[Effect of germacrone in alleviating HUVECs damaged by H2O2-induced oxidative stress].

This study focuses on the protective effect of germacrone on human umbilical vein endothelial cells(HUVECs) damaged by H2O2-induced oxidative stress and its possible mechanisms. The oxidative damage model was established by using 500 µmol•L⁻¹ H2O2 to treat HUVECs for 3 hours, and then protected with different concentrations of germacrone for 24 hours. The effect of germacrone on cell viability of HUVECs damaged by H2O2 was detected by MTT. The contents of PGI2, TXB2, ET-1, t-PA, PAI-1, TNF-α and IL-6 were detected by ELISA. The content of NO was detected by using nitrate reductase method. Colorimetry was used to detect NOS and GSH-Px. The contents of MDA, SOD and LDH were detected by TBA, WST-1 and microplate respectively. Apoptosis was observed by Hoechst 33258 fluorescent staining. The mRNA expressions of Bax, Bcl-2 and Caspase-3 in cells were detected by RT-PCR. The results showed that the cell damage rate was 52% after treated with 500 µmol•L⁻¹ H2O2 for 3 hours. The cell activity was increasing with the rise of germacrone concentration within the range of 20-200 mol•L⁻¹. Compared with normal group, the contents of PGI2, NO, T-NOS, t-PA, SOD, GSH-Px and Bcl-2 mRNA expressions were lower after damaged with H2O2. The contents of PAI-1, ET-1, IL-6, TNF-α, TXB2, LDH, MDA, Bax mRNA and Caspase-3 mRNA expressions were increased. Compared with model group, the contents of PGI2, NO, T-NOS, t-PA, SOD, GSH-Px and Bcl-2 mRNA expressions were increased after treated with germacrone. The contents of PAI-1, ET-1, IL-6, TNF-α, TXB2, LDH, MDA, Bax mRNA and Caspase-3 mRNA expressions were lower after treated with germacrone. According to Hoechst 33258 fluorescence staining, compared with normal group, the cell membrane and the nucleus showed strong dense blue fluorescence, and the number of cells significantly decreased in model group. Compared with model group, blue fluorescence intensity decreased in drug group. The above findings demonstrate that germacrone may improve the effect on HUVECs damaged by H2O2-induced oxidative stress by resisting oxidation and inhibiting cell apoptosis.

Association of learning environment and self-directed learning ability among nursing undergraduates: a cross-sectional study using canonical correlation analysis.

OBJECTIVES: This study explores the relationship between the perception of the learning environment and self-directed learning (SDL) ability among nursing undergraduates. DESIGN, SETTING AND PARTICIPANTS: A cross-sectional study was conducted in December 2020 with 1096 junior and senior undergraduate nursing students (aged 16-22) from Wannan Medical College in Anhui Province, China. OUTCOME MEASURES: The Chinese version of the Dundee Ready Educational Environment Measure questionnaire and a validated Chinese version of college students' SDL ability scale were used to assess students' perceptions about their learning environment and their SDL ability. Canonical correlation analysis was performed to evaluate their correlation. RESULTS: The total score for the learning environment was 120.60 (scoring rate: 60.30%), and the score for SDL ability was 89.25 (scoring rate: 63.75%). Analysis indicated that the first canonical correlation coefficient was 0.701 and the contribution rate was 94.26%. The perception of the learning environment was mainly determined by students' perception of learning (SPL) and academic self-perceptions (SASP), with SDL ability mainly determined by self-management ability and cooperative learning ability. SPL and SASP were positively correlated with self-management ability and cooperative learning ability. Multiple linear regression analysis revealed that SPL, SASP, students' perceptions of atmosphere and students' social self-perceptions had a significant impact on SDL ability. CONCLUSIONS: The SDL ability of nursing undergraduates was not high. SPL and SASP were positively correlated with self-management ability and cooperative learning ability. Nursing educators can improve students' SDL ability by changing their learning environment, using, for example, new student-centred teaching methods.