Chronic magnesium deficiency causes reversible mitochondrial permeability transition pore opening and impairs hypoxia tolerance in the rat heart.

Chronic magnesium (Mg) deficiency induces and exacerbates various cardiovascular diseases. We previously investigated the mechanisms underlying decline in cardiac function caused by chronic Mg deficiency and the effectiveness of Mg supplementation on this decline using the Langendorff-perfused isolated mouse heart model. Herein, we used the Langendorff-perfused isolated rat heart model to demonstrate the chronic Mg-deficient rats (Mg-deficient group) had lower the heart rate (HR) and left ventricular pressure (LVDP) than rats with normal Mg levels (normal group). Furthermore, decline in cardiac function due to hypoxia/reoxygenation injury was significantly greater in the Mg-deficient group than in the normal group. Experiments on mitochondrial permeability transition pore (mPTP) using isolated mitochondria revealed that mitochondrial membrane was fragile in the Mg-deficient group, implying that cardiac function decline through hypoxia/reoxygenation injury is associated with mitochondrial function. Mg supplementation for chronic Mg-deficient rats not only improved hypomagnesemia but also almost completely restored cardiac and mitochondrial functions. Therefore, proactive Mg supplementation in pathological conditions induced by Mg deficiency or for those at risk of developing hypomagnesemia may suppress the development and exacerbation of certain disease states.

Improving the communication skills of medical students --A survey of simulated patient-based learning in Chinese medical universities.

BACKGROUND: It is useful to advance simulated patient (SP) participation in teaching to improve the communication skills of medical students, so this study aims to explore the current state of Chinese mainland SP education. METHODS: A cross sectional survey was designed utilizing well defined quantitative research methods and descriptive statistics. The questionnaire sought information which elucidated the current status of SP-based education, the origin of SP-based learning, SP training, challenges of this learning strategy and future developments. Questionnaires were distributed to 79 medical colleges in mainland China, and 68 were returned. Of these, 64 constituted valid responses (81%). RESULTS: The number of SP-based education activities in medical colleges offering 5-year、7-year and 8-year clinical medicine programs was significantly higher than that in medical colleges which offered only a single 5-year program (p < 0.01). Communication skills training accounted for 73% of the content of SP-based learning activities, and was expected to rise in the future to 90%, in response to a need to improve doctor-patient relationships. Persons recruited as 'simulated patients' included students (21% of the total), residents (49%), medical staff (15%) and teaching staff (14%). Colleges, planning a SP-based education program, preferred teachers (80%) and students (55%) to assume 'simulated patient' roles. In objective structured clinical education (OSCE) scenarios, co-scoring by both SPs and teachers featured more highly in the 'consultation' station and 'doctor-patient communication' station. A number of factors were identified as hindering future development and implementation of SP-based learning including budget restraints, SP selection and training. CONCLUSIONS: SP-based learning programs offer clear benefits for improving the clinical education of medical students and their communication skills. The main obstacles to achieving more widespread and higher quality SP-based education are insufficient funding and the lack of standardized training and performance evaluation processes for simulated patients. Medical colleges should consider reducing the proportion of students and teachers acting as SPs, and attract more citizens to participate in SP-based learning activities. Formalised training and evaluation of SPs performance are necessary to establish a 'standard simulated patient' for a particular medical discipline, thus improving SP-based activities and student learning.

Increased extracellular and intracellular Ca²âº lead to adipocyte accumulation in bone marrow stromal cells by different mechanisms.

