Double-tract reconstruction is superior to esophagogastrostomy in controlling reflux esophagitis and enhancing quality of life after proximal gastrectomy:Results from a prospective randomized controlled clinical trial in China

Objective:The aim of this study was to prospectively compare double-tract reconstruction(DTR)and esophagogastrostomy(EG)after proximal gastrectomy(PG)regarding the incidence of reflux esophagitis,quality of life(QOL),nutritional status and surgical safety.Methods:This study was a randomized controlled trial.Patients eligible for PG were enrolled and randomly assigned to the EG group and DTR group.The characteristics of patients,parameters for surgical safety,incidence of reflux esophagitis,nutrition status and QOL were collected and compared between the two groups.Univariate analysis and multivariate analysis were performed to determine the significant factors affecting the incidence of reflux esophagitis after PG.Results:Thirty-seven patients of the EG group and 36 patients of the DTR group were enrolled.The incidence of reflux esophagitis was significantly lower in the DTR group than in the EG group(8.3%vs.32.4%,P=0.019).The DTR group demonstrated a more favorable QOL than the EG group after PG.The nutritional status was balanced within the EG group and the DTR group.The operation time was longer in the DTR group than in the EG group(191 min vs.221 min,P=0.001),while surgical safety was similar in the two groups.Conclusions:Our research demonstrated that DTR is superior to EG after PG in terms of the incidence of reflux esophagitis and provides a more satisfactory QOL without increasing surgical complications or sacrificing nutritional status.

Current status and perspectives of conversion therapy for advanced gastric cancer

The concept and strategy of advanced gastric cancer treatment have gradually undergone profound changes with the in-depth understanding of the biology and heterogeneous characteristics of gastric cancer.Moreover,the development and application of new anticancer drugs,including chemotherapy drugs,molecularly targeted drugs and immunotherapy drugs for advanced gastric cancer are reported.The connotation of conversion therapy refers to the unresectable or borderline resectable tumors for surgical technical and/or oncological reasons,after active and effective chemotherapy and other comprehensive treatment,the primary gastric lesions can be reduced to a lower stage,while the metastatic lesions can be effectively controlled,to achieve R0 resection and improve the long-term survival rate.Current promising research results of conversion therapy are mostly from single-arm phase II clinical studies with small samples or retrospective studies.Conversion therapy still faces many challenges,including limited diagnostic and assessment methods,insufficient evidence of highly effective treatment regimens,difficulty in clarifying surgical indications,etc.Therefore,the integrated conversion therapy for advanced gastric cancer needs to be carried out with the close cooperation of a multidisciplinary team.Prospective,multi-center randomized controlled trial studies should be conducted in the future,and precision medicine such as molecular biology should be combined to provide better anticancer drug regimens and higher-level clinical evidence for conversion therapy of advanced gastric cancer.

Characteristics of lymph node stations/basins metastasis and construction and validation of a preoperative combination prediction model that accurately excludes lymph node metastasis in early gastric cancer

Objective:To explore the candidate indications for function-preserving curative gastrectomy and sentinel lymph node navigation surgery in early gastric cancer(EGC).Methods:The clinicopathological data of 561 patients with EGC who underwent radical gastrectomy for gastric cancer at Peking University Cancer Hospital from November 2010 to November 2020 with postoperative pathological stage pT1 and complete examination data,were collected.Pearson’s Chi-square test was used and binary logistic regression was employed for univariate and multivariate analyses.Combined analysis of multiple risk and protective factors for lymph node metastasis(LNM)of EGC was performed.A negative predictive value(NPV)combination model was built and validated.Results:LNM occurred in 85 of 561 patients with EGC,and the LNM rate was 15.15%.NPV for LNM reached 100%based on three characteristics,including ulcer-free,moderately well differentiation and patient<65years old or tumor located at the proximal 1/3 of the stomach.Regarding lymphatic basin metastasis,multivariate analysis showed that the metastatic proportion of the left gastric artery lymphatic basin was significantly higher in male patients compared with female patients(65.96%vs.38.89%,P<0.05).The proportion of right gastroepiploic artery lymphatic basin metastasis in patients with a maximum tumor diameter>2 cm was significantly greater than that noted in patients with a maximum tumor diameter≤2 cm(60.78%vs.28.13%,P<0.05).Conclusions:Characteristics of lymph node stations/basins metastasis will facilitate precise lymph node resection.The NPV for LNM reaches 100%based on the following two conditions:young and middle-aged EGC patients,well-differentiated tumors,and without ulcers;or well-differentiated tumors,without ulcers,and tumors located in the proximal stomach.These findings can be used as the recommended indications for functionpreserving curative gastrectomy and sentinel lymph node navigation surgery.

Compressor geometric uncertainty quantification under conditions from near choke to near stall

Geometric and working condition uncertainties are inevitable in a compressor,deviating the compressor performance from the design value.It’s necessary to explore the influence of geometric uncertainty on performance deviation under different working conditions.In this paper,the geometric uncertainty influences at near stall,peak efficiency,and near choke conditions under design speed and low speed are investigated.Firstly,manufacturing geometric uncertainties are analyzed.Next,correlation models between geometry and performance under different working conditions are constructed based on a neural network.Then the Shapley additive explanations(SHAP)method is introduced to explain the output of the neural network.Results show that under real manufacturing uncertainty,the efficiency deviation range is small under the near stall and peak efficiency conditions.However,under the near choke conditions,efficiency is highly sensitive to flow capacity changes caused by geometric uncertainty,leading to a significant increase in the efficiency deviation amplitude,up to a magnitude of-3.6%.Moreover,the tip leading-edge radius and tip thickness are two main factors affecting efficiency deviation.Therefore,to reduce efficiency uncertainty,a compressor should be avoided working near the choke condition,and the tolerances of the tip leading-edge radius and tip thickness should be strictly controlled.

Numerical simulation method of surge experiments on gas turbine engines

In order to obtain the surge margin of an aero-engine during its operation,an engine surge experiment is required.A multi-dimensional simulation method for an aero-engine is established in this paper.The simulation of a surge experiment using high-pressure air-injection is then carried out on a turbo-shaft engine to obtain the surge boundary using this method.More specifically,firstly,a body-force model is employed to calculate the compressor performance owing to its capability of capturing the main three-dimensional features of compressor surge and avoiding excessive simulation time required by the traditional fully-three-dimensional Reynolds Averaged Navier-Stokes(RANS)method.Then,a one-dimensional model combining a lumped-parameter plenum model is used for the combustor to account for the propagation of pressure waves and the heat-release process,and a zero-dimensional throttle model is used to mimic the choking effect at the turbine nozzle.Finally,the air-injection system is modeled by imposing an injection boundary condition,which can be used conveniently in changing injection parameters.Based on the established method,the influences of different test parameters,such as the air-injection location,the pressure,the orifice size,the number of injection orifices,and the injection time duration on the surge characteristics and boundary are further studied,which offer effective guidance to optimize an actual experimental design.