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Aerosol particles play critical roles in climate and human health. However, aerosol composition and evolution, particularly secondary organic aerosol (SOA), and aerosol interactions with clouds in high-altitude background areas in China remain less understood. Here, we conducted real-time measurements of submicron aerosols (PM 1) using aerosol mass spectrometers at a forested mountain site (1128 m a.s.l.) in southeastern China in November 2022. The average (±1σ) PM 1 mass concentration was 4.3±4.8 µ g m -3 , which was ubiquitously lower than that at other mountain sites in China. Organic aerosol (OA) constituted the largest fraction of PM 1 (42.9 %) and was predominantly secondary, as indicated by the high oxygen-to-carbon (O / C) ratio (0.85–0.96) and carbon oxidation state (0.21–0.49). Notably, the remarkably enhanced PM 1 concentrations observed during the daytime on cloudless days were identified to be likely to be produced from cloud evaporation. While more oxidized oxygenated OA was scavenged efficiently during cloud events, cloud evaporation was found to release a significant amount of less oxidized oxygenated OA from air masses transported from polluted regions. The distinct decrease in OA / Δ CO with the increase in O / C during the cloud evaporative period further demonstrates that OA remaining in cloud droplets is generally in a moderate oxidation state. Moreover, organic nitrates were also estimated and showed a higher contribution to the total nitrate during the cloudy period (27 %) than during the evaporative period (3 %). Overall, our results demonstrate the importance of SOA and the influences of cloud processes in regional mountain areas in southeastern China. [ABSTRACT FROM AUTHOR]

Aerosol particles play crucial roles in both climate dynamics and human health. However, there remains a significant gap in our understanding of aerosol composition and evolution, particularly regarding secondary organic aerosols (SOA), and their interaction with clouds in high-altitude background areas in China. Here we conducted real-time measurements of submicron aerosols (PM1) using aerosol mass spectrometers at a forested mountain site (1128 m a.s.l.) in southeastern China in November 2022. Our results revealed that organic aerosol (OA) constituted a substantial portion of PM1 (41.1 %), with the OA being primarily of secondary origin, as evidenced by a high oxygen-to-carbon (O/C) ratio (0.85–0.96). Positive matrix factorization resolved two distinct SOA factors: less oxidized oxygenated OA (LO-OOA) and more oxidized OOA (MO-OOA). Interestingly, MO-OOA was scavenged efficiently during cloud events, while cloud evaporation contributed significantly to LO-OOA. The ratio of OA/ΔCO increased with a decrease in the O/C ratio, suggesting that OA remaining in cloud droplets generally maintained a moderate oxidation state. Furthermore, our results indicated a higher contribution of organic nitrates to total nitrate during cloudy periods (27 %) compared to evaporative periods (3 %). Notably, a substantial contribution of nitrate in PM1 (20.9 %) was observed, particularly during high PM periods, implying that nitrate formed in polluted areas interacted with clouds and significantly impacted the regional background site. Overall, our study underscores the importance of understanding the dynamics of secondary organic aerosols and the impacts of cloud processing in regional mountainous areas in southeastern China. [ABSTRACT FROM AUTHOR]

