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Effect of αGal on corneal xenotransplantation in a mouse model
Choi, Hyuk Jin,Kim, Mee Kum,Lee, Hyun Ju,Jeong, So Hee,Kang, Hee Jung,Park, Chan‐,Sik,Park, Chung‐,Gyu,Joon Kim, Sang,Wee, Won Ryang Blackwell Publishing Ltd 2011 Xenotransplantation Vol.18 No.3
<P>Choi HJ, Kim MK, Lee HJ, Jeong SH, Kang HJ, Park C‐S, Park C‐G, Kim SJ, Wee WR. Effect of αGal on corneal xenotransplantation in a mouse model. Xenotransplantation 2011; 18: 176–182. © 2011 John Wiley & Sons A/S.</P><P><B>Abstract: </B><B> Background: </B> It has been reported that hyperacute rejection (HAR) does not occur after pig‐to‐nonhuman corneal xenotransplantation. However, considering that immune privilege is already disrupted in most human corneal recipients, and the expression of αGal can be gradually reduced after pig‐to‐rat corneal transplantation, the long‐term survival of corneal grafts from wild‐type pigs cannot be guaranteed. Accordingly, we aimed to investigate the effect of αGal on the change in anti‐Gal antibodies, using sensitized α1,3‐galactosyltransferase gene‐knockout (GTKO) mice recipients.</P><P><B>Methods: </B> C57BL/6 (B6) and GTKO mice were divided into 5 groups and underwent orthotopically full thickness cormeal transplantation as follows (n=4 for each group): (1) group 1: B6 to B6; (2) group 2: fresh porcine posterior corneal lamella to B6; (3) fresh porcine posterior corneal lamella to GTKO; (4) group 4: decellularized porcine posterior corneal lamella to GTKO, and (5) group 5: B6 to GTKO. Before transplantation, all GTKO recipients were sensitized using intraperitoneal injections of rabbit blood cells. Median survival times (MST) for the corneal grafts of the different groups were compared and plasma concentrations of IgG/IgM anti‐Gal antibodies were evaluated at 1 week, 2 weeks and 3 weeks post‐transplantation.</P><P><B>Results: </B> There were no differences in MSTs between groups. Although there was no HAR of fresh porcine posterior corneal grafts even in sensitized GTKO recipients, αGal expression was induced in the transplanted fresh porcine corneal grafts and plasma concentration of IgG anti‐Gal antibody was gradually increased in fresh porcine cornea‐grafted GTKO recipients. On the contrary, αGal expression did not increase in the grafts and plasma concentration of anti‐Gal antibodies did not change after transplantation using decellularized porcine corneas.</P><P><B>Conclusions: </B> Our findings suggest that αGal may affect the long‐term survival of porcine corneal xenografts via antibody‐mediated rejection, although αGal does not have an effect on acute rejection and decellularized porcine corneas may enable the long‐term survival of porcine corneal xenografts.</P>
WiMedia 분산시스템을 위한 이동성 지원 릴레이 전송 프로토콜
위성남 ( Sung Nam Wee ),( Ronesh Asnil Sherma ),이우용 ( Woo Young Lee ),( Tushar Keshav ),박상혁 ( Sang Hyuk Park ),이연우 ( Yeonwoo Lee ),이성로 ( Seong Ro Lee ) 한국정보처리학회 2012 한국정보처리학회 학술대회논문집 Vol.19 No.1
본 논문에서는 UWB 기술 기반 WiMedia Distributed Medium Access Control (D-MAC) 프로토콜에서, 디바이스들의 이동성으로 인해 발생하는 Distributed Reservation Protocol (DRP) 예약 충돌 현상을 분석한다. 그리고 DRP 예약 충돌시 발생하는 성능 저하를 감소시키기 위해 DRP Conflict Resolution 방식과 DRP 릴레이 통신 기술을 제안한다. 본 논문에서 제안하는 DRP 릴레이 통신 프로토콜은 충돌대상 디바이스에게 예약된 자원을 유지할 수 있도록 Direct Link 뿐만 아니라, DRP 예약 충돌 시 릴레이 노드를 경유하여 또 다른 Indirect Link 링크를 빠르게 예약할 수 있는 분산적인 자원 예약 프로토콜을 제안한다.