Mesenchymal stem cells found in bone marrow stromal cells (BMSCs) are the common progenitors for both adipocyte and osteoblast. An increase in marrow adipogenesis is associated with age-related osteopenia and anemia. Both extracellular and intracellular Ca(2+) ([Ca(2+)]o and [Ca(2+)]i) are versatile signaling molecules that are involved in the regulation of cell functions, including proliferation and differentiation. We have recently reported that upon treatment of BMSCs with insulin and dexamethasone, both high [Ca(2+)]o and high [Ca(2+)]i enhanced adipocyte accumulation, which suggested that increases in [Ca(2+)]o caused by bone resorption may accelerate adipocyte accumulation in aging and diabetic patients. In this study, we used primary mouse BMSCs to investigate the mechanisms by which high [Ca(2+)]o and high [Ca(2+)]i may enhance adipocyte accumulation. In the process of adipocyte accumulation, two important keys are adipocyte differentiation and the proliferation of BMSCs, which have the potential to differentiate into adipocytes. Use of MTT assay and real-time RT-PCR revealed that high [Ca(2+)]i (ionomycin)-dependent adipocyte accumulation is caused by enhanced proliferation of BMSCs but not enhanced differentiation into adipocytes. Using fura-2 fluorescence-based approaches, we showed that high [Ca(2+)]o (addition of CaCl2) leads to increases in [Ca(2+)]i. Flow cytometric methods revealed that high [Ca(2+)]o suppressed the phosphorylation of ERK independently of intracellular Ca(2+). The inhibition of ERK by U0126 and PD0325901 enhanced the differentiation of BMSCs into adipocytes. These data suggest that increased extracellular Ca(2+) provides the differentiation of BMSCs into adipocytes by the suppression of ERK activity independently of increased intracellular Ca(2+), which results in BMSC proliferation.

Enhanced accumulation of adipocytes in bone marrow stromal cells in the presence of increased extracellular and intracellular [Ca²âº].

The bone marrow stroma contains osteoblasts and adipocytes that have a common precursor: the pluripotent mesenchymal stem cell found in bone marrow stromal cells (BMSCs). Local bone marrow Ca(2+) levels can reach high concentrations due to bone resorption, which is one of the notable features of the bone marrow stroma. Here, we describe the effects of high [Ca(2+)](o) on the accumulation of adipocytes in the bone marrow stroma. Using primary mouse BMSCs, we evaluated the level of adipocyte accumulation by measuring Oil Red O staining and glycerol-3-phosphate dehydrogenase (GPDH) activity. High [Ca(2+)](o) enhanced the accumulation of adipocytes following treatment with both insulin and dexamethasone together but not in the absence of this treatment. This enhanced accumulation was the result of both the accelerated proliferation of BMSCs and their differentiation into adipocytes. Using the fura-2 method, we also showed that high [Ca(2+)](o) induces an increase in [Ca(2+)](i). An intracellular Ca(2+) chelator suppressed the enhancement in adipocyte accumulation due to increased [Ca(2+)](o) in BMSCs. These data suggest a new role for extracellular Ca(2+) in the bone marrow stroma: increased [Ca(2+)](o) induces an increase in [Ca(2+)](i) levels, which in turn enhances the accumulation of adipocytes under certain conditions.

Effects of COVID-19 on Japanese medical students' knowledge and attitudes toward e-learning in relation to performance on achievement tests.

The COVID-19 pandemic forced many educational institutions to turn to electronic learning to allow education to continue under the stay-at-home orders/requests that were commonly instituted in early 2020. In this cross-sectional study, we evaluated the effects of the COVID-19 pandemic on medical education in terms of students' attitudes toward online classes and their online accessibility; additionally, we examined the impacts of any disruption caused by the pandemic on achievement test performance based on the test results. The participants were 674 students (412 in pre-clinical, 262 in clinical) at Juntendo University Faculty of Medicine; descriptive analysis was used to examine the respondents' characteristics and responses. The majority of respondents (54.2%) preferred asynchronous classes. Mann-Whitney U tests revealed that while pre-clinical students preferred asynchronous classes significantly more than clinical students (39.6%, p < .001), students who preferred face-to-face classes had significantly higher total achievement test scores (U = 1082, p = .021, r = .22). To examine the impacts of pandemic-induced changes in learning, we conducted Kruskal-Wallis tests and found that the 2020 and 2021 scores were significantly higher than those over the last three years. These results suggest that while medical students may have experienced challenges adapting to electronic learning, the impact of this means of study on their performance on achievement tests was relatively low. Our study found that if possible, face-to-face classes are preferable in an electronic learning environment. However, the benefit of asynchronous classes, such as those that allow multiple viewings, should continue to be recognized even after the pandemic.

