Bile duct ligation of C57BL/6 mice as a model of hepatic encephalopathy

Background: Bile duct ligation (BDL) has been used for experimental research on hepatic encephalopathy (HE) caused by chronic liver disease. However, little research has been done on a BDL model in C57BL/6 mouse. Therefore, we evaluated the suitability of a BDL model in C57BL/6 mouse for the study of HE and determined which behavioral tests are appropriate for the identification of HE in this model. Methods: Twelve to fourteen-week-old male C57BL/6 mice were randomly assigned to either sham group or BDL group. Histological changes in liver were confirmed by hematoxylin/ eosin and Masson’s trichrome staining. Liver function alterations were detected by alanine aminotransferase (ALT) and ammonia levels. To identify behavioral changes, open field, elevated plus maze, novel object recognition, and passive avoidance tests were performed. Results: Inflammatory liver injury and fibrosis were observed 14 days after BDL. ALT and ammonia levels were significantly higher in BDL group than in sham group. There were no differences in general locomotor activity or anxiety between the groups. No difference was observed between these two groups in the novel object recognition test, but BDL group showed significant learning/memory impairment in the passive avoidance test compared to sham group. Conclusions: Fourteen days of BDL in 12–14-week-old male C57BL/6 mice is a clinically relevant model for HE, as these mice have liver fibrosis with impaired liver function, hyperammonemia, and learning/memory impairment. Passive avoidance can be used as the major behavioral test in this model of HE.ope