Wee, Jang Ho,Choi, Yong Sun,Bae, Woong Jin,Kim, Su Jin,Cho, Hyuk Jin,Hong, Sung-Hoo,Lee, Ji Youl,Kim, Sae Woong 대한비뇨기과학회 2012 Investigative and Clinical Urology Vol.53 No.7
<P><B>Purpose</B></P><P>To evaluate the efficacy of photoselective vaporization of the prostate (PVP) with the 120 W Greenlight high performance system (HPS) laser for the treatment of benign prostatic hyperplasia (BPH) with intravesical prostatic protrusion (IPP).</P><P><B>Materials and Methods</B></P><P>This study was conducted on 389 BPH patients who underwent PVP with the 120 W HPS laser from April 2009 to August 2011. The patients were divided into groups according to IPP: group I was defined as IPP of 0 to 5 mm (n=216), group II as IPP of 5 to 10 mm (n=135), and group III as IPP above 10 mm (n=38). Prostate volume, prostate-specific antigen, International Prostate Symptom Score (IPSS), maximal urinary flow rate (Qmax), and postvoid residual volume (PVR) were assessed and checked at postoperative 1, 3, 6, and 12 months.</P><P><B>Results</B></P><P>There was a significant difference in the mean prostate size in each group (p<0.05). The preoperative total IPSS score, IPSS voiding symptom score, and quality of life score were not significantly different. However, the IPSS storage symptom score was significantly different between groups 1 and 2 and group 3. IPSS scores, Qmax, and PVR at postoperative 1, 3, 6, and 12 months showed significant improvement compared with preoperative values.</P><P><B>Conclusions</B></P><P>The degree of IPP can affect storage symptoms. However, there is no significant correlation between the degree of IPP and postoperative results. Also, the degree of IPP does not affect short- and long-term PVP results. Proper elimination of bladder outlet obstruction is important for symptomatic relief.</P>
자발성 피막 파열을 일으킨 안상부 기형종 : 증례보고 Case Report
위성찬,김재휴,김수한,강삼석,이제혁,우정현,정상우 대한신경외과학회 1992 Journal of Korean neurosurgical society Vol.21 No.11
A case of spontaneously ruptured suprasellar teratoma, diagnosed preoperatively by computerized tomography(CT) and magnetic resonance image(MRI), is presented. The patient, a 51-year-old man was hospitalized for headache and focal seizure of left upper extremity since 5 days before admission. The CT scan showed an ill-defined hypodense mass in the suprasellar region and multiple small hypodense lesions in the subarachnoid space and cisterns, which were not enhanced by contrast media. The multiple small lesions in the cisterns seemingly derived from the ruptured tumor showed high signal intensity on T₁WI MRI. During operation the ruptured materials were confirmed to be fat globules and the arachnoid membrane was severely thickened and adhesed
고양이에서 실험적 지주막하 출혈후 혈관활성제에 대한 뇌혈관의 반응성에 관하여
위성찬,심재봉,김재휴,김수한,강삼석,이제혁,백영홍 대한신경외과학회 1992 Journal of Korean neurosurgical society Vol.21 No.11
고양이를 이용하여 대조군(제1군), 인공적 지주막하출혈 시행 3일째(제2군), 7일째(제3군) 및 14일째(제4군)의 뇌기저동맥과 후교통동맥을 절단 적출하여 이 표본들에 대한 KCI, norepinephrine(NE), 5-hydroxytryptamine(5-HT) 및 acetylcholine(ACh)의 영향을 비교 관찰하여 다음과 같은 성적을 얻었다. 1) 상기 4약물은 기저동맥과 후교통동맥표본을 모두 수축시켰고, NE, 5-HT 및 ACh는 양표본을 용량-의존적으로 수축시켰으며, 후교통동맥표본에서의 수축반응이 기저동맥표본보다 유의하게 컸었다. 2) KC1 35mM의 수축반응은 기저동맥표본의 제2군에서 대조군보다 감약되었으나 제3군과 4군에서는 대조군과 차이가 없었으며, 후교통동맥표본에서는 각군에서 대조군과 유의한 차이를 보이지 않았다. 3) 기저동맥표본의 제2군에서의 NE의 수축반응은 대조군의 수축반응보다 감약되어 나타났으나, 제3군과 4군에서의 그것은 대조군과 차이가 없었고, 후교통동맥표본의 NE 수축반응은 여러 실험군간에 유의한 차이가 없었다. 4) 5-HT의 수축반응은 기저동맥표본의 제2군에서는 억제되었으나, 후교통동맥표본의 제2군에서는 증강되었으며, 양표본의 기타 실험군에서의 수축반응은 대조군과 유의한 차이가 없었다. 5) ACh의 수축반응은 기저동맥과 후교통동맥의 양표본에서 제2군에서의 수축반응이 모두 대조군의 그것보다 억제되었고, 기타 실험군에서의 수축반응은 대조군과 차이가 없었다. 이상의 실험결과를 요약하면 지주막하출혈 3일째인 고양이의 기저동맥표본에서는 KCl, NE, 5-HT 및 ACh에 의한 수축반응이 대조군보다 모두 감약되었고, 후교통동맥표본에서는 ACh의 수축반응은 억제되었으나 5-HT의 수축반응은 증강되었으며, 지주막하출혈후 7일 및 14일째에는 4약물의 수축반응이 대조군의 수축반응과 차이가 없었다. 