• 제목/요약/키워드: New class

검색결과 3,339건 처리시간 0.044초

Chemoprevention of Helicobacter pylori-associated Gastric Carcinogenesis in a Mouse Model; Is It Possible?

  • Hahm, Ki-Baik;Song, Young-Joon;Oh, Tae-Young;Lee, Jeong-Sang;Surh, Young-Joon;Kim, Young-Bae;Yoo, Byung-Moo;Kim, Jin-Hong;Ha, Sang-Uk;Nahm, Ki-Taik;Kim, Myung-Wook;Kim, Dae-Yong;Cho, Sung-Won
    • BMB Reports
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    • 제36권1호
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    • pp.82-94
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    • 2003
  • Although debates still exist whether Helicobacter pylori infection is really class I carcinogen or not, H. pylori has been known to provoke precancerous lesions like gastric adenoma and chronic atrophic gastritis with intestinal metaplasia as well as gastric cancer. Chronic persistent, uncontrolled gastric inflammations are possible basis for ensuing gastric carcinogenesis and H. pylori infection increased COX-2 expressions, which might be the one of the mechanisms leading to gastric cancer. To know the implication of long-term treatment of antiinflammatory drugs, rebamipide or nimesulide, on H. pylori-associated gastric carcinogenesis, we infected C57BL/6 mice with H. pylori, especially after MNU administration to promote carcinogenesis and the effects of the long-term administration of rebamipide or nimesulide were evaluated. C57BL/6 mice were sacrificed 50 weeks after H. pylori infection. Colonization rates of H. pylori, degree of gastric inflammation and other pathological changes including atrophic gastritis and metaplasia, serum levels and mRNA transcripts of various mouse cytokines and chemokines, and NF-${\kappa}B$ binding activities, and finally the presence of gastric adenocarcinoma were compared between H. pylori infected group (HP), and H. pylori infected group administered with long-term rebamipide containing pellet diets (HPR) or nimesulide mixed pellets (HPN). Gastric mucosal expressions of ICAM-1, HCAM, MMP, and transcriptional regulations of NF-${\kappa}B$ binding were all significantly decreased in HPR group than in HP group. Multi-probe RNase protection assay showed the significantly decreased mRNA levels of apoptosis related genes and various cytokines genes like IFN-$\gamma$, RANTES, TNF-$\alpha$, TNFR p75, IL-$1{\beta}$ in HPR group. In the experiment designed to provoke gastric cancer through MNU treatment with H. pylori infection, the incidence of gastric carcinoma was not changed between HP and HPR group, but significantly decreased in HPN group, suggesting the chemoprevention of H. pylori-associated gastric carcinogenesis by COX-2 inhibition. Long-term administration of antiinflammatory drugs should be considered in the treatment of H. pylori since they showed the molecular and biologic advantages with possible chemopreventive effect against H. pylori-associated gastric carcinogenesis. If the final concrete proof showing the causal relationship between H. pylori infection and gastric carcinogenesis could be obtained, that will shed new light on chemoprevention of gastric cancer, that is, that gastric/cancer could be prevented through either the eradication of H. pylori or lessening the inflammation provoked by H. pylori infection in high risk group.

국내외 종자산업의 현황과 GSP사업의 역할 (Current status of global seed industry and role of golden seed project in Korea)