공적연금과 주택소유가 개인연금에 미치는 영향에 관한 연구

학위논문(박사) -- 서울대학교대학원 : 사회과학대학 사회복지학과, 2022.2. 홍백의.This study attempts to analyze the factors affecting individual pensions, especially homeownership and public pension that can function as income sources in one’s later life. Old age poverty is always a serious issue in Korea. About half of retired Koreans consider their main problem in old age is economic difficulties and furthermore, approximately 44% of Korean senior citizens are living under poverty as of 2019. Among several ways to address the financial difficulty, the pension system is one of the more stable and effective ways, which is designed to prevent the entire loss of income after retirement. Typically, it is considered a rule-of-thumb that a replacement rate of roughly 70% of gross income from a variety of pension sources, is adequate for retirement. However, the benefit level of the public pension system in Korea is far from satisfying level to support the stable old age life, as the replacement rate of public pension in Korea is only about 40 percent. There is a growing expectation that the gap between the ideal replacement rate and actual coverage should be filled by the individual. In such environment, it is natural that the role of the private sector in the pension system becomes increasingly important. As one of the main purposes of purchasing an individual pension is to secure future income, the purchase level of individual pension is largely affected by the other types of retirement preparations. And because the public pension is a major source of future income for many individuals, it can have a considerable effect on an individual pension. There are two theories asserting the relationship between public pension and individual pension: life cycle theory and extended life cycle theory. According to life-cycle theory, public pension and individual pension have a substitutive relationship; public pension tends to crowd out individual pension purchases. However, these two also can have a complementary relationship, or a positive relationship, in regard to extended life cycle theory. Previous studies that explored the relationship between public pension and savings, showed both positive and negative outcomes. Besides individual and public pension, homeownership also has a similar role in old age; it can provide income in old age and protects individuals from poverty. Homeownership can offer a financial benefit to older people as an ‘income in cash’ and ‘income in kind.’ House can provide direct cash to the owners, as one can realize the housing asset in the form of cash. It also can provide an array of non-cash benefits, as expenditure regarding residence can be dramatically reduced compared to that of the rent. In a later year when individuals have no consistent income, owning a house will be a great benefit for retirees. The pension and homeownership also are known to have two contradictory relationships; According to Kemeny’s trade-off theory explains the negative relationship between the two while extended life cycle theory assumes a positive relationship. The individual pension, public pension and homeownership not only just shares role as a ‘future income’; They all occur during one's working time, within the boundary of a limited budget. Which means, in other words, they have parallel growth over ones’ working years and eventually have a competing relation. Among other things, mandatory public pension contributions and home purchases are two cases of considerable and steady expenditure across one’s life that need to be paid concurrently for a long time. The status of pension participation and housing can change one’s level of budget constraint and thus can impact the level of individual pensions, which also requires a sizable and constant contribution. Considering their parallel growth during the work period and functional similarity in later life, it will be rational to assume that individual pension participation can be altered by public pension and home purchases. Based on these discussion, the following three principal research questions was be investigated in this dissertation. 1) What is the effect of public pension on individual pension? Does the effect differ depending on one’s pension status (uninsured, NPS, SOP) and pension contribution? 2) What is the effect of homeownership on individual pension? What is the effect of house prices on individual pensions? 3) What does the interaction of the two - public pension and housing — say? To answer the research question, this study used the National Survey of Tax and Benefit (NaSTaB) wave 2 to 12; the target data was the head of the household between 20 and 60, and the final sample contained 3,461 individuals. The dependent variables were individual pension participation status and individual pension purchase level, and independent variables were public pension participation status, public pension contribution level, homeownership, house price, and interaction terms of public pension and housing. To address the censored data problem, double hurdle analysis was applied with a control function approach to deal with the endogeneity issue. The result shows that public pension participation status and public pension participation level both had a significantly positive impact on individual pension purchase. Public pension participation status had significant positive effects on individual pension participation and purchase amount; Compared to the non-public pension