Effect of humic acid on visible light photocatalytic inactivation of bacteriophage f2 with electrospinning Cu-TiO2 nanofibers: insight into the mechanisms.

Photocatalytic disinfection is a promising technology with low cost and high efficiency. However, most of the current studies on photocatalytic disinfection ignore the widespread presence of natural organic matter (NOM) in water bodies, so the incomplete conclusions obtained may not be applicable. Herein, this paper systematically studied the influence of humic acid (HA), one of the most important components of NOM, on the photocatalytic inactivation of bacteriophage f2 with electrospinning Cu-TiO2 nanofibers. We found that with the addition of HA, the light transmittance of the solution at 550 nm decreased from 94 to 60%, and the band gap of the photocatalyst was increased from 2.96 to 3.05 eV. Compared with reacting without HA, the degradation amount of RNA of f2 decreased by 88.7% after HA was added, and the RNA concentration increased from 1.95 to 4.38 ng·µL-1 after the reaction. Hence, we propose mechanisms of the effect of HA on photocatalytic disinfection: photo-shielding, passivation of photocatalysts, quenching of free radicals, and virus protection. Photo-shielding and photocatalyst passivation lead to the decrease of photocatalyst activity, and the reactive oxygen species (ROSs) (·OH, ·O2-, 1O2, H2O2) are further trapped by HA. The HA in water also can protect the shape of phage f2 and reduce the leakage of protein and the destruction of ribonucleic acid (RNA). This work provides an insight into the mechanisms for the influence of HA in photocatalytic disinfection process and a theoretical basis for its practical application.

A Clinical Prediction Model Based on Post Large Artery Atherosclerosis Infarction Pneumonia.

BACKGROUND AND PURPOSE: Stroke-associated pneumonia (SAP) has been found as a common complication in acute ischemic stroke (AIS) patients. Large artery atherosclerosis (LAA) infarct is a major subtype of AIS. This study aimed to build a clinical prediction model for SAP of LAA type AIS patients. METHODS: This study included 295 patients with LAA type AIS. Univariate analyses and logistic regression analyses were conducted to determine the independent predictors for the modeling purpose. Nomogram used receiver operating characteristics to assess the accuracy of the model, and the calibration plots were employed to assess the fitting degree between the model and the practical scenario. One hundred and five patients were employed for the external validation to test the stability of the model. RESULTS: From the univariate analysis, patients' ages, neutrophil-to-lymphocyte ratios, National Institute of Health Stroke scale (NIHSS) scores, red blood cell, sex, history of coronary artery disease, stroke location and volume-viscosity swallow test showed statistical difference in the development group for the occurrence of SAP. By incorporating the factors above into a multivariate logistic regression analysis, patients' ages, neutrophil-to-lymphocyte ratios, NIHSS, and volume-viscosity swallow test emerged as the independent risk factors of the development of SAP. The nomogram based on the mentioned 4 variables above achieved a receiver operating characteristic of 0.951 and a validation group of 0.946. CONCLUSIONS: The proposed nomogram is capable of predicting predict the occurrence of SAP in LAA type AIS patients, and it may identify high-risk patients in time and present information for in-depth treatment.

Polymyxin for the treatment of intracranial infections of extensively drug-resistant bacteria in children after neurosurgical operation.

BACKGROUND: Increased meningitis caused by extensively drug-resistant bacillary presents a significant challenge in antibiotic selection. The aim of our study was to evaluate the efficacy and safety of polymyxin in the treatment of post-neurosurgical meningitis due to the extensively drug-resistant bacillary in children. METHODS: We performed a retrospective study on post-neurosurgical meningitis caused by the extensively drug-resistant bacillary in children, who were treated with polymyxin for ≥ 3 days. RESULTS: Among five post-neurosurgical meningitis cases that were included, the children were infected by Acinetobacter baumannii (n = 3), Klebsiella pneumonia (n = 1), and Pseudomonas aeruginosa (n = 1). The drug susceptibility test showed that they were extensively drug-resistant bacillary. Two patients received intravenous polymyxin E. Three children received intravenous combined with intraventricular injection of polymyxin B. One patient infected by Klebsiella pneumonia eventually died of septic shock. No serious adverse effects of polymyxin were observed. CONCLUSIONS: Polymyxin is a safe and effective therapy for post-neurosurgical, multidrug-resistant bacillary meningitis in children.

Visible-light-driven photocatalytic inactivation of bacteriophage f2 by Cu-TiO2 nanofibers in the presence of humic acid.

Pathogenic viruses in drinking water are great threats to public health. Visible-light-driven photocatalysis is a promising technology for virus inactivation. However, the existing photocatalytic antiviral research studies have mostly been carried out in single-component systems, neglecting the effect of natural organic matter, which exists widely in actual water bodies. In this paper, electrospun Cu-TiO2 nanofibers were prepared as photocatalysts, and their photocatalytic antiviral performance in the presence of humic acid (HA) was comprehensively studied for the first time. The properties of the reaction mixture were measured during the reaction. In addition, the safety, reliability and stability of photocatalytic disinfection in the mixed system were evaluated. The results showed that the virus removal efficiency decreased with the increase of the HA concentration. The type of reaction solution, such as PBS buffer solution or water, did not affect the removal efficiency noticeably. Under acidic conditions, the electrostatic forces between photocatalysts and viruses were strengthened, leading to higher virus removal efficiency. As the reaction time went on, the pH value in the solution increased first and then tended to be stable, the conductivity remained stable, and the dissolved oxygen increased first and then decreased. The safety test showed that the concentration of Cu ions released into the solution was lower than specified by the international standards. No photoreactivation was observed, and the addition of HA significantly reduced the reutilization efficiency of the photocatalysts.

