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Mechanism Underlying a Proteasome Inhibitor, Lactacystin-Induced Apoptosis on SCC25 Human Tongue Squamous Cell Carcinoma Cells (사람혀편평상피세포암종세포에서 proteasome 억제제인 lactacystin에 의해 유도된 세포자멸사의 기전에 대한 연구)

  • Baek, Chul-Jung;Kim, Gyoo-Cheon;Kim, In-Ryoung;Lee, Seung-Eun;Kwak, Hyun-Ho;Park, Bong-Soo;Tae, Il-Ho;Ko, Myung-Yun;Ahn, Yong-Woo
    • Journal of Oral Medicine and Pain
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    • v.34 no.3
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    • pp.261-276
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    • 2009
  • Lactacystin, a microbial natural product synthesized by Streptomyces, has been commonly used as a selective proteasome inhibitor in many studies. Proteasome inhibitors is known to be preventing the proliferation of cancer cells in vivo as well as in vitro. Furthermore, proteasome inhibitors, as single or combined with other anticancer agents, are suggested as a new class of potential anticancer agents. This study was undertaken to examine in vitro effects of cytotoxicity and growth inhibition, and the molecular mechanism underlying induction of apoptosis in SCC25 human tongue sqaumous cell carcinoma cell line treated with lactacystin. The viability of SCC25 cells, human normal keratinocytes (HaCaT cells) and human gingiva fibroblasts (HGF-1 cells), and the growth inhibition of SCC25 cells were assessed by MTT assay and clonogenic assay respectively. The hoechst staining, hemacolor staining and TUNEL staining were conducted to observe SCC25 cells undergoing apoptosis. SCC25 cells were treated with lactacystin, and Western blotting, immunocytochemistry, confocal microscopy, FAScan flow cytometry, MMP activity, and proteasome activity were performed. Lactacystin treatment of SCC25 cells resulted in a time- and does-dependent decrease of cell viability and a does-dependent inhibition of cell growth, and induced apoptotic cell death. Interestingly, lactacytin remarkably revealed cytotoxicity in SCC25 cells but not normal cells. And tested SCC25 cells showed several lines of apoptotic manifestation such as nuclear condensation, DNA fragmentation, the reduction of MMP and proteasome activity, the decrease of DNA contents, the release of cytochrome c into cytosol, the translocation of AIF and DFF40 (CAD) onto nuclei, the up-regulation of Bax, and the activation of caspase-7, caspase-3, PARP, lamin A/C and DFF45 (ICAD). Flow cytometric analysis revealed that lactacystin resulted in G1 arrest in cell cycle progression which was associated with up-regulation in the protein expression of CDK inhibitors, $p21^{WAF1/CIP1}$ and $p27^{KIP1}$. We presented data indicating that lactacystin induces G1 cell cycle arrest and apoptois via proteasome, mitochondria and caspase pathway in SCC25 cells. Therefore our data provide the possibility that lactacystin could be as a novel therapeutic strategy for human tongue squamous cell carcinoma.

Factors Related to Poor School Performance of Elementary School Children (국민학교아동의 학습부진에 관련된 요인)

  • Park, Jung-Han;Kim, Gui-Yeon;Her, Kyu-Sook;Lee, Ju-Young;Kim, Doo-Hie
    • Journal of Preventive Medicine and Public Health
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    • v.26 no.4 s.44
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    • pp.628-649
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    • 1993
  • This study was conducted to investigate the factors related to the poor school performance of the elementary school children. Two schools in Taegu, one in the affluent area and the other in the poor area, were selected and a total of 175 children whose school performance was within low 10 percentile (poor performers) and 97 children whose school performance were within high 5 percentile (good performers) in each class of 2nd, 4th and 6th grades were tested for the physical health, behavioral problem and family background. Each child had gone through a battery of tests including visual and hearing acuity, anthropometry (body weight, height, head circumference), intelligence (Kodae Stanford-Binet test), test anxiety (TAI-K), neurologic examination by a developmental pediatrician and heavy metal content (Pb, Cd, Zn) in hair by atomic absorption spectrophotometry. A questionnaire was administered to the mothers for prenatal and prenatal courses of the child, family environment, child's developmental history, and child's behavioral and learning problems. Another questionnaire was administered to the teachers of the children for the child's family background, arithmatic & language abilities and behavioral problem. The poor school performance had a significant correlation with male gender, high birth order, broken home, low educational and occupational levels of parents, visual problem, high test anxiety score, attention deficit hyperactivity disorder (ADHD), poor physical growth (weight, height, head circumference) and low I.Q. score. The factors that had a significant correlation with the poor school performance in multiple logistic regression analysis were child's birth order (odds ratio=2.06), male gender(odds ratio=5.91), broken home(odds ratio=9.29), test anxiety score(odds ratio=1.07), ADHD (odds ratio=9.67), I.Q. score (odds ratio=0.85) and height less than Korean standard mean-1S.D.(odds ratio=11.12). The heavy metal contents in hair did not show any significant correlation with poor school performance. However the lead and cadmium contents were high in males than in females. The lead content was negatively correlated with child's grade(P<0.05) and zinc was positively correlated with grade (P<0.05). among the factors that showed a significant correlation with the poor school performance, high birth order, short stature and ADHD may be modified by a good family planning, good feeding practice for infant and child, and early detection and treatment of ADHD. Also, teacher and parents should restrain themselves from inducing excessive test anxiety by forcing the child to study and over-expecting beyond the child's intellectual capability.