Risk Factors Associated with Poor Computer-based Testing (CBT) Scores - Comparing Students' Performance "Without/With COVID-19" and Backgrounds.

Objective: The present study compared students' CBT scores during the 2-year period before ("without COVID-19") and 2-year period during ("with COVID-19") the COVID-19 pandemic, and analyzed factors associated with poor results. Materials: A total of 530 students (368 males and 162 females), who had taken CBT within the period between 2018 and 2021. Methods: Analysis was performed based on the questionnaire results, and the students' performance was compared between "without/with COVID-19" to identify the causes of poor CBT scores. Results: The overall mean IRT score was 515.5±85.4. The without and with COVID-19 groups' scores were 495.7±85.9 and 534.4±80.8, respectively (p<0.01). Among all students, 43 (8.1%) had IRT scores lower than 400 as poor CBT scores; 27 (10.4%) without and 16 (5.9%) with COVID-19, revealing a decrease in the latter. The multivariate analysis of the risk of students having poor CBT scores showed that students with poor performance during the third year (odds ratio:7.02), starting preparation for CBT late (2.19), and not taking any practice examination (4.58) are more likely to have poor CBT results. Conclusions: Due to the COVID-19 pandemic, students spent more time on online home study, and this may have consequently improved their CBT scores. Such learning performance is desirable for medical students, but they have lost the opportunity to gain valuable experiences that they could have acquired through extracurricular activities, such as club activities. In this respect, we cannot simply be pleased by the improvement in students' CBT scores.

[Sequential changes in inflammatory and stress responses during 24-hour running].

Running for an extended period of time can cause severe stress on the body, subsequently damaging skeletal muscle and resulting in changes in blood components. However, few reports have examined vital responses during and after running. This study analyzed inflammatory responses during and after running and changes in stress responses as determined by serial changes in blood components. Venous blood was obtained before starting, 6 h after starting, 12 h after starting, and immediately after finishing 24 h of continuous running. Samples were analyzed for high-sensitivity C-reactive protein (hsCRP), pentraxin 3 (ptx3), white blood cells (WBC), myoglobin, creatine kinase (CK), and hormones. Diet and physical activity were standardized 24 h before and after running. Subjects comprised 16 men who agreed to participate in experimental running on November 8 and 9, 2008, at Tokyo Gakugei University. Mean running distance was 151.32 +/- 32.1 km (range, 83.6-210.0 km) in 24 h. A significant increase in hsCRP was seen from 12 h after starting to completion. Compared to hsCRP, ptx3 gradually increased from before starting to after completion, showing a significant difference between pre and post-run ptx3 levels. WBC count increased significantly until 6 h after starting. Neutrophils in leukocytosis increased significantly during the first 6 h. Eosinophils decreased significantly over the course of the 24 h. Cortisol increased, and testosterone decreased significantly from 6 h after starting. Dehydroepiandrosterone sulfate (DHEA-S), myoglobin, and CK increased over the course of the 24 h. Reactive oxygen metabolites (d-ROMs) changed within the normal range though there was a significant decrease, and biological anti-oxidant potential (BAP) stabilized. Active natural killer cells decreased significantly after 24 h running. Biopyrrin (BPn) increased significantly. Changes in stress oxide were small both during and after running, and adaptation for antioxidation was good. DHEAS, a biomarker of aging, was found to increase over the course of the 24 h, suggesting that controlling decreases in DHEA-S may be possible using exercise, particularly in males. The key finding was that DHEA S levels tended to increase with continuous aerobic exercise.

Intracellular magnesium and tolerance against hypoxia in immature rat heart.

BACKGROUND: Neonatal hearts show greater resistance to hypoxia than adult hearts do, but the mechanism is unclear. In immature rat hearts, we examined the association between high tolerance for hypoxia and the kinetics of magnesium (Mg), which has myocardial protective effects in adult hearts. METHODS: The hearts of 1-, 2-, 3-, and 10-week-old rats were Langendorff perfused and subjected to 45 min hypoxia and 30 min reoxygenation. The myocardial Mg content was measured by atomic absorption spectrophotometry. RESULTS: In 1-week-old rat hearts, the tension-rate product recovered more immediately with reoxygenation than in the other groups, and aspartate aminotransferase release did not increase throughout the experiment. In 10-week-old rat hearts, total tissue Mg content decreased significantly with reoxygenation (607.0 ± 22.9 µg/g dry weight) from its control level (793.2 ± 16.7 µg/g dry weight). However, in neonates, the total tissue Mg did not decrease with reoxygenation. CONCLUSIONS: The high resistance against hypoxia-reoxygenation injury in neonatal rat hearts is caused, at least in part, by a high ability to maintain myocardial Mg.

