• Journal of The Korean Association For Science Education
• /
• v.17 no.3
• /
• pp.261-271
• /
• 1997

This study evaluates on students' understanding and misunderstanding of homeostasis, classification of animals and plants, and food production in plants, and analyzes the teacher factor as a possible source of students' misconception. A total number of 863 students and 47 biology teachers at the middle and high school were randomly selected. Students' conceptions and misconceptions were measured with concept evaluation statements (CES) which was translated into Korean by author. The CES was developed and validated by Simson and Marek (1988). Teacher's misconceptions were investigated the way in which teachers marked students' work. The supposed answer given to the teachers to mark was based on misconceptions held by students tested in concept evaluation statements. The results of this study are as follows : 1. 0% of 7th Grade students, 4.5% of 9th Grade students and 5.4% of 11th Grade students understood homeostasis. There was a significant difference at the level of students' understanding of homeostasis according to schools and gender(P<0.05). Many students had a tendency of understanding the conception of the homeostasis by experiences and unscientific use of everyday language rather than a scientific concept. 2. 0.4% of 7th Grade students, 3.1% of 9th Grade students and 2.9% of 11th Grade students understood classification of animals and plants. There was a significant difference at the level of students' understanding of classification of animals and plants according to schools and gender(P<0.05). Students classified animals and plants through personal experiences and observations instead of trying to classify through microscopic analysis of animals and plants cell. 3. 1.2% of 7th Grade students, 10.3% of 9th Grade students and 19.4% of 11th Grade students understood food production in plants. There was a significant difference at the level of students' understanding of food production in plants according to schools and gender(P<0.05). Students had a misconception that food production in plants was done by an absorption of nutrients from soil not by photosynthesis. 4. A large proportion of teachers surveyed in this study appear to have misconceptions about homeostasis (38.1%), classification of animals and plants (34.1%), food production in plants (40.4%). The male teachers had. more misconceptions than female teachers(P<0.05). However, they didn't show any significant differences according to schools and teaching experience(P<0.05). 5. According to the investigation of teachers' perception, 29.8% of the teachers acknowledged that they might be a cause for students' misconceptions. This study shows that 38.3% of teachers did not understand the analyzed biological concepts precisely. By comparing the data of students and teachers, it turned out that teachers participate in the students' misconceptions. And teachers themselves acknowledged that students' misconceptions could be caused by them. Therefore. teachers' right understanding of fundamental biological concepts should precede to students' biology education. New training programs for biology teachers seem to be urgent.

• Applied Microscopy
• /
• v.23 no.2
• /
• pp.11-26
• /
• 1993

This experiment was performed to study the morphological responses of the pigment epithelial cell and the Bruch's membrane of the retina of rat following X-ray irradiation. Male rats were divided into normal and experimental groups. The heads of the rats, under sodium thiopental anesthesia, were exposed to 3,000 rads or 6,000 rads of radiation in a single dose, respectively. The source was a Mitsubishi Linear Accelerator ML-4MV. The target to skin distance was 80cm, and the. dose rate was 200 rads/min. The experimental groups were sacrificed on the 6th hour, 2nd and 6th day after X-ray irradiation. Under anesthesia, 1% glutaraldehyde-1% paraformaldehyde solution(0.1M Millonig's phosphate buffer, pH 7.3) was perfused through the left ventricle and ascending aorta. Pieces of the tissue taken from the posterior region of the retina were fixed in 2.5% glutaraldehyde-1.5% paraformaldehyde(0.1M Millonig's phosphate buffer, pH 7.3) and 1% osmium tetroxide(0.1M Millonig's phosphate buffer, pH7.3), and embedded in araldite mixture. The ultrathin sections contrasted with uranyl acetate and lead citrate were observed with JEM 100 CX-II electron microscope. The results were as follow; 1. The morphological changes of the pigment epithelial cells were not pronounced after exposure to 3,000 rads of X-ray. But on the 6th hour after exposure to 6,000 rads of X-ray, bulging nuclear membrane protruding into the cytoplasm and nuclear chromatin clumped into numerous masses along the nuclear membrane were observed. At the 2nd and 6th day post-irradiation, partial cytolysis or necrosis were seen. 2. The thickness of the Bruch's membrane of the experimental groups were increased in the time and dose range covered by this study, and splitting or diffusing basal laminae of the choriocapillary layer were observed frequently in the experimental group. Above results suggest that large amount(6,000 rads) of head irradiation induce direct hazardous effects on the pigment epitherial cells and Bruch's membrane of the retina of the rat, but pigment epithelial cells are more radioresistant than Bruch's membrane.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.10 no.2
• /
• pp.1-14
• /
• 2006