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A study on the state of inservice education for dental hygienists and their relevant awareness (치과위생사의 보수교육 실태 및 인식에 관한 연구)

  • Jung, Jae-Yeon;Kim, Kyung-Mi;Cho, Myung-Sook;Ahn, Geum-Sun;Song, Kyoung-Hee;Choi, Hye-Jung;Choi, Youn-Seon;Hwang, Yoon-Sook
    • Journal of Korean society of Dental Hygiene
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    • v.7 no.1
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    • pp.73-89
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    • 2007
  • The purpose of this study was to examine the reality of inservice education provided to members of Korean Dental Hygienists Association, the state of relevant academic conferences, and the perception of the members about inservice education and academic conference. It's basically meant to help boost their participation in inservice education and their satisfaction with it, and to show some of the right directions for that. The subjects in this study were dental hygienists who attended a symposium on July 1, 2006. After a survey was conducted, the answer sheets from 489 participants were analyzed, and the findings of the study were as follows: 1. General hospitals and university hospitals made up the largest group(91.4%) that gave a monthly leave of absence, and the second largest group was dental hospitals(75.4%), followed by dental clinics(58.3%) and public dental clinics(48.0%). The most common closing time in dental clinics and dental hospitals was 5 p.m., and that was 12 p.m. in general hospitals and university hospitals. The dental hygienists in public dental clinics didn't work on Saturdays. By type of workplace, treatment was the most common duty for the dental hygienists in dental clinics and dental hospitals to perform, and those who worked at general hospitals, university hospitals and public health clinics were in charge of extensive range of jobs. 2. The rates of the dental hygienists who took that education stood at 94.9% in public dental clinics, 78.7% in dental hospitals and 75.3% in dental clinics, general hospitals and university hospitals. Regarding how many marks they got on an yearly basis, those who got eight marks or more made up the largest group(55.6%), followed by four marks or more(11.8%), six marks or more(3.4%), and two marks or more(1.5%). As for the usefulness of inservice education for their job performance, the largest number of the dental hygienists(40.8%) found it to be helpful, and the second greatest group(37.5%) considered its effectiveness to be so-so. The third largest group(8.4%) found it to be of great use, and the fourth biggest group(4.2%) considered it to be of no service. The fifth biggest group(l.3%) thought it was absolutely useless. By type of workplace, the workers in dental clinics, dental hospitals, general hospitals and university hospitals wanted the most to learn how to take care of clinical work(acquisition of up-to-date technology), and those in public health clinics hoped the most to learn about public dental health. By type of workplace, the workers in dental clinics had their sight set on self-development the most, and the dental hygienists in dental hospitals, general hospitals, university hospitals and public health clinics were most in pursuit of acquiring new knowledge. By type of workplace, the specific given conditions at work were most singled out by the dental clinic workers as the reason, and the dental hospital employees pointed out time constraints the most. The dental hygienists in general hospitals and university hospitals cited time constraints and financial burden the most, and the public health clinic personnels mentioned inaccessibility of a place for inservice education as the reason. 3. The public health clinic workers participated in academic conferences the most(90.8%), followed by the general and university hospital personnels(68.8%), dental hospital employees(65.6%) and dental clinic workers(65.5%). By type of workplace, the public health clinic workers(73.5%) expressed the most satisfaction, followed by the general and university hospital employees(67.7%), dental clinic workers(62.3%) and dental hospital personnels(54.1%). By type of workplace, the employees of dental clinics, dental hospitals, general hospitals and university hospitals preferred Saturdays, and the public health clinic workers had a liking for weekdays. As for a favored place, hotels were most preferred, followed by university hospitals, general hospitals, college lecture rooms, district halls and local public institutions. Hotels were most favored regardless of the type of workplace. 4. Regarding outlook on inservice education, they had the highest opinion on the facilities and given conditions of lecture rooms($3.41{\pm}0.83$), followed by the professionalism of lecturers($3.34{\pm}0.83$), procedures of receipt and attendance confirmation($3.34{\pm}0.83$) and class size($3.13{\pm}0.89$). On the contrary, they took the most dismal view of the inaccessibility of a place of inservice education($2.08{\pm}0.92$), followed by limited opportunity and limited date for that education($2.51{\pm}0.99$), extra financial burden($2.53{\pm}1.18$) and high tuition fee($2.57{\pm}0.96$).