Photocatalytic disinfection performance in virus and virus/bacteria system by Cu-TiO2 nanofibers under visible light.

The presence of pathogenic microorganisms in water is a great threat to human health, and photocatalysis is promising for disinfection. However, the research on virus inactivation with visible-light photocatalysis is still limited, especially the coexistence of virus and its host bacteria. In this study, bacteriophage f2 and its host E. coil 285 were used as the model microorganisms, and the disinfection performance of prepared Cu-TiO2 nanofibers under visible light was investigated. The result showed that the prepared Cu-TiO2 nanofibers showed a brilliant ability in terms of removing bacteriophage f2 and E. coil 285 under visible light. Series experiments indicated that the initial pH didn't affect the photocatalytic disinfection performance significantly. In the certain range, the removal efficiency of bacteriophage f2 increased with the increase of catalyst dosage, light intensity and temperature, but decreased with the increase of initial virus concentration. In virus/bacteria mixed system, bacteriophage f2 exhibited stronger resistance to photocatalytic oxidation than E. coil 285, and the removal of bacteriophage f2 was obviously affected by being mixed with E. coil 285, while the removal of E. coil 285 almost remained unchanged after being mixed with bacteriophage f2. Further research proved that competitive adsorption in mixed system played a certain role in E. coli 285 inactivation, while the free reactive oxygen species (ROSs) in the bulk phase played a crucial role in phage f2 inactivation.

Removal of Waterborne Pathogen by Nanomaterial-Membrane Coupling System.

The waterborne pathogenic viruses threaten human health. And the nanomaterial-membrane coupling system is promising in virus removal. In this study, phage MS2 was selected as the model virus to investigate the removal of virus with the coupling system. Results revealed that commercial nano TiO2 (Degussa Aeroxide P25) showed both of excellent adsorption and photocatalysis performance for virus removal compared with nano ZnO, nano Fe3O4, carbon nanotube, graphene, nano Ni and Nano TiO2 (anatase). In P25 photocatalysis process, the removal efficiency of phage MS2 increased with the increase of P25 concentration (0~1000 mg L-1), virus initial concentration (102~106 PFU mL-1), UV irradiation doses (5~120 mJ cm-2) and UV light intensity (0.126~0.742 mW cm-2). However, when the P25 concentration increased to over 1000 mg L-1, the virus removal efficiency would remain stable with the increase of P25 concentration. The nanomaterial-membrane coupling system showed excellent performance for virus removal, which was mainly attributed to the adsorption and photocatalysis of P25, and the intercept of membrane. When the P25 concentration was 100 mg L-1, UV irradiation dose was 20 mJ cm-2 and transmembrane pressure was 20 kPa, the phage MS2 removal efficiency could be up to 100%.

Plasma copeptin concentration and outcome after pediatric traumatic brain injury.

Higher plasma copeptin level has been associated with poor outcomes of critical illness. The present study was undertaken to investigate the plasma copeptin concentrations in children with traumatic brain injury (TBI) and to analyze the correlation of copeptin with disease outcome. Plasma copeptin concentrations of 126 healthy children and 126 children with acute severe TBI were measured by enzyme-linked immunosorbent assay. Twenty-one patients (16.7%) died and 38 patients (30.2%) had an unfavorable outcome (Glasgow Outcome Scale score of 1-3) at 6 months. Plasma copeptin level was obviously higher in patients than in healthy children (46.2±20.8 pmol/L vs. 9.6±3.0 pmol/L, P<0.001). Plasma copeptin level was identified as an independent predictor for 6-month mortality [odds ratio (OR) 1.261, 95% confidence interval (CI) 1.112-1.538, P=0.005] and unfavorable outcome (OR 1.313, 95% CI 1.146-1.659, P=0.003). The predictive value of copeptin was similar to that of Glasgow Coma Scale (GCS) score for 6-month mortality [area under curve (AUC) 0.832, 95% CI 0.755-0.892 vs. AUC 0.873, 95% CI 0.802-0.926, P=0.412] and unfavorable outcome (AUC 0.863, 95% CI 0.790-0.918 vs. AUC 0.885, 95% CI 0.816-0.935, P=0.596). Copeptin improved the AUC of GCS score for 6-month unfavorable outcome (AUC 0.929, 95% CI 0.869-0.967, P=0.013), but not for 6-month mortality (AUC 0.887, 95% CI 0.818-0.936, P=0.600). Thus, plasma copeptin level represents a novel biomarker for predicting 6-month clinical outcome in children with TBI.

Relationship between plasma leptin levels and clinical outcomes of pediatric traumatic brain injury.

High plasma leptin level has been associated with mortality after adult intracerebral hemorrhage. The present study was undertaken to investigate the plasma leptin concentrations in children with traumatic brain injury and to analyze the correlation of leptin with pediatric traumatic brain injury outcome. Plasma leptin concentration of eighty-nine healthy children and 142 children with acute severe traumatic brain injury was measured by enzyme-linked immunosorbent assay. Twenty-six patients (18.3%) died and 42 patients (29.6%) had an unfavorable outcome (Glasgow outcome scale score of 1-3) at 6 months after traumatic brain injury. Upon admission, plasma leptin level in patients was substantially higher than that in healthy controls. A forward stepwise logistic regression selected plasma leptin level as an independent predictor for 6-month mortality and unfavorable outcome of patients. A receiver operating characteristic curve analysis showed plasma leptin level better predicted 6-month mortality and unfavorable outcome. The prognostic value of leptin was similar to that of Glasgow Coma scale score for 6-month clinical outcomes. Thus, plasma leptin level represents a novel biomarker for predicting 6-month clinical outcome in children with traumatic brain injury.