An acceptability study of the introduction of total online or partial online PBL in a large classroom setting in biochemistry.

BACKGROUND: Traditional problem-based learning (PBL) relying on tutored learning in small groups is very resource-intensive. Little is known about the benefits of PBL in a large classroom setting. This paper introduced a PBL case into the traditional didactic biochemistry course and investigated the acceptability of total online or partial online PBL in a large classroom setting introduced during the coronavirus pandemic. METHODS: The students were allocated into either total online Group 1, partial online Group 2, or partial online and with poorer academic performance Group 3. A questionnaire comprising of 8 closed-ended questions and 2 open-ended questions and final exam performances were used to evaluate the acceptability of total online or partial online PBL in a large classroom setting. The 8 closed-ended questions were analysed by the Kruskal-Wallis test or chi-square tests. The word cloud analysis of the 2 open-ended questions were conducted by Wenjuanxing. Students' performances in the final examination were analysed by One-way Anova. RESULTS: Both total online and partial online PBL were rated highly by the students. Overall, there were no significant differences in the effectiveness evaluation of PBL between Group 2 and Group 3. There were no significant differences in final exam performances between Group 1 and Group 2. However, Group 1 rated the effectiveness of PBL much higher than Group 2 and 3. Word cloud analysis of the 2 open-ended questions showed students' positive perspectives of PBL. In biochemistry teaching, from the perspective of the students, the expected optimal number of useful PBL cases might be 2. CONCLUSIONS: Both total online and partial online PBL in a large classroom setting were widely accepted as a beneficial supplement to traditional biochemistry classes.

Meta-analyzing the efficacy of 3D printed models in anatomy education.

Three-dimensional printing models (3DPs) have been widely used in medical anatomy training. However, the 3DPs evaluation results differ depending on such factors as the training objects, experimental design, organ parts, and test content. Thus, this systematic evaluation was carried out to better understand the role of 3DPs in different populations and different experimental designs. Controlled (CON) studies of 3DPs were retrieved from PubMed and Web of Science databases, where the participants were medical students or residents. The teaching content is the anatomical knowledge of human organs. One evaluation indicator is the mastery of anatomical knowledge after training, and the other is the satisfaction of participants with 3DPs. On the whole, the performance of the 3DPs group was higher than that of the CON group; however, there was no statistical difference in the resident subgroup, and there was no statistical difference for 3DPs vs. 3D visual imaging (3DI). In terms of satisfaction rate, the summary data showed that the difference between the 3DPs group (83.6%) vs. the CON group (69.6%) (binary variable) was not statistically significant, with p > 0.05. 3DPs has a positive effect on anatomy teaching, although there are no statistical differences in the performance tests of individual subgroups; participants generally had good evaluations and satisfaction with 3DPs. 3DPs still faces challenges in production cost, raw material source, authenticity, durability, etc. The future of 3D-printing-model-assisted anatomy teaching is worthy of expectation.

The benefits of using atypical presentations and rare diseases in problem-based learning in undergraduate medical education.

BACKGROUND: The nature of student learning in problem-based learning (PBL) largely depends on the quality of the case scenarios presented to them. The effect of case scenarios with higher challenge degree, especially common disease with atypical symptoms (CDAS)- and rare disease (RD)-based case scenarios, on undergraduate medical students remains unclear. This study compared the impact of all scenarios pertaining to common disease with typical symptoms (CDTS) case scenarios, CDTS interspersed with CDAS case scenarios, and CDTS interspersed with RD case scenarios on perceptions of undergraduate students studying organ/system integration curriculum via PBL. METHODS: After finishing four CDTS case scenarios, 294 third-year medical students were randomly allocated into three groups: CDTS, CDAS and RD, studying via CDTS, CDAS and RD case scenarios, respectively. A questionnaire with 15 items was conducted to evaluate the students' perceptions. The students' responses were scored using a 4-point rating scale. The data were analysed using the Kruskal-Wallis test. RESULTS: Among the three PBL conditions, the ones with a higher degree of challenge were rated higher by the students, which included the quality of the case scenarios and the overall performances of the students. The CDAS and RD cases were more effective in developing students' self-directed learning skills, stimulating them to acquire more knowledge required for future work. The satisfaction percentage of RD case scenario sessions was higher. CONCLUSIONS: Of all the three kinds of case scenarios, both CDTS interspersed with CDAS and RD case scenarios had more positive effects on the self-evaluated performance of students. Increasing the challenge and variety of case scenarios by the inclusion of CDAS and RD especially RD might be an effective stimulus in improving students' performance in PBL sessions.

Acetylshikonin induces apoptosis of human leukemia cell line K562 by inducing S phase cell cycle arrest, modulating ROS accumulation, depleting Bcr-Abl and blocking NF-κB signaling.

