Yimin Li

Hybrid metamaterial switching for manipulating chirality based on VO2 phase transition

Polarization manipulations of electromagnetic waves can be obtained by chiral and anisotropic metamaterials routinely, but the dynamic and high-efficiency modulations of chiral properties still remain challenging at the terahertz range. Here, we theoretically demonstrate a new scheme for realizing thermal-controlled chirality using a hybrid terahertz metamaterial with embedded vanadium dioxide (VO2) films. The phase transition of VO2 films in 90° twisted E-shaped resonators enables high-efficiency thermal modulation of linear polarization conversion. The asymmetric transmission of linearly polarized wave and circular dichroism simultaneously exhibit a pronounced switching effect dictated by temperature-controlled conductivity of VO2 inclusions. The proposed hybrid metamaterial design opens exciting possibilities to achieve dynamic modulation of terahertz waves and further develop tunable terahertz polarization devices.

Human alveolar epithelial type II cells in primary culture

Alveolar epithelial type II (AEII) cells are a key structure and defender in the lung but also are the targets in many lung diseases, including acute respiratory distress syndrome, ventilator‐induced lung injury, and pulmonary fibrosis. We sought to establish an optimized method for high yielding and long maintenance of characteristics of primary human AEII cells to facilitate the investigation of the mechanisms of lung diseases at the cellular and molecular levels. Adult human peripheral normal lung tissues of oncologic patients undergoing lung resection were collected. The AEII cells were isolated and identified by the expression of pro‐surfactant protein (SP)C, epithelial sodium channel (αENaC) and cytokeratin (CK)‐8, the lamellar bodies specific for AEII cells, and confirmed by the histology using electron microscopy. The phenotype of AEII cells was characterized by the expression of surfactant proteins (SP‐A, SP‐B, SP‐C, SP‐D), CK‐8, KL‐6, αENaC, and aquaporin (AQP)‐3, which was maintained over 20 days. The biological activity of the primary human AEII cells producing SP‐C, cytokines, and intercellular adhesion molecule‐1 was vigorous in response to stimulation with tumor necrosis factor‐α. We have modified previous methods and optimized a method for isolation of high purity and long maintenance of the human AEII cell phenotype in primary culture. This method provides an important tool for studies aiming at elucidating the molecular mechanisms of lung diseases exclusively in AEII cells.

Sepsis and ARDS: The Dark Side of Histones

Despite advances in management over the last several decades, sepsis and acute respiratory distress syndrome (ARDS) still remain major clinical challenges and the leading causes of death for patients in intensive care units (ICUs) due to insufficient understanding of the pathophysiological mechanisms of these diseases. However, recent studies have shown that histones, also known as chromatin-basic structure proteins, could be released into the extracellular space during severe stress and physical challenges to the body (e.g., sepsis and ARDS). Due to their cytotoxic and proinflammatory effects, extracellular histones can lead to excessive and overwhelming cell damage and death, thus contributing to the pathogenesis of both sepsis and ARDS. In addition, antihistone-based treatments (e.g., neutralizing antibodies, activated protein C, and heparin) have shown protective effects and have significantly improved the outcomes of mice suffering from sepsis and ARDS. Here, we review researches related to the pathological role of histone in context of sepsis and ARDS and evaluate the potential value of histones as biomarkers and therapeutic targets of these diseases.

Proteomic Analysis of Lung Tissue in a Rat Acute Lung Injury Model: Identification of PRDX1 as a Promoter of Inflammation

Acute respiratory distress syndrome (ARDS) remains a high morbidity and mortality disease entity in critically ill patients, despite decades of numerous investigations into its pathogenesis. To obtain global protein expression changes in acute lung injury (ALI) lung tissues, we employed a high-throughput proteomics method to identify key components which may be involved in the pathogenesis of ALI. In the present study, we analyzed lung tissue proteomes of Pseudomonas aeruginosa-induced ALI rats and identified eighteen proteins whose expression levels changed more than twofold as compared to normal controls. In particular, we found that PRDX1 expression in culture medium was elevated by a lipopolysaccharide (LPS) challenge in airway epithelial cells in vitro. Furthermore, overexpression of PRDX1 increased the expression of proinflammatory cytokines interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α), whereas knockdown of PRDX1 led to downregulated expression of cytokines induced by LPS. In conclusion, our findings provide a global alteration in the proteome of lung tissues in the ALI rat model and indicate that PRDX1 may play a critical role in the pathogenesis of ARDS by promoting inflammation and represent a novel strategy for the development of new therapies against ALI.

