Objective To develop a predictive model for postoperative acute kidney injury(AKI)in elderly patients using machine learning methods.Methods The preoperative information and postopera-tive follow-up information of elderly patients who underwent surgery from June 2019 to July 2020 were col-lected,and the laboratory examination results were extracted.A total of 115 preoperative variables were in-cluded.A model of postoperative AKI was constructed using five methods:extreme gradient boosting(XGB),gradient boosting machine(GBM),random forest(RF),support vector machine(SVM),and elastic net logistic regression(ELA).The performance of the model was evaluated using area under the re-ceiver operating characteristic curve(AUROC),area under the precision recall curve(AUPRC),and Brier score.To simplify the model for clinical application,the original model was obtained and some varia-bles with low correlation were removed,and the model was evaluated again using the above method.Results This study ultimately included 5 929 elderly patients,3 359 males(56.7％)and 2 570 females(43.3％),aged 65-99 years.Among them,154 patients(2.6％)experienced postoperative AKI.Among the prediction models constructed using five machine learning methods,XGB has the highest AUROC and AU-PRC,with values of 0.798(95％CI 0.705-0.888)and 0.230(95％CI 0.079-0.374),respectively.Its Brier score is the lowest among all models,the score is 0.023(95％CI 0.014-0.029).After simplifying the XGB model,72 variables were retained.The AUROC of the simplified model was 0.790(95％CI 0.711-0.861),slightly lower than that of the original model.The AUPRC was 0.176(95％CI 0.070-0.313),and the Brier score was 0.024(95％CI 0.017-0.033),and there was no significant statistical difference,indicating that there was no significant difference in the predictive ability of the simplified model compared to the original model.Conclusion Among the five machine learning methods used to construct postoperative AKI prediction models,XGB has the best predictive performance.The simplified XGB predic-tion model still retains high predictive performance and is easier to be promoted in clinical practice.

Objective:To evaluate the relationship between preoperative pain threshold and chronic postsurgical pain (CPSP) in the patients undergoing thoracoscopic pneumonectomy.Methods:One hundred patients of both sexes, aged 18-75 yr, with body mass index of 18-35 kg/m 2, of American Society of Anesthesiologists Physical Status classification Ⅰ or Ⅱ, scheduled for thoracoscopic pneumonectomy at West China Hospital of Sichuan University from December 2019 to February 2020, were selected. The pain threshold was measured using Pain Vision at 1 day before surgery. Telephone follow-up was implemented by a pain questionnaire to assess CPSP (numerical rating scale score ≥1) at 3 months after surgery. Multivariate logistic regression was used to identify the risk factors for CPSP, and the receiver operating characteristic curve was used to evaluate the accuracy of preoperative pain threshold in predicting CPSP. Results:Ninety-four patients were finally enrolled, of which 38 cases (40%) developed CPSP. The results of multivariate logistic regression analysis showed that low preoperative pain threshold was an independent risk factor for CPSP ( OR=0.899, 95% confidence interval 0.854-0.946, P<0.001). The area under the receiver operating characteristic curve was 0.882 (95% confidence interval 0.804-0.960), Youden Index was 0.673, the sensitivity was 0.816, and the specificity was 0.857. Conclusions:Low preoperative pain threshold is an independent risk factor for CPSP, and preoperative pain threshold can predict the occurrence of CPSP in the patients undergoing thoracoscopic pneumonectomy.