participation group, NPS and SOP participants had a better chance and amount of individual pension purchase. The contribution amount also had a similar result, as it had a significant effect on both the participation and purchase amount model. This result indicates that the two pension systems in Korea are in a complementary relationship. One of the major reasons for this relationship would be precautionary motives; low and decreasing public pension replacement rate, and unstable financial future of public pension might trigger precautionary motives. Homeownership and house price had a positive effect on individual pension participation, which indicates that the relationship between the two is complementary, rather than substitutional. However, homeownership had a significant negative effect on individual pension purchase amount — this showed some possibility of a trade-off between pension and housing; the owner might purchase a smaller amount of individual pension than non-owners, because they can utilize the house as a pension at a later age, or because they might face greater financial constraint (such as housing mortgage) than non-owners. The result of interaction effect analysis showed that there was a positive interaction effect between homeownership and public pension (both status and contribution) on individual pension participation, while there was no interaction effect between homeownership and public pension on the individual pension purchase amount. On the other hand, there was no interaction effect between house price and public pension contribution or status on individual pension participation. Meanwhile, there was a significant interaction effect between house price and public pension on the individual pension purchase amount. The result of the interaction effect generally indicates there is a tendency for a complementary relationship among public pension, housing and individual pension. The results have a few primary theoretical implications: First, this study emphasized the importance of housing in individuals’ old age and old age preparation, which have been somewhat excluded from the academic field. Although the importance of housing and homeownership in old age is widely accepted, study on housing in pension or old age preparation was largely understudied in the academic field compared to its importance. This study shed light on under-recognized ‘housing’ in the pension field and reviewed the role of housing in individual pension purchases in Korea to overcome the limitation of previous literatures. Second, this study has its meaning in that it surveyed the relationship of housing and pension at the micro level using Kemeny’s trade-off theory. Although original Kemeny’s theory explains the trade-off between pension and homeownership on the national level, its mechanism (need-induced or constraint-induced trade-off) can be applied to micro level as well. However, there were few attempts explaining the pension-homeownership relationship using Kemeny’s theory except for a handful of recent movements. This study can find its significance in that it seeks to convert macro-level discourse into micro-view. Third, this study has a contribution to the academic field that this is one of the very first studies that investigated the interaction effect of public pension and housing on individual pension purchase. This study assumed that the result of individual pension purchase will be altered by how public pension and housing are arranged, and the findings show the meaningful interaction effect between public pension and housing on individual pension purchase. The results have a few primary political implications and suggestions as well: First, this study provides some significant information on individual pension purchases that could be important political preliminary data. For proper policy intervention, understanding the accurate situation on related features is of paramount importance; However, in terms of individual pension, comprehensive evidence of the actual situation was insufficient to this point. This study could be important baseline information that could be used in political settings. Second, there are needs to aid people in vulnerable groups to participate in individual pensions if they want to. The result found a complementary relationship among public pension, individual pension and housing which indicates that those with a better household economy tends to have a better outcome in an individual pension. This also indicates that less economically viable ones might have the risk to be excluded or not actively involved in the individual pension system. There is a need for policy-level intervention to those economically vulnerable ones, but those who has the will to participate in individual pension. Finally, the expanding role of the public sector will be also necessary. Expanding coverages of public pension and the increasing role of basic pension probably can work as solutions to narrow the gap between the groups. Extending the pension credit policy to various other areas can be a way to expand coverages in more effective ways. Moreover, it will be also necessary to consider ways to partially strengthen the role of the Basic Pension for the socially disadvantaged, or vulnerable groups.본 연구는 미래 노후 소득원이 될 수 있는 공적연금 및 주택소유 관련 변인들이 사적연금 가입 여부와 가입액에 어떠한 영향을 미치는지를 분석하고자 하였다. 한국의 노인 중 과반이 노후의 가장 큰 문제점으로 경제적 어려움을 꼽았으며, 2019년도 기준 44%의 노인이 빈곤한 것으로 나타나는 등 한국 노인의 노후 소득과 빈곤 문제는 사회적으로 중요한 이슈이다. 