Students' perception of the educational environment of medical schools in Korea: findings from a nationwide survey / 한국의학교육

PURPOSE: The purpose of this study was to examine students' perception of the educational environment of medical schools in Korea. METHODS: A total of 9,096 of 12,035 students (75.6%) responded to our questionnaire. This study was conducted at the end of the 2013 academic year using the Dundee Ready Education Environment Measure (DREEM) at 40 medical schools in Korea. DREEM comprises five domains: students' perceptions of learning (SPL); students' perceptions of teachers (SPT); students' academic self-perceptions; students' perceptions of atmosphere; and students' social self-perception. The data were analyzed using descriptive statistics, independent t-test, and one-way analysis of variance. RESULTS: The overall mean DREEM score was 113.97 (of 200), and the scores for the 40 medical schools ranged from 100.24 to 134.32. The overall mean and domains scores of the DREEM differed significantly between educational systems, grades, genders, and academic achievement levels. Graduate-level medical students had higher scores for the DREEM and its five domains than undergraduate medical students. The scores were lowest in second-year students (mean, 111.80). Male students' perceptions were significantly higher than those of female students except for SPL and SPT. High academic achievers' perceptions were also greater versus low academic achievers. CONCLUSION: Students' perceptions of their educational environment are positive in Korea. The learning environment should be evaluated by curriculum planners and administrators of medical schools to improve its quality.

A New Direction for Basic Medical Science Education / 한국의학교육

No abstract available.

Transient lysosomal activation is essential for p75 nerve growth factor receptor expression in myelinated Schwann cells during Wallerian degeneration / 대한해부학회지

Myelinated Schwann cells in the peripheral nervous system express the p75 nerve growth factor receptor (p75NGFR) as a consequence of Schwann cell dedifferentiation during Wallerian degeneration. p75NGFR has been implicated in the remyelination of regenerating nerves. Although many studies have shown various mechanisms underlying Schwann cell dedifferentiation, the molecular mechanism contributing to the re-expression of p75NGFR in differentiated Schwann cells is largely unknown. In the present study, we found that lysosomes were transiently activated in Schwann cells after nerve injury and that the inhibition of lysosomal activation by chloroquine or lysosomal acidification inhibitors prevented p75NGFR expression at the mRNA transcriptional level in an ex vivo Wallerian degeneration model. Lysosomal acidification inhibitors suppressed demyelination, but not axonal degeneration, thereby suggesting that demyelination mediated by lysosomes may be an important signal for inducing p75NGFR expression. Tumor necrosis factor-alpha (TNF-alpha) has been suggested to be involved in regulating p75NGFR expression in Schwann cells. In this study, we found that removing TNF-alpha in vivo did not significantly suppress the induction of both lysosomes and p75NGFR. Thus, these findings suggest that lysosomal activation is tightly correlated with the induction of p75NGFR in demyelinating Schwann cells during Wallerian degeneration.

Nidogen Plays a Role in the Regenerative Axon Growth of Adult Sensory Neurons Through Schwann Cells

We previously reported that nidogen is an extracellular matrix protein regulating Schwann cell proliferation and migration. Since Schwann cells play a critical role in peripheral nerve regeneration, nidogen may play a role in it via regulation of Schwann cells. Here, we demonstrate direct evidence that nidogen induces elongation of regenerative axon growth of adult sensory neurons, and that the effect is Schwann cell dependent. Continuous infusion of recombinant ectodomain of tumor endothelial marker 7, which specifically blocks nidogen function in Schwann cells, suppressed regenerative neurite growth in a sciatic nerve axotomy model. Taken together, it is likely that nidogen is required for proper regeneration of peripheral nerves after injury.