Objective:To study the collapse of the contralateral femoral head after the total hip arthroplasty (THA) in patients with bilateral steroid-induced femoral head necrosis leg-length discrepancy (LLD) influences.Methods:A total of 108 patients with bilateral steroid-induced femoral head necrosis who were treated in Honghui Hospital Affiliated to Xi′an Jiaotong University from June 2014 to June 2016 underwent THA surgery on the hip joints that had symptoms and developed to Association Research Circulation Osseous (ARCO) Ⅲ. At the same time, the non-surgical hip-preserving treatment of the non-collapsed femoral head developed to the ARCO Ⅱ stage was performed. The follow-up period was 2 years, and 98 cases were finally included. According to the size of the leg-length discrepancy [LLD<3 mm group ( n=50), LLD≥3 mm group ( n=48)] and the type of leg-length discrepancy[non collapse side longer group ( n=58) and shorter group ( n=58)], the collapse of the femoral head and the THA were observed. Results:Finally, a total of 56 cases of femoral head collapse occurred in the non collapse side of the hip, of which 50 cases underwent THA within 24 months. There were significant statistical differences in THA and femoral head collapse between LLD<3 mm group and LLD≥3 mm group, non collapse side longer group and non collapse side shorter group ( P<0.05). The 2-year survival rate without collapse in the LLD<3 mm group and LLD≥3 mm group were 52.1% and 34.0%, respectively, and the 2-year survival rates in the longer and shorter non-collapsed limb groups were 56.9% and 22.5%, respectively. Compared with patients with moderate lesions, the survival rate of femoral heads in patients with larger lesions was lower ( OR: 4.25, 95% CI: 1.55-11.26; P=0.003). LLD<3 mm group ( OR: 0.24, 95% CI: 0.06-0.50; P<0.01) or non collapse side longer group ( OR: 0.13, 95% CI: 0.04-0.29; P<0.01) had lower risk of contralateral femoral head collapse after THA. Conclusions:For patients with bilateral steroid-induced femoral head necrosis who have collapsed lateral THA, postoperative leg-length discrepancy extremities is a potential risk factor for collapse of non-collapsed femoral head. LLD<3 mm and avoiding shortening of the uncollapsed limb may reduce the risk of collapse of the uncollapsed femoral head.

Objective To evaluate the value of perioperative multimodal stratified analgesia guided by PPRS-CYMZ 2.0. Methods One hundred and sixteen patients of both sexes, aged 16-85 yr, of A-merican Society of Anesthesiologists physical statusⅠ-Ⅲ, scheduled for elective surgery in our hospital in August 2016, were included in this study and assigned into empirical analgesia group(group E, n=79) and stratified analgesia group(group S, n=73). The risk of postoperative pain was estimated by an expe-rienced associate chief anesthesiologist based on his clinical experience, and the perioperative analgesic protocol was determined in group E. The risk of postoperative pain was assessed using the perioperative pain risk scale PPRS-CYMZ 2.0 by another experienced associate chief anesthesiologist, the risk was stratified according to the scores, and the corresponding stratified analgesic protocol was determined in group S. Vis-ual analog scale scores and parents′satisfaction with analgesia were recorded on postoperative day 30. The requirement for preventive analgesia, total pressing times of patient-controlled analgesia(PCA)pump in 0-6 h, 6-24 h and 24-72 h periods, PCA background infusion dose and consumption of rescue analgesics were recorded. The development of adverse events during postoperative hospital stay and postoperative re-covery were also recorded. Analgesia-related parameters of medical economics were calculated. Results There was no significant difference in postoperative pain risk stratification between group E and group S(P>0.05), and the majority of patients were at moderate risk. Compared with group E, no significant change was found in visual analog scale scores on postoperative day 30, PCA background infusion dose or incidence of postoperative adverse effects(P>0.05), the requirement for preventive analgesia and satisfaction scores were significantly increased in high risk patients, the consumption of rescue analgesics was decreased in moderate risk patients(P<0.05), no significant change was found in the total pressing times of PCA pump in each time period in low risk patients(P>0.05), the total pressing times of PCA pump was significantly decreased, and the direct analgesic cost per patient and total analgesic cost were decreased in moderate and high risk patients, and the first ambulation time and length of postoperative hospital stay were shortened in high risk patients in group S(P<0.05). Conclusion PPRS-CYMZ 2.0 can achieve perioperative multi-modal stratified analgesia and individualized treatment.