이러한 노년의 경제적 문제에 대한 가장 효과적인 해결책 중 하나로 공적연금이 꼽히는데, 통상적으로 연금의 소득대체율이 은퇴 전 임금의 70% 정도가 되면 이상적인 노후 소득 수준으로 인식된다. 하지만 한국의 공적연금은 소득대체율이 40% 정도에 불과해, 이상적인 소득대체율과 비교해 매우 낮은 수준이다. 오늘날 실질적 소득대체율과 이상적 소득대체율의 차이는 상당부분 개인의 책임으로 인식되고 있으며, 이에 자연스럽게 개인연금의 중요성이 점점 커지고 있는 실정이다. 개인연금 구매의 주요 목적 중 하나가 부족한 노후 소득을 충당하는 것이기 때문에 개인연금의 구매 수준은 다른 유형의 노후소득에 크게 영향을 받을 수밖에 없다. 본 연구에서는 공적연금이 개인연금 구매에 주요한 영향을 미칠 것으로 가정하였다. 공적연금은 많은 이들에게 중요한 노후소득의 원천이기 때문에, 개인연금에 상당한 영향을 미칠 수 있다는 가정이다. 실제로 공적연금과 개인연금의 관계에 관한 많은 연구들이 존재하는데, 둘 사이에는 공적연금이 사적연금을 구축하는 대체 관계와 (life-cycle theory), 공적연금과 사적연금의 상호보완적 관계 (extended life-cycle theory)가 모두 나타나는 것으로 알려져 있다. 주택 소유 역시 연금과 유사한 역할을 한다. 주택 소유는 노년기에 ‘현금 소득’과 ‘현물 소득’으로 금전적 혜택을 제공할 수 있고, 빈곤으로부터 개인을 보호할 수 있다. 주택 자산은 현금 형태로 실현 가능하기 때문에 주택 소유자에게 직접 현금을 제공할 수 있다. 또한 주택을 소유할 경우 임대에 비해 주거 관련 지출이 상당부분 줄어들 수 있기 때문에 다양한 비현금성 혜택도 존재한다. 따라서 개인에게 일정한 소득이 없는 인생의 후반기에는, 주택을 소유하는 것이 은퇴자들에게 큰 혜택이 될 수 있다. 연금-주택의 관계성에 대한 연구들도 둘의 관계는 대체관계 (Kemeny’s trade-off theory)와 보완관계 (extended life-cycle theory)가 모두 나타날 수 있다고 보고하고 있다. 개인연금, 공적연금 및 주택 소유는 노후소득으로서의 역할만 공유하는 것은 아니다. 세 요인 모두 개인의 생애 노동기간 동안의 소득 범위 내에서 발생한다. 이는 연금과 주택구입은 경쟁관계에 놓일 수 있다는 것을 의미한다. 그 중에서도, 공적연금 기여금과 주택 구입 관련 비용은 상당 기간 동안 지불되어야 하며 생애 전반에 걸쳐 지속적인 지출이 필요하다. 때문에 공적 연금 가입과 주택 소유 여부는 개인의 예산 제약 수준에 영향을 미쳐 개인연금 구입에도 영향을 미칠 가능성이 크다. 이와 같은 논의들을 바탕으로 다음의 세 가지 주요 연구 질문을 설정하였다. 첫 번째, 공적연금이 개인연금에 미치는 영향은 어떠한가? 공적연금 가입 형태와 공적연금 기여액에 따라 그 효과가 다른가? 두 번째, 주택 소유가 개인연금에 미치는 영향은 어떠한가? 또한 주택가격이 개인연금에 미치는 영향은 어떠한가? 세 번째, 공적연금과 주택소유의 상호작용 효과는 어떠한가? 연구질문에 대한 분석을 위해 본 연구는 재정패널 2차~12차 데이터를 사용하였다. 분석대상은 20 - 60세의 가구주이며, 총 3,461명의 데이터가 활용되었다. 종속 변수는 개인연금 가입 여부와 개인연금 가입액이었고, 독립 변수는 공적연금 가입여부, 공적연금 가입액, 주택 소유, 주택 가격, 그리고 공적 연금과 주택의 상호작용이었다. 주요 분석 모델은 이중허들 모형과 통제함수 모형을 활용하였다. 분석 결과 공적연금 가입 형태와 공적연금 기여액이 모두 개인연금 가입과 가입액에 유의한 긍정적 영향을 미치는 것으로 나타나, 상호보완적 관계가 확인되었다. 더 관대한 유형의 공적연금에 가입한 그룹과 더 많은 공적연금 기여액을 납부하는 그룹이 개인연금에 더 많이 가입하고, 가입액도 높은 것으로 나타났다. 이러한 관계가 나타난 주요 이유 중 하나는 예방적 동기일 것으로 추정된다. 낮은 공적연금 대체율과 공적연금의 불안정한 재정상태에 대한 심리적 불안이 예방적 동기를 유발할 수 있으며, 이것은 공적연금과 개인연금 사이의 관계에 영향을 미쳤을 가능성이 크다. 주택 소유여부와 주택 가격 역시 개인연금 가입에 긍정적인 영향을 미쳤는데, 이것은 둘 사이의 관계가 대체적이기보다는 상호보완적임을 나타낸다. 그러나 주택 소유여부는 개인연금 가입액에 유의한 부정적 영향을 미치는 것으로 나타나, 연금과 주택소유 사이의 trade-off 관계의 가능성을 보여주었다. 주택 소유자는 주택을 노후에 연금으로 활용할 수 있기 때문에 비소유자보다 적은 금액의 개인연금을 구입하거나, 비소유자보다 더 큰 재정적 제약에 직면할 수 있어 이러한 결과가 나타났다고 볼 수 있다. 한편, 상호작용 효과 분석 결과에 의하면 주택 소유와 공적 연금(가입형태, 기여액)은 개인연금 가입에는 긍정적 상호작용 효과가 있는 반면, 개인연금 가입액에 관해서는 상호작용 효과가 없는 것으로 나타났다. 주택 가격과 공적 연금 (가입형태, 기여액)은 개인의 연금 가입에 상호작용 효과가 없는 것으로 나타난 반면, 개인연금 가입액에 대해서는 유의한 상호작용 효과가 있었다. 대체적으로 상호작용 효과의 결과는 공적연금, 주택, 개인연금 사이에 상호보완적 경향이 있음이 확인됐다. 본 연구는 몇 가지 중요한 이론적 의미를 가지고 있다. 첫째, 본 연구는 그동안 학계에서 다소 배제되었던 개인의 노후 준비 측면에서의 주택의 중요성을 강조하였다. 노년기에 주택 소유의 중요성은 널리 받아들여지고 있지만, 복지나 노후 준비와 관련된 연구에서 주택에 대한 관심은 그 중요성에 비해 학계에서 크게 미흡한 실정이었다. 본 연구는 복지 분야에서 연구 비중이 낮았던 '주택'을 조명하고, 한국의 개인연금 구매에 있어 주택의 역할을 검토해 기존 문헌의 한계를 극복하였다. 둘째, 본 연구는 Kemeny의 trade-off 이론을 이용하여 미시적 수준에서 주택과 연금의 관계를 조사하였다는 의미가 있다. Kemeny의 이론은 대체로 국가 수준에서 연금과 주택 소유 사이의 trade-off를 설명하였지만, 미시적 수준에서도 적용될 수 있다. 그러나 현재까지는 Kemeny의 이론을 이용하여 연금-주택소유의 미시적 관계를 설명하려는 시도는 거의 없었다. 본 연구는 거시적 수준의 담론을 미시적 시각으로 전환하여 살펴보았다는 점에서 그 의의를 찾을 수 있다. 셋째, 본 연구는 공적연금과 주택이 개인연금 구매에 미치는 상호작용 효과를 조사한 최초의 연구라는 점에서 의미가 있다. 본 연구는 공적연금과 주택의 상호작용에 따라 개인연금 구매 결과가 달라질 것으로 가정하였으며, 연구결과 유의한 상호작용 효과를 확인하였다. 마지막으로, 본 연구는 개인연금에 대한 중요한 정치적 예비 자료가 될 수 있다는 정책적 함의를 지닌다. 정확한 정책 개입을 위해서는, 관련된 기능에 대한 적확한 상황을 파악하는 것이 무엇보다 중요함에도, 개인연금에 대한 정확하고 종합적인 정보가 부족한 실정이었다. 본 연구는 개인연금에 관하여 정책적 환경에서 사용될 중요한 기초자료가 될 수 있다. 또한, 본 연구는 다음과 같은 정책적인 제안을 제시하였다. 첫째, 개인연금에 가입하지 못하는 취약계층을 지원하는 제도가 필요하다는 것이다. 본 연구는 공적연금, 개인연금, 주택 간에 상호보완적 관계를 발견해 부익부 빈익빈 현상을 확인하였는데, 이는 경제적으로 취약한 사람들이 개별연금제도로부터 더 배제될 위험이 있다는 것을 나타내기도 한다. 경제적으로 어렵지만 개인연금에 참여할 의사가 있는 사람들에 보조금을 지원하는 등의 정책적 노력을 통해 부익부 빈익빈 현상을 완화시킬 필요가 있다. 둘째, 공공부문의 역할 확대도 필요할 것이다. 연금 크레딧 확대를 통해 공적연금의 적용범위를 확대하고 사회적 약자나 취약계층을 위해 기초연금 역할을 증가시키는 노력은 계층 간 격차를 줄이는 해법으로 작용할 수 있을 것이다.I. Introduction 1 II. Background and Literature Review 11 1. Pension Background 11 1.1 Definition and Role of pension 11 1.2 Types of pensions and the multi-pillar system 13 1.3. Pension System in Korea 17 2. Housing, Homeownership and welfare 28 2.1. Growing importance of housing in welfare 29 2.2. Trend in Homeownership 31 2.3. Role and effects of homeownership 33 2.4. Homeownership in Korea 41 3. Literature Review 45 3.1. Theories on Public pension and individual pension 45 3.2. Theories on Homeownership and pension relationship 56 4. Pension and Homeownership: role and relation 68 4.1. Shared role in later life 68 4.2. Parallel Growth and competing relationship 72 4.3. Interaction effects 74 5. Other factors associate with individual pension purchase 76 6. Summary and Conclusion 81 III. Research Question and Analytical Framework 86 IV. Methodology 89 1. Data and Sample 89 2. Definition of Variables 91 3. Analytical Method 95 3.1. Double Hurdle Panel Model 95 3.2. Dealing with Endogeneity 98 V. Research Results 101 1. Description of data 101 1.1.Basic Statistics 101 1.2.Information regarding Dependent Variable 103 1.3.Information regarding Major Independent Variables 114 2. Double Hurdle Analysis 118 2.1. Effect of public pension on individual pension purchase 118 2.2. Effect of housing on individual pension purchase 124 2.3. Interaction of housing and public pension status 130 2.4. Interaction of housing and public pension contributions 137 2.5. Control Variables 142 VI. Conclusion 145 1. Summary of the study 145 2. Theoretical Implication 148 3. Political Implication and Suggestion 151 4. Limitation of the study 156 Reference 159 Appendix 178 Abstract (Korean) 208박

