• Molecules and Cells
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• 제25권3호
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• pp.358-367
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• 2008

The embryonic germ cell (EGCs) of mice is a kind of pluripotent stem cell that can be generated from pre- and post-migratory primordial germ cells (PGCs). Most previous studies on DNA methylation of EGCs were restricted to 12.5 days post coitum (dpc). This study was designed to establish and characterize murine EGC lines from migrated PGCs as late as 13.5 dpc and to estimate the degrees of methylation of their imprinted genes as well as of the non-imprinted locus, Oct4, using an accurate and quantitative method of measurement. We established five independent EGC lines from post migratory PGCs of 11.5-13.5 dpc from C57BL/6 ${\times}$ DBA/2 F1 hybrid mouse fetuses. All the EGCs exhibited the typical features of pluripotent cells including hypomethylation of the Oct4 regulatory region. We examined the methylation status of three imprinted genes; Igf2, Igf2r and H19 in the five EGC lines using bisulfite genomic sequencing analysis. Igf2r was almost unmethylated in all the EGC lines irrespective of the their sex and stage of isolation; Igf2 and H19 were more methylated than Igf2r, especially in male EGCs. Moreover, EGCs derived at 13.5 dpc exhibited higher levels of DNA methylation than those from earlier stages. These results suggest that in vitro derived EGCs acquire different epigenotypes from their parental in vivo migratory PGCs, and that sex-specific de novo methylation occurs in the Igf2 and H19 genes of EGCs.

• 한국동물생명공학회지
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• 제35권1호
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• pp.42-49
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• 2020

As a preclinical study, many researchers have been attempted to convert the porcine PSCs into several differentiated cells with transplantation of the differentiated cells into the pigs. Here, we attempted to derive neuronal progenitor cells from pig embryonic germ cells (EGCs). As a result, neuronal progenitor cells could be derived directly from pig embryonic germ cells through the serum-free floating culture of EB-like aggregates (SFEB) method. Treating retinoic acid was more efficient for inducing neuronal lineages from EGCs rather than inhibiting SMAD signaling. The differentiated cells expressed neuronal markers such as PAX6, NESTIN, and SOX1 as determined by qRT-PCR and immunostaining. These data indicated that pig EGCs could provide valid models for human therapy. Finally, it is suggested that developing transgenic pig for disease models as well as differentiation methods will provide basic preclinical data for human regenerative medicine and lead to the success of stem cell therapy.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.783-788
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• 2005

This document provides the concerning information of the MEPC Committee and DE sub-Committee of International Maritime Organization in accordance with enforcement of an International Air Pollution Prevention Certificate at May 19 2005years.

• 한국항해항만학회지
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• 제40권1호
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• pp.1-6
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• 2016

본 연구에서는 선박에서 발생하는 대기오염물질을 처리하기 위해 사용되는 습식 스크러버를 이용한 배기가스 세정시스템(EGCS: Exhaust Gas Cleaning System)에서 발생되는 폐수를 재이용 할 수 있는 순환시스템을 개발하기 위해 진행되었다. 선박 배기가스 DePM, DeSOx 순환처리장치 (Recycle system)의 세정수의 입자성물질과 분산유를 효과적으로 제거할 수 있는 수 처리 시스템을 개발한 결과 원심분리형 Purifier만으로는 미세한 분산유의 처리가 어렵다는 결과가 도출되어 원심분리형 Purifier 후처리로 유수분리 경사 분리판을 이용한 유수분리기의 일종인 Coalescer를 본 시스템에 적용하였다. Coalescer는 2차 분산 상태의 에멀젼화 된 미세 기름입자를 합착시켜 분리하는 기술이다. 선박 배기가스 DePM, DeSOx 순환처리장치 (Recycle system)에서 배출되는 세정수를 Purifier와 Coalescer를 이용하여 처리한 결과 입자성물질은 55% 분산유는 유입수 대비 99%이상 처리되는 것을 확인하였다. 따라서 선박 대기오염 저감을 위한 습식세정탑 시스템에 본 세정수 처리시스템을 도입하면 세정수로서 재사용이 가능하다고 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.2164_2165
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• 2009

가로등 지중전선로에서의 누전차단기는 일정상당의 대지정전용량 및 누설전류증가로 인한 오동작때문에 정전을 발생시켜 많은 민원을 야기하였다. 본 연구는 사용장소별 5~35[V]이내에서 설정값에 따라 전압을 감지하여 제어부를 차단하도록 하고 가로등이나 기계기구에 연결되는 전선로는 누설전류(15~200[mA])값을 1[mA]단위로 사용여건에 따라 조정 할 수 있는 전압감지식 누전차단기의 설치시 동작에 대한 것이다. 동작시험 결과 설정값에 따라 잘 조정되었고 대지정전용량 이나 영상 분전류의 영향을 받지 않았다. 국제 안전전압 25[V](50[mA])와 우리나라 15[V](30[mA])이하에서도 사용할 수 있으며 최소 5[V], (10[mA])에서 오동작 없이 잘 동작하여 고차단 안전차단장치임을 확인하였다.

• 한국동물생명공학회지
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• 제34권3호
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• pp.139-147
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• 2019

Stem cells are progenitor cells that are capable of self-renewal and differentiation into various cells. Especially, pluripotent stem cells (PSCs) have in vivo and in vitro differentiation capacity into three germ layers and can proliferate infinitely. The differentiation ability of PSCs can be applied for regenerative medicine and tissue engineering. In domestic animals, their PSCs have a potential for preclinical therapy as well as the production of transgenic animals and agricultural usage such as cultured meat. Among several domestic animals, a pig is considered as an ideal model for biomedical and agricultural purposes mentioned above. In this reason, studies for pig PSCs including embryonic stem cells (ESCs), embryonic germ cells (EGCs) and induced pluripotent stem cells (iPSCs) have been conducted for decades. Therefore, this review will discuss the history of PSCs derived from various origins and recent progress in pig PSC research field.

• Journal of Gastric Cancer