A gloves-associated outbreak of imipenem-resistant Acinetobacter baumannii in an intensive care unit in Guangdong, China

BackgroundImipenem-resistant Acinetobacter baumannii (IRAB) is an important cause of hospital-acquired infection. We aimed to describe an outbreak of IRAB infection and to investigate its possible source in an intensive care unit.MethodsAn environmental investigation was undertaken. Antimicrobial susceptibility testing was performed by microdilution. These isolates were genotyped by use of repetitive extragenic palindromic polymerase chain reaction (rep-PCR; DiversiLab). The study included 11 patients infected with IRAB and 14 control patients free of IRAB. Case and control patients were compared for possible predisposing factors. A multifaceted intervention was implemented to control the outbreak.ResultsThirty-nine IRABs were isolated from patients and the environmental surveillance culture in August, November, and December 2011. All isolates were resistant to imipenem. The IRAB strains belonged to seven clones (A–G) by the use of rep-PCR. There were four epidemic clones (D–G) in the outbreak, and Clone D was predominant. For the case–control study, patients with chronic obstructive pulmonary disease were susceptible to infection with IRAB. The hospital mortality of the case group was significantly higher than that of the control group.ConclusionsThe outbreak strains were transmitted among infected patients and equipment by inappropriate use of gloves. A combination of aggressive infection control measures is essential for preventing recurrent nosocomial outbreaks of IRAB.

Compliance with severe sepsis bundles and its effect on patient outcomes of severe community-acquired pneumonia in a limited resources country.

Introduction Validation of compliance with severe sepsis bundles is still needed. The purpose of this study was to determine compliance and its outcomes in severe community-acquired pneumonia (CAP) patients in a limited resources country. Material and methods A prospective cohort study of 212 severe CAP patients was carried out. The implementation programme was organized into two continuous phases. The primary outcomes were compliance and hospital mortality. Results Compliance with administration of antibiotics and vasopressors as well as plateau pressure on average < 30 cm H2O was high in both groups. In the bundles group, patients received more serum lactate monitoring (62.3% vs. 11.3%), more blood cultures (47.1% vs. 24.5%), more fluid resuscitation (63.2% vs. 26.4%) and volumes infused (1319.8 ±1107.4 ml vs. 461.9 ±799.3 ml), more inotropic dobutamine and/or packed red blood cells (21.7% vs. 10.0%), more low-dose steroids (56.5% vs. 15.0%), and more glucose control (51.9% vs. 6.6%) compared with such patients in the control group. The rates of total compliance with 6-hour, 24-hour, and 6/24-hour bundles in the prospective period were 47.1%, 51.9%, and 42.5%, respectively. Hospital mortality was reduced from 44.3% to 29.2% (p = 0.023) in the bundles group, and the compliant subgroup had a more than twofold decrease in mortality (17.8% vs. 37.7%, p = 0.003). Serum lactate measured, blood cultures, and fluid resuscitation showed independent relationships with decreased mortality. Conclusions Total compliance was relatively low, but the implementation of severe sepsis bundles could clearly reduce mortality from severe CAP.

Survival Predictors for Severe ARDS Patients Treated with Extracorporeal Membrane Oxygenation: A Retrospective Study in China

Extracorporeal membrane oxygenation (ECMO) is increasingly being applied as life support for acute respiratory distress syndrome (ARDS) patients. However, the outcomes of this procedure have not yet been characterized in severe ARDS patients. The aim of this study was to evaluate the outcomes of severe ARDS patients supported with ECMO and to identify potential predictors of mortality in these patients. A total of 38 severe ARDS patients (aged 51.39±13.27 years, 32 males) who were treated with ECMO in the specialized medical intensive care unit of Guangzhou Institute of Respiratory Diseases from July 2009 to December 2014 were retrospectively reviewed. The clinical data of the patients on the day before ECMO initiation, on the first day of ECMO treatment and on the day of ECMO removal were collected and analyzed. All patients were treated with veno-venous ECMO after a median mechanical ventilation duration of 6.4±7.6 days. Among the 20 patients (52.6%) who were successfully weaned from ECMO, 16 patients (42.1%) survived to hospital discharge. Of the identified pre-ECMO factors, advanced age, a long duration of ventilation before ECMO, a higher Acute Physiology and Chronic Health Evaluation II (APACHE II) score, underlying lung disease, and pulmonary barotrauma prior to ECMO were associated with unsuccessful weaning from ECMO. Furthermore, multiple logistic regression analysis indicated that both barotrauma pre-ECMO and underlying lung disease were independent predictors of hospital mortality. In conclusion, for severe ARDS patients treated with ECMO, barotrauma prior to ECMO and underlying lung disease may be major predictors of ARDS prognosis based on multivariate analysis.