  • 신완식
    • Journal of Plant Biotechnology
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    • 제42권2호
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    • pp.71-76
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    • 2015
  • 선진국들은 종자산업을 국가 신성장 동력산업으로 설정하여 정부차원의 지원을 강화하고 있으며, 글로벌 종자기업은 세계의 종자시장을 선점하기 위하여 종자개발분야에 막대한 예산을 투자하고 있으며, 우리나라도 2000년대 후반 들어 국내종자산업 발전을 위한 정책 추진을 통해 종자산업 육성을 위한 토대를 형성하고 있다. 본 논문에서는 국내외 종자시장 현황을 살펴보고 이에 따른 GSP사업의 역할에 대한 전망을 통해 GSP 사업 추진의 효율성을 제고해 보고자 한다. 세계 종자산업은 글로벌 거대 기업의 대형화로 인하여 독점체제를 형성하고 있어 상위 10개 종자기업이 전체 시장의 73%를 점유하고 있는 것으로 나타났다. 종자업체의 대형화는 종자선택에 대한 제약으로 인하여 가격상승을 불러일으키는 부작용을 초래할 것으로 보여진다. 국내 종자시장은 농업생산량 감소로 인하여 정체상태가 유지되고 있으며, 전반적인 국내 농업생산량의 축소에 따른 종자수요 감소로 인하여 국내 종자시장 규모의 정체와 업체의 영세성과 채소, 벼등 일부 특정품목에 대한 육종기술은 세계적인 수준이나 양배추, 파프리카 및 사료작물 등 글로벌 품종의 육종기술이 상대적으로 취약하고 국내 종자기업들의 신규 전문인력 채용은 거의 이루어지지 않고 있으며, 대학 등의 종자관련 전문인력 양성에 대한 인프라가 부족하여 우수한 육종 전문가 양성이 미흡한 실정이다. 따라서 종자산업은 농산업의 핵심으로 국가의 기간산업을 지탱하는 원천 산업으로서 국가정책적으로 우선순위가 매우 높은 만큼 미래성장 산업으로 정부의 지속적인 투자가 뒷받침되어야 할 것이다. 이에 대한 일환으로 GSP 사업을 추진을 2012년부터 야심차게 추진하고 있으며, 수출전략형 종자개발(10개 품목)과 수입대체 종자개발(10품목)을 통해 수출과 국내 종자자급율 확보를 목표로 종자관련 기업체와 대학 및 연구소의 우수한 전문인력이 투입되어 종자개발연구에 매진하고 있다. 우리나라 종자산업의 발전을 위해서는 GSP 사업의 우수한 성과가 반드시 도출되어야 할 것이며, 이를 위해서는 품종개발 단계외에 종자 수출에 대한 별도의 지원 프로그램 추진이 필요하다.

파월국군장병의 고엽제 위해에 관한 예비적 역학조사 (A Preliminary Epidemiologic Study on Korean Veterans Exposed to Herbicides in Vietnam War)

  • 김정순;임현술;이홍복;이원영;박영주;김성수
    • Journal of Preventive Medicine and Public Health
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    • 제27권4호
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    • pp.711-734
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    • 1994
  • Among chemical agents in herbicides, dioxin (2, 3, 7, 8-tetrachloro dibenzo-$\rho$-dioxin : TCDD), a chemical contaminant in herbicides sprayed during the Vietnam War has been known to be the major agent causing toxic effects. Approximately 320,000 korean soldiers participated the Vietnam War from 1964 to 1974. Although the potential hazards of the herbicides among Korean veterans exposed were implicated, the problem had not been a public issue until 1991 when Korean veterans were informed U.S. companies, the herbicides manufacturer payed fund, from which a trust fund for New Zealand and Australian Class members were established in 1985. After a series of appeals and demonstration by the Korean Veterans demanding medical care and compensation for their serious health damages, a bill of medical care and compensation for herbicides victims was promulgated in March 1993 and become effective from May 1993, This study was carried out with two major objectives : the first to understand the health problems caused from the herbicides by reviewing literatures published, and the second to examine the nature and extent of health impacts among Korean veterans exposed and to develop valid study methods for the major study by interviewing and reviewing records on a part of veterans (638 persons) registered and completed medical examination in Seoul Veterans Administration Hospital from June to October 1993. The results obtained are as followings: 1. The literature review of 107 papers revealed that 1) Dioxin is teratogenic, carcinogenic and affects almost all organs including nervous, endocrine, and reproductive systems in animal experiments. 2) The diseases showing evidence of causal association were Hodgkin's disease, non-Hodgkin's disease, lung cancer, lymphoma, soft tissue sarcoma, chloroacne and polyneuropathy when judged on the basis of consistency in study results and biological plausibility. 2. Interview and medical record review study on 638 veterans, though limited validity owing to lack of control group, crude estimates of dioxin exposure levels (no biomarkers measurable), and uncertainty of diagnosis, showed that: 1) Most of the study subject's were in their 40's of age and had been dispatched to Vietnam during the period from $1965{\sim}1970$ around one year. 2) Most frequently complained symptoms in medical examination were motor weakness (32%), sensory abnormalities in extremities (23%), skin diseases (22%), and pain in extremities (20%) whereas in Interview they were more frequent in order of skin problem (44%), motor weakness (38%), sensory abnormalities and pain in extremities(17% and 19% each). Kappa indices on the same category of complaints between two sources of information were variable and relatively low. 3) On medical examination, only a part of the 638 subjects had initial impression (442 pts) and final diagnosis (218 pts) suggesting decision making on diagnosis appeared to be difficult even with all available modern medical technologies: in initial impression disorders from peripheral and central neuropathy were predominant whereas in final diagnosis various types of skin disorder were most frequent 4) When dose-response relationship between several conditions (from questionnaire) and arbitrary exposure scores were examined by CMH linear trend test, spontaneous abortion, sexual problems and health problem of offsprings showed statistically significant linear trends. However, pregnancy, accident and suicidal attempts did not show any relationship in this study capacity. 5) Among complaints, psychosis and neurosis (anxiety, phobia) in interview study, and memory disorder and psychosis in medical record study revealed linear trend. 6) Skin disorder was the only condition showing linear trend in initial impression and none in final diagnosis on medical examination. Even though objective to select out dioxin-related disease or group of diseases from this study was not achieved the research experiences provided firm basis for developing various methodological approaches. 3. From this preliminary study we concluded that a larger scale major epidemiologic study on health impacts of herbicides among Korean veterans exposed is not only Indispensible but also well designed study with more valid exposure information and diagnosis may be able to establish causal relationship between certain groups of diseases and exposure to the herbicides among Korean veterans.