Objective To evaluate the effect of electroconvulsive therapy (ECT) on the expression of phosphorylated glutamate receptor 1 (p-GluR1) and Ca2+/calmodulin-dependent protein kinase Ⅱ α (p-CaMK Ⅱ α) under small dose ketamine combined with propofol anesthesia in the depressed rats.Methods Forty healthy adult male Sprague-Dawley rats,weighing 200-250 g,aged 2-3 months,were used in this study.Mental depression was induced by exposing the animals to chronic unpredictable mild stress (CUMS).Forty mentally depressed rats were divided randomly into 5 groups (n =8 each) using a random number table:M0-4 groups.Propofol 80 mg/kg and ketamine 10 mg/kg were injected intraperitoneally in M0-4 groups.After disappearance of righting reflex,M1-4 groups received ECT of 60,120,180 and 240 mC once a day for 7 consecutive days,respectively,by means of a current (frequency 50 Hz,sine-wave,pulse width 0.7 ms,1-s duration) delivered via ear-clip electrodes,while group M0 received ECT of no quantity of electric charge via ear-clip electrodes.Before CUMS,at 1 day after CUMS and at 1 day after ECT,sucrose preference test was applied to evaluate the depressive behavior.The sucrose preference percentage (SPP) was calculated.At 4 days after CUMS and 4 days after ECT,the learning and memory function was assessed using Morris water maze test.The rats were then sacrificed,and hippocampi were isolated to detect the expression of GluR1,p-GluRl,CaMK Ⅱ α and p-CaMK Ⅱ α by Western blot.Results The SPP was significantly lower after CUMS than before CUMS in M0-4 groups (P＜0.05).Compared with that after CUMS,the SPP was significantly increased,the escape latency was shortened,and the space exploration time was prolonged after ECT in M1-4 groups (P＜0.05).There was no significant difference in SPP after ECT between M1-4 groups (P＞0.05).Compared with group M0,the SPP was significantly increased,and the expression of pGluR1 and p-CaMK Ⅱ α was up-regulated in M1-4groups (P＜0.05).Compared with group M2,the escape latency was significantly prolonged,the space exploration time was shortened,and the expression of pGluR1 and p-CaMK Ⅱ α was down-regulated after ECT in the other groups (P＜0.05).There was no significant difference in GluR1 and CaMK Ⅱ α expression after ECT between the five groups (P＞ 0.05).Conclusion ECT can induce cognitive decline when applied for anti-depression under small dose ketamine combined with propofol anesthesia,and the mechanism is related to increased phosphorylation of GluR1 and CaMK Ⅱ α expression in rats.

Objective To explore the effect of low-dose ketamine combined with propofol anesthesia on expres?sion of glutamine receptor subunit 1 (GluR1) and 2 (GluR2) in the hippocampus of depressed rats after electroconvulsive therapy. Methods Healthy adult male Sprague-Dawley rats, weighing 200~250 g, were used in this study. Mental depres?sion was induced by chronic unpredictable mild stress. Thirty-two depressed rats were randomly divided into 4 groups (n=8): metal depression group (group A), ECT group (group B), ECT+propofol group (group C) and ECT+propofol+ket?amine group (group D). Eight normal rats served as control group. Control group received no treatment. Group A received intraperitoneal injection of normal saline 8 mL/kg plus sham ECT. Group B, C and D received ECT once a day for 7 con?secutive days following intraperitoneal injection of normal saline 8 mL/kg, propofol 80 mg/kg and propofol 80 mg/kg +ketamine 10mg/kg, respectively. Sucrose preference test and Morris water maze were performed to assess depressed be?havior and learning and memory function, respectively. RT-PCR and Western-blot assay were used to detect the expres?sion of GluR1 , GluR2 and their mRNA expression. Results After ECT, compared with control group and group A, changes of SPP in group B, C and D were obvious. The change of SPP in group D was much higher than all other groups (P<0.05). Rats in group B showed prolonged escape latency and shortened space exploration time, which were significantly different from all other groups (P<0.05). Rats in group D showed the most shortened escape latency and prolonged space exploration time (P<0.05). The expression of GluR1 was significantly increased in group B, C and D compared with group A (P<0.05). The expression of GluR2 and mRNA was significantly decreased in group B and C (P<0.05). The difference in GluR2 and mRNA expression was not significant among group A, D and control group (P>0.05). Conclusion Low-dose ketamine combined with propofol anesthesia exert effective antidepressive action and improve learning and memory function of depressed rats after electroconvulsive therapy. The beneficial effects of the ketamine combined with propofol anesthesia may be related to up-regulation expression of GluR1 and GluR2 in hippocampus.