Extracellular Signal-regulated Kinase Activation Is Required for Serine 727 Phosphorylation of STAT3 in Schwann Cells in vitro and in vivo

In the peripheral nerves, injury-induced cytokines and growth factors perform critical functions in the activation of both the MEK/ERK and JAK/STAT3 pathways. In this study, we determined that nerve injury-induced ERK activation was temporally correlated with STAT3 phosphorylation at the serine 727 residue. In cultured Schwann cells, we noted that ERK activation is required for the serine phosphorylation of STAT3 by neuropoietic cytokine interleukin-6 (IL-6). Serine phosphorylated STAT3 by IL-6 was transported into Schwann cell nuclei, thereby indicating that ERK may regulate the transcriptional activity of STAT3 via the induction of serine phosphorylation of STAT3. Neuregulin-1 (NRG) also induced the serine phosphorylation of STAT3 in an ERK-dependent fashion. In contrast with the IL-6 response, serine phosphorylated STAT3 induced by NRG was not detected in the nucleus, thus indicating the non-nuclear function of serine phosphorylated STAT3 in response to NRG. Finally, we determined that the inhibition of ERK prevented injury-induced serine phosphorylation of STAT3 in an ex-vivo explants culture of the sciatic nerves. Collectively, the results of this study show that ERK may be an upstream kinase for the serine phosphorylation of STAT3 induced by multiple stimuli in Schwann cells after peripheral nerve injury.

Netrin-1 Specifically Enhances Cell Spreading on Fibronectin in Human Glioblastoma Cells

Netrins are secreted molecules and involved in axon guidance, cell migration and tumor development. Recent studies revealed that netrins perform novel functions in such processes as epithelial development and angiogenesis without operating through the classical netrin receptors, DCC (Deleted in Colorectal Cancer) and Unc5h. In the present study, we investigated the roles of netrin-1 and its receptors in cell spreading of human glioblastoma cells, and found that netrin-1 haptotactically enhanced fibronectin-induced cell spreading and focal adhesion formation in U373 glioblastoma cells. Netrin-1 binding to the U373 cell membrane was blocked by an antibody against alpha v integrin subunit, but not by an anti-DCC or anti-Unc5h antibody. In addition, enhancement of the fibronectin response by netrin-1 was abrogated by a function blocking antibody against integrin alpha v beta 3. Since the alpha v subunit of the integrin family plays an important role in the pathophysiological aspects of cell migration, including tumor angiogenesis and metastasis, our data provide important insight into the molecular mechanism of netrin function.

Basic Medicine, What and How Should We Teach? / 한국의학교육

No Abstract available.

Status of Clerkship Education and Its Evaluation in Korean Medical Schools / 한국의학교육

PURPOSE: The aim of this study is to identify the status of clerkship education and its evaluation in Korea. METHODS: Questionnaires were sent to 943personnel in 23clinical departments of 41medical schools nationwide from April, 1 to April 10, 2004. We analyzed the 638 questionnaires that were collected from 39medical schools. RESULTS: The most frequently used methodologies for clerkship education were small group lecture(17.1%), observation of ambulatory care(15.7%), seminar(12.9%), observation and support of operation(12.4%), ward rounding(12.1%). The relative proportion of educational methodologies was varied according to the type of clinical departments. Most of the clinical clerkship activity was conducted in the university hospital. Also, the clerkship activities were educated by professors(57.8%), fellows(9.1%), residents(30.6%) and others(2.5%). The evaluation methods were written exam(21.8%), attendance(17.5%), report(14.0%), and oral exam(12.0%). In terms of evaluating items, acquirement of clinical knowledge has been mainly tested. However, students' ability to communicate, build human relationship, and clinical skills has been less frequently evaluated in most of medical schools. CONCLUSION: It is most likely that the current status of clerkship education and its evaluation in Korea is focused on the education and assessment of clinical knowledge. To improve this, the following areas need to be enriched: interaction between faculty and students, experience-based clerkship, effective feedback, time management, objectivity of evaluation, performance evaluation.

Effect of Exercise to Improve of Rat Lower Limb Healing after Physical Injury / 체질인류학회지

The aim of this report is to show that treadmill running exercise under well-controlled conditions is to improve of regeneration in rat gastrocnemius muscles after physical injury. For this, rats were submitted to bouts of exercise on a treadmill up a 10 degrees decline for 60 min and gastrocnemius muscles were analysed at different exercise periods by immunohistochemistry in comparison with injured nonexercised muscles. Rats were used with guidelines for experimental procedures as set forth in the Declaration of Helsinki. We analysed the regenerative processes by detection of immunoreactivity for the two intermediate filaments, desmin and vimentin. Desmin and vimentin are specific components of the cytoskeleton of striated muscle fibers and of mononuclear cells of mesenchymal origin including myoblasts, respectively. We found that non-exercised rats had more desmin-and vimentin-positive myofibers than that of exercised rats at 9th, 16th, 23th, 30th day after physical injury. At 30th day, non-exercised rats had several desmin-and vimentinpositive myofibers, but exercised rats had numerous normal myofibers. These results show that exercise is able to improve regeneration processes in physical injured gastrocnemius muscles of rats.

The Development Tasks of Medical School Accreditation in Korea / 한국의학교육

The Accreditation Board for Medical Education in Korea, ABMEK, is nongovernmental appraisal organization that was established at July 2, 1998. The organization is contributing to the improvement of medical education by progressing the first cycle accreditation successfully. But, the organization has various problems and subjects related to the accreditation system. The authors examined the related literature focusing on the current status and problems of accreditation system. The result of this research was as follows. First, the ABMEK needs to propel legal personality of organization and should install independent executive office. Second, the ABMEK should establish the alteration procedure of accreditation standards and develop the accreditation standards of the second cycle that take into account international flowing of medical education. Third, the ABMEK must decide forms and scope to investigate medical college present situation. Finally, to propel development tasks effectively, it needs to get the recognition of Ministry of Education and Human Development.

Protective Effect of Morin Hydrate on Reactive Oxygen Injury in Rabbit Corneal Epithelium

PURPOSE: Free radicals are responsible for tissue injury in corneal preservation and transplantation. Morin hydrate, a flavonoid from Brazil wood, has been shown to be cytoprotective in several types of cells. The aim of this study was to investigate the effectiveness of morin hydrate on rabbit cornea against damage induced by oxyradicals and nitric oxide. METHODS: The rabbit cornea was studied in modified Ussing chambers to determine the effects of hydrogen peroxide (H2O2) or sodium nitroprusside (SNP) by measuring the bioelectrical properties (short-circuit current (Isc), tissue resistance (Rt) and potential difference (PD)). RESULTS: 1.0 mM H2O2 markedly increased the Isc at the tear side (T-side), but not at stromal side (S-side), suggesting the site of action of H2O2 was the apical membrane (T-side). After pretreatment with morin hydrate (T-side, 1.0 mM), H2O2-induced increase of Isc and PD was markedly reduced. In addition adding morin hydrate with H2O2 simultaneously, the increase of Isc and PD was also markedly reduced. Exposure of cornea to SNP at the T-side increased nitric oxide, and increased the bioelectrical properties (PD and Isc). This effect was attenuated by the treatment with morin hydrate. CONCLUSIONS: This study demonstrated that morin hydrate behaved as a antioxidant. This property of morin hydrate may help prevent protect cornea in preservative solutions from free radical damage.

Effect of Ethanol on the Regulation of Smooth Muscle Tone in Rat Aorta

BACKGROUND AND OBJECTIVES: The aim of this study was to determine the effect of ethanol on the regulation of vascular tone. MATERIAL AND METHODS: Using rat aorta ring, isometric contraction and 45Ca uptake were measured. Phorbol 12,13-dibutyrate (PDBu), phenylephrine, KCl were used for the regulation of smooth muscle tone. RESULTS: Ethanol induced transient contraction in rat aorta ring by dose-dependent manner. Ethanol suppressed the dose dependent contractile responses of vascular strip by phenylephrine, KCl and PDBu. Endothelium-dependent relaxation by acetylcholine was inhibited by ethanol. Ethanol depressed 45Ca uptake by high KCl but not by phenylephrine or PDBu in rat aorta. n-butanol selectively suppressed tonic contraction by high KCl, but t-butanol did not at the same concentration of butanol in rat aorta. PDBu-induced contraction was selectively suppressed by n-butanol but not by t-butanol. CONCLUSIONS: These findings suggest that the action of ethanol on phospholipase D is involved in the decreased response of rat aorta strip by vasoconstrictors.

Properties of stretch-activated K+ channels in an G292 osteoblast-like cell / 대한치과교정학회지

K+ -selective ion channels were studied in excised inside-out membrane patches from human osteoblast-like cells(G292). There classes of K+ channels were present and could be distinguished on the basis of conductance. Conductances were 270+/-27 pS, 113+/-12 pS, 48+/-8 pS according to their approximate conductances in symmetrical 140 mM KCI saline at holding potential of -80 mV. It was found that the small conductance (48 pS) K+ channel activation was dependent on membrane voltage. In current-voltage relationship, small conductance K+ channel showed outward rectification, and it was activated by the positive potential inside the membrane. In recordings, single channel currents were activayed by a negative pressure outside the membrane. The membrane pressure increased P(open) of the K+ channel in a pressure-dependent manner. In the excised-patch clamp recordings, G292 osteoblast-like cells have been shown to contain three types of K+ channels. Only the small conductance (48 pS) K+ channel is sensitive to the membrane stretch. These findings suggest that a hyperpolarzing current, mediated in part by this channel, may be associated with early events during the mechanical loading of the osteoblast. In G292 osteoblast-like cells, K+ channel is sensitive to membrane tension, and may represent a unique adaptation of the bone cell membrane to mechanical stress.

Effects of Hyperthermia on Neuronal Nitric Oxide Synthase Expression after Cerebral Ischemia in Gerbils

PURPOSE: This study was aimed to elucidate the effect of hyperthermia on neuronal nitric oxide synthase(nNOS) expression in both cerebral hemispheres after left common carotid artery occlusion in gerbils. METHODS: Using Mongolian gerbils, cerebral ischemia was produced by occluding carotid artery for 1-4 hours. Rectal temperature was maintained at 36degrees C for normothermia and 40degrees C for hyperthermia by heating pad. Western blot and RT-PCR was used to examine the nNOS and the mRNA expression. Neuronal damages were observed by histological study. RESULTS: After cerebral ischemia, mRNA of nNOS was expressed more abundantly in ischemic hemisphere than control in both normothermia and hyperthermia. Hyperthermia reduced nNOS protein expression markedly. In pathological study, neurons of hippocampal region were degenerated by ischemia. Hyperthermia by itself induced neuronal degeneration in both control and ischemic region. In immunohistochemistry of brain, there was no significant difference of nNOS expression between normothermia and hyperthermia. CONCLUSION: These findings suggest that increase in body temperature might enhance nNOS mRNA expression but reduce nNOS protein, and that hyperthermia aggravates neuronal damage by ischemia, independent of nNOS gene expression.

Quantitative Analysis of Cultured Erythroid Progenitors in Liquid System / 대한혈액학회지

BACKGROUND: Hemopoiesis and erythropoiesis have been studied mainly in immortalized cell lines and semisolid medium. But cell lines do not represent normal erythropoiesis, besides, in semisolid medium the cells are immobilized that it is difficult to do additional immunologic, biochemical, and molecular biologic experiments. In the present study we used a two-phase liquid culture system to isolate and quantify erythroid progenitors from peripheral blood and cord blood. METHODS: Peripheral and cord blood were obtained from three healthy donors and three full-term deliveries, respectively. Mononuclear cells were separated by density gradient centrifugation and were cultured in the first phase at a density of 5x106/mL in alpha- minimal essential medium ( -MEM). After 5~7 days of incubation at 37degrees C in an atmosphere of 5% CO2 with extra humidity, the nonadherent cells were harvested and recultured in the original volume of -MEM containing 10ng/mL stem cell factor and 1U/mL erythropoietin (EPO). Cellular morphology was observed by preparing cytocentrifuge slides stained with Wright Giemsa. On days 8, 10, 12, and 16 of the second phase, hemoglobin (Hb)- containing cells were counted on hemocytometer after staining with acid benzidine and glycophorin A-positive erythroid cells were scored by a flow cytometer. RESULTS: Pronormoblasts first started to appear on days 4~5 in the secondary culture. On day 10 basophilic normoblasts could be seen and on days 12~14 orthochromatic normoblasts were present. Both from peripheral and cord blood the maximum number of benzidine and glycophorin A-positive cells were achieved after 10 days and the total erythroid cell yield was approximately 1x106/mL. CONCLUSION: Using two-phase liquid culture, erythroid cell yield reached 1x106/mL both from peripheral and cord blood. In addition, this culture system permits the study of the effect of various culture conditions and components without terminating the culture, therefore it might provide us a useful experimental tool for studying pathogenesis and therapeutic modalities in genetic erythroid disorders as well as erythroid cell development.

Regulation of AQP-4 water channel expression in the brain during development and by ischemia

Water transport is mediated by two distinct pathways, diffusional and channel-mediated water transport. The first molecular water channel was identified from human erythrocytes in 1992. Genetically-related proteins from other mammalian tissues have subsequently been identified to transport water, and the group is referred to as the "Aquaporins". Aquaporin-4 (AQP4) is most abundant in the brain, which may be involved in CSF reabsorption and osmoregulation. However, ontogeny and regulatory mechanisms of AQP4 channels have not been reported. Northern blot analysis showed that AQP4 mRNA began to be expressed in the brain just before birth and that its expression gradually increased by PN7 and then decreased at adult level. AQP4 was expressed predominantly in the ependymal cells of ventricles in newborn rats. And then its expression decreased in ependymal cells and increased gradually in other regions including supraoptic and paraventricular nuclei. AQP4 is also expressed in the subfornical organ, in which the expression level is not changed after birth. Cryogenic brain injury did not affect expression of AQP4 mRNA, while ischemic brain injury decreased it. Osmotic water permeability of AQP4 channel expressed in Xenopus oocytes was inhibited by the pretreatment of BAPTA/AM and calmidazolium, a Ca2+/ Calmodulin kinase inhibitor, in a dose-dependent manner. These results indicate that the expression and the function of AQP4 channel are regulated by developmental processes and various pathophysiological conditions. These results will contribute to the understanding of fluid balance in the central nervous system and the osrmoregulatory mechanisms of the body.

Effects of Hydrogen Peroxide on Rabbit Corneal Bioelectric Properties

The rabbit cornea was studied in vitro in modified Ussing chambers to determine the effects of ion transport inhibitors and hydrogen peroxide(H2O2) on ion transport through the cornea by measuring the bioelectric properties. Apical(tear side, T side) addition of furosemide, bumetanide and SITS were ineffective on resting Isc(short circuit current). Apical addition of 1.0mM amiloride(Na+/H+ antiport inhibitor) and NPAA(Cl- channel blocker) markedly reduced the resting Isc, but basolateral(stromal side, S side) addition of amiloride was ineffective. The site of action of these agents was the apical membrane. H2O2, an oxygen free radical, markedly increased the lsc when was added to the T side, but S side addition of the H2O2 was ineffective. To determine the degree of cellular catalase participation in protection against H2O2 induced injury the cornea was pretreated with ATAZ for 30 min prior to H2O2 action. The increase of lsc by H2O2 was markedly potentiated after pretreatment with ATAZ on T side compared to that of S side addition. This result indicates that the corneal endothelial H2O2 may be largely degraded by catalase. When H2O2 was added to the T side, Isc was raised by increased ion transport. All ion transport inhibitors that were used inhibited the H2O2 effect on Isc. Moreover, amiloride and NPAA markedly inhibited induced lsc by H2O2. These results suggest that H2O2 stimulates the corneal epithelial ion transport and that its site of action is apical membrane Na+/H+ antiport system and CI- channel system.

Effect of H2O2 on alveolar epithelial barrier properties / 결핵

No abstract available.