1.Research progress on the impact and mechanism of neutrophil extracellular traps (NETs) components in atherosclerosis.
Xin CHEN ; Jing-Jing ZHU ; Xiao-Fan YANG ; Yu-Peng MA ; Yi-Min BAO ; Ke NING
Acta Physiologica Sinica 2025;77(1):107-119
Atherosclerosis (AS) is a prevalent clinical vascular condition and serves as a pivotal pathological foundation for cardiovascular diseases. Understanding the pathogenesis of AS has significant clinical and societal implications, aiding in the development of targeted drugs. Neutrophils, the most abundant leukocytes in circulation, assume a central role during inflammatory responses and closely interact with AS, which is a chronic inflammatory vascular disease. Neutrophil extracellular traps (NETs) are substantial reticular formations discharged by neutrophils that serve as an immune defense mechanism. These structures play a crucial role in inducing dysfunction of the vascular barrier following endothelial cell injury. Components released by NETs pose a threat to the integrity of vascular endothelium, which is essential as it acts as the primary barrier to maintain vascular wall integrity. Endothelial damage constitutes the initial stage in the onset of AS. Recent investigations have explored the intricate involvement of NETs in AS progression. The underlying structures of NETs and their active ingredients, including histone, myeloperoxidase (MPO), cathepsin G, neutrophil elastase (NE), matrix metalloproteinases (MMPs), antimicrobial peptide LL-37, alpha-defensin 1-3, and high mobility group protein B1 have diverse and complex effects on AS through various mechanisms. This review aims to comprehensively examine the interplay between NETs and AS while providing insights into their mechanistic underpinnings of NETs in this condition. By shedding light on this intricate relationship, this exploration paves the way for future investigations into NETs while guiding clinical translation efforts and charting new paths for therapeutic interventions.
Extracellular Traps/physiology*
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Humans
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Atherosclerosis/immunology*
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Neutrophils/physiology*
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Leukocyte Elastase/metabolism*
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Peroxidase/physiology*
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Matrix Metalloproteinases/physiology*
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Cathepsin G/metabolism*
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Cathelicidins
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HMGB1 Protein/physiology*
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Histones
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Animals
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Endothelium, Vascular
2.Quality changes of volatile oil and chlorogenic acid compounds during extraction process of Artemisiae Argyi Folium: process analysis based on chemical composition, physicochemical properties, and biological activity.
Dan-Dan YANG ; Hao-Zhou HUANG ; Xin-Ming CHEN ; Lin HUANG ; Ya-Nan HE ; Zhen-Feng WU ; Xiao-Ming BAO ; Ding-Kun ZHANG ; Ming YANG
China Journal of Chinese Materia Medica 2025;50(11):3001-3012
To explore the variation laws of volatile oil during the extraction process of Artemisiae Argyi Folium and its impact on the quality of the medicinal solution, as well as to achieve precise control of the extraction process, this study employed headspace solid phase microextraction gas chromatography-mass spectrometry(HS-SPME-GC-MS) in combination with multiple light scattering techniques to conduct a comprehensive analysis, identification, and characterization of the changes in volatile components and the physical properties of the medicinal solution during the extraction process. A total of 82 volatile compounds were identified using the HS-SPME-GC-MS technique, including 21 alcohols, 15 alkenes, 14 ketones, 9 acids, 6 aldehydes, 5 phenols, 3 esters, and 9 other types of compounds. At different extraction time points(15, 30, 45, and 60 min), 71, 72, 64, and 44 compounds were identified in the medicinal solution, respectively. It was observed that the content of volatile components gradually decreased with the extension of extraction time. Through multivariate statistical analysis, four compounds with significant differences during different extraction time intervals were identified, namely 1,8-cineole, terpinen-4-ol, 3-octanone, and camphor. RESULTS:: from multiple light scattering techniques indicated that at 15 minutes of extraction, the transmittance of the medicinal solution was the lowest(25%), the particle size was the largest(0.325-0.350 nm), and the stability index(turbiscan stability index, TSI) was the highest(0-2.5). With the extension of extraction time, the light transmittance of the medicinal solution improved, stability was enhanced, and the particle size decreased. These laws of physicochemical property changes provide important basis for the control of Artemisiae Argyi Folium extraction process. In addition, the changes in the bioactivity of Artemisiae Argyi Folium extracts during the extraction process were investigated through mouse writhing tests and antimicrobial assays. The results indicated that the analgesic and antimicrobial effects of the medicinal solution were strongest at the 15-minute extracting point. In summary, the findings of this study demonstrate that the content of volatile oil in Artemisiae Argyi Folium extracts gradually decreases with the extension of extraction time, and the variation in volatile oil content directly influences the physicochemical properties and pharmacological efficacy of the medicinal solution. This discovery provides important scientific reference for the optimization of Artemisiae Argyi Folium extraction processes and the development and application of process analytical technologies.