Objective: Fundamental researches have shown that soluble CD73 (sCD73) can inhibit inflammatory response and limit excessive tissue damage caused by continuous immune cell activation. A Finnish prospective, observational study of acute kidney injury (FINNAKI) showed no association between sCD73 and 90-day mortality in sepsis patients. Clinical data of this study was used for secondary analysis to explore whether the relationship between sCD73 and 90-day mortality was consistent in septic shock and non-septic shock patients., Methods: The FINNAKI study was a prospective, observational cohort study conducted in 17 intensive care units (ICUs) in Finland from September 1st, 2011 to February 1st, 2012. Sepsis/septic shock was defined according to Sepsis-1 definition. Demographic characteristics, treatment, comorbidities and 90-day mortality of the patients were analyzed. To evaluate the difference (interaction test) between the relationship of sCD73 and 90-day mortality in septic shock and non-septic shock patients, likelihood ratio test was used to integrate the product term (sCD73×septic shock or non-septic shock) into multivariable Logistic regression. Sensitivity analysis was performed with the definition of Sepsis-3. The interaction between sCD73 and 90-day mortality in patients with septic shock and non-septic shock were verified by generalized additive model (GAM)., Results: A total of 588 patients with severe sepsis/septic shock were enrolled. 164 patients died in 90 days, and the 90-day mortality was 27.89%. Based on the Sepsis-1 definition, there were 159 non-septic shock patients and 429 septic shock patients. Compared with the non-septic shock patients, lactate (Lac) level, sequential organ failure assessment (SOFA) score, fluid balance on the first day, and ratio of mechanical ventilation, 12-hour acute kidney injury (AKI), renal replacement therapy (RRT), and postoperative ICU transition in the septic shock patients were significantly increased and the proportion of emergency admission to ICU was significantly decreased. Based on the Sepsis-3 definition, there were 383 non-septic shock patients and 205 septic shock patients; the results of clinical data analysis between the two groups were similar to those based on Sepsis-1. Based on Sepsis-1, there was no significant difference in 90-day mortality between non-septic shock and septic shock patients [23.90% (38/159) vs. 29.37% (126/429), P > 0.05]. However, based on Sepsis-3, the 90-day mortality of patients with septic shock was significantly higher than that of patients with non-septic shock [37.56% (77/205) vs. 22.72% (87/383), P < 0.01]. Multivariate Logistic regression analysis and interaction test showed that after adjusting all confounding factors (except the number of complications) in non-sepsis shock and sepsis shock patients, sCD73 and 90-day mortality were significantly different in both Sepsis-1 and Sepsis-3. The P values for interaction tests were 0.046 and 0.027, respectively. In patients with non-septic shock, sCD73 tended to be positively associated with 90-day mortality [Sepsis-1: odds ratio (OR) = 1.46, 95% confidence interval (95%CI) was 0.99-2.13, P = 0.053; Sepsis-3: OR = 1.34, 95%CI was 1.02-1.74, P = 0.034]. In septic shock patients, sCD73 tended to be negatively associated with 90-day mortality (Sepsis-1: OR = 0.91, 95%CI was 0.69-1.20, P = 0.494; Sepsis-3: OR = 0.80, 95%CI was 0.55-1.17, P = 0.249). The results of GAM model validation were consistent with the results of Logistic regression equation cross validation., Conclusions: The relationship between sCD73 and 90-day mortality is significantly different from patients with non-sepsis shock and sepsis shock. In patients with non-sepsis shock, sCD73 is trend to positively associated with 90-day mortality, and there is a negative trend between sCD73 and 90-day mortality in patients with septic shock.

Objective: To investigate the relationship between 1-hour lactate (1 h Lac) and 30-day mortality in critical care patients in intensive care unit (ICU)., Methods: A retrospective, observational cohort study was performed with adult critical patients (age ≥ 16 years old) having lactate records within 1 hour after ICU admission from Medical Information Mart for Intensive Care-III database (MIMIC-III). According to the 1 h Lac level, the patients were divided into three groups: < 2 mmol/L, 2-4 mmol/L, and > 4 mmol/L groups. The baseline characteristics were analyzed. Multivariable Logistic regression analysis was performed to assess the association between 1 h Lac and 30-day mortality. The receiver operating characteristic (ROC) curve was used to analyze the predictive value of 1 h Lac for 30-day mortality, and Kaplan-Meier survival curve was performed according to the best cut-off value. In addition, sensitivity analysis was carried out for each classification variable., Results: A total of 3 969 ICU patients were included, with 673 died in 30 days, and the total mortality was 16.95%. There were 1 664, 1 588, 717 patients in Lac < 2 mmol/L, 2-4 mmol/L and > 4 mmol/L group, respectively. There were significant differences in age, ICU duration, ICU type, heart rate, leukocyte count, hemoglobin, creatinine, sequential organ failure score (SOFA), ventilator application, vasoactive drug use and main diagnosis among the three groups. Multivariable Logistic regression analysis showed that a 1 mmol/L increment in Lac was associated with 0.24 times higher risk of 30-day mortality [odds ratio (OR) = 1.24, 95% confidence interval (95%CI) was 1.19-1.29, P < 0.000 1]. ROC curve analysis showed that the area under ROC curve (AUC) of 1 h Lac for predicting 30-day mortality of severe patients was 0.694 (95%CI was 0.669-0.718). The cut-off value was 3.35 mmol/L with sensitivity of 0.499 and specificity of 0.779, whilst positive likelihood ratio was 2.260, and negative likelihood ratio was 0.643. According to the cut-off value of 1 h Lac, the patients were divided into high lactate group (≥ 3.35 mmol/L) and low lactate group (< 3.35 mmol/L). In the two subgroups, 30-day mortality was 31.58% (336/1 064) and 11.60% (337/2 905), respectively. The Kaplan-Meier survival curve showed that the 30-day cumulative survival rate of high lactate group was significantly lower than that of low lactate group (Log-rank test: χ 2 = 247.72, P < 0.000 1). Multiple Logistic regression analysis showed that the 30-day mortality rate of high lactate group was 2.34 times that the level of low lactate group (OR = 2.34, 95%CI was 1.90-2.88, P < 0.000 1), after the adjustment of age, time of admission, type of ICU, hemoglobin, leukocyte count, use of vasopressor, use of ventilator and main diagnosis of patients. Stratified analysis showed that the relationship between 1 h Lac and 30-day mortality was stable., Conclusions: 1 h Lac is associated with 30-day mortality in critical care patients. The risk of death was significantly increased in critically ill patients with 1 h Lac higher than 3.35 mmol/L.