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Background@#Extracellular vesicles (EVs) derived from plants have emerged as potential candidates for cosmetic and therapeutic applications. In this study, we isolated EVs from Aloe vera peels (A-EVs) and investigated the antioxidant and wound healing potential of A-EVs. @*Methods@#A-EVs were isolated by ultracentrifugation and tangential flow filtration and were characterized using transmission electron microscopy, nanoparticle tracking analysis. The cytotoxicity and cellular uptake of A-EVs were investigated by WST-1 assay and flow cytometry. The antioxidant effect of A-EVs was evaluated by superoxide dismutase (SOD) activity assay and cellular antioxidant activity (CAA) assay. The wound healing potential was assessed by in vitro scratch assay using human keratinocytes (HaCaT) and fibroblasts (HDF). The expression of nuclear factor erythroid 2–related factor 2 (Nrf2) and their associated genes was analyzed by quantitative RT-PCR. @*Results@#A-EVs displayed a round shape and had diameters from 50 to 200 nm. A-EVs showed good cytocompatibility on human skin cells and were internalized into HaCaT cells via clathrin-, caveolae-mediated endocytosis, and membrane fusion. The SOD activity and CAA assays exhibited that A-EVs had antioxidant activity and reduced intracellular ROS levels in H2O2-treated HaCaT cells in a dose-dependent manner. A scratch assay showed that A-EVs enhanced the migration ability of HaCaT and HDF. Moreover, A-EVs significantly upregulated the mRNA expression of Nrf2, HO-1, CAT, and SOD genes in H2O2-treated HaCaT cells. Our findings reveal that A-EVs could activate the antioxidant defense mechanisms and wound healing process via the Nrf2 activation. @*Conclusion@#Overall results suggest that the A-EVs are promising as a potential agent for skin regeneration.
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Background@#Extracellular vesicles (EVs) derived from plants have emerged as potential candidates for cosmetic and therapeutic applications. In this study, we isolated EVs from Aloe vera peels (A-EVs) and investigated the antioxidant and wound healing potential of A-EVs. @*Methods@#A-EVs were isolated by ultracentrifugation and tangential flow filtration and were characterized using transmission electron microscopy, nanoparticle tracking analysis. The cytotoxicity and cellular uptake of A-EVs were investigated by WST-1 assay and flow cytometry. The antioxidant effect of A-EVs was evaluated by superoxide dismutase (SOD) activity assay and cellular antioxidant activity (CAA) assay. The wound healing potential was assessed by in vitro scratch assay using human keratinocytes (HaCaT) and fibroblasts (HDF). The expression of nuclear factor erythroid 2–related factor 2 (Nrf2) and their associated genes was analyzed by quantitative RT-PCR. @*Results@#A-EVs displayed a round shape and had diameters from 50 to 200 nm. A-EVs showed good cytocompatibility on human skin cells and were internalized into HaCaT cells via clathrin-, caveolae-mediated endocytosis, and membrane fusion. The SOD activity and CAA assays exhibited that A-EVs had antioxidant activity and reduced intracellular ROS levels in H2O2-treated HaCaT cells in a dose-dependent manner. A scratch assay showed that A-EVs enhanced the migration ability of HaCaT and HDF. Moreover, A-EVs significantly upregulated the mRNA expression of Nrf2, HO-1, CAT, and SOD genes in H2O2-treated HaCaT cells. Our findings reveal that A-EVs could activate the antioxidant defense mechanisms and wound healing process via the Nrf2 activation. @*Conclusion@#Overall results suggest that the A-EVs are promising as a potential agent for skin regeneration.