Oils, Volatile/pharmacology*
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Artemisia/chemistry*
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Gas Chromatography-Mass Spectrometry
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Drugs, Chinese Herbal/pharmacology*
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Chlorogenic Acid/pharmacology*
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Solid Phase Microextraction
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Quality Control
3.Multiple biomarkers risk score for accurately predicting the long-term prognosis of patients with acute coronary syndrome.
Zhi-Yong ZHANG ; Xin-Yu WANG ; Cong-Cong HOU ; Hong-Bin LIU ; Lyu LYU ; Mu-Lei CHEN ; Xiao-Rong XU ; Feng JIANG ; Long LI ; Wei-Ming LI ; Kui-Bao LI ; Juan WANG
Journal of Geriatric Cardiology 2025;22(7):656-667
BACKGROUND:
Biomarkers-based prediction of long-term risk of acute coronary syndrome (ACS) is scarce. We aim to develop a risk score integrating clinical routine information (C) and plasma biomarkers (B) for predicting long-term risk of ACS patients.
METHODS:
We included 2729 ACS patients from the OCEA (Observation of cardiovascular events in ACS patients). The earlier admitted 1910 patients were enrolled as development cohort; and the subsequently admitted 819 subjects were treated as validation cohort. We investigated 10-year risk of cardiovascular (CV) death, myocardial infarction (MI) and all cause death in these patients. Potential variables contributing to risk of clinical events were assessed using Cox regression models and a score was derived using main part of these variables.
RESULTS:
During 16,110 person-years of follow-up, there were 238 CV death/MI in the development cohort. The 7 most important predictors including in the final model were NT-proBNP, D-dimer, GDF-15, peripheral artery disease (PAD), Fibrinogen, ST-segment elevated MI (STEMI), left ventricular ejection fraction (LVEF), termed as CB-ACS score. C-index of the score for predication of cardiovascular events was 0.79 (95% CI: 0.76-0.82) in development cohort and 0.77 (95% CI: 0.76-0.78) in the validation cohort (5832 person-years of follow-up), which outperformed GRACE 2.0 and ABC-ACS risk score. The CB-ACS score was also well calibrated in development and validation cohort (Greenwood-Nam-D'Agostino: P = 0.70 and P = 0.07, respectively).
CONCLUSIONS
CB-ACS risk score provides a useful tool for long-term prediction of CV events in patients with ACS. This model outperforms GRACE 2.0 and ABC-ACS ischemic risk score.
4.Quercetin Confers Protection against Sepsis-Related Acute Respiratory Distress Syndrome by Suppressing ROS/p38 MAPK Pathway.
Wei-Chao DING ; Juan CHEN ; Quan LI ; Yi REN ; Meng-Meng WANG ; Wei ZHANG ; Xiao-Hang JI ; Xin-Yao WU ; Shi-Nan NIE ; Chang-Bao HUANG ; Zhao-Rui SUN
Chinese journal of integrative medicine 2025;31(11):1011-1020
OBJECTIVE:
To identify the underlying mechanism by which quercetin (Que) alleviates sepsis-related acute respiratory distress syndrome (ARDS).
METHODS:
In vivo, C57BL/6 mice were assigned to sham, cecal ligation and puncture (CLP), and CLP+Que (50 mg/kg) groups (n=15 per group) by using a random number table. The sepsisrelated ARDS mouse model was established using the CLP method. In vitro, the murine alveolar macrophages (MH-S) cells were classified into control, lipopolysaccharide (LPS), LPS+Que (10 μmol/L), and LPS+Que+acetylcysteine (NAC, 5 mmol/L) groups. The effect of Que on oxidative stress, inflammation, and apoptosis in mice lungs and MH-S cells was determined, and the mechanism with reactive oxygen species (ROS)/p38 mitogen-activated protein kinase (MAPK) pathway was also explored both in vivo and in vitro.