근육 량과 비흡연자 폐암 발생 위험 간의 연관성

학위논문(석사) -- 서울대학교대학원 : 의과대학 의학과, 2023. 8. 이상민.Background: Lung cancer in never-smokers (LCINS) is an emerging global health concern since its prevalence and disease burden continuously increase within the poorly understood etiology. Body composition abnormalities are major preventable risk factors for various cancer. However, their role in incident LCINS diagnosis remains uninvestigated. Detectable body composition abnormalities might be important modifiable etiologic factors for LCINS. We aimed to evaluate the association of muscle mass, subcutaneous, and visceral adiposity with the risk of incident LCINS diagnosis. Methods: This cross-sectional case-control study used prospectively collected data derived from a readily approved ongoing LCINS cohort. Body compositions of 326 newly-diagnosed LCINS patients and 348 never-smoker controls were analyzed via deep-learning-based automated volumetric analysis of unenhanced torso computed tomography images. The cross-sectional area at the third lumbar vertebra and waist-level volume of muscle and fat were quantified, then normalized by height to generate skeletal muscle index, fat index, skeletal muscle volume index (SMVI), and fat volume index. Sarcopenia was defined as reduced skeletal muscle index (men, <55 cm2/m2; women, <39 cm2/m2). Odds ratios (ORs) of LCINS were estimated using sex-specific, mutually-adjusted generalized additive and linear logistic regression models. Age-matched sensitivity analysis was performed using univariable and multivariable conditional logistic regression models. Results: LCINS patients (n=326; 44[13.5%] men) were older (mean ± SD age, men, 65.2 ± 12.4 years vs 58.7 ± 9.9; women, 64.5 ± 9.9 vs 53.9 ± 10.3) and more often presented with sarcopenia (men, 77.3% vs 41.2%; women, 43.3% vs 23.6%) than controls (n=348; 68 [19.5%] men). The risk of incident LCINS decreased in a dose-response manner with increased skeletal muscle index (men, adjusted OR [aOR] 0.89, 95% CI 0.83–0.94; women, aOR 0.86, 95% CI 0.83–0.89). The aORs of incident LCINS for men and women in the lowest quartile of skeletal muscle index were 12.71 (p=0.002) and 20.52 (p<0.001), respectively, compared with those in the highest quartile. Similar patterns were observed for SMVI. Sarcopenia was strongly correlated to incident LCINS (men, aOR 6.28; women, aOR 4.32; both p<0.001). No adiposity measures showed meaningful associations with incident LCINS diagnosis. Sensitivity analysis strengthened these results. Conclusion: Muscle mass demonstrated a strong, independent, dose-response inverse relationship with the risk of incident LCINS diagnosis. Reduced muscle mass might be an easily-detectable and potentially modifiable clinical indicator for incident LCINS.배경: 비흡연자 폐암의 유병률과 질병 부담은 전세계적으로 계속해서 증가하는 추세이나, 그 원인 및 예방 가능한 인자에 대해서는 잘 알려져 있지 않다. 체성분 이상 (비만, 복부 비만, 근 감소증, 근 감소형 비만 등) 은 다양한 암의 중요한 위험인자로 알려져 있으나, 비흡연자 폐암 발생 혹은 초기 진단과의 관련성은 밝혀져 있지 않다. 본 연구는 체성분 이상과 비흡연자 폐암 초기 진단 간 관계를 평가하기 위해 수행되었다. 방법: 본 연구는 단면적 환자-대조군 연구로서, 전향적으로 모집한 326 명의 새로 진단된 비흡연자 폐암 환자와 348 명의 비흡연자 건강 대조군을 대상으로, 양 군의 체성분을 비교 분석하여 폐암 진단과의 연관성을 살펴보았다. 모든 대상자에게서 복부 전산화 단층촬영 영상을 추출하여, 이를 딥러닝 기술을 기반으로 한 자동화 방식을 통해 분석하였다. 허리 부근에서의 근육, 내장지방, 피하지방의 단면적과 부피를 측정하여 키로 나누어 표준화된 지표인 골격근 지수, 내장지방 지수, 피하지방 지수를 생성하였다. 근감소증은 골격근 지수 저하를 기준으로 정의하였다. 각각의 체성분 지표와 비흡연자 폐암 간 관계는 일반화 가중 및 선형 로지스틱 회귀모델을 사용해 분석하였다. 결과: 비흡연자 폐암 환자들이 정상 대조군에 비해 나이가 더 많았으며, 더 많은 비율로 근감소증을 보였다. 골격근 지수는 비흡연자 폐암 발생 위험과 강한 반비례관계를 보였다. 골격근 지수를 사분화 하였을 때, 최하 사분위에 속한 대상자에서 비흡연자 폐암 위험이 최고사분위에 속한 대상자에 비해 남성에서 12 배, 여성에서 20 배 이상으로 높았다. 근감소증은 비흡연자 폐암과 강한 양의 상관관계를 보였다. 반면, 지방 지표들은 비흡연자 폐암과 유의미한 관계를 보이지 않았다. 이러한 결과는 민감도 분석에서 더욱 두드러졌다. 결론: 근육량은 비흡연자에서 폐암 발생 위험과 독립적인 음의 상관관계를 가진다. 근감소증 및 근육량 감소는 비흡연자 폐암 진단 과정에서 중요한 교정 가능한 유발 인자일 수 있다.Abstract ⅰ Table of Contents ⅳ List of Tables ⅴ List of Figures ⅵ Introduction 1 Methods 5 Results 11 Discussion 17 Bibliography 23 Abstract in Korean 31 Tables 33 Figures 38석

Inflammasome and Cognitive Symptoms in Human Diseases: Biological Evidence from Experimental Research

Cognitive symptoms are prevalent in the elderly and are associated with an elevated risk of developing dementia. Disease-driven changes can cause cognitive disabilities in memory, attention, and language. The inflammasome is an innate immune intracellular complex that has a critical role in the host defense system, in that it senses infectious pathogen-associated and endogenous danger-associated molecular patterns. An unbalanced or dysregulated inflammasome is associated with infectious, inflammatory, and neurodegenerative diseases. Due to its importance in such pathological conditions, the inflammasome is an emerging drug target for human diseases. A growing number of studies have revealed links between cognitive symptoms and the inflammasome. Several studies have shown that reducing the inflammasome component mitigates cognitive symptoms in diseased states. Therefore, understanding the inflammasome regulatory mechanisms may be required for the prevention and treatment of cognitive symptoms. The purpose of this review is to discuss the current understanding of the inflammasome and its relationships with cognitive symptoms in various human diseases.ope

Perceptions and Attitudes towards Interprofessional Education in Medical Schools

Since the World Health Organization identified interprofessional education (IPE) as an important component in primary health care in the 1980s, medical and health sciences educators have continued to debate factors for implementing effective IPE in the classroom. Although IPE research is widespread internationally, few studies have been done in South Korea. This study explored the current status of IPE and examined factors that influence IPE in South Korea. A total of 30 (70%) out of 41 medical education experts in medical schools participated. Forty-seven percent of the participants reported that they allocated less than 5% of their time implementing IPE in the curriculum of their schools throughout the 4 years of medical school. Although all experts (100%) agreed that IPE is essential for medical students, they expressed practical difficulties in implementing IPE in the current education system. Factors that influence IPE are scheduling and curriculum (e.g., rigid curriculum vs. providing learning environment) and attitudes (e.g., lack of reciprocal respect vs. willingness to change). In addition, participants reported that communication skills and collaborative practice employing clinical practice or role-playing would be appropriate education methods and content for IPE in the future. The findings of this study provide a foundation for the implementation of IPE in South Korea. Future research directions for IPE in medical, nursing, and pharmacy schools are discussed.ope