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The Perception of Gifted Science Teachers Regarding a Individualized Instruction for Scientifically Gifted (영재 개별화 교육에 관한 과학영재 지도교사들의 인식)

  • Kim, Su-yeon;Han, Shin;Jeong, Jinwoo
    • Journal of the Korean Society of Earth Science Education
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    • v.9 no.2
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    • pp.199-216
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    • 2016
  • The purpose of this study is to figure out how much gifted science education teachers in charge of the class realize the necessity of individualized curriculum and program for scientifically gifted, to find out the problems of the gifted science educational institutions from exploring them in depth in the light of the reality in the gifted science educational institutions, and to draw implications about the applicable direction of more aggressive individualized curriculum and program for scientifically gifted. I chose 15 people with the incumbent teachers who have ever taught scientifically gifted and have a degree in the gifted education or science subject education as study participants and had a depth interview with them. According to result of the study, 14 of 15 study participants recognized the necessity of individualized education in science should understand the personal requirements according to the tendency of the gifted students and should be a study led by students themselves. Of the problems in gifted science education, teachers regarded the reduction in the financial support as the biggest problem and the vocation and professionalism of teachers were referred as a very important factor. With constraints of time and space, there were plenty of opinions that can't ignore the influence of educational environment associated with the university entrance examination. There were many opinions that there is excessive expansion of the agencies and the target for gifted students, no standardized measurement tools and programs and the lack of the system for the coherent observation as a teacher. Also, the unified curriculum of gifted science education institutions were pointed out as the problem and the individualized programs which were already under way have a lot of weakness and being offered marginally. Thus, from now on, to apply for individualized education of gifted science, teachers demanded optimized education conditions and consistent policy support, and expressed the opinion that there needs of a possible continuous observation system. Besides, the curriculum and programs matched the needs of the students should be taken priority the most, and there were another answers that fellow learning within the cooperative learning can be an alternative of the individualized. Along with that, there were lots of opinions that the treatment to overcome an inferiority complex according to the individualized should be followed.

THE STUDY ON THE EFFECTS OF THE INSULIN-LIKE GROWTH FACTOR-I ON THE BIOLOGICAL ACTIVITY OF THE HUMAN PERIODONTAL LIGAMENT CELLS (Insulin-like growth factor-I 이 치주인대세포의 생물학적 활성도에 미치는 영향에 대한 연구)

