Photochemical transformation of liquid crystal monomers in simulated environmental media: Kinetics, mechanism, toxicity variation and QSAR modeling.

Liquid crystal monomers (LCMs) are a new class of emerging pollutants with high octanol-water partition coefficients; however, their transformation behavior and associated risk to environments with high organic matter content has rarely been reported. In this study, we investigated the photodegradation kinetics, mechanism, and toxicity variation of 23 LCMs on leaf wax models (e.g., organic solvents methanol and n-hexane). The order of the photolysis rates of these LCMs were biphenylethyne LCMs > phenylbenzoate LCMs > diphenyl/terphenyl LCMs under simulated sunlight, while the phenylcyclohexane LCMs were resistant to photodegradation. The phenylbenzoate and biphenylethyne LCMs mainly undergo direct photolysis, while the diphenyl/terphenyl LCMs mainly undergo self-sensitized photolysis. The main photolysis pathways are the cleavage of ester bonds for phenylbenzoate LCMs, the addition, oxidation and cleavage of alkynyl groups for biphenylethyne LCMs, and the cleavage/oxidation of chains attached to phenyls and the benzene ring opening for diphenyl/terphenyls LCMs. Most photolysis products remained toxic to aquatic organisms to some degree. Additionally, two quantitative structure-activity relationship models for predicting kobs of LCMs in methanol and n-hexane were developed, and employed to predict kobs of 93 LCMs to fill the kobs data gap in systems mimicking leaf surfaces. These results can be helpful for evaluating the fate and risk of LCMs in environments with high content of organic phase.

Photochemical behaviour and toxicity evolution of phenylbenzoate liquid crystal monomers in water.

Liquid crystal monomers (LCMs) are a group of emerging pollutants that pose potential environmental risks because of their ubiquitous occurrence and toxicity. Understanding their environmental transformation is essential for assessing the ecological risk. In this study, we investigated the photochemical transformation kinetics, mechanism, and photo-induced toxicity of three phenylbenzoate LCMs in water. Their apparent photolytic rate constants were within (0.023 - 0.058) min-1, and the half-lives were < 30.0 min, showing lower persistence in water. Dissolved organic matter significantly inhibited their photolysis because of light-shielding effect and quenching of excited triplet states of LCMs. Their photolysis mainly occurred through excited triplet states, and the reactive oxygen species (i.e., ⋅OH, 1O2 and ⋅O2-) contributed to their degradation. The main photolysis pathways were ester bond cleavage, ⋅OH substitution/addition, and defluorination. Experiments and computational simulation revealed that some ·OH addition/substitution products have similar toxicity with LCMs. Additionally, the ∙OH reaction rate constants (kOH) of LCMs were determined to be > 1 × 109 M-1 s-1, evidence for their high reactivity toward ⋅OH. We have further developed reliable methods to estimate kOH of other phenylbenzoate-like LCMs with quantum chemical calculations. These results are useful for understanding the transformation and fate of LCMs in aquatic environments.

Humoral immunity and transcriptome differences of COVID-19 inactivated vacciane and protein subunit vaccine as third booster dose in human.

Under the background of the severe human health and world economic burden caused by COVID-19, the attenuation of vaccine protection efficacy, and the prevalence and immune escape of emerging variants of concern (VOCs), the third dose of booster immunization has been put on the agenda. Systems biology approaches can help us gain new perspectives on the characterization of immune responses and the identification of factors underlying vaccine-induced immune efficacy. We analyzed the antibody signature and transcriptional responses of participants vaccinated with COVID-19 inactivated vaccine and protein subunit vaccine as a third booster dose. The results from the antibody indicated that the third booster dose was effective, and that heterologous vaccination with the protein subunit vaccine as a booster dose induced stronger humoral immune responses than the homologous vaccination with inactivated vaccine, and might be more effective against VOCs. In transcriptomic analysis, protein subunit vaccine induced more differentially expressed genes that were significantly associated with many important innate immune pathways. Both the homologous and heterologous boosters could increase the effectiveness against COVID-19, and compared with the inactivated vaccine, the protein subunit vaccine, mediated a stronger humoral immune response and had a more significant correlation with the innate immune function module, which provided certain data support for the third booster immunization strategy.

Genotypic and Phenotypic Characteristics of Moraxella catarrhalis from Patients and Healthy Asymptomatic Participants among Preschool Children.

(1) Background: M. catarrhalis can ascend into the middle ear, where it is a prevalent causative agent of otitis media in children, or enter the lower respiratory tract, where it is associated with community-acquired pneumonia (CAP). In this study, we aimed to provide an overview of the prevalence of M. catarrhalis in preschool children. (2) Methods: M. catarrhalis strains were isolated from samples. All isolates were characterized in terms of serotypes (STs), virulence genes, multilocus sequence type, and antibiotic susceptibility. (3) Results: The percentages of strains expressing lipooligosaccharides (LOSs), serotype A, B, C, or unknown were 67.61%, 15.71%, 4.28%, and 12.38%, respectively. Among the strains, 185 (88.10%) carried ompB2, 207 (98.57%) carried ompE, and 151 (71.90%) carried ompCD. The most frequently identified STs were ST449 (n = 13), ST64 (n = 11), and ST215 (n = 10). The resistance rates to the antibiotics cefuroxime, azithromycin, and erythromycin were 43.33%, 28.10%, and 39.05%, respectively. (4) Conclusions: High prevalence of some-specific ST types and high rates of antibiotic resistance indicate the necessity for an increased vigilance of resistant strains, a rational use of antibiotics in preschool children, and most importantly, the surveillance of healthy asymptomatic participants preschool children with M. catarrhalis. Our findings provide a platform for the development of novel M. catarrhalis vaccines.

Incidence, Etiology, and Environmental Risk Factors of Community-Acquired Pneumonia Requiring Hospitalization in China: A 3-Year, Prospective, Age-Stratified, Multicenter Case-Control Study.

Background: Community-acquired pneumonia (CAP) is a leading infectious cause of hospitalization and death worldwide. Knowledge about the incidence and etiology of CAP in China is fragmented. Methods: A multicenter study performed at 4 hospitals in 4 regions in China and clinical samples from CAP patients were collected and used for pathogen identification from July 2016 to June 2019. Results: A total of 1674 patients were enrolled and the average annual incidence of hospitalized CAP was 18.7 (95% confidence interval, 18.5-19.0) cases per 10000 people. The most common viral and bacterial agents found in patients were respiratory syncytial virus (19.2%) and Streptococcus pneumoniae (9.3%). The coinfections percentage was 13.8%. Pathogen distribution displayed variations within age groups as well as seasonal and regional differences. The severe acute respiratory syndrome coronavirus 2 was not detected. Respiratory virus detection was significantly positively correlated with air pollutants (including particulate matter ≤2.5 µm, particulate matter ≤10 µm, nitrogen dioxide, and sulfur dioxide) and significantly negatively correlated with ambient temperature and ozone content; bacteria detection was opposite. Conclusions: The hospitalized CAP incidence in China was higher than previously known. CAP etiology showed that differences in age, seasons, regions, and respiratory viruses were detected at a higher rate than bacterial infection overall. Air pollutants and temperature have an influence on the detection of pathogens.