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열처리 온도에 따른 니켈실리사이드 실리콘 기판쌍의 직접접합 (Direct Bonding of Si(100)/NiSi/Si(100) Wafer Pairs Using Nickel Silicides with Silicidation Temperature)

  • 송오성;안영숙;이영민;양철웅
    • 한국재료학회지
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    • 제11권7호
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    • pp.556-561
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    • 2001
  • 실리사이드반웅을 이용하여 니켈모노실리사이드의 양측계면에 단결정실리콘을 적층시켜 전도성이 우수하며 식각특성이 달라 MEMS용 기판으로 채용이 가능한 SOS (Silicon-on-Silicide) 기판을 제작하였다. 실리콘 기판 전면에 Ni를 열증착법으로$ 1000\AA$두께로 성막하고, 실리콘 기판 경면과 맞블여 후 $300~900^{\circ}C$온도범위에서 15시간동안 실리사이드 처리하여 니켈모노실리사이드가 접합매체로 되는 기판쌍들을 완성하였다. 완성된 기판쌍들은 IR (infrared) 카메라를 이용하여 비파괴적으로 접합상태를 확인하고. 주사전자현미경 (scaning electron microscope)과 투과전자현미경 (tranmission electron microscope)을 이용하여 수직단면 미세구조를 확인하였다. Ni 실리사이드의 상변화가 일어나는 온도를 제외하고는 Si NiSi ∥Si 기판쌍은 기판전면에 52%이상 완전접합이 진행되었음을 확인하였고 생성 실리사이드의 두께에 따라 나타나는 명암부에 비추어 기판쌍 중앙부에 두꺼운 니켈노실리아드가 형성되었다고 판단되었다. 완성된 Si NiSi ∥ Si 기판쌍을 SBM 수직단면에 의괘 확인한 결과 접합이 완성된 기판중심부의 접합계면은 $1000\AA$ 두께의 NiSi가 균일하게 형성되었으며 배율 30,000배의 해상도에서 계면간 분리부분없이 완전한 접합이 진행되었음을 확인하였다. 반면 기판쌍 에지 (edge)부분에는 실리사이드가 헝성되지 않은 비접합상태가 발견되었다. 수직단면루과전자현미경 결과물에 근거하여 접합된 중심부에서는 피접합되는 실리콘의 경면과 니켈이 성막된 실리콘 경면 상부계면에 10-20$\AA$의 비정질막이 발견되었으며, 산화막으로 추정되는 이 막이 접합률을 현저히 저하시키는 것을 확인하였다. 접합이 진행되지 않은 에지부는 이러한 산화막이 열처리 진행중 급격히 성장하여 피접합 실리콘층의 분리가 발생하였다. 따라서 Si NiSi ∥Si 기판쌍의 접합률을 향상시키기 위해서는 피접합 실리콘 계면과 Ni 상부층간의 비정질부를 적극적으로 제거하여야 함을 알 수 있었다.