  • Kim, Seong-Jin;Lee, Jae-Mok;Suh, Jo-Young
    • Journal of Periodontal and Implant Science
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    • v.24 no.2
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    • pp.219-237
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    • 1994
  • The ultimate goal of clinical periodontal therapy is to achieve regeneration of a healthy connective tissue reattachment. Conventional therapy including scaling, root planing, gingival curettage, gingivectomy and flap procedures of various types results primarily in repair rather than regeneration of the periodontium. In order for periodontal regeneration to occur, progenitor periodontal ligament cells must migrate to the denuded root surface, attach to it, proliferate and mature into an organized and functional fibrous attachment apparatus. Polypeptide growth factors belong to a class of potent biologic mediators which regulate cell differentiation, proliferation, migration and metabolism. Insulin-like growth factor-I (IGF- I ) of these factors appear to have an important role in periodontal wound healing and bone formation. The purpose of this study is to evaluate the effects of IGF- I on the periodontal ligament cells to use as a regeneration promoting agent of periodontal tissue. Human periodontal ligament cells were obtained from periodontal tissue explants culture of the first premolar tooth extracted for the orthodontic treatment. Cells were cultured in Dulbecco's modified Eagle medium(DMEM) with 10% fetal bovine serum. Fourth to seventh passage cells were plated in 24 well tissue culture plates and medium changed to serum-free medium prior to addition of growth factors. Cell proliferation was measured by the incorporation of $[^3H]-thymidine$ into DNA, Protein synthesis was determined by measurement of $[^3H]-proline$ incorporation into collagenase-digestible protein(CDP) and noncollagenous protein(NCP) according to the method of Peterkofsky and Diegelmann (1971), And alkaline phosphatase activity was measured as one parameter of osteoblastic differentiation. The results were as follows : The DNA synthetic activity was increased in a dose-dependent manner with IGF- I except for 0.1ng/ml concentration of IGF- I At the concentration of 10, 100ng/ml, IGF- I significantly increased the DNA synthetic activity(P<0.05) The total protein, collagen and noncollagen synthesis was increased in a dose-dependent manner with IGF- I except for 0.1ng/ml concentration of IGF- I. At the concentration of 1, 10, 100ng/ml, IGF- I significantly increased the total protein, collagen and noncollagen synthesis activity(P<0.95, P<0.001). The % of collagen was not effected according to the concentration of IGF- I. The alkaline phosphatase activity was increased in a dose-, time-dependent manner with IGF- I (10, 100ng/ml). In conclusions, the present study shows that IGF- I has a potentiality to enhance the DNA synthesis of periodontal ligament cells with including the increase of the total protein and collagen synthetic activity. The use of IGF- I to mediate biological stimulation of periodontal ligament cells shows promise for future therapeutic applications.

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The Behavior and an Attitude for Weight Control of High-School Students (고등학생의 체중조절에 대한 관련 행동 및 태도)

  • Choi, Jong-Cheol;Park, Young-Soo
    • The Journal of Korean Society for School & Community Health Education
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    • v.3
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    • pp.59-78
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    • 2002
  • The purpose of this study was based on students in high school to find out how interest eating and controlling weight on normal time by sex to let them get a better sense's of view on weight controlling so they can get healthy, and healthy school life and concentrate on studying, As a result of analyzing the data collected for the subject of high school students, the conclusions were as follows; First, out of 325 students, 44.6% were male students, and 179 were female students, Compared to the BMI, normal mass were 50.8%, which were 165 students, less weighted were 39.7%, which were 129 students, and over weighted were 9.5%, which were 31 student. Also average height for male students were 173.8 cm, for female students were 161.5 cm, average weight were 67.2 kg for male students, and for female students were 53.2kg. Using BMI analysing the results and the male students had an average of 22.2%, and the female students had an average of 20.3%, so male students were a little higher than the female students. Second, the interest rate for weight control were 82.2%, that's 267 students for, 'interested' and 7.8%, which were 58 student for 'not interested', so most students were interested, in controlling weight. Interest rate were 83.6% for male students, 81.0% were female students. BMI told that group of less weighted were 82.9%, group of normal were 79.4% and group of over weighted were 93.5%. The rate were all high not relating to BMI. Third, compared to the past, more people said 'normal'(41.3%), people who said 'a little fat'(36.3%) decreased, but they still think they are fat even though they are not, also when they are less weighted they still think they are fat. Fourth, for 'weight control, and food' both male and female said they were related, and for 'weight control and exercising' they also said they were related, but more male said that they were related, However for relations between' controlling weight and school's physical education class' the answers were usually disagree. Fifth, for the 'satisfaction of their present weight', both BMI and the students answered and this results were mostly same as the past result, so most students prefer to lose weight. Also, both male and female think that the reason they have this weight now is, because of 'the amount of exercises' and 'the amount of food they eat', so they find that it's related to each other. Sixth, for the experience on weight control, both male and female had experiences, and they answered 'exercising and food treatment' is the good way to control weight. Also for 'the reason they started to control there weight', both male and female answered, 'they thought there weight were not normal'. Seventh, 'Do you pick on food to control weight?' and 'Do you feel nervous before you eat?' and for last 'control of drinking water' the answer was all different, and both male and female answered negatively. Eighth, time wasted on exercising per day, for less than 30 minute were 81.5%, the form of exercises that students did were 'not much or walking on the way to school and way to home'. Usually for their free time, male students spend on exercising however female student did not. Also both female and male students showed that they like to exercise, but majority of female student disliked to exercise. To everyone's point of view 'like'(32.9%), 'like a lot'(20.9%), so everyone agrees. The knowledge information on controlling weight, they answered, usually found from commercials, newspaper or magazines and from parents or friend. From the past many high school students wanted to control their weight, so there should had been a good education on this, however there wasn't any of those education and still it doesn't exist. Also most school's education are arranged to entrance pressure so they have a lot of knowledge and informations to it, but for real they don't have any activity or actions on it. Through this research, we felt that, we should correct students with wrong understanding on controlling weight and wrong knowledge. Also we suggest to make an activity program for this.