Scopolamine promotes neuroinflammation and delirium-like neuropsychiatric disorder in mice

Postoperative delirium is a common neuropsychiatric syndrome resulting a high postsurgical mortality rate and decline in postdischarge function. Extensive research has been performed on both human and animal delirium-like models due to their clinical significance, focusing on systematic inflammation and consequent neuroinflammation playing a key role in the pathogenesis of postoperative cognitive dysfunctions. Since animal models are widely utilized for pathophysiological study of neuropsychiatric disorders, this study aimed at examining the validity of the scopolamine-induced delirium-like mice model with respect to the neuroinflammatory hypothesis of delirium. Male C57BL/6 mice were treated with intraperitoneal scopolamine (2 mg/kg). Neurobehavioral tests were performed to evaluate the changes in cognitive functions, including learning and memory, and the level of anxiety after surgery or scopolamine treatment. The levels of pro-inflammatory cytokines (IL-1β, IL-18, and TNF-α) and inflammasome components (NLRP3, ASC, and caspase-1) in different brain regions were measured. Gene expression profiles were also examined using whole-genome RNA sequencing analyses to compare gene expression patterns of different mice models. Scopolamine treatment showed significant increase in the level of anxiety and impairments in memory and cognitive function associated with increased level of pro-inflammatory cytokines and NLRP3 inflammasome components. Genetic analysis confirmed the different expression patterns of genes involved in immune response and inflammation and those related with the development of the nervous system in both surgery and scopolamine-induced mice models. The scopolamine-induced delirium-like mice model successfully showed that analogous neuropsychiatric changes coincides with the neuroinflammatory hypothesis for pathogenesis of delirium.ope

A Study on Conduct Barring Limitation of Shipowner's Liability

Considering that shipping industries activate international trade among nations and contribute to the economies of those nations, with regard to public interest, it is necessary to establish institutional strategies for shipping industries. A shipowner’s limitation of liability entails that the shipowner can limit his liability in certain circumstances when loss or damage has been caused to the property of others carried on his vessel during its voyage. However, in cases where the right to limitation is denied, if the standard of determination is obscure and unclear, a legal dispute often occurs and the shipowner’s or the claimant’s rights to a fair result can be compromised, which goes against the legislative purpose of the act on the limitation of liability. Therefore, due to the nature of maritime incidents in which foreign legal relationships are frequently involved, it is necessary to establish a uniform standard regarding conduct that bars the limitation of a shipowner’s liability. The Korean Commercial Code also confirms the right on the shipowner to limit his liability. However, the application of this Code should be discussed in conjunction with the provisory clause, which sets forth conduct barring limitation under certain circumstances. Thus, despite an effective claim under the limitation regime, when the shipowner indulges in illegal behavior leading to such liabilities, the right to any limitation may be denied. This thesis would analyze the shipowner’s limitation of liability and its conduct barring limitation from the perspective of the shipowner’s willful misconduct or other reckless acts or omissions while duly recognizing the concern about the incurrence of such damage, by referencing cases based on the regime in each country. In addition, the question of who has the onus of providing proof, which is not specified in the Code, will be discussed. This thesis would analyze international conventions such as the 「International Convention relating to the Limitation of the Liability of Owners of Sea-going ships, 1957」and the 「Convention on Limitation of Liability for Maritime Claims, 1976」 and then, the regime of the shipowner’s limitation of liability in each country such as the UK, the US, and Japan. In addition, a legal stance and direction for improvement with regard to the provision for shipowner’s limitation of liability are suggested.제1장 서론 1 제1절 연구의 목적 1 제2절 연구의 범위 및 방법 2 제2장 선박소유자 등의 책임제한제도의 일반론 4 제1절 서설 4 제2절 의의와 연혁 4 Ⅰ. 선박소유자 등의 책임제한제도의 의의 4 Ⅱ. 선박소유자 등의 책임제한제도의 연혁 5 제3절 선박소유자 등의 책임제한제도에 관한 국제협약의 개관 11 Ⅰ.「1957년 항해선소유자의 책임제한에 관한 국제협약」의 개관 11 Ⅱ.「1976년 해사채권에 대한 책임제한에 관한 협약」의 개관 13 제4절 상법상 선박소유자 등의 책임제한제도의 개관 17 Ⅰ. 의의 17 Ⅱ. 책임제한의 주체 19 Ⅲ. 책임제한의 대상채권 19 Ⅳ. 책임제한의 한도액 21 제3장 책임제한의 주관적 배제사유에 관한 국제협약의 내용 23 제1절 서설 23 제2절 「1957년 항해선소유자의 책임제한에 관한 국제협약」 23 Ⅰ. 선박소유자 등의 범위 24 Ⅱ. 책임제한 배제의 요건 25 Ⅲ. 입증책임 27 제3절 「1976년 해사채권에 대한 책임제한에 관한 협약」 28 Ⅰ. ‘책임있는 자’의 범위 29 Ⅱ. 책임제한 배제의 요건 31 Ⅲ. 입증책임 38 제4절 소결 39 제4장 책임제한의 주관적 배제사유에 관한 비교법적 고찰 41 제1절 서설 41 제2절 선주국가의 입장 42 Ⅰ. 영국 42 Ⅱ. 일본 46 제3절 화주국가의 입장 53 Ⅰ. 미국 53 제4절 소결 58 제5장 상법상 선박소유자 등의 책임제한의 주관적 배제사유에 관한 해석론 61 제1절 서설 61 제2절 상법의 해석론 63 Ⅰ. 선박소유자 등의 범위 63 Ⅱ. 책임제한 배제의 요건 69 Ⅲ. 입증책임 71 제3절 판례의 태도 72 Ⅰ. 선박소유자 등의 범위 72 Ⅱ. 책임제한 배제의 요건 74 Ⅲ. 입증책임 75 제4절 소결 76 제6장 결론 80 참고문헌 82Maste