Present study examines the numerical issues of cell structure simulation for various regimes of detonation phenomena ranging from weakly unstable to highly unstable detonations. Inviscid fluid dynamics equations with $variable-{\gamma} $ formulation and one-step Arrhenius reaction model are solved by a MUSCL-type TVD scheme and 4th order accurate Runge-Kutta time integration scheme. A series of numerical studies are carried out for the different regimes of the detonation phenomena to investigate the computational requirements for the simulation of the detonation wave cell structure by varying the reaction constants and grid resolutions. The computational results are investigated by comparing the solution of steady ZND structure to draw out the minimum grid resolutions and the size of the computational domain for the capturing cell structures of the different regimes of the detonation phenomena.

• Korean Journal of Medicinal Crop Science
• /
• v.26 no.1
• /
• pp.72-81
• /
• 2018

Background: Polysaccharides are the most important functional constituent in Astragalus membranaceus. The purpose of the present study was to evaluate the effect of polysaccharides isolated from the aboveground parts of A. membranaceus (AMA) and polysaccharides isolated from the roots of A. membranaceus (AMR) immune function by modulated cytotoxic T cell and Th1- and Th2-related cytokines kinetics. Methods and Results: Sprague-Dawley rats were randomly divided into exhaustive exercise case groups and non-exercise case, AMA and AMR samples were administered orally for 30 days (500 mg/kg/day and 10 mg/kg/day, respectively) and were compared to those rats in the groups fed commercial sports drink (SPD) and vehicle. Both exhaustive exercise groups and non-exercise groups had a lower ratio of $CD4^+$ and $CD8^+$ cells in the spleens of the rat fed AMA and AMR compared to those in the rats fed SPD and vehicle group. These results suggested that AMA and AMR promote an increase in the proportion of cytotoxic T cells. The IL-4-producing T lymphocytes decreased significantly in the AMR (10 mg/kg/day) group compared to SPD and vehicle, whereas the AMA group increased the IL-4 concentration more than the SPD and vehicle in exhaustive exercise group. However, the populations of IFN-${\gamma}$-producing T lymphocytes of AMR and AMA increased. AMA decreased the concentration of IFN-${\gamma}$ to inhibit the Th1 response and thereby increased the concentration of IL-4 to induce a Th2 response that was related to humoral immunity in the non-exercise group. Conclusions: These results showed that, in addition to Th1/Th2 regulation, AMR and AMA played an important immuno-modulatory role after exhaustive exercise-induced Th1/Th2 lymphocyte imbalance, which might be correlated with cytokine producing immunoregulatory cells.

• Microbiology and Biotechnology Letters
• /
• v.36 no.4
• /
• pp.343-352
• /
• 2008

Frankincense, the gum resin derived from Boswellia species, is complex mixtures composed of about $5{\sim}9%$ highly aromatic essential oil, $65{\sim}85%$ alcohol-soluble resins, and the remaining water-soluble gums. The anti-inflammatory properties of frankincense, alcohole-soluble resins, are well-recognized, but the question of whether aromatic essential oil also plays a role in the allergic asthma remains unanswered. This study was performed to evaluate anti-inflammatory effects of Boswellia sacra essential oil (BSEO) on ovalbumin (OVA)-induced asthma mouse model. BALB/c mice after intraperitoneal OVA sensitization were challenged with intratracheal OVA. One experimental group was inhaled with 0.3% BSEO for the later 8 weeks. BALB/c mice were sensitized and challenged with OVA and developed airway eosinophilia, mucus hypersecretion, and airway hyperresponsiveness. In contrast, the BSEO treated mice had reduced a number of eosinophils among BALF cells, goblet cell hyperplasia, and airway hyperresponsiveness. Cytokine analysis of BALF revealed that BSEO caused an increase in Th1 cytokine (interferon-$\gamma$ (IFN-$\gamma$)) and a decrease in Th2 cytokines (interleukin-4 (IL-4), IL-5 and IL-13) levels. In addition, the OVA-specific serum IgE and eotaxin levels were also reduced. In mice inhaled BSEO, $CD4^+$, $CD3^+/CCR3^+$, and $B220^+/CD23^+$ mediastinal lymph nodes cells were also decreased. These results suggest that inhaled BSEO as a immunomodulator in Th1/Th2 mediated asthma may have therapeutic potential for the treatment in allergic airway inflammation by a simple, cost-effective way.

