Objective To investigate the diagnosis and prognosis evaluation value of neutrophil elastase (NE) in ventilator-associated pneumonia (VAP).Methods A retrospective analysis was conducted.The data of patients undergoing mechanical ventilation admitted to Department of Central Intensive Care Unit (ICU) of Boai Hospital of Zhongshan City Affiliated to Southern Medical University from September 2012 to October 2015 were enrolled.The patients were divided into two groups according to whether they suffered from VAP or not.The content of NE in serum and bronchoalveolar lavage fluid (BALF) at the time of mechanical ventilation start,VAP diagnosis (the worst value from 48 hours after mechanical ventilation start to weaning in non-VAP patients),and at the time before mechanical ventilation weaning,as well as inflammation parameters,clinical pulmonary infection score (CPIS),duration of mechanical ventilation and prognosis were recorded.Receiver operating characteristic curve (ROC) was used to analyze the predictive value of NE on VAP diagnosis and prognosis.Results Finally 38 patients were enrolled in the VAP group,and 40 in non-VAP group,and baseline data was similar between the two groups.There was no significant difference in the content of NE in serum and BALF between VAP group and non-VAP group [serum NE (μg/L):67.04 (63.00,75.75) vs.69.00 (63.75,75.00),BALF NE (μg/L):96.26 (85.26,176.01) vs.95.26 (86.76,107.11),both P ＞ 0.05].From continuous monitoring,no significant change in the content of NE in serum and BALF during mechanical ventilation was found in the non-VAP group,but the content of NE in serum and BALF at the time of VAP diagnosis in VAP group was significantly higher than that at mechanical ventilation start [μg/L:157.00 (153.04,165.75) vs.67.04 (63.00,75.75),178.04 (153.00,188.25) vs.96.26 (85.26,176.01),both P ＜ 0.05],and NE content in serum and BALF was significantly decreased at the time after VAP clinical recovery and before mechanical ventilation weaning [μg/L:75.67 (64.51,110.55) vs.157.00 (153.04,165.79),95.50 (66.56,183.02) vs.178.04 (153.00,188.25),both P ＜ 0.05].The NE in the start time of VAP in VAP group was divided into four groups according to quartile,it was found that with the increase of NE content in serum and BALF,the CPIS was increased,the duration of mechanical ventilation was prolonged,and the prognosis was poor (all P ＜ 0.01).Compared with non-VAP group,white blood cell count (WBC),neutrocyte proportion,C-reactive protein (CRP),and procalcitonin (PCT) in VAP group were significantly increased (all P ＜ 0.01).NE in BALF was significantly positively correlated with WBC,neutrocyte proportion,CRP and PCT (r value was 0.507,0.432,0.779,and 0.519,respectively,all P =0.000),among which the highest correlation was CRP.NE in BALF used for VAP diagnosis has good accuracy,with sensitivity of 87.4％,and specificity of 90.6％,and sensitivity and specificity of NE in serum for VAP diagnosis was 78.6％ and 79.2％ respectively.Conclusion NE can be used as one of the indicators for VAP diagnosis,and it is related to the prognosis of VAP.

Circular RNA (circRNA) is a novel endogenous noncoding RNA (ncRNA).CircRNA has been widely concerned in recent years and is a hotspot in the field of ncRNA research owing to stable structure,high abundance and organization specificity.More and more studies have shown that circRNA plays a vital role in the regulation of gene expression.It will be more important in the development and progression of neurological diseases.This review will focus on the formation,characteristics and biological functions of circRNA,as well as the possible mechanism by which it modulates neurological diseases.

Objective:Serum soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) is a useful biomarker of bacterial infection. However, the diagnostic value of sTREM-1 of alveolar fluid in pulmonary infection is still unclear. This article aimed to explore the value of sTREM-1 of alveolar fluid in the early diagnosis of ventilator-associated pneumonia (VAP) by systematic review of relevant literatures.Methods:CNKI, Wanfang, VIP, PubMed/Medline and Embase databases were retrieved. Articles on diagnosis of VAP by sTREM-1 before June 30, 2019 were collected. QUADAS-2 scale provided by Cochrane Collaboration Network was used to evaluate the quality of diagnostic experiments. RevMan 5.3 and Stata 13.0 software were used to complete Meta-analysis. The levels of sTREM-1 between VAP and non-VAP patients were analyzed by Meta-analysis, and then diagnostic test Meta-analysis was conducted. Heterogeneity, sensitivity and publication bias were analyzed.Results:A total of 24 articles were enrolled. QUADAS-2 scale indicated that the selected literature had low bias and high clinical adaptability. ① In Meta-analysis of sTREM-1 level in alveolar fluid, 20 articles were selected and found to have high heterogeneity ( I2 = 94.4%, P = 0.000). The random effects models were used for Meta-analysis. It was indicated that the sTREM-1 level in alveolar fluid of VAP group was significantly higher than that of non-VAP group with significant difference [standardized mean difference ( SMD) was 1.47, 95% confidence interval (95% CI) was 1.00-1.95, Z = 6.14, P = 0.000]. By subgroup analysis and Meta-regression analysis, no source of heterogeneity was found. Sensitivity analysis suggested that the results of this Meta-analysis were robust and credible, and Begg funnel plot analysis showed that there was no significant publication bias ( Z = 1.46, P = 0.143). ② A total of 18 articles were included in the Meta-analysis of diagnostic experiments. Deek funnel plot showed publication bias ( P = 0.012). The combined sensitivity was 0.87 (95% CI was 0.81-0.91), specificity was 0.80 (95% CI was 0.73-0.86), and diagnostic odds ratio ( DOR) was 26 (95% CI was 13-50). Subgroup analysis of three different sources of alveolar fluid (bronchoalveolar lavage fluid, endotracheal aspiration fluid and exhaled ventilator condensate) showed that STREM-1 had a certain value in early diagnosis of VAP. The I2 of combined DOR was 35.4%, and I2 of sensitivity was 79.46%, I2 of specificity was 77.61%, suggesting heterogeneity in the selected literature. Subgroup analysis found that nationality, subject design, sample source, sample size and diagnostic "gold criteria" were related to heterogeneity, but not age. The area under synthetic receiver operating characteristic (SROC) curve (AUC) was 0.90 (95% CI was 0.87-0.92). Conclusions:The detection of sTREM-1 level in alveolar fluid can be used for the early diagnosis of VAP with high sensitivity and specificity. If combined with other biomarkers, it may have more diagnostic value.