비정질 금속 입자의 불균일 변형 거동 분석에 대한 연구

학위논문 (석사)-- 서울대학교 대학원 공과대학 재료공학부, 2017. 8. 박은수.The size reduction of metallic glasses into nanoscale has been proposed as a promising route to overcome limited plasticity of metallic glasses and to develop novel nanostructured materials with exceptional mechanical properties. However, a lack of comprehensive understanding about mechanical behavior of nanoscale metallic glasses is attenuating both academic and industrial values of metallic glasses. Hence, this work aimed at addressing remaining issues on size effect and providing a basic guideline for designing desirable nanomechanical behaviors. With these ends in view, the mechanical response of metallic glass particles was thoroughly analyzed to clarify the effect of size on the mechanical behavior of metallic glasses and to investigate the effect of intrinsic and extrinsic factors on nanomechanical behaviors. To address the effect of size on not only mechanical properties but also shear avalanches which require uniform sample shapes and large plastic deformation range, metallic glass specimens examined in this study were prepared into spherical shape via gas atomization to have wide diameter ranges (300 nm to 4 μm). A Pd42.5Cu30Ni7.5P20 MG (Pd-MG), with outstanding glass forming ability and thermal stability, is chosen as a model system. Mechanical properties of Pd-MG particles were measured based on contact mechanics and sample size dependences of each mechanical property are confirmed. This finding indicates that conflicting results reported in regard to the size dependence of yield strength may have been originated from extrinsic factors that obscure size effects such as dissimilarities in the shape of nanoscale MG specimens. Moreover, in order to investigate the effect of size on shear avalanches of Pd-MG particles, a statistical analysis on the size distribution of strain bursts is carried out. The complementary cumulative distribution functions (CCDFs) of strain burst sizes revealed that strain localization is weakened and self-organized critical behavior extends up to larger strain bursts upon sample size reduction. The results demonstrate that the self-organized critical behavior of plastic carriers (shear transformation zones or shear bands) is strengthened with the decrease of sample size. Then, to elucidate the origin of inhomogeneous deformation of Pd-MG particles and to figure out intrinsic properties which have influences on nanomechanical behaviors, the deformation map for nanoscale Pd-MG is constructed. The map suggests that Pd-MG particles deform inhomogeneously at room temperature because critical boundaries which involve in the determination of deformation behavior intersect at a diameter range near the diameter of the smallest particle tested. Moreover, notable correlations between nanomechanical behaviors and intrinsic properties are found based on deformation map: (1) normalized critical stress curves for inhomogeneous deformation rely more heavily on sample size when Poissons ratio is large, (2) iso-viscosity contour locates at lower stress level when activation energy is small and shear transformation zone (STZ) volume is large, and thus, it depends on Poissons ratio, glass transition temperature, and elastic modulus. The findings demonstrate that not only Poissons ratio but also glass transition temperature and elastic modulus are controlling factors for nanomechanical behaviors. Another fruitful insight that the deformation map provides is that deformation behavior of nanoscale MGs can be tuned by manipulating extrinsic factors that can shift critical boundaries. From this point of view, the potential of electron beam irradiation as a candidate for extrinsic controlling factors is investigated via in situ compression tests inside a TEM with a high accelerating voltage of 300 keV. The result reveals that the deformation behavior of nanoscale MGs can change from inhomogeneous deformation to homogeneous deformation with viscosity value comparable to that of supercooled liquid under external stress with the aid of electron beam irradiation. To sum up, controversial issues regarding the size dependence of mechanical properties and shear avalanches are addressed through unprecedented systematic investigations on the inhomogeneous deformation behavior of MG particles. Moreover, intrinsic and extrinsic factors influencing the deformation behavior of nanoscale MGs are figured out based on the deformation map for nanoscale MGs. These results suggest that the tailor-made design of nanoscale MGs with desirable mechanical behaviors can be practicable by manipulating intrinsic and extrinsic factors.Chapter 1. Introduction 1 1.1. Mechanical behavior of metallic glass 1 1.1.1. Deformation mechanism and mechanical property 4 1.1.2. Deformation mode 7 1.1.3. Deformation map for metallic glass 9 1.1.4. Shear avalanches in metallic glass 11 1.2. Mechanical behavior of nanoscale metallic glass 13 1.2.1. Effect of size on mechanical property 15 1.2.2. Effect of size on deformation mode 23 1.2.3. Deformation map for nanoscale metallic glass 27 1.2.4. Effect of size on shear avalanches 29 1.2.5. Effect of intrinsic and extrinsic factors on deformation behavior of nanoscale metallic glass 30 1.3. Thesis objective and research strategy 32 Chapter 2. Experimental procedure 33 2.1. Sample preparation 33 2.1.1. Fabrication of metallic glass particle via gas atomization 33 2.1.2. Fabrication of metallic glass ribbon via melt spinning 34 2.2. Microstructure characterization 35 2.2.1. Transmission electron microscopy on metallic glass particle 35 2.3. Thermal analysis 36 2.3.1. Differential scanning calorimetry on metallic glass ribbon 36 2.3.2. Thermomechanical analysis on metallic glass ribbon 36 2.4. Mechanical analysis 37 2.4.1. Compression test on metallic glass particle 37 2.4.2. High temperature tensile creep test on metallic glass ribbon 38 Chapter 3. Result and discussion 40 3.1. Effect of size on mechanical properties of metallic glass 40 3.1.1. Compressive deformation behavior of metallic glass particle 43 3.1.2. Size-independent elastic modulus 45 3.1.3. Size-dependent yield strength 48 3.1.4. Size-dependent elastic recovery limit 54 3.1.5. Summary 58 3.2. Effect of size on shear avalanches in metallic glass 59 3.2.1. Stress distribution during plastic deformation of sphere-type specimens 64 3.2.2. Statistical analysis on the size distribution of strain bursts 68 3.2.3. Size-scaling behavior of strain bursts 72 3.2.4. Summary 75 3.3. Effect of intrinsic factor on deformation behavior of nanoscale metallic glass 76 3.3.1. Tuning parameter of critical stress curve: Poissons ratio 77 3.3.2. Tuning parameters of iso-viscosity contour: Activation energy and shear transformation zone volume 79 3.3.3. Tuning parameters and intrinsic properties 81 3.3.4. Intrinsic properties and deformation behavior of nanoscale metallic glass 90 3.3.5. Summary 98 3.4. Effect of extrinsic factor on deformation behavior of nanoscale metallic glass 99 3.4.1. Knock-on displacement by electron beam irradiation 100 3.4.2. Deformation mode transition upon electron beam irradiation inside a transmission electron microscope 103 3.4.3. Summary 107 Chapter 4. Conclusion 108Maste