RESULTS:
Que alleviated lung injury in mice, as reflected by a reversal of pulmonary histopathologic changes as well as a reduction in lung wet/dry weight ratio and neutrophil infiltration (P<0.05 or P<0.01). Additionally, Que improved the survival rate and relieved gas exchange impairment in mice (P<0.01). Que treatment also remarkedly reduced malondialdehyde formation, superoxide dismutase and catalase depletion, and cell apoptosis both in vivo and in vitro (P<0.05 or P<0.01). Moreover, Que treatment diminished the release of inflammatory factors interleukin (IL)-1β, tumor necrosis factor-α, and IL-6 both in vivo and in vitro (P<0.05 or P<0.01). Mechanistic investigation clarifified that Que administration led to a decline in the phosphorylation of p38 MAPK in addition to the suppression of ROS expression (P<0.01). Furthermore, in LPS-induced MH-S cells, ROS inhibitor NAC further inhibited ROS/p38 MAPK pathway, as well as oxidative stress, inflammation, and cell apoptosis on the basis of Que treatment (P<0.05 or P<0.01).
CONCLUSION
Que was found to exert anti-oxidative, anti-inflammatory, and anti-apoptotic effects by suppressing the ROS/p38 MAPK pathway, thereby conferring protection for mice against sepsis-related ARDS.
Animals
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Sepsis/drug therapy*
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Quercetin/therapeutic use*
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Respiratory Distress Syndrome/enzymology*
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p38 Mitogen-Activated Protein Kinases/metabolism*
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Mice, Inbred C57BL
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Reactive Oxygen Species/metabolism*
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Apoptosis/drug effects*
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Male
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Oxidative Stress/drug effects*
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MAP Kinase Signaling System/drug effects*
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Lung/drug effects*
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Mice
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Lipopolysaccharides
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Macrophages, Alveolar/pathology*
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Inflammation/pathology*
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Protective Agents/therapeutic use*
5.Clinical trial of dapagliflozin combination with sacubitril/valsartan sodium in the treatment of patients with heart failure after acute myocardial infarction intervention
Mei-Mei LI ; Hui-Li LIN ; Shao-Peng CHEN ; Xin-Bao HONG
The Chinese Journal of Clinical Pharmacology 2024;40(7):954-958
Objective To observe the efficacy of dapagliflozin tablets combination with sacubitril/valsartan sodium tablets in the treatment of patients with heart failure(HF)after acute myocardial infarction(AMI)intervention.Methods Patients with HF after AMI intervention were randomly divided into control group and treatment group.The control group was given conventional anti-heart failure therapy+sacubitril/valsartan sodium tablets(50 mg for the first time,then gradually increased to 200 mg each time,twice a day),and the treatment group was additionally treated with dapagliflozin(10 mg every time,once a day)on the basis of the control group,and the course of treatment was 6 months.The two groups were compared in terms of clinical efficacy,cardiac function[left ventricular ejection fraction(LVEF),left ventricular remodeling index(LVRI),6-minute walking distance(6MWD)],heart failure markers[brain natriuretic peptide(BNP),N-terminal pro-brain natriuretic peptide(NT-proBNP),troponin(Tn)],and serum related biochemical indicators[soluble human stromelysin-2(ST2),angiotensin 2(AT-Ⅱ),soluble intercellular adhesion molecule-1(sICAM-1)],incidence rates of major adverse cardiovascular events(MACE)during follow-up and adverse drug reactions during treatment.Results Six cases dropped out during treatment,and finally 46 cases were included in control group and treatment group,respectively.After treatment,the effective rates of treatment in treatment group(91.30%)was significantly higher than that in control group(76.09%,P<0.05).After treatment,the LVEF values in control group and treatment group were(51.38±4.82)%and(54.43±4.63)%;LVRI values were(1.47±0.15)and(1.35±0.17)g·mL-1;6MWD values were(390.53±40.32)and(362.61±38.51)m;the BNP levels were(28.34±2.47)and(26.51±2.16)pmol·L-1;NT-proBNP levels were(262.61±53.18)and(227.68±46.73)ng·L-1;sICAM-1 levels were(84.61±7.14)μg·L-1 and(74.68±7.08)μg·L1,and there were statistical differences between both groups(all P<0.05).During follow-up,the incidence rate of MACE in treatment group(6.52%)was significantly lower than that in control group(21.74%,P<0.05).The main adverse drug reactions in the two groups were renal dysfunction,hypotension,urogenital infection and hyperkalemia,but there was no significant difference in the incidence of adverse reactions between treatment group(13.04%)and control group(10.87%,P>0.05).Conclusion Dapagliflozin tablets combined with sacubitril/valsartan sodium tablets can significantly improve cardiac function and related indicators and reduce the incidence of MACE in patients with HF after AMI intervention.