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태화강 하류에서 겨울철 조류 발생과 수질의 공간적 특성 (Winter Algal Bloom and Spatial Characteristics of Water Quality in the Lower Taewha River, Ulsan, Korea)

  • 손은락;박정임;이보라;이진우;김종설
    • 미생물학회지
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    • 제49권1호
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    • pp.30-37
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    • 2013
  • 본 연구에서는 태화강 하류에서 조수 및 조사 지점에 따른 태화강 수질 특성을 알아보고, 겨울 조류 발생에 영향을 주는 환경요인을 분석하고자 하였다. 2010년 5월에서 2011년 1월까지 태화강 하류의 신삼호교, 구삼호교, 명정천, 태화교, 명촌교 등 5개 지점에서, 사리의 만조와 간조에 시료를 채취하였다. 염분도, 용존산소(DO), 생물학적 산소 요구량(BOD), 화학적 산소 요구량(COD), 엽록소 a(Chl a), 여러 영양염류 등의 환경변수를 측정하였다. 염분도는 하류 방향으로 갈수록 증가하였으며, Chl a의 지점별 평균값은 만조 $10-26mg/m^3$, 간조 $11-53mg/m^3$였다. 특히 태화교의 경우 11월 21일-12월 22일에 Chl a 농도가 $138-296mg/m^3$로 급격히 증가하였으며, Cryptophyceae의 Rhodomonas lacustris가 우점하는 식물플랑크톤이었다. 태화교에서 Chl a 농도는 염분도, BOD, DO, COD, pH, T-N와 양의 상관관계, 수온, 기온, $NO_3{^-}$-N과는 음의 상관관계가 있었다. 반면 명촌교의 경우 Chl a 농도는 8월 25일에 $55mg/m^3$로 최고값을 보였으며, Chl a 농도는 $NH_3$-N, T-N, $PO_4{^{3-}}$-P, T-P, 일반세균과 양의 상관관계를 나타내었다. 연구의 결과는 태화강 하류에서 조사 지점에 따른 수질의 변동폭이 매우 크며, 조류 발생의 양상도 태화교와 명촌교 사이에 차이가 있음을 보여준다.

