Insertional mutagenesis is a widely used method to determine the function(s) of a gene. To study the function(s) of the gene nsdAmgh in Streptomyces roseoflavus, a homologous recombination vector pSRNA2500 was structured in this paper. The recombination donor vector was then transformed into Strempomyces roseoflavus strain Men-myco-93-63 by conjugative transfer. The transformants were subjected to selection under the pressure of high temperature and appropriate antibiotics. As a result, several disrupted mutants of nsdAmgh gene, with a phenotype of Am(s)Km(r), were isolated and verified using PCR and Dot-blotting and Southern blotting hybridization methods. Functional analysis showed that the disrupted mutants of nsdAmgh had a two-fold higher inhibition against Verticillium dahlia Kleb than that of the wild strain Men-myco-93-63, which all will provide a new study route for future research about positive and negative regulator in Men-myco-93-63.
Genes, Bacterial ; Genetic Vectors ; Mutagenesis, Insertional ; Polymerase Chain Reaction ; Streptomyces ; genetics

Objective:To investigate the influencing factors for anastomotic biliary stric-ture after liver transplantation.Methods:The retrospective case-control study was conducted. The clinical data of 428 recipients who underwent allogeneic orthotopic liver transplantation in the First Hospital of Jilin University from September 2014 to August 2021 were collected. There were 324 males and 104 females, aged (52±10)years. Observation indicators: (1) surgical conditions of recipients; (2) occurrence of anastomotic biliary stricture after liver transplantation and its treat-ment; (3) analysis of influencing factors for anastomotic biliary stricture after liver transplantation. Follow-up was conducted using outpatient examination to detect occurrence of anastomotic biliary stricture and treatment up to August 30, 2021. Measurement data with normal distribution were represented as Mean± SD, and comparison between groups was analyzed using the t test. Measure-ment data with skewed distribution were represented as M( Q1, Q3) or M(range), and comparison between groups was analyzed using the Mann-Whitney U test. Count data were represented as absolute numbers, and the chi-square test was used for comparison between groups. Logistic regression model was used for multivariate analysis. Results:(1) Surgical conditions of recipients: the operation time of 428 recipients was 465(420,520)minutes, the cold ischemia time was 368(320,450)minutes, and the volume of intraoperative blood loss was 2 500(1 500,4 000)mL. Of the 428 recipients, 142 cases were performed continuous biliary posterior wall anastomosis + interrup-ted anterior wall anastomosis by polygluconate sutures, 286 cases were anastomosed with polypro-pylene sutures, including 169 cases undergoing continuous biliary posterior wall anastomosis combined with interrupted anterior wall anastomosis, 73 cases undergoing completely interrupted biliary anterior and posterior wall anastomosis, and 44 cases undergoing completely continuous biliary anterior and posterior wall anastomosis. None of the 428 recipients had indwelling T tubes. (2) Occurrence of anastomotic biliary stricture after liver transplantation and its treatment:all the 428 recipients were followed up for 3 to 72 months, with a median follow-up time of 28 months. During the follow-up, 50 patients developed anastomotic biliary stricture, of which 41 patients were treated with endoscopic retrograde cholangiopancreatography, 8 patients were treated with percutaneous transhepatic cholangial drainage, and 1 patient was treated with surgery, showing no recurrence. (3)Analysis of influencing factors for anastomotic biliary stricture after liver transplanta-tion: results of univariate analysis showed that anastomosis method and donor liver cold ischemia time were related factors for postoperative anastomotic biliary stricture of recipients undergoing allogeneic orthotopic liver transplantation ( χ2=15.74, Z=-2.04, P<0.05). Results of multivariate analysis showed that completely interrupted biliary anterior and posterior wall anastomosis and donor liver cold ischemia time were independent influencing factors for postoperative anastomotic biliary stricture of recipients undergoing allogeneic orthotopic liver transplantation ( odds ratio=0.25, 1.00, 95% confidence interval as 0.08-0.85, 1.00-1.01, P<0.05). Conclusions:Suture type is not an influencing factor for postoperative anastomotic biliary stricture of recipients undergoing allogeneic orthotopic liver transplantation. Completely interrupted biliary anterior and posterior wall anastomosis and donor liver cold ischemia time were independent influencing factors.

Objective:To explore the feasibility and advantages of planned initiation of extracorporeal membrane oxygenation(ECMO)prior to liver transplantation.Methods:From November 2017 to July 2021, clinical data were retrospectively reviewed for 3 liver transplantation recipients assisted by ECMO.There were such preoperative symptoms of right ventricular dysfunction as fatigue, chest tightness and palpitations.In the first case, right heart catheterization was not performed due to patient refusal; another two patients were screened by transthoracic Doppler echocardiography(TDE)and diagnosed through right heart catheterization as portopulmonary hypertension(POPH)and pulmonary hypertension.Results:Three recipients with pulmonary hypertension received catheterization in right femoral artery and vein.After freeing of diseased liver and before blocking inferior vena cava, V-A ECMO support was performed.The dose of heparin was adjusted according to activated clotting time(ACT)and perioperative vital signs remained stable.They were ventilated for 54, 12 and 62 hours and supported by ECMO for 27, 61 and 14 hours.All were smoothly discharged.During a mean follow-up period of 26(9-22)months, liver functions were normal.Conclusions:Patients with end-stage liver disease with pulmonary hypertension should undergo routine TDE examinations during waiting period before liver transplantation.Those with pulmonary hypertension should undergo further right heart catheterization to confirm the diagnosis and severity of the disease.Planned application of ECMO through multidisciplinary consultations can expand surgical indications for liver transplantation, maintain intraoperative hemodynamic stability and facilitate smooth liver transplantation and postoperative patient recovery.

Objective:To investigate the application value of electroencephalogram (EEG) combined with regional cerebral oxygen saturation (rSO 2) in monitoring cerebral perfusion during carotid endarterectomy (CEA). Methods:A retrospective analysis of clinical data of 42 patients with atherosclerotic carotid artery stenosis admitted to and accepted CEA in our hospital from January 2018 to December 2019 was performed. CEA was performed under EEG combined with rSO 2 monitoring. The efficacy and safety of EEG combined with rSO 2 in monitoring cerebral perfusion abnormalities during CEA were analyzed. Results:After carotid artery occlusion, 24 patients (57.1%) had normal EEG and rSO 2; 15 (35.7%) had abnormal changes of EEG, among whom 13 (31.0%) were accompanied by rSO 2 anomaly; 16 (38.1%) had abnormal rSO 2, among whom 13 (31.0%) were accompanied by EEG anomaly. Of these 18 patients with abnormal EEG and/or rSO 2 monitoring, 17 patients recovered after increasing their blood pressure and 1 patient recovered after diverter tube usage. Intraoperative EEG and rSO 2 monitoring results were consistent (Kappa=0.745, P=0.000). The positive rates of combined monitoring, EEG alone or rSO 2 alone were 42.9%, 35.7% and 38.1%, respectively. All patients were evaluated clinically and radiologically before discharge, and no new ischemic lesions or clinical symptoms were found. Conclusions:EEG and rSO 2 monitoring are well consistent in CEA; the combined monitoring can make up for the deficiency of single monitoring to increase surgical safety.