결론적으로 지주막하 출혈에 의한 뇌혈관근의 반응성 변화는 초기(출혈후 3일째)에 현저하며 그 이후에는 점차 원상태로 회복되는 것으로 추론하였다. The effect of subarachnoid hemorrhage(SAH) on the sensitivity of the isolated cat basilar and posterior communicating arteries to vasoactive agents(KCl, norepinephrine : NE, 5-hydroxytryptamine : 5-HT, acetylcholine : ACh) was examined using isometric tension recording method. The SAH was prepared by injecting 3㎖ of fresh autologous arterial blood into cisterna magna after removal of 1.5㎖ cerebrospinal fluid. Forty cats were divided into four groups according to the timing of sacrifice ; control cats, and the operated cats sacrificed on Day 3, 7 and 14 after experimental SAH. In the preparations of the basilar arteries in animals sacrificed on Day 3, the contractile responses to KCl, NE, 5-HT and ACh were significantly weakened compared with the control group. In the preparations of posterior communicating arteries obtained from Day 3, the contractile response to ACh was inhibited but that to 5-HT was enhanced compared with the control groups. No significant contractile responses to above mentioned 4 drugs were observed in arterial rings from both basilar and posterior communicating arteries obtained from Day 7, and 14 when compared with control vessel. These results suggest that change of cerebrovascular reactivity to vasoactive agents in cats is more remarkable in Day 3 and then gradually disappears in the course of SAH.
고혁진 ( Hyuk Jin Ko ),박영석 ( Young S. Park ),위경우 ( Kyeong Woo Wee ),이재현 ( Jae Hyun Lee ) 한국금융학회 2009 금융연구 Vol.23 No.3
신용카드사는 주로 한도관리를 통하여 카드사용자의 채무불이행을 통제한다. 카드사의 입장에서는 한도를 적게 부여하는 것이 잠재적 채무불이행금액을 줄이는데 유리하지만, 카드사용금액이 줄어들어 카드사의 이익을 줄이는 방향으로 영향을 미칠 수 있다. 또한 한도의 증가는 재무적곤경에 처한 카드사용자에게 유동성을 제공하며, 이후 카드사용자의 현금흐름이 개선되면 카드사용자는 채무불이행을 극복하게 된다. 따라서 카드사의 입장에서는 부정적 효과와 긍정적 효과의 상충관계를 고려하여 사용자의 속성에 맞는 적정한도를 찾아내고 이를 기준으로 한도를 부여하는 것이 중요하다. 여기서 적정한도란 카드사용자의 위험속성에 부합하는 한도를 의미한다. 본 연구에서는 카드사용자를 신용등급으로 분류하여 각 계좌의 시점별 적정한도를 추정하여 초과한도(부족한도)를 추정하였고 초과한도가 채무불이행 패턴에 미치는 영향을 분석하였다. 실증 결과 전체적으로 초과한도는 연체를 줄이는 방향으로 영향을 미쳤다. 세부적으로 초과한도는 연체빈도, 연체금액과는 음의관계를, 생존기간과는 양의관계를 나타냈다. 물론 그룹별로 차이가 존재하고 있으나, 이러한 효과는 흥미롭게도 신용도가 낮은 그룹에서 크게 나타났다는 것이다. 최근 국내의 가계채무의 급증은 경기침체 심화에 따른 기대소득의 감소 그리고 대출이자율의 상승과 맞물려 한계가계의 추가자금조달의 필요성을 증가시키기고 있다. 본 연구는 가계자금조달에서 신용한도와 채무불이행과의 관계를 분석한 연구라는 점에서 시의성이 높을 것으로 판단된다. In general, credit card companies control card holders` default by managing their credit limits. It is advantageous for card companies to impose smaller limits to reduce the amount of potential default; however, it may also reduce profits of card companies resulted from downsized card using amount. Besides, the increase of credit limits would provide liquidity to card holders who are in financial distress, serving as a positive platform later for card users to overcome default problem with their improved cash flow. Hence it would be critical for card companies to figure out fair credit limits for each user and impose proper limits coincident with card users` attribute after considering both positive and negative effects of adjusting credit limits. Here, the fair credit limit refers to the one that is in line with the risk attribute of a card user. This study classified card users based on their credit rating and estimated excess limits (deficient limits) after evaluating fair credit limits of each account at a each time. Furthermore, the impact of excess limit on the delinquency patterns was also analyzed in this study. The specific procedure of analysis is as follows: ① After card users were classified into groups based on their risk attribute, the average limits of each group were calculated, and the results were regarded as fair credit limits. ② Excessive limits (deficient limits) were calculated after subtracting average limits from actual limits of each group. ③ Pure excess limits (pure