DISEASE DIAGNOSED AND DESCRIBED BY NIRS

  • Tsenkova, Roumiana N.
    • 한국근적외분광분석학회:학술대회논문집
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    • 한국근적외분광분석학회 2001년도 NIR-2001
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    • pp.1031-1031
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    • 2001
  • The mammary gland is made up of remarkably sensitive tissue, which has the capability of producing a large volume of secretion, milk, under normal or healthy conditions. When bacteria enter the gland and establish an infection (mastitis), inflammation is initiated accompanied by an influx of white cells from the blood stream, by altered secretory function, and changes in the volume and composition of secretion. Cell numbers in milk are closely associated with inflammation and udder health. These somatic cell counts (SCC) are accepted as the international standard measurement of milk quality in dairy and for mastitis diagnosis. NIR Spectra of unhomogenized composite milk samples from 14 cows (healthy and mastitic), 7days after parturition and during the next 30 days of lactation were measured. Different multivariate analysis techniques were used to diagnose the disease at very early stage and determine how the spectral properties of milk vary with its composition and animal health. PLS model for prediction of somatic cell count (SCC) based on NIR milk spectra was made. The best accuracy of determination for the 1100-2500nm range was found using smoothed absorbance data and 10 PLS factors. The standard error of prediction for independent validation set of samples was 0.382, correlation coefficient 0.854 and the variation coefficient 7.63%. It has been found that SCC determination by NIR milk spectra was indirect and based on the related changes in milk composition. From the spectral changes, we learned that when mastitis occurred, the most significant factors that simultaneously influenced milk spectra were alteration of milk proteins and changes in ionic concentration of milk. It was consistent with the results we obtained further when applied 2DCOS. Two-dimensional correlation analysis of NIR milk spectra was done to assess the changes in milk composition, which occur when somatic cell count (SCC) levels vary. The synchronous correlation map revealed that when SCC increases, protein levels increase while water and lactose levels decrease. Results from the analysis of the asynchronous plot indicated that changes in water and fat absorptions occur before other milk components. In addition, the technique was used to assess the changes in milk during a period when SCC levels do not vary appreciably. Results indicated that milk components are in equilibrium and no appreciable change in a given component was seen with respect to another. This was found in both healthy and mastitic animals. However, milk components were found to vary with SCC content regardless of the range considered. This important finding demonstrates that 2-D correlation analysis may be used to track even subtle changes in milk composition in individual cows. To find out the right threshold for SCC when used for mastitis diagnosis at cow level, classification of milk samples was performed using soft independent modeling of class analogy (SIMCA) and different spectral data pretreatment. Two levels of SCC - 200 000 cells/$m\ell$ and 300 000 cells/$m\ell$, respectively, were set up and compared as thresholds to discriminate between healthy and mastitic cows. The best detection accuracy was found with 200 000 cells/$m\ell$ as threshold for mastitis and smoothed absorbance data: - 98% of the milk samples in the calibration set and 87% of the samples in the independent test set were correctly classified. When the spectral information was studied it was found that the successful mastitis diagnosis was based on reviling the spectral changes related to the corresponding changes in milk composition. NIRS combined with different ways of spectral data ruining can provide faster and nondestructive alternative to current methods for mastitis diagnosis and a new inside into disease understanding at molecular level.

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대동맥판 치환술의 임상 성적 (Clinical Results of Aortic Valve Replacement)

  • 나국주;오정우;안병희;김상형
    • Journal of Chest Surgery
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    • 제30권2호
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    • pp.152-157
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    • 1997
  • 전남대학교병원 흉부외과학교실에서는 1986년 8월 부터 1995년 7월 까지 65례의 대동맥판치환술을 경험하였다. 48명이 남자였고 17명의 환자가 여자였으며 19세에서 68세의 연령분포를 보였다. 판막질환의 원인은 류마티성 질환이 29례 (44.6%), 선천성 판막질환이 6례 (6.2%), 심내막염이 6례 (6.2%) 등을 보였다 동반된 수술은 10례에서 있었는데 5례가 선천성 심장 질환의 교정술이었고심막절제술 1례, 관상동맥우회로 조성술 1례, 발살바 동맥동 수술 2례, 대동맥 판막하막 절제술이 1례 등이었다. 사용된 판막은 St. Jude-Medical판이 42개, Duromedics판막이 22개, Bjork-Shiley판막이 2개, Carpentier-Edward판막 이 1개 있었다. 병원내 사망은 3례(4.6%)있었고 만기사망이 2례(3.2%)있었다. 수술후 사망례를 제외하고 100%의 환자에서 추적 관리가 되었고 10년 생존율은 85.3%를 보였다. 술후 합병증은 저심박출증이 8례, 부정맥이 5례, 기계판막과 관련된 용혈이 1례 있었다. 수술후NYHA기능분류는 수술전 2.79$\pm$ 0.66에서 수술후 1.25 $\pm$ 0.49로 개선되었고 단기 및 중장기 추적 조사 결과 우수한 기계판의 혈역학적 동태를 보였고 혈전증의 발생율은 아주 낮았다.

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St. Jude 기계판막을 이용한 판막 치환술의 장기 성적 (Long Term Results of Valve Replacement with the St. Jude Medical Heart Valves: Thirteen Year Experience)