• Korean Journal of Microbiology
• /
• v.52 no.1
• /
• pp.18-24
• /
• 2016

We investigated 23 lactic acid bacteria isolated from Korean breast milk-fed infant in order to select strains which show superior anti-allergic effect. The candidates were cultivated and then we obtained dried powders of tyndallized cells and supernatant concentrate separately. Screening was carried out with down-regulation of interleukin (IL) 4 and up-regulation of IFN-${\gamma}$ in mouse splenocytes. As a result of the screening, we selected Lactobacillus rhamnosus IDCC 3201 (RH3201) for oral feeding to ovalbumin-sensitized BALB/c mice. Oral administration of RH3201 as dead cell bodies and supernatant concentrate suppressed hyper-production of serum immunoglobulin (Ig) E levels compared to vehicle group. Such anti-allergic effects were achieved by improvement of the balance between cytokines produced from type-1 helper T (Th1) and type-2 helper T (Th2) lymphocytes. Therefore, RH3201 has potential to improve atopic symptoms by immunomodulatory effect.

• Journal of Korean Society on Water Environment
• /
• v.36 no.6
• /
• pp.559-567
• /
• 2020

The abnomal responseses on growth and morphology of attached diatoms by various heavy metals were studied. Ulnaria ulna (Nitzsch) Compère was employed as experimental species and exposed to the five heavy metals such as Cu, Zn, Pb, Cd, and As with four concentrations (0, 0.01, 0.1, and 2 mg L-1), respectively. The samples of Ulnaria ulna were examined on the changes of cell growth and teratological forms on the 7th, 14th, 21th, and 28th day, respectively, after exposure to the heavy metals. The samples exposed to the highest concentration, 2.0 mg L-1, of all the heavy metals showed the most obvious decreases of growth. The samples exposed to Cd (μ=0.049day-1) and As (μ=0.048day-1) showed the highest decreasing rate of growth (p=0.021(Cd), p=0.002(As)) and the highest morphological changes of diatom valves were also samples exposed to Cd (10.41%) and As (10.13%) (p=0.009 (Cd), p=0.005(As)). In contrast, Pb induced the lowest decreasing rate (μ=0.090 day-1) and the least change in valve morphology (3.31%). The Cd and As showed relatively stronger effects on growth rates compared to Cu, Zn, and Pb. For the percentage of emergence of morphological species by the type, the highest percentage were observed in sampled exposed to type 1 (43.4%) and followed by type 2 (29.1%). The type 2 and 4 were most abundant in samples exposed to Zn and Pb while the type 3 was most abundant in Cd and As. The Cu induced only type 1, suggesting that the frequency of emergence of each type varied among hevay metals. This research suggests that the degrees of abnomal changes on growth rate and valve morphology of Ulnaria ulna can be used as a bioindicater species for heavy metal contamination in freshwater.

• Development and Reproduction
• /
• v.19 no.4
• /
• pp.243-252
• /
• 2015

The pregnancy and abortion process involves a complex mechanism with various immune cells present in the implantation sites and several hormones associated with pregnancy, such as leptin, ghrelin and nesfatin-1. However, the mechanism underlying spontaneous abortion by maternal T helper 17 (Th17) present in the implantation sites and nesfatin-1, which is of anorexigenic hormones, is not fully understood so far. Therefore, the purpose of this study was to examine the possible roles of Th17 cells present in the implantation sites and nesfatin-1 expressed in the uterus on spontaneous abortion using the $CBA/j{\times}DBA/2$ mouse model. Th17 transcription factor, ROR-${\gamma}t$ mRNA expression was significantly increased in the abortion sites compared with the implantation sites of abortion model mice on day 14.5 and 19.5 of pregnancy. In addition, the expression levels of IL-17A mRNA were significantly higher in abortion sites than in implantation sites on day 14.5 and 19.5. Moreover, the nesfatin-1/NUCB2 protein and mRNA levels were increased in abortion sites compared with levels in implantation sites of both normal pregnant and abortion model mice on day 14.5 of pregnancy. Interestingly, nesfatin-1/NUCB2 serum levels were not changed throughout the whole pregnancy in abortion model mice, but its serum level was dramatically increased on day 14.5, and then rapidly decreased on day 19.5 in normal pregnant mice. In this study, we showed for the first time the expression of nesfatin-1/NUCB2 mRNA and protein in implantation sites during pregnancy. The present results suggest that Th17 cells in the uterus may play an important role in the period of implantation and for maintenance of pregnancy. Furthermore, the present results suggest that Th17 cells in implantation sites may be a key regulator for maintenance of pregnancy and provides evidence that activation of these cells may be regulated by nesfatin-1/NUCB2. Further study is needed to elucidate the role of nesfatin-1 expressed in the uterus during pregnancy.