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Regulation of Tumor Neceosis Factor-${\alpha}$ Receptors and Signal Transduction Pathways

  • Han, Hyung-Mee
    • Toxicological Research
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    • v.8 no.2
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    • pp.343-357
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    • 1992
  • Tumor necrosis factor-${\alpha}$(TNF), a polypeptide hormone secreted primarily by activated macrophages, was originally identified on the basis of its ability to cause hemorrhagic necrosis and tumor regression in vivo. Subsequently, TNF has been shown to be an important component of the host responses to infection and cancer and may mediate the wasting syndrome known as cachexia. These systemic actions of TNF are reflected in its diverse effects on target cells in vitro. TNF initiates its diverse cellular actions by binding to specific cell surface receptors. Although TNF receptors have been identified on most of animal cells, regulation of these receptors and the mechanisms which transduce TNF receptor binding into cellular responses are not well understood. Therefore, in the present study, the mechanisms how TNF receptors are being regulated and how TNF receptor binding is being transduced into cellular responses were investigated in rat liver plasma membranes (PM) and ME-180 human cervical carcinoma cell lines. $^{125}I$-TNF bound to high ($K_d=1.51{\pm}0.35nM$)affinity receptors in rat liver PM. Solubilization of PM with 1% Triton X-100 increased both high affinity (from $0.33{\pm}0.04\;to\;1.67{\pm}0.05$ pmoles/mg protein) and low affinity (from $1.92{\pm}0.16\;to\;7.57{\pm}0.50$ pmoles/mg protein) TNF binding without affecting the affinities for TNF, suggesting the presence of a large latent pool of TNF receptors. Affinity labeling of receptors whether from PM or solubilized PM resulted in cross-linking of $^{125}I$-TNF into $M_r$ 130 kDa, 90 kDa and 66kDa complexes. Thus, the properties of the latent TNF receptors were similar to those initially accessible to TNF. To determine if exposure of latent receptors is regulated by TNF, $^{125}I$-TNF binding to control and TNF-pretreated membranes were assayed. Specific binding was increased by pretreatment with TNF (P<0.05), demonstrating that hepatic PM contains latent TNF receptors whose exposure is promoted by TNF. Homologous up-regulation of TNF receptors may, in part, be responsible for sustained hepatic responsiveness during chronic exposure to TNF. As a next step, the post-receptor events induced by TNF were examined. Although the signal transduction pathways for TNF have not been delineated clearly, the actions of many other hormones are mediated by the reversible phosphorylation of specific enzymes or target proteins. The present study demonstrated that TNF induces phosphorylation of 28 kDa protein (p28). Two dimensional soidum dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) resolved the 28kDa phosphoprotein into two isoforms having pIs of 6.2 and 6.1. The pIs and relative molecular weight of p28 were consistent with those of a previously characterized mRNA cap binding protein. mRNA cap binding proteins are a class of translation initiation factors that recognize the 7-methylguanosine cap structure found on the 5' end of eukaryotic mRNAs. In vitro, these proteins are defined by their specific elution from affinity columns composed of 7-methylguanosine 5'-triphosphate($m^7$GTP)-Sepharose. Affinity purification of mRNA cap binding proteins from control and TNF treated ME-180 cells proved that TNF rapidly stimulates phosphorylation of an mRNA cap binding protein. Phosphorylation occurred in several cell types that are important in vitro models of TNF action. The mRNA cap binding protein phosphorylated in response to TNF treatment was purifice, sequenced, and identified as the proto-oncogene product eukaryotic initiation factor-4E(eIF-4E). These data show that phosphorylation of a key component of the cellular translational machinery is a common early event in the diverse cellular actions of TNF.