  • 김창곤;구자홍;조중구;김공수
    • Journal of Chest Surgery
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    • 제30권9호
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    • pp.891-898
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    • 1997
  • 1984년 5월부터 1996년 1월까지 전북대학교병원 흉부외과에서 130명의 환자에게 51. Jude MEdical기계판막을 이용하여 판막 치환수술을 시행하였다. 승모판 치환술, 대동맥판 치환술, 동시에 승모판 치환술 및 대동맥 판 중복치 환술을 받은 환자는 각각 68례, 42례, 20례이었다. 조기사망은 7례로 전체 환자의 5.4%에서 발생하 였고 조기합병증은 17례(13.1%)에서 발생하였다. 1996년 12월까지 97.6%에서 추적 관찰하였고 추적기간은 최소 5.5개월에서 최대 153.5개월로 평균 63.6$\pm$27.6개월(5.3$\pm$2.3년)이었고 총 추적기간은 678.7환자-년이었다. 판막관련 만기사망은 6례(4.9%)의 만기사망 중 4례(3.3%)이었다. 판막관련 만기 합병증은 11례(9.1%)에서 발 생하였는데 혈전색증(6계), 출혈(4례), 판막주위누출(Irll)이 발생하였다. 판막관련 합병증 발생률(Linearized rate)은 1.68%/환자-년, 항응고제와 관련된 출혈은 0.92%/환자-년, 혈전색증은 0.61%/환자-년, 판막주위 누출은 0.15%/환자-년의 발생빈도를 보였고 재수술률은 0.15%/환자-년(재수술은 1례), 판막관련 만기사망은 0.61%/환자-년의 발생빈도를 보였다. 10년간 합병증이 발생하지 않을 확률은 87.4 \ulcorner.2%이었다. 술후 심흉곽비와 뉴욕 심장학회(NYHA) 기능분류는 수술전후에 뚜렷하게 개선되었다. 수술후 생존율은 5년, 10년에 각각 90.4$\pm$ 2.7%, 87.5$\pm$3.3%이었다.

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숀 증후군의 외과적 치료 (Surgical Experiences of Shone's Syndrome)

  • 원태희;이정렬;김용진;노준량
    • Journal of Chest Surgery
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    • 제30권9호
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    • pp.862-868
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    • 1997
  • 서울대학교병원 흉부외과에서는 1985년부터 1994년까지 총 9례의 숀 증후군 환자를 치험하였다. 남자 환 아가 떼이었고 여자 환아가 1례이었다. 첫 수술을 시행한 연령은 깨월에서 11세까지로 평균 연령은 33.0 $\pm$ 31.0 개월이었다. 선천성 승모판 협착증 및 대동맥 축착증은 모든 환아에서 존재하였고 승모판 상부 링 및 대동맥하 협착은 각각 4례의 환아에서 발견되었다. 2례의 환아에 있어서는 숀 증후군의 4가지 병변 모두를 가지고 있었다. 3례의 환아에 있어서는 한번에 완전 해부학적 교정술을 시행하였으며 나머지 2례의 환아에 있어서는 개흉술 하에 대동맥 축착증을 교정하고 나중에 정중 흉골 절개 하에 나머지 병변을 교정하는 단계적 수술을 시행하였다. 9례의 환아에 있어서 총 45개의 수술적 치료를 시행하여 1례당 평균 수술적 치료 는 5.0 $\pm$ 0.7개이었다 세번째 수술을 시행한 환아는 2례이었으며 각각 지속적인 승모판 협착으로 승모판 치 환술을 시행한 환아와 지속적인 대동맥 축착으로 대동맥 축착 성형술을 시행한 환아이었다. 한번에 완전 교정술을 시행한 환아와 1차 단계적 수술을 시행한 환아에 있어서 수술 사망률은 없었으나 2차 단계 \ulcorner수술을 시행한 6례중 2례가 사망하여 수술 사망률은 22.2%이었으며 사망한 2례 모두 1차 대동칵 축착증 교정술후 계속되는 심부전 및 인공 호흡기 이탈이 되지 않아 각각 1차 수술 후 9일과 15일 후에 완전 교정술을 시행했던 환아들로 모두 좌심실 형성부전에 의한 심부전으로 사망하였다. 세번째 수술시 사망한 환아는 없었다. 생존한 7례 모두 11개월에서 12년까지(평균 6.7 $\pm$ 3.6년)장기 추적 조사하였으며 모두 뉴욕 심장 협회 활 동도 1군에 속해 있었으며 판막 치환술로 인하여 쿠마딘을 복용하고 있는 환아와 마지막 추적조사시 흉부 X선 사진상 약간의 심비대가 있어 디곡신을 복용하고 있는 환아를 제외하고는 어떤 약도 복용하고 있지 않았 다 결론적으로 숀 증후군은 수술 사망률 및 이환율이 높은 질환이긴 하나 각각의 해부학적 병변의 특징을 잘 파악하여 적절한 치료를 한다면 좋은 장기성적을 기대할 수 있다는 것이다.

