Objective:To develop and validate a clinical prediction model for the risk of malignant ventricular arrhythmia in patients with acute myocardial infarction (AMI) during hospitalization, and evaluate the effect of the prediction model.Methods:A retrospective study was conducted. A total of 2 649 patients with AMI admitted to cardiology department of Changzhou No.2 People's Hospital of Nanjing Medical University from December 2012 to August 2020 were enrolled. The clinical characteristics including gender, age, medical history, discharge diagnosis, vital signs during hospitalization, electrocardiogram characteristics at admission, laboratory examination indexes, interventional treatment, drug usage, malignant ventricular arrhythmias [mainly included sustained ventricular tachycardia (VT), ventricular flutter or ventricular fibrillation (VF)], and death were recorded. All patients were divided into two groups according to whether VT/VF occurred during their hospitalization. Independent risk factors for VT/VF during hospitalization were evaluated by multivariate Logistic regression analysis, and a clinical prediction model was constructed. The receiver operating characteristic curve (ROC curve) was plotted, and the area under ROC curve (AUC) was calculated to evaluate the accuracy of the prediction model.Results:A total of 2 649 eligible patients with AMI were enrolled, of whom 134 (5.06%) developed VT/VF during hospitalization. The in-hospital mortality rate in VT/VF group was significantly higher than that in non-VT/VF group (38.1% vs. 1.7%, P < 0.01). Compared with the non-VT/VF group, the patients in the VT/VF group with lower systolic blood pressure [SBP (mmHg, 1 mmHg = 0.133 kPa): 125.9±28.2 vs. 132.0±24.2], higher random blood glucose (mmol/L: 8.6±4.8 vs. 7.4±3.7), worse cardiac function [Killip heart function grade ≥ 3: 36.6% vs. 10.7%, left ventricular ejection fraction (LVEF) < 0.50: 56.7% vs. 33.6%, frequent premature ventricular contractions: 12.7% vs. 1.2%] and more hypokalemia (46.3% vs. 17.3%), with significant differences (all P < 0.05). Multivariate Logistic regression analysis showed that Killip classification of cardiac function ≥ 3 [odds ratio ( OR) = 3.540, 95% confidence interval (95% CI) was 2.336-5.363], random blood glucose > 11.1 mmol/L ( OR = 1.841, 95% CI was 1.171-2.893), LVEF < 0.50 ( OR = 0.546, 95% CI was 0.374-0.797), frequent premature ventricular contractions ( OR = 12.361, 95% CI was 6.077-25.144), potassium < 3.5 mmol/L ( OR = 4.268, 95% CI was 2.910-6.259), SBP < 90 mmHg ( OR = 0.299, 95% CI was 0.150-0.597) and creatinine (Cr) > 100 μmol/L ( OR = 2.498, 95% CI was 1.170-5.334) were independent risk factors for VT/VF in patients with AMI (all P < 0.05). The clinical prediction model of VT/VF risk was constructed based on the variables selected by multivariate regression analysis. The ROC curve analysis showed that the AUC of the model in predicting VT/VF was 0.779 (95% CI was 0.735-0.823, P < 0.001); the optimal cut-off value of the model was 17, the sensitivity was 76.1%, the specificity was 67.3%. Conclusions:The incidence of VT/VF during hospitalization of AMI patients significantly increases the risk of in-hospital death. The independent risk factors of VT/VF are Killip grade ≥ 3, random blood glucose > 11.1 mmol/L, LVEF < 0.50, frequent ventricular premature beats, potassium < 3.5 mmol/L, SBP < 90 mmHg and Cr > 100 μmol/L. The newly constructed clinical prediction model has certain predictive value for the occurrence risk of VT/VF.