6.Effects of total flavonoids of Oxytropis falcata Bunge on CCl4-induced liver fibrosis in rats
Tian-Yan YANG ; Xin-Huan MA ; Zhi-Wei XU ; Rong-Kun LI ; Fang-Xiong MA ; Bao-Feng HE ; Liang CHEN ; Xiao-Qing CHEN ; Jun ZHANG
The Chinese Journal of Clinical Pharmacology 2024;40(14):2073-2077
Objective To investigate the effects of total flavones from Oxytropis falcata Bunge on hepatic fibrosis(HF)induced by carbon tetrachloride and liver transforming growth factor(TGF-β)/Smad signaling pathway.Methods Forty-eight male rats were randomly divided into normal group(intraperitoneal injection of peanut oil,intragastric administration of 0.9%NaCl),model group(intraperitoneal injection of 40%CC14 peanut oil solution induced HF model,intragastric administration of 0.9%NaCl),positive control group(modeling,intragastric administration of 0.2 mg·kg-1 of colchicine),experimental-L,-M,-H groups(modeling,intragastric administration of 100,200 and 400 mg·kg-1 of total flavonoid extract of Oxytropis falcata Bunge),8 individuals in each group,for 4 consecutive weeks.The histopathological changes were observed by hematoxylin-eosin and Masson staining.Serum liver function and liver fibrosis were measured;erum inflammatory factors were detected;fluorescence quantitative polymerase chain reaction(RT-qPCR)was used to determine gene expression in liver.Results The pathological injury of liver tissue in the model group was serious,and a large number of inflammatory factors and collagen fibers were accumulated,while the rest of the treatment groups had different degrees of remission.In normal group,model group,positive control group,experimental-L,-M,-H groups,glutamic-pyruvic transaminase levels were(49.28±12.44),(5 885.42±948.37),(4 454.60±489.27),(4 650.47±843.53),(3 761.75±887.30)and(3 544.90±1 066.75)μg·L-1;glutamic-oxaloacetic transaminase levels were(186.90±46.89),(5 936.23±793.81),(3 971.37±780.28),(4 360.30±863.35),(3 943.10±439.47)and(3 971.38±631.08)μg·L-1;hyaluronic acid levels were(45.08±17.16),(104.32±36.06),(66.83±20.09),(70.30±21.07),(60.00±9.68)and(59.02±10.73)μg·L-1;laminin levels were(23.13±3.89),(60.85±13.66),(35.67±9.92),(39.98±9.39),(36.55±12.21)and(34.68±24.83)μg·L-1;type Ⅲ procollagen level were(24.98±5.34),(82.58±30.14),(40.70±16.14),(51.08±23.21),(43.60±12.48)and(44.20±11.66)p±g·L-1;interleukin(IL)-1β levels were(37.63±1.24),(46.10±3.23),(39.22±2.36),(41.33±0.93),(40.25±2.04)and(39.18±2.23)pg·mL-1;tumor necrosis factor-α levels were(314.58±20.56),(383.71±16.97),(349.00±7.93),(348.88±25.11),(325.75±27.84)and(335.07±21.33)pg·mL-1;TGF-β1 mRNA expression of relative quantity respectively were 1.00±0.00,60.99±15.70,9.61±1.59,7.37±1.09,6.41±0.64,6.87±1.09;Smad7 mRNA relative expression were 1.00±0.00,0.34±0.05,0.21±0.03,0.35±0.02,0.38±0.02,0.42±0.03.The above indexes in the model group were compared with the normal group,and the above indexes in the experimental-M,-H groups were compared with the model group,and the differences were statistically significant(P<0.05,P<0.01,P<0.001).Conclusion Total flavonoids of Oxytropis falcata Bunge have protective effects on CC14-induced liver fibrosis in rats,and the mechanism may be related to the regulation of TGF-β/Smad pathway.
