

Primary acinic cell carcinoma (ACC) of the lung is extremely rare. The World Health Organization tumor classification defines ACC as "a malignant epithelial neoplasm that demonstrates some cytological differentiation towards (serous) acinar cells". It is considered to be a low-grade malignant tumor. Since the first case described by Fechner in 1972, less than 30 cases have been reported in the literature. The rarity of this tumor may leads it to be confused with other primary lung tumors and incorrectly diagnosed. We reported a female patient with primary ACC of the lung with mediastinum deviation at age of 27 years received a right pneumonectomy. She was followed up for 12 months postoperatively and remains well.