Objective To investigate the role of autophagy and synaptophysin (SYP) in cognitive impairment in de?pressed rats receiving electroconvulsive shock (ECS). Methods Clean and healthy adult male Sprague-Dawley rats were acclimatized to a standard laboratory environment for 7 days. The chronic unpredictable mild stress (CUMS) was used to establish the rat model of depression. Behavior tests were conducted before and after CUMS to evaluate the depression and cognition level of rats. After establishment of the model, 24 rats were randomly divided into ESC group (group E) and depression group (group D) with 12 rats in each group. The rats in group E were administered 80 mg/kg of propofol (10 mg/mL) by intraperitoneal injection, followed by ECS treatment. The rats in group D were administered propofol by intra?peritoneal injection, followed by sham-ECS treatments. The above interventions were conducted daily for 7 consecutive days. After the interventions, rats underwent behavior tests as before. Subsequently, rats were killed and specimens were collected for measurements. Immunohistochemistry was performed to examine autophagy markers such as Beclin 1 and LC3Ⅱand ELISA was used to detect SYP in the hippocampus. Results Group E after ECS significantly increased the percentage of sucrose preference (68.2%±8.7%), rearing times (7.0±1.9), total horizontal distance [(569.5±70.0) cm], es? cape latency [(21.9±5.3)s] and space exploration time [(20.5±3.9)s] compared with group D or group E before ECS. There was no significant difference in these index between groups before ECS or in group E between before and after ECS(P>0.05). Compared with group D, group E had upregulated protein expression levels of Beclin 1 and LC3Ⅱin CA1, CA3, DG as well as the area near the hippocampus and increased SYP contents (P<0.05). Conclusions Cognitive impairment in depression rats following ECS correlates with activated autophagy and increased SYP by ECS.

Objective To evaluate the effects of exendin-4 on glial brillary acidic protein (GFAP ) and interleukin-1β(IL-1β) expression in hippocampi of aged rats .Methods Forty-eight healthy male Sprague-Dawley rats ,aged 22-24 weeks ,weighing 500-700 g ,were randomly divided into 4 groups (n=12 each) using a random number table:control group (group C ) ,exendin-4 group (group E ) ,operation group (group O ) and exendin-4 plus operation group (group OE) .The rats were anesthetized with intraperitoneal fentanyl and droperidol .Groups C and E did not receive anesthesia or splenectomy .In O and OE groups ,splenectomy was carried out .In E and OE groups , exendin-4 5 μg/kg was injected intraperitoneally at 30 min before skin incision and 12 h after operation .C and O groups received the equal volume of normal saline instead of exendin-4 .Learning and memory function was assessed using Morris water maze test (escape latency (EL) and total swimming distance (TSD) at 1 day before operation (T0 ) .The fasting blood glucose was measured after anesthesia (T1 ) ,at the end of operation (T2 ) and on postoperative day 1 (T3 ) .The rats were sacrificed after assessment of the cognitive function at T 3 and the hippocampi were removed for determination of the expression of GFAP (by immuno-histochemistry ) and IL-1β(by Western blot ) .Results There was no significant difference in the EL and TSD at T0 between the four groups ( P>0.05) .Compared with group C ,the EL and TSD were significantly prolonged at T3 and fasting blood glucose was increased at T2 ,3 ,and the expression of IL-1βand GFAP was up-regulated at T3 in O and OE groups ( P<0.05) .Compared with group O ,the EL and TSD were significantly prolonged at T3 and fasting blood glucose was decreased at T2 ,3 ,and the expression of IL-1βand GFAP was down-regulated at T3 in group OE ( P<0.05) . Conclusion Exendin-4 can improve the postoperative cognitive function of aged rats by inhibiting inflammatory responses in hippocampi and maintaining stable perioperative blood glucose .