7.Construction and validation of an in-hospital mortality risk prediction model for patients receiving VA-ECMO:a retrospective multi-center case-control study
Yue GE ; Jianwei LI ; Hongkai LIANG ; Liusheng HOU ; Liuer ZUO ; Zhen CHEN ; Jianhai LU ; Xin ZHAO ; Jingyi LIANG ; Lan PENG ; Jingna BAO ; Jiaxin DUAN ; Li LIU ; Keqing MAO ; Zhenhua ZENG ; Hongbin HU ; Zhongqing CHEN
Journal of Southern Medical University 2024;44(3):491-498
Objective To investigate the risk factors of in-hospital mortality and establish a risk prediction model for patients receiving venoarterial extracorporeal membrane oxygenation(VA-ECMO).Methods We retrospectively collected the data of 302 patients receiving VA-ECMO in ICU of 3 hospitals in Guangdong Province between January,2015 and January,2022 using a convenience sampling method.The patients were divided into a derivation cohort(201 cases)and a validation cohort(101 cases).Univariate and multivariate logistic regression analyses were used to analyze the risk factors for in-hospital death of these patients,based on which a risk prediction model was established in the form of a nomogram.The receiver operator characteristic(ROC)curve,calibration curve and clinical decision curve were used to evaluate the discrimination ability,calibration and clinical validity of this model.Results The in-hospital mortality risk prediction model was established based the risk factors including hypertension(OR=3.694,95%CI:1.582-8.621),continuous renal replacement therapy(OR=9.661,95%CI:4.103-22.745),elevated Na2+ level(OR=1.048,95%CI:1.003-1.095)and increased hemoglobin level(OR=0.987,95%CI:0.977-0.998).In the derivation cohort,the area under the ROC curve(AUC)of this model was 0.829(95%CI:0.770-0.889),greater than those of the 4 single factors(all AUC<0.800),APACHE Ⅱ Score(AUC=0.777,95%CI:0.714-0.840)and the SOFA Score(AUC=0.721,95%CI:0.647-0.796).The results of internal validation showed that the AUC of the model was 0.774(95%CI:0.679-0.869),and the goodness of fit test showed a good fitting of this model(χ2=4.629,P>0.05).Conclusion The risk prediction model for in-hospital mortality of patients on VA-ECMO has good differentiation,calibration and clinical effectiveness and outperforms the commonly used disease severity scoring system,and thus can be used for assessing disease severity and prognostic risk level in critically ill patients.
8.Epidemiological and clinical characteristics of respiratory syncytial virus infections in children in Jiangsu Province, 2014-2023
Wenxin GU ; Ke XU ; Shenjiao WANG ; Fei DENG ; Qigang DAI ; Xin ZOU ; Qingxiang SHANG ; Liling CHEN ; Yu XIA ; Wenjun DAI ; Jie ZHA ; Songning DING ; Min HE ; Changjun BAO
Chinese Journal of Epidemiology 2024;45(11):1537-1543
Objective:To analyze the epidemiological and clinical characteristics of respiratory syncytial virus (RSV) infection in children in Jiangsu Province from 2014 to 2023.Methods:The acute respiratory infection cases in children aged 0-14 years were selected from outpatient/emergency or inpatient departments in 2 surveillance sentinel hospitals, respectively, in Nanjing, Suzhou and Taizhou of Jiangsu from 1 July 2014 to 31 December 2023, and RSV nucleic acid test was conducted and the intensity of the RSV infection was accessed by WHO influenza epidemiological threshold method, and case information and clinical data were collected. χ2 test was used to compare the differences between groups, and the Bonferroni method was used for pairwise comparisons between groups. Results:In 4 946 cases of acute respiratory infections, the RSV positive rate was 8.21% (406/4 946), and the age M( Q1, Q3) of the cases was 1 (0, 3) years. The RSV positive rate was 10.92% (258/2 362) during 2014-2019 and 6.06% (118/1 948) during 2019-2023, the difference was significant ( χ2=31.74, P<0.001). RSV infection mainly occurred from October to March during 2014-2019, with the incidence peak in December and moderate or higher intensity. The seasonality of RSV infection was not obvious during 2019-2023, with low intensity. The RSV positive rate was highest in children in age group 0- years (17.85%, 151/846), and the positive rate declined gradually with age ( χ2=184.51, P<0.001). The RSV positive rate was higher in inpatient cases (9.84%, 244/2 480) than in outpatient/emergency cases (6.57%, 162/2 466) ( χ2=17.54, P<0.001). In the 155 RSV infection cases with complete clinical data, the clinical symptoms mainly included cough (99.35%, 154/155), fever (55.48%, 86/155), and shortness of breath (45.16%, 70/155). In the cases aged <6 months, the proportion of those with fever was low, but the proportion of those with shortness of breath, transferred to intensive care units, and receiving oxygen therapy were higher (all P<0.05). Children aged <6 months and those with underlying diseases were more likely to have severe RSV infection (all P<0.05). Conclusions:RSV infection in children in Jiangsu Province showed seasonal prevalence in winter from 2014 to 2019. Since 2020, the seasonal characteristics of the epidemic have changed, the epidemic period has been dispersed and the epidemic intensity has decreased. Infants <1 year old were at high risk for RSV infection, and those <6 months old and with underlying diseases might have severe infection.