Original ResearchEducation, Research, and Quality ImprovementQuality Assessment of Clinical Practice Guidelines for Respiratory Diseases in China: A Systematic Appraisal

BACKGROUND There has been a significant increase in the publication of clinical practice guidelines (CPGs) for respiratory diseases in China. However, little is known about the quality and potential impacts of these CPGs. Our objective was to critically evaluate the quality of Chinese CPGs for respiratory diseases that were published in peer-reviewed medical journals. METHODS A systematic search of scientific literature published between 1979 and 2013 was undertaken to identify and select CPGs that were related to respiratory diseases. Four Chinese databases (the Chinese Biomedical Literature database [CBM], the China National Knowledge Infrastructure [CNKI], the VIP database, and the WANFANG database) were used. The quality of eligible guidelines was assessed independently by four reviewers using the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. The overall agreement among reviewers was evaluated using an intraclass correlation coefficient. RESULTS A total of 109 guidelines published in 27 medical journals from 1979 to 2013 were evaluated. The overall agreement among reviewers was considered good (intraclass correlation coefficient, 0.838; 95% CI, 0.812-0.862). The scores of the six AGREE domains were low: 57.3% for scope and purpose (range, 4.2%-80.5%), 23.8% for stakeholder involvement (range, 2.8%-54.2%), 7.7% for rigor of development (range, 0%-27.1%), 59.8% for clarity and presentation (range, 22.2%-80.6%), 10.9% for applicability (range, 0%-22.9%), and 0.6% for editorial independence (range, 0%-16.7%). Scores for all guidelines were below 60%, and only three guidelines (2.8%) were recommended for clinical practice with modifications. CONCLUSIONS The quality of the guidelines was low, and stakeholder involvement, rigor of development, applicability, and editorial independence should be considered in the future development of CPGs for respiratory diseases in China.

Quality Assessment of Clinical Practice Guidelines for Respiratory Diseases in China: A Systematic Appraisal.

BACKGROUND There has been a significant increase in the publication of clinical practice guidelines (CPGs) for respiratory diseases in China. However, little is known about the quality and potential impacts of these CPGs. Our objective was to critically evaluate the quality of Chinese CPGs for respiratory diseases that were published in peer-reviewed medical journals. METHODS A systematic search of scientific literature published between 1979 and 2013 was undertaken to identify and select CPGs that were related to respiratory diseases. Four Chinese databases (the Chinese Biomedical Literature database [CBM], the China National Knowledge Infrastructure [CNKI], the VIP database, and the WANFANG database) were used. The quality of eligible guidelines was assessed independently by four reviewers using the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. The overall agreement among reviewers was evaluated using an intraclass correlation coefficient. RESULTS A total of 109 guidelines published in 27 medical journals from 1979 to 2013 were evaluated. The overall agreement among reviewers was considered good (intraclass correlation coefficient, 0.838; 95% CI, 0.812-0.862). The scores of the six AGREE domains were low: 57.3% for scope and purpose (range, 4.2%-80.5%), 23.8% for stakeholder involvement (range, 2.8%-54.2%), 7.7% for rigor of development (range, 0%-27.1%), 59.8% for clarity and presentation (range, 22.2%-80.6%), 10.9% for applicability (range, 0%-22.9%), and 0.6% for editorial independence (range, 0%-16.7%). Scores for all guidelines were below 60%, and only three guidelines (2.8%) were recommended for clinical practice with modifications. CONCLUSIONS The quality of the guidelines was low, and stakeholder involvement, rigor of development, applicability, and editorial independence should be considered in the future development of CPGs for respiratory diseases in China.

The Predictive Value of Plasma Galectin-3 for Ards Severity and Clinical Outcome.

Background: Galectin-3 is a &bgr;-galactoside-binding lectin implicated as a mediator in a variety of inflammatory and fibrotic diseases. However, information about galectin-3 release in patients with acute respiratory distress syndrome (ARDS) is very limited. We sought to determine whether plasma galectin-3 levels were increased in ARDS patients and were associated with disease severity. Methods: Patients admitted to intensive care unit (ICU) within 48 h and diagnosed with ARDS were identified. In addition, healthy subjects were assigned to a control group. Plasma samples were collected from patients within 48 h after ICU admission as well as healthy subjects. Plasma galectin-3 levels were measured by enzyme-linked immunosorbent assay. The primary outcome was mortality at 28 days. Results: Sixty-three ARDS patients were identified. Among these, 27 patients died within 28 days of admission. The plasma galectin-3 levels of the patients were significantly higher than those of control subjects (median [IQR]: 12.37 [7.94–18.79] vs. 5.01 [4.15–5.69] ng/mL, respectively, P <0.0001). Furthermore, galectin-3 levels were significantly higher in non-surviving patients than in those who survived (15.38 [11.59–22.98] vs. 10.07 [7.39–15.54] ng/mL, respectively, P = 0.0136). Plasma galectin-3 levels were significantly correlated with acute physiology and chronic health evaluation II scores and arterial oxygen tension/inspiratory oxygen fraction ratios (Spearman rho = 0.44, P <0.0001 and −0.616, P <0.0001, respectively). At an optimal cutoff of 10.59 ng/mL, the sensitivity and specificity of galectin-3 for prediction of 28-day mortality were 81.48% (95% CI 0.62–0.94) and 55.56% (95% CI 0.38–0.72), respectively. Conclusions: Higher levels of galectin-3 were significantly associated with disease severity and worse outcomes in ARDS patients.