Objective To evaluate the effect of small-dose ketamine on the onset time and course of modified electroconvulsive therapy (MECT) in mentally depressed rats.Methods Sixty SPF adult male SpragueDawley rats,aged 2-3 months,weighing 220-250 g,were randomly divided into 6 groups (n =10 each) using a random number table:normal control group (group C),depression group (group D),ECT group,propofol + ECT group (group PE),ketamine + ECT group (group KE) and ketamine + propofol + ECT group (group KPE).The depression model was established by chronic unpredictable mild stress (CUMS).Mter CUMS,C,D and ECT groups received intraperitoneal normal saline 8 ml/kg,group PE received intraperitoneal propofol 100 ml/kg,group KE received intraperitoneal ketamine 10 ml/kg,and group KPE received intraperitoneal ketamine 10 ml/kg + propofol 80 ml/kg.All the groups received ECT once a day for 7 consecutive days starting from the time point when righting reflex was lost except C and D groups.Open-field test was performed before CUMS,at 1 day after CUMS and at the end of each ECT (T0 8).The total distance and the number of standing on the back legs were recorded.Morris water maze test was performed at 2 days after CUMS and 1 day after the end of therapy,and the escape latency and time of staying at the original platform quadrant were recorded.Results Compared with group C,the total distance was shortened and the number of standing on the back legs was reduced,the escape latency was prolonged,and the time of staying at the original platform quadrant was shortened at T1-8 in D,ECT,PE and KE groups and at T1 5 in KPE group,and no significant was found in KPE group in the total distance,number of standing on the back legs,escape latency,and time of staying at the original platform quadrant at T6-8.Compared with group D,the total distance was prolonged and the number of standing on the back legs was increased at T6-8 in ECT and PE groups and at T4-8 in KE and KPE groups,the escape latency was prolonged,and the time of staying at the original platform quadrant was shortened in ECT group,and the escape latency was shortened,and the time of staying at the original platform quadrant was prolonged in KPE group.Compared with ECT and PE groups,the total distance was prolonged and the number of standing on the back legs was increased at T4-7 in group KE and at T4-8 in group KPE,and the escape latency was shortened,and the time of staying at the original platform quadrant was prolonged in KPE group.Compared with group KE,the total distance was prolonged and the number of standing on the back legs was increased at T6.7,the escape latency was shortened,and the time of staying at the original platform quadrant was prolonged in KPE group.Conclusion Small-dose ketamine can shorten the onset time and course of MECT in mentally depressed rats.

Objective To evaluate the effect of advanced age on sepsis-caused heterogeneity of nicotinic acetylcholine receptors (nAChR) in the cytomembrane of skeleton muscle in rats.Methods Twenty SPF adult rats (aged 4-5 months,weighing 250-280 g) and 20 aged male Sprague-Dawley rats (aged 18-20 months,weighing 550-600 g),were obtained from the Experimental Animal Centre of Chongqing Medical University.The adult rats were randomly divided into control group (CAd group,n =10) and sepsis group (SAd group,n =10).The aged rats were randomly divided into control group (CAg group,n =10) and sepsis group (SAg group,n =10).Sepsis was produced by cecal ligation and puncture.The specimens of anterior tibial muscle were obtained at 24 h after operation for determination of the expression of neuronal nAChR (α7-nAChR) and fetal nAChR (γ-nAChR) using immunohistochemistry and Western blot.Results The expression of γ-nAChR and α7-nAChR in the cytomembrane of anterior tibial muscle was significantly higher in CAg and SAd groups than in CAd group,and in SAg group than in CAg and SAd groups.Conclusion Advanced age can aggravate sepsis-induced heterogeneity of nAChR in the cytomembrane of skeleton muscle in rats.