9.Construction and validation of an in-hospital mortality risk prediction model for patients receiving VA-ECMO:a retrospective multi-center case-control study
Yue GE ; Jianwei LI ; Hongkai LIANG ; Liusheng HOU ; Liuer ZUO ; Zhen CHEN ; Jianhai LU ; Xin ZHAO ; Jingyi LIANG ; Lan PENG ; Jingna BAO ; Jiaxin DUAN ; Li LIU ; Keqing MAO ; Zhenhua ZENG ; Hongbin HU ; Zhongqing CHEN
Journal of Southern Medical University 2024;44(3):491-498
Objective To investigate the risk factors of in-hospital mortality and establish a risk prediction model for patients receiving venoarterial extracorporeal membrane oxygenation(VA-ECMO).Methods We retrospectively collected the data of 302 patients receiving VA-ECMO in ICU of 3 hospitals in Guangdong Province between January,2015 and January,2022 using a convenience sampling method.The patients were divided into a derivation cohort(201 cases)and a validation cohort(101 cases).Univariate and multivariate logistic regression analyses were used to analyze the risk factors for in-hospital death of these patients,based on which a risk prediction model was established in the form of a nomogram.The receiver operator characteristic(ROC)curve,calibration curve and clinical decision curve were used to evaluate the discrimination ability,calibration and clinical validity of this model.Results The in-hospital mortality risk prediction model was established based the risk factors including hypertension(OR=3.694,95%CI:1.582-8.621),continuous renal replacement therapy(OR=9.661,95%CI:4.103-22.745),elevated Na2+ level(OR=1.048,95%CI:1.003-1.095)and increased hemoglobin level(OR=0.987,95%CI:0.977-0.998).In the derivation cohort,the area under the ROC curve(AUC)of this model was 0.829(95%CI:0.770-0.889),greater than those of the 4 single factors(all AUC<0.800),APACHE Ⅱ Score(AUC=0.777,95%CI:0.714-0.840)and the SOFA Score(AUC=0.721,95%CI:0.647-0.796).The results of internal validation showed that the AUC of the model was 0.774(95%CI:0.679-0.869),and the goodness of fit test showed a good fitting of this model(χ2=4.629,P>0.05).Conclusion The risk prediction model for in-hospital mortality of patients on VA-ECMO has good differentiation,calibration and clinical effectiveness and outperforms the commonly used disease severity scoring system,and thus can be used for assessing disease severity and prognostic risk level in critically ill patients.
10.Three-dimensional Printing of Inertial Microchannel with Complex Cross-section and Characterization of Particle Inertial Focusing
Qiao GU ; Xin-Jie ZHANG ; Yao LIU ; Yang BAO ; Hang-Jie ZHU ; Ya-Wei CHEN
Chinese Journal of Analytical Chemistry 2024;52(1):93-101
Projection micro stereolithography three-dimensional(3D)printing method was proposed in this study to fabricate complex microchannels of combined cross-sections.By using 3D printing and polydimethylsiloxane(PDMS)replication methods,two inertial microfluidic chips of three-step and five-step cross-sections were fabricated,and the dimension precisions of the microchannels were controlled within 20 μm.Using the microfluidic chips,the movements of two fluorescent polystyrene particles with diameters of 10 and 6 μm in the stepped channels were investigated.In addition,numerical simulations were applied to demonstrate the inertial focusing mechanisms of particles in the channels.It was found that 10-μm particles had three equilibrium positions in the three-step channel,which located at the inner walls of the three steps,respectively,and most particles focused at the inner step.The 6-μm particles also had three equilibrium positions in the three-step channel.However,the particles migrated to the middle and the outer steps under high flow rates.In the five-step channel,when the flow rate was increased gradually,10-μm particles had a single and two equilibrium positions,respectively,and the particles migrated towards the inner channel wall under high flow rates.In comparison to 10-μm particles,6-μm particles had two stable equilibrium positions in the five-step channel at all flow rate range.It could be concluded that the quantity,shape and strength of the secondary flow vortex could be altered by changing structure of the combined cross-section,thus the equilibrium positions and quantities of the focusing particles could be also regulated.The research outcome might provide new insights for precise cell inertial manipulation and promote the application and development of inertial microfluidic technology in biomedical and other fields.

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