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Background: Complementary and alternative medicine (CAM) has emerged to combat the global COVID-19 pandemic. However, no studies have been conducted to evaluate the attitudes, knowledge, and barriers of Chinese clinical and nursing students in implementing CAM during this period. Objective: The aim of this study was to investigate the attitude, knowledge, and barriers of Chinese clinical and nursing students in using CAM in the context of COVID-19. Methods: An online-based cross-sectional survey was carried out among Chinese medical students, majoring in clinical medicine or nursing, in Nanjing, Jiangsu Province, and Zhengzhou, Henan Province from May to July 2022. A total of 402 clinical and 644 nursing students responded to a self-administered questionnaire through the Questionnaire Star and WeChat APPs. SPSS 25 (version 25) was used for data analysis. Proportions were compared by Chi-square test. Level of significance between groups was analyzed using independent student t-test and Mann-Whitney U test. Results: The average score of attitude was 46.63 (SD: 7.38) in clinical students and 49.84 (SD: 6.76) in nursing students. The top four most commonly used CAM treatments in China were proprietary Chinese medicine, diet therapy, decoction, and acupuncture and moxibustion (59.66 %, 22.28 %, 11.66 %, 9.85 %). The students had a good mastery of knowledge about CAM-based prevention and control of COVID-19 (mean score 7.36). The score of CAM knowledge in nursing students was significantly higher than that in clinical students (7.56 VS 7.04, P = 0.000). Gender, grade, previous use, age, and knowledge score could affect students' attitude towards CAM. The main barriers in spreading CAM use included time-consumption, bad taste, and fear of treatment-related pain (24.5 %). Compared with clinical students, nursing students were more likely to recommend CAM to patients in the future (P = 0.002). Conclusions: During the COVID-19 pandemic, nursing students were more positive towards CAM use, had a better mastery of CAM knowledge than clinical students. CAM is expected to provide better outcomes in COVID-19 patients. Future studies should focus on the changes in students' attitudes over time and exploration of influencing factors on CAM use.
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The bacterial pathogen Acidovorax citrulli causes the destructive fruit blotch (BFB) on cucurbit plants. Pseudomonas chlororaphis YL-1 is a bacterial strain isolated from Mississippi soil and its genome harbors some antimicrobial-related gene clusters, such as phenazine, pyrrolnitrin, and pyoverdine. Here, we evaluated the antimicrobial activity of strain YL-1 as compared with its deficient mutants of antimicrobial-related genes, which were obtained using a sacB-based site-specific mutagenesis strategy. We found that only phenazine-deficient mutants ΔphzE and ΔphzF almost lost the inhibitory effects against A. citrulli in LB plates compared with the wild-type strain YL-1, and that the main antibacterial compound produced by strain YL-1 in LB medium was phenazine-1-carboxylic acid (PCA) based on the liquid chromatography-mass spectrometry (LC-MS) analysis. Gene expression analyses revealed that PCA enhanced the accumulation of reactive oxygen species (ROS) and increased the activity of catalase (CAT) in A. citrulli. The inhibition effect of PCA against A. citrulli was lowered by adding exogenous CAT. PCA significantly upregulated the transcript level of katB from 6 to 10 h, which encodes CAT that helps to protect the bacteria against oxidative stress. Collectively, the findings of this research suggest PCA is one of the key antimicrobial metabolites of bacterial strain YL-1, a promising biocontrol agent for disease management of BFB of cucurbit plants.
RESUMO
Pseudomonas chlororaphis YL-1 has extensive antimicrobial activities against phytopathogens, and its genome harbors a pyoverdine (PVD) biosynthesis gene cluster. The alternative sigma factor PvdS in Pseudomonas aeruginosa PAO1 acts as a critical regulator in response to iron starvation. The assembly of the PVD backbone starts with peptide synthetase enzyme PvdL. PvdF catalyzes formylation of l-OH-Orn to produce l-N5-hydroxyornithine. Here, we describe the characterization of PVD production in YL-1 and its antimicrobial activity in comparison with that of its PVD-deficient ΔpvdS, ΔpvdF, and ΔpvdL mutants, which were obtained using a sacB-based site-specific mutagenesis strategy. Using in vitro methods, we examined the effect of exogenous iron under low-iron conditions and an iron-chelating agent under iron-sufficient conditions on PVD production, antibacterial activity, and the relative expression of the PVD transcription factor gene pvdS in YL-1. We found that strain YL-1, the ΔpvdF mutant, and the ΔpvdS(pUCP26-pvdS) complemented strain produced visible PVDs and demonstrated a wide range of inhibitory effects against Gram-negative and Gram-positive bacteria in vitro under low-iron conditions and that with the increase of iron, its PVD production and antibacterial activity were reduced. The antibacterial compounds produced by strain YL-1 under low-iron conditions were PVDs based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Moreover, the antibacterial activity observed in vitro was correlated with in vivo control efficacies of strain YL-1 against rice bacterial leaf blight (BLB) disease caused by Xanthomonas oryzae pv. oryzae. Collectively, PVDs are responsible for the antibacterial activities of strain YL-1 under both natural and induced low-iron conditions.IMPORTANCE The results demonstrated that PVDs are essential for the broad-spectrum antibacterial activities of strain YL-1 against both Gram-positive and Gram-negative bacteria under low-iron conditions. Our findings also highlight the effect of exogenous iron on the production of PVD and the importance of this bacterial product in bacterial interactions. As a biocontrol agent, PVDs can directly inhibit the proliferation of the tested bacteria in addition to participating in iron competition.