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A Pilot Study in Cognition and Attitude of Nursing Students on Oriental Nursing (한방간호에 대한 간호학생들의 인식 및 태도에 대한 예비연구)

  • Han, Sang-Sook;Kim, Won-Ock;Hyun, Kyung-Sun;Won, Jeong-Sook;Choi, Kyung-Ock;Chang, Kyung-Hwa;Lee, Mi-Aie;Kim, Sook-Young;Jeon, Eun-Young;Kim, Jeong-Sook;Lee, Eun-Sook;Bae, Yeong-Suk
    • Journal of East-West Nursing Research
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    • v.8 no.1
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    • pp.81-88
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    • 2003
  • This research has been conducted to examine the cognition and attitude of nursing students on Oriental Nursing, the subject of this research being 789 nursing students from 9 different universities who took the Oriental Nursing class. A questionnaire, the construct validity and reliability of which have been verified through enquiries into records and references as well as preliminary researches, was used as a research tool. The questionnaire, a set of 86 questions, was developed by the researchers of this study, and the reliability of the questionnaire is Cronbach's=.85. The collected data have been analysed using SPSS windows programme 11.0 for t-test and ANOVA, and the results are as follows: 1. There was a significant difference in cognition and attitude points according to the academic year (F=14.15, p=.000). After the post-hoc test, it was revealed that the points of the students in their 4th year were significantly higher than the points of the students in their 2nd or 3rd year. 2. There was a significant difference in cognition and attitude points according to the credits the students have taken (F=28.66, p=.000). After the post-hoc test, it was revealed that the points of the students who have taken from $3{\sim}5$ to $6{\sim}8$ credits were significantly higher than the points of those who have taken from 1 to 2 credits. 3. There was a significant difference in cognition and attitude points according to the period of time the students have experienced Oriental Nursing (F=32.06, p=.000). After the post-hoc test, it was revealed that the points of the students who have practised Oriental Nursing from 1 to 2 weeks were significantly higher than the points of those who have not practised it at all. 4. There was no significant difference in cognition and attitude points according to the treatment or hospitalisation of the students themselves or their family members. 5. The cognition and attitude points of the students who are deeply interested in Oriental Nursing were significantly higher than the points of those who are not (t=8.83, p=.000). 6. The cognition and attitude points of the students who have higher expectations for the development of Oriental Nursing were significantly higher than the points of those who have not(t=5.90, p=.000). 7. The cognition and attitude points of the students who believe that the Oriental Nursing will contribute to the expansion of the roles of nurses were significantly higher than the points of those who do not (t=6.60, p=.000). 8. The cognition and attitude points of the students who expect that the Oriental Nursing will be effective in prevention of chronic diseases were significantly higher than the points of those who do not (t=5.80, p=.000). According to the results above, it was confirmed that proper education on Oriental Nursing can have affirmative effects on the cognition and attitude of the nursing students towards Oriental Nursing.

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Statistical Analysis of Operating Efficiency and Failures of a Medical Linear Accelerator for Ten Years (선형가속기의 10년간 가동률과 고장률에 관한 통계분석)

  • Ju Sang Gyu;Huh Seung Jae;Han Youngyih;Seo Jeong Min;Kim Won Kyou;Kim Tae Jong;Shin Eun Hyuk;Park Ju Young;Yeo Inhwan J.;Choi David R.;Ahn Yong Chan;Park Won;Lim Do Hoon
    • Radiation Oncology Journal
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    • v.23 no.3
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    • pp.186-193
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    • 2005
  • Purpose: To improve the management of a medical linear accelerator, the records of operational failures of a Varian CL2l00C over a ten year period were retrospectively analyzed. Materials and Methods: The failures were classified according to the involved functional subunits, with each class rated Into one of three levels depending on the operational conditions. The relationships between the failure rate and working ratio and between the failure rate and outside temperature were investigated. In addition, the average life time of the main part and the operating efficiency over the last 4 years were analyzed. Results: Among the recorded failures (total 587 failures), the most frequent failure was observed in the parts related with the collimation system, including the monitor chamber, which accounted for $20\%$ of all failures. With regard to the operational conditions, 2nd level of failures, which temporally interrupted treatments, were the most frequent. Third level of failures, which interrupted treatment for more than several hours, were mostly caused by the accelerating subunit. The number of failures was increased with number of treatments and operating time. The average life-times of the Klystron and Thyratron became shorter as the working ratio increased, and were 42 and $83\%$ of the expected values, respectively. The operating efficiency was maintained at $95\%$ or higher, but this value slightly decreased. There was no significant correlation between the number of failures and the outside temperature. Conclusion: The maintenance of detailed equipment problems and failures records over a long period of time can provide good knowledge of equipment function as well as the capability of predicting future failure. Wore rigorous equipment maintenance Is required for old medical linear accelerators for the advanced avoidance of serious failure and to improve the qualify of patient treatment.