Acetylshikonin, a natural naphthoquinone derivative compound from Lithospermum erythrorhyzon, has been reported to kill bacteria, suppress inflammation, and inhibit tumor growth. However, the effect of acetylshikonin on human chronic myelocytic leukemia (CML) cells apoptosis and its detailed mechanisms remains unknown. The purpose of the present study was to investigate whether acetylshikonin could inhibit proliferation or induce apoptosis of the K562 cells, and whether by regulating the NF-κB signaling pathway to suppress the development of CML. K562 cells were treated with serial diluted acetylshikonin at different concentrations. Our data showed that K562 cell growth was significantly inhibited by acetylshikonin with an IC50 of 2.03 µM at 24 h and 1.13 µM at 48 h, with increased cell cycle arrest in S-phase. The results of annexin V-FITC/PI and AO/EB staining showed that acetylshikonin induced cell apoptosis in a dose-dependent manner. K562 cells treated with acetylshikonin underwent massive apoptosis accompanied by a rapid generation of reactive oxygen species (ROS). Scavenging the ROS completely blocked the induction of apoptosis following acetylshikonin treatment. The levels of the pro-apoptotic proteins Bax, cleaved caspase-9, cleaved PARP and cleaved caspase-3 increased with increased concentrations of acetylshikonin, while the level of the anti-apoptotic protein Bcl-2 was downregulated. The levels of Cyt C and AIF, which are characteristic proteins of the mitochondria-regulated intrinsic apoptotic pathway, also increased in the cytosol after acetylshikonin treatment. However, the mitochondrial fraction of Cyt C and AIF were decreased under acetylshikonin treatment. In addition, acetylshikonin decreased Bcr-Abl expression and inhibited its downstream signaling. Acetylshikonin could lead to a blockage of the NF-κB signaling pathway via decreasing nuclear NF-κB P65 and increasing cytoplasmic NF-κB P65. Moreover, acetylshikonin significantly inhibited the phosphorylation of IkBα and IKKα/ß in K562 cells. These results demonstrated that acetylshikonin significantly inhibited K562 cell growth and induced cell apoptosis through the mitochondria-regulated intrinsic apoptotic pathway. The mechanisms may involve the modulating ROS accumulation, inhibition of NF-κB and BCR-ABL expression. The inhibition of BCR-ABL expression and the inactivation of the NF-κB signaling pathway caused by acetylshikonin treatment resulted in K562 cell apoptosis. Together, our results indicate that acetylshikonin could serve as a potential therapeutic agent for the future treatment of CML.

Selenocysteine antagonizes oxygen glucose deprivation-induced damage to hippocampal neurons.

Designing and/or searching for novel antioxidants against oxygen glucose deprivation (OGD)-induced oxidative damage represents an effective strategy for the treatment of human ischemic stroke. Selenium is an essential trace element, which is beneficial in the chemoprevention and chemotherapy of cerebral ischemic stroke. The underlying mechanisms for its therapeutic effects, however, are not well documented. Selenocysteine (SeC) is a selenium-containing amino acid with neuroprotective potential. Studies have shown that SeC can reduce irradiation-induced DNA apoptosis by reducing DNA damage. In this study, the in vitro protective potential and mechanism of action of SeC against OGD-induced apoptosis and neurotoxicity were evaluated in HT22 mouse hippocampal neurons. We cultured HT22 cells in a glucose-free medium containing 2 mM Na2S4O2, which formed an OGD environment, for 90 minutes. Findings from MTT, flow cytometry and TUNEL staining showed obvious cytotoxicity and apoptosis in HT22 cells in the OGD condition. The activation of Caspase-7 and Caspase-9 further revealed that OGD-induced apoptosis of HT22 cells was mainly achieved by triggering a mitochondrial-mediated pathway. Moreover, the OGD condition also induced serious DNA damage through the accumulation of reactive oxygen species and superoxide anions. However, SeC pre-treatment for 6 hours effectively inhibited OGD-induced cytotoxicity and apoptosis in HT22 cells by inhibiting reactive oxygen species-mediated oxidative damage. Our findings provide evidence that SeC has the potential to suppress OGD-induced oxidative damage and apoptosis in hippocampal neurons.

A Novel Water-soluble Ratiometric Fluorescent Probe Based on FRET for Sensing Lysosomal pH.

A new ratiometric fluorescent probe based on Förster resonance energy transfer (FRET) for sensing lysosomal pH has been developed. The probe (RMPM) was composed of imidazo[1,5-α]pyridine quaternary ammonium salt fluorophore as the FRET donor and the rhodamine moiety as the FRET acceptor. It's the first time to report that imidazo[1,5-α]pyridine quaternary ammonium salt acts as the FRET donor. The ratio of fluorescence intensity of the probe at two wavelengths (I424/I581) changed significantly and responded linearly toward minor pH changes in the range of 5.4-6.6. It should be noted that it's rare to report that a ratiometric pH probe could detect so weak acidic pH with pKa = 6.31. In addition, probe RMPM exhibited excellent water-solubility, fast-response, all-right selectivity and brilliant reversibility. Moreover, RMPM has been successfully applied to sensing lysosomal pH in HeLa cells and has low cytotoxicity.