Objective:To document any effect of environmental enrichment on nerve regeneration in a mouse model of sciatic nerve compression and explore its mechanism.Methods:A crushed sciatic nerve model was successfully established in 22 C57BL/6 mice, and they were then randomly divided into an intervention group and a control group. The mice of the intervention group were raised in a cage with an enriched environment, while those of the control group were kept in a standard cage. Two weeks later, both groups′ gait was analyzed and the compound muscle action potential (CMAP) of the sciatic nerve was measured. The proportion of myelinated sciatic nerve fibers was examined using toluidine blue staining, and the expression of myelin basic protein (MBP), growth associated protein-43 (GAP43) and p75 neurotrophin receptor (p75 NTR) was measured using immunofluorescence intensity. Results:①The latency of the CMAP [(1.05±0.04)ms] was significantly shortened in the intervention group compared with the control group and the amplitude was significantly higher. ②Gait analysis showed a significant increase in the average contact intensity, stride length and stride rate of the intervention group compared with the control group. However, the step axis angle of the intervention group was significantly smaller than in the control group on average. ③The stained nerve fibers in the intervention group were orderly and dense, and the average number of myelinated fibers was significantly greater than in the control group. ④Quantitative analysis of the immunofluorescence showed that the levels of MBP, GAP43 and p75 NTR in the sciatic nerves of the intervention group were, on average, significantly higher than in the control group. Conclusion:An enriched environmental can promote the regeneration and functional recovery of crushed sciatic nerves by promoting the proliferation and myelination of Schwann cells.

Objective:To investigate the effect of preoperative hemoglobin (Hb) level on the risk of developing acute kidney injury (AKI) after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI).Methods:A retrospective study was conducted. The hospitalized patients diagnosed with AMI who underwent PCI from May 2015 to May 2020 in the department of cardiology in the Affiliated Changzhou No.2 People's Hospital of Nanjing Medical University were enrolled. According to the serum creatinine (SCr) level before and after interventional therapy, the patients were divided into an AKI group and a non-AKI group. The difference in patients' Hb levels between the AKI and non-AKI groups was compared. Univariate and multivariate Logistic regression analyses were used to analyze the effects of Hb levels on the risk of AKI after interventional therapy in patients with AMI. Kaplan-Meier survival curve was used to evaluate the effects of Hb levels on patients with AMI in all-cause death in the hospital.Results:A total of 922 AMI patients were enrolled in this study, of which 165 patients (17.9%) developed AKI. Compared with the non-AKI group, female patients in the AKI group had a higher proportion [35.8% (59/165) vs. 26.9% (204/757)], older (age: 69.78±14.56 vs. 66.61±13.44), with a lower rate of smoking [42.4% (70/165) vs. 51.7% (391/757)] and a higher prevalence of hypertension [73.3% (121/165) vs. 63.5% (481/757)], however, the patients in AKI group also had a worse cardiac function [the proportion of Killip grade 3 or above was higher: 33.9% (56/165) vs. 13.9% (105/757)], lower Hb level (g/L: 127.61±22.18 vs. 132.79±19.45), and there were less patients using angiotensin converting enzyme inhibitor/angiotensin Ⅱreceptor blocker [ACEI/ARB, 60.0% (99/165) vs. 74.5% (564/757)] and more patients using diuretics [24.8% (41/165) vs. 17.7% (134/757)] in AKI group, the differences were statistically significant (all P < 0.05). Compared with non-AKI group, patients in AKI group had a longer operation time [operation time > 60 minutes: 4.2% (7/165) vs. 1.5% (11/757)] and received more contrast media during the operative procedure [contrast media > 100 mL: 16.4% (27/165) vs. 3.6% (27/757)], the individuals had a higher rate of intra-operative hypotension [16.4% (27/165) vs. 8.2% (62/757)], and more patients were implanted more than 2 stents [8.5% (14/165) vs. 3.6% (27/757), all P < 0.05]. Univariate Logistic regression analysis suggested that each 1 g/L increase in preoperative Hb level was associated with a 1.2% decrease in the risk of postoperative AKI [odds ratio ( OR) = 0.988, 95% confidence interval (95% CI) was 0.980-0.996, P = 0.003]. Meanwhile, for every 1 standard deviation increase in preoperative Hb level, the risk of postoperative AKI decreased by 22.1% ( OR = 0.779, 95% CI was 0.661-0.918, P = 0.003). The patients were divided into low, medium and high concentration groups according to Hb levels (Hb levels were < 110 g/L, 110-150 g/L, ≥ 150 g/L, respectively), and multivariate Logistic regression analysis showed that the risk of AKI was significantly reduced in the high concentration group compared with that in the low concentration group ( OR = 0.463, 95% CI was 0.241-0.888, P = 0.020). The Kaplan-Meier survival curve analysis indicated that the short term survival after coronary intervention in AMI patients with low Hb concentration was significantly lower than that in patients with medium and high Hb concentration (Log-Rank: χ2= 23.215, P < 0.001). Conclusions:Preoperative lower Hb level is an independent risk factor for postoperative AKI in AMI patients. AMI patients with lower Hb levels have an increased risk of all-cause mortality within 1 month after AMI.