Research about influence on the teeth health by the smoking - research intended for students of dental technology in Daegu - (흡연이 치아건강에 미치는 영향에 관한 연구 - 대구지역 치기공과 학생을 중심으로 -)

  • Kim, Jeong-Sook;Jung, Hyo-Kyung;Lee, Jong-Do
    • Journal of Technologic Dentistry
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    • v.31 no.3
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    • pp.35-45
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    • 2009
  • This survey study was conducted on dental technician school students in April 2008 to investigate the effects of smoking on oral health. 110 male and 39 female students were surveyed and cross analysis was performed to examine the relationship between oral health status and smoking-related and oral health maintenance characteristics of smoking and non-smoking group. T-test and one-way ANAVA was used to analyze the average difference verification of two independent samples(smoking group and non-smoking group) and followings are the results. In general characteristics, 74 male students(74.7%) and 25 female(25.3%) students smoked and the percentage of male students were higher in smoking group. Regarding class grade, 2nd-year students(37 students, 37.4%) and 1st-year students(18 students, 36.0%) took the highest percentage of smoking and non-smoking group, respectively. Concerning the experience of drinking, smoking group consumed more alcoholic beverages(94 students, 94.9%) With respect to the frequency of between-meal consumption, respondents who eat between-meal once or twice smoked more. Respecting preferences of sweet food, respondents who enjoyed sweet food smoked more. Concerning smoking characteristics, many of smoking group had been smoked fo a long time(two to five years) and it was worrisome. About the amounts of smoking, 50 respondents(52.6%) of smoking group smoked 20 cigarettes a day with the highest proportion. With regard to the awareness of harmfulness, 70 respondents(70.7%) considered smoking as very harmful and showed that smoking group were aware of its harmfulness but it was habitualized. Respecting smokers in family members, father was more common as smokers(58 respondents, 58.6%) in family and showed that the influence of father. Main reasons of poor periodontal health were alchoholic consumption, smoking, and oral parafunctional habit(57 respondents, 56.7%) in smoking group and neglect of oral hygiene(21 respondents, 42.0%) in non-smoking group. With regard to the scaling, 80 respondents of smoking group(80.8%) didn't received scaling and showed that more oral health education was required. Regarding the periodontal status, non-smoking group was $1.26{\pm}0.44$, respondents who received scaling was $1.43{\pm}0.50$, respondents who regularly floss was $1.50{\pm}0.52$, respondents who brush more than three times a day was $1.38{\pm}0.49$ and had better periodontal health. Bleeding during tooth brushing was more frequent in smoking group ($1.51{\pm}0.70$). Regarding mouth order, non-smoking group was $2.34{\pm}0.62$, after scaling was $2.02{\pm}0.76$, patients who regularly floss was $1.50{\pm}0.52$, patients who brush more than three times a day was $1.81{\pm}0.87$. Concerning the experience of dental caries treatment, smoking group was $1.20{\pm}0.40$, patients who do not floss was $1.30{\pm}0.46$, patients who brush once a day was $1.29{\pm}0.45$. With regard to dental prosthesis, non-smoking group was $3.78{\pm}1.62$, patients who received scaling was $1.43{\pm}0.50$, patients who regularly floss was $1.40{\pm}0.51$, patients who brush more than three times a day was $1.24{\pm}0.43$. From these results, oral health education and smoking has correlation and more oral health education needs to be carried out to educate students with non-health related majors about harmfulness of smoking on oral health. Also more study are required.

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