deficient limits) were calculated after the effect of other factors that might influence the excessive limits (deficient limits) calculated in ② was controlled. ④ The impact of pure excessive limits (pure deficient limits) on default was analyzed. Here are the results of the analysis. First, let`s take a look at the impact of each group`s excess limits on delinquency. Overall, pure excessive limits had a negative relation with delinquency, so pure excessive limits contributed to reducing delinquency, influencing positively. The pure excess limits in total limits reduced delinquency in groups with relatively good credit ratings and the pure excessive limits in financial service limits decreased delinquency in groups with bad credit ratings. The relation between excess limits and frequency of delinquency is as follows. As predicted, excess limits had a negative correlation with the frequency of delinquency. In other words, as accounts got more excessive limits on average during the survival length, the accounts underwent less delinquency. The survival length had a positive correlation with excessive limits in all groups. A notable point is that excessive limits in financial service of the grade1 had a negative correlation with the survival length. It is hard to interpret this relation because the grade1 is the one with excellent credit rating. The fact that the best credit group experienced delinquency even with excessive limits could be interpreted as some uncontrollable adverse events happened to the card users. It might be difficult to prolong the survival length by just increasing credit limits to a certain degree. Next, let`s take a look at the impact of excess limits on the delinquent amount in each group. The delinquent amount is important in that it influences the profit and loss of card companies directly. One of the reasons that caused the credit card crisis in 2003 was the excess credit limits given to users, so positive coefficient, in general, was expected. However, it turned out that excluding the grade 4 and 5, the excess limits had a negative relation with the delinquent amount. In particular, the grade 6 that took up most of the delinquent amount with bad credit ratings had a negative relation and the coefficient was the lowest, which is quite notable. Therefore, it is needed for credit card companies to increase the credit limits to a certain level for users with grade6 in an effort to reduce the delinquency amount. Meanwhile, this study also analyzed panel data analysis(fixed effect model) in addition to using pooled OLS method in an attempt to substantiate the result of research further. Also, an analysis using the 2SLS model was added to control endogeneity with pure excess line ratio of previous month as an instrumental variable. As a result, the coefficient varied slightly, but the same signs and significance consistent to those in the pooled OLS came out. Thus, the result of this study is judged to be reliable. Recently, the surge of household debt has led households in marginal state to need more funds, which is also influenced by the rise of loan rates and decrease of expected income stemmed from deepened economic slow-down. According to the result of this study, positive effect of excess limits, which is providing more buffer to financially distressed households to overcome default based on provided liquidity, is bigger than negative effects, which is increasing the default amount. Yet, it should be noted that providing liquidity to users with long-term financial difficulty will make the potential default amount bigger. This study is judged to be timely and proper in that it analyzed the relation between the credit limit and default in household finance, which hasn`t been studied in depth so far.