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PURPOSE: This study explores the effects of a professionalism course based on problem-based learning (PBL) for 2nd year dental students on professional role concept and on ethical reasoning. It also investigates students' attitudes toward professionalism development program. METHODS: The experimental group (n=36) participated in the 5-week professionalism course, which uses PBL approach while the control group (n=89) did not receive the professionalism instruction during the same period. The professionalism development program was implemented via discussions among students in small-group tutorial. Four professors, who served as group facilitators participated in faculty seminars before every tutorial. After each tutorial, students had to write essays on the cases they discussed in their groups. Both groups completed Professional Role Orientation Inventory and Defining Issue Test (KDIT) prior to and post intervention period. The experimental group also responded to questionnaires about the value of professionalism program. RESULTS: Analysis of covariance indicated that the experimental group's responsibility score significantly improved (F=32.552, p<0.001) while their perception of agency decreased (F=29.510, p<0.001). The program had little influence on ethical reasoning measured by DIT. Twenty-eight students (78%) responded that they learned the value of other opinions. Seventy percent of the students responded that the course is worthwhile or very worthwhile. CONCLUSION: The result reveals that students' professional role concept is associated with the learning experience in professionalism program based on PBL. Opportunities to think of professionalism in clinical situations improved students' sense of responsibility as dentist.
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Humans , Dentists , Education, Dental , Ethics, Dental , Learning , Orientation , Problem-Based Learning , Professional Competence , Professional Role , Students, Dental , Surveys and QuestionnairesABSTRACT
PURPOSE: This study was performed to investigate the differences in career choice motives and moral reasoning ability between students in baccalaureate and graduate-entry medical programs. METHODS: Forty-five students from a baccalaureate program and thirty-eight students from a graduate-entry program participated in this study. The students were required to fill out both the Career Choice Motivation Inventory and Defining Issues Test(DIT). The Career Choice Motivation Inventory is a 20-item questionnaire, which investigates five dimensions: effect of others, job security, interest in science, service and working with people, and working condition. Independent t-test was performed to compare the two groups. Pearson correlation coefficients were calculated to investigate the relationship among variables. RESULTS: There were significant differences in career choice motivations between the two groups. Students in the graduate-entry program were more likely to be motivated by scientific interest and opportunities to care for people. Status and job security were stronger factors in the baccalaureate students. For the students in this program, there were positive associations among their motives- interest in medical science, serving people, and working condition. There was no significant difference in moral reasoning ability between the two groups. CONCLUSION: Students in the graduate-entry medical program seem to have more professional and altruistic motivations for entering medicine. Although there is nostatistical significance, graduate students have numerically higher moral reasoning abilities compared to their counterparts. These results validate that a graduate-entry program provides an important alternative for student selection.
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Humans , Career Choice , Motivation , School Admission Criteria , Surveys and QuestionnairesABSTRACT
PURPOSE: The purpose of this study was to investigate the perceived sources of stress among dental students. The relationships of these stresses to the year of study and gender were also examined. METHODS: The responses from the first to fourth year dental students to 30 items adapted from Dental Environment Stress (DES) questionnaire were subjected to confirmatory factor analysis. The Likert scale, ranging from 0 (not applicable) to 4 (very stressful), was applied to these items. A total of 341 students (male=196, female=145) participated, their average age being 24.7. Multivariate analysis of variance (MANOVA) was conducted to analyze the effects of the year of study and gender on stressors. RESULTS: Confirmatory factor analysis established a five-factor model including 1) clinical practice, 2) academic load and pressure, 3) personal problems, 4) low self-esteem, and 5) school administration or climate. Subscales for each factor show good internal consistency with Cronbach's alpha ranging from .71 to .88. Mean score for factor II (academic load and pressure) was the highest among all factors for all of 4 years, which meant that primary stressors were amount of classwork, shortage of time, and competition among classmates regardless of the year of study. MANOVA result showed that the amount of stress from clinical practice and school climate generally increased through the years (p < .01), and that female students were more stressed than male students (p < .01). CONCLUSION: Students' stress is related to the features of the curricula and the learning environment. In reducing this stress, it would be helpful to modify the curriculum as well as to introduce mentor or counselor programs.