소고기 고온숙성 시 저선량 전자선 및 X선 조사의 적용

학위논문 (석사)-- 서울대학교 대학원 : 농업생명과학대학 농생명공학부, 2018. 2. 조철훈.The effects of irradiation source (electron beam [EB] and X-ray [XR]), aging temperature (4 °C and 14 °C), and aging time (0, 3, 7, and 14 days) were evaluated on microbial quality, physicochemical properties, and calpain-1 autolysis in beef M. semimembranosus. Regardless of irradiation source, irradiation prior to aging reduced the total number of aerobic bacteria in beef and this reduction was maintained during aging. Irradiation did not affect the pH, b* value, shear force, or myofibrillar fragmentation index of beef at day 0. Degradation of sarcoplasmic and myofibrillar proteins was greater in beef aged at 14 °C compared with beef aged at 4 °C. EB- or XR-irradiated samples showed slower autolysis of calpain-1however, beef tenderness was not affected. Therefore, EB or XR irradiation can be applied to beef prior to aging to control microbial growth during high temperature (14 °C) aging, thus shortening the aging time without adversely affecting the physicochemical properties of beef.Chapter I. Literature review 1 1.1. Meat aging 1 1.1.1. Physicochemical changes during aging 1 1.1.2. Endogenous proteolytic enzymes 3 1.1.3. Dry vs. Wet aging 4 1.1.4. High temperature aging 5 1.2. Irradiation 7 1.2.1. Radiation 7 1.2.2. Food irradiation 8 1.2.3. Mechanism of bacterial inactivation 9 1.2.4. Electron beam vs. X-ray irradiation 11 Chapter II. Application of high temperature aging of beef with low-dose electron beam and X-ray irradiation 2.1. Introduction 12 2.2. Materials and methods 15 2.2.1. Sample preparation and irradiation processing 15 2.2.2. Microbial analysis 16 2.2.3. pH 16 2.2.4. Instrumental color measurement 16 2.2.5. Shear force measurement 17 2.2.6. Myofibrillar fragmentation index (MFI) 17 2.2.7. SDS-PAGE and Western blot 18 2.2.7.1. Preparation of meat extraction 18 2.2.7.2. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) 19 2.2.7.3. Western blot 20 2.2.8. Statistical analysis 21 2.3. Results and discussion 22 2.3.1. Total aerobic bacteria 22 2.3.2. pH 25 2.3.3. Surface color 27 2.3.4. Shear force 30 2.3.5. Myofibrillar fragmentation index (MFI) 33 2.3.6. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) 35 2.3.7. Western blot 38 2.4. Conclusion 40 References 41 Summary in Korean 54Maste

Accuracy and Efficacy of Impedance Cardiography as a Non-Invasive Cardiac Function Monitor

PURPOSE: The most common method of monitoring cardiac output (CO) is thermodilution using pulmonary artery catheter (PAC), but this method is associated with complications. Impedance cardiography (ICG) is a non-invasive CO monitoring technique. This study compared the accuracy and efficacy of ICG as a non-invasive cardiac function monitoring technique to those of thermodilution and arterial pressure contour. MATERIALS AND METHODS: Sixteen patients undergoing liver transplantation were included. Cardiac index (CI) was measured by thermodilution using PAC, arterial waveform analysis, and ICG simultaneously in each patient. Statistical analysis was performed using intraclass correlation coefficient (ICC) and Bland-Altman analysis to assess the degree of agreement. RESULTS: The difference by thermodilution and ICG was 1.13 L/min/m², and the limits of agreement were -0.93 and 3.20 L/min/m². The difference by thermodilution and arterial pressure contour was 0.62 L/min/m², and the limits of agreement were -1.43 and 2.67 L/min/m². The difference by arterial pressure contour and ICG was 0.50 L/min/m², and the limits of agreement were -1.32 and 2.32 L/min/m². All three percentage errors exceeded the 30% limit of acceptance. Substantial agreement was observed between CI of thermodilution with PAC and ICG at preanhepatic and anhepatic phases, as well as between CI of thermodilution and arterial waveform analysis at preanhepatic phase. Others showed moderate agreement. CONCLUSION: Although neither method was clinically equivalent to thermodilution, ICG showed more substantial correlation with thermodilution method than with arterial waveform analysis. As a non-invasive cardiac function monitor, ICG would likely require further studies in other settings.ope