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운영연구(OR)의 도서관응용 -그 몇가지 잠재적응용분야에 대하여- (The Application of Operations Research to Librarianship : Some Research Directions)

  • 최성진
    • 한국문헌정보학회지
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    • 제4권
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    • pp.43-71
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    • 1975
  • Operations research has developed rapidly since its origins in World War II. Practitioners of O. R. have contributed to almost every aspect of government and business. More recently, a number of operations researchers have turned their attention to library and information systems, and the author believes that significant research has resulted. It is the purpose of this essay to introduce the library audience to some of these accomplishments, to present some of the author's hypotheses on the subject of library management to which he belives O. R. has great potential, and to suggest some future research directions. Some problem areas in librianship where O. R. may play a part have been discussed and are summarized below. (1) Library location. It is usually necessary to make balance between accessibility and cost In location problems. Many mathematical methods are available for identifying the optimal locations once the balance between these two criteria has been decided. The major difficulties lie in relating cost to size and in taking future change into account when discriminating possible solutions. (2) Planning new facilities. Standard approaches to using mathematical models for simple investment decisions are well established. If the problem is one of choosing the most economical way of achieving a certain objective, one may compare th althenatives by using one of the discounted cash flow techniques. In other situations it may be necessary to use of cost-benefit approach. (3) Allocating library resources. In order to allocate the resources to best advantage the librarian needs to know how the effectiveness of the services he offers depends on the way he puts his resources. The O. R. approach to the problems is to construct a model representing effectiveness as a mathematical function of levels of different inputs(e.g., numbers of people in different jobs, acquisitions of different types, physical resources). (4) Long term planning. Resource allocation problems are generally concerned with up to one and a half years ahead. The longer term certainly offers both greater freedom of action and greater uncertainty. Thus it is difficult to generalize about long term planning problems. In other fields, however, O. R. has made a significant contribution to long range planning and it is likely to have one to make in librarianship as well. (5) Public relations. It is generally accepted that actual and potential users are too ignorant both of the range of library services provided and of how to make use of them. How should services be brought to the attention of potential users? The answer seems to lie in obtaining empirical evidence by controlled experiments in which a group of libraries participated. (6) Acquisition policy. In comparing alternative policies for acquisition of materials one needs to know the implications of each service which depends on the stock. Second is the relative importance to be ascribed to each service for each class of user. By reducing the level of the first, formal models will allow the librarian to concentrate his attention upon the value judgements which will be necessary for the second. (7) Loan policy. The approach to choosing between loan policies is much the same as the previous approach. (8) Manpower planning. For large library systems one should consider constructing models which will permit the skills necessary in the future with predictions of the skills that will be available, so as to allow informed decisions. (9) Management information system for libraries. A great deal of data can be available in libraries as a by-product of all recording activities. It is particularly tempting when procedures are computerized to make summary statistics available as a management information system. The values of information to particular decisions that may have to be taken future is best assessed in terms of a model of the relevant problem. (10) Management gaming. One of the most common uses of a management game is as a means of developing staff's to take decisions. The value of such exercises depends upon the validity of the computerized model. If the model were sufficiently simple to take the form of a mathematical equation, decision-makers would probably able to learn adequately from a graph. More complex situations require simulation models. (11) Diagnostics tools. Libraries are sufficiently complex systems that it would be useful to have available simple means of telling whether performance could be regarded as satisfactory which, if it could not, would also provide pointers to what was wrong. (12) Data banks. It would appear to be worth considering establishing a bank for certain types of data. It certain items on questionnaires were to take a standard form, a greater pool of data would de available for various analysis. (13) Effectiveness measures. The meaning of a library performance measure is not readily interpreted. Each measure must itself be assessed in relation to the corresponding measures for earlier periods of time and a standard measure that may be a corresponding measure in another library, the 'norm', the 'best practice', or user expectations.

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