Improvement of Aspects of Subjective Sleep Quality of Healthy Volunteers by Ingestion of Porcine Placental Extract: A Randomized Cross-Over Pilot Study.

Objectives: This study assessed the effects of oral porcine placental extract (PPE) on sleep quality of healthy volunteers not satisfied with their sleep. Design: This study used a randomized, placebo-controlled, double-blind, cross-over clinical pilot study. Setting: This study was conducted under an outpatient multicenter setting in Japan. Interventions: A total of 20 healthy Japanese volunteers aged between 28 and 73, whose Pittsburgh Sleep Quality Index global scores were between 6 and 10, successfully completed the study. At first, PPE at 300 mg/kg or placebo was ingested for 2 weeks. Then, after a 2-week washout period, each group ingested under a cross-over setting the opposite sample (placebo or PPE) for another 2 weeks. Main Outcome Measures: Objective measurement of the sleep made with an activity tracker and subjective measurements of sleep quality by use of St. Mary's Hospital Sleep Questionnaire were done just before and after the administration time slots. Results: No effect of PPE on the sleep length was observed. Several measures in the subjective St. Mary's Hospital Sleep Questionnaire, i.e., changes in Q5 (sleep depth) and Q9 (sleep wellness) between pre- and post-ingestions, were significantly different between groups in the direction of improvement of subjective sleep quality in the PPE group. Conclusions: Although oral PPE at 300 mg/day for 2 weeks did not affect the length of sleep itself, it significantly improved several measures of subjective sleep quality. These results suggest that PPE might be a way to improve sleep quality without hypnotic drugs. Clinical Trial Registration: www.umin.ac.jp/ctr/, identifier: UMIN000026468.

JAK-STAT-dependent regulation of scavenger receptors in LPS-activated murine macrophages.

In atherosclerosis progression, atherosclerotic plaques develop upon accumulated foam cells derived from macrophages that take up modified low-density lipoprotein (LDL). CD36 and CD204 are the principal scavenger receptors responsible for the uptake of modified LDL. Lipopolysaccharide (LPS) exacerbates atherosclerosis by enhancing the expression of scavenger receptors and thus increasing the uptake of modified LDL into macrophages. However, the signaling pathways that mediate LPS and scavenger receptor expression have not been fully elucidated. We used mouse bone marrow-derived macrophages and investigated the effects of LPS in vitro. LPS enhanced the phosphorylation of extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription-1 (STAT-1). Inhibitors of the mitogen-activated protein kinase (MAPK)/ERK kinase (MEK) pathway (U0126 and PD0325901) suppressed the uptake of acetylated-LDL (Ac-LDL) and the expression of CD204 but not CD36 in LPS-activated macrophages. Inhibitors of the Janus tyrosine kinase (JAK)-STAT pathway (ruxolitinib and tofacitinib) suppressed the uptake of Ac-LDL and the expression of both CD36 and CD204 in LPS-activated macrophages. We next injected LPS into the peritoneal cavity of mice and analyzed the effects of LPS. MEK inhibitor U0126 suppressed the uptake of Ac-LDL and the expression of CD204 but not CD36 in LPS-activated macrophages. JAK inhibitor ruxolitinib suppressed the uptake of Ac-LDL and the expression of both CD36 and CD204 in LPS-activated macrophages. These results suggest that scavenger receptors in LPS-activated mouse macrophages are regulated through a JAK-STAT-dependent pathway. Although further evaluation is necessary, JAK-STAT inhibition could be useful in atherosclerosis therapy, at least for atherosclerosis exacerbated by LPS.