• Korean Journal of Veterinary Research
• /
• v.45 no.2
• /
• pp.139-149
• /
• 2005

In order to study about the lobule and layer formation and cell migration of the mouse cerebellum from at the birth to 15th day effected by 2.5, 5 and 10 Gy r-raddiation at the 19th pregnancy. The routine tissue preparation and staining procedure, Immunohistochemical staining method by the several antibody and western brotting method were utilized from the birth to the15th day. The results were as followings. 1. The body and cerebellum weights were more slowly increase of the the 2.5 Gy, 5 Gy and 10 Gy irradiation group compare to the control group, and the health condition of the 2.5 Gy group was a little bad. but the 10 Gy group was more severe and begun to die from the 12th day after birth. 2. The thickness, proliferation and migration of the 2.5, 5 and 10 Gy irradiated external granular cells from the maginal zone to the medullary area forming the molecular layer from the 6th day to the 15th day after birth were thinner, weaker and more slower according to the radiated dosages than the control group in the cresyl violet staining. 3. The proliteration, migration and lobulation of the 5 Gy radiated groups from the first day to the 15th day after birth were more weak, incomplete and irregular shape in the immunostaining with Dab, Cdk5, P35, calbindin and Zebrin antibody. 4. In the western blotting analysis using the Reelin, Dab, Cdk5 and P35 antibody. The Bands were in the 60 KD, 80 KD, 33 KD and 35 KD, and there were no differences between the control and irradiated groups in the molecular band except the Reelin. 5. As a results, the proliferation and migration of the outer granular and purkinje cells, and lobulation of the cerebellum by the several dosaege of the ${\gamma}$-ray radiation were proportionally incomplete according to dosage.

• Restorative Dentistry and Endodontics
• /
• v.27 no.1
• /
• pp.1-11
• /
• 2002

Immune responses associated with bacterial infection involve various inflammatory cells. Clinical symptoms and pathologic features are particularly influenced by the predominant cells Among inflammatory cells, T cells have the heterogenity. T cells may develop into the mature cells expressing the cell surface markers with different functions and T helper cells are categorized into Th1 and Th2 cells based on their different patterns of cytokine production. The objective of this study was to investigate the change of expression of surface markers on T cells and the Th1/Th2 immune response in pulpal inflammation associated with specific bacteria. We experimentally induced pulpal inflammation in rat incisors by drilling without coolant and innoculated with Streptococcus mutans (S.M. group), Porphyromonas endodontalis (P.E. group), or only sterile cotton (control group). After 1, 2, and 5 days, mandibular incisors were extracted and the pulp tissues were extirpated The expressions of IL-2 recepters (CD25) and ICAM-1 (CD54) on CD4+ and CD8+ cells in the pulps were determined using a flow cytometer, and the concentration of IL-2, IFN-$\gamma$ and IL-4 was measured by enzyme-linked immunosorbent assay. The results were as follows: 1 In the S.M. group, CD4+ cells were more increased at 2nd day than 1st day and in the P.E. group, CD8+ cells were more increased at 2nd day than 1st day. 2. The percentages of CD4+, CD4+25+ and CD4+54+ cells were decreased in the pulp tissues at 5th day after irritation in all groups. 3. The ratios of CD4+/CD8+, CD4+/CD4+25+ and CD4+/CD4+54+ in the pulps at 2nd day after irritation by P. endodontalis were significantly lower than the other groups. 4. The higher concentrations of IFN-$\gamma$ than IL-4 in the pulps at 2nd day after irritation by P. endodontalis showed that T helper 1 reaction were predominant in the early stage of the pulpal inflammation induced by P. endodontalis. 5. The higher concentrations of IL-4 than IFN-$\gamma$ in the pulps at 1st day and 5th day after irritation by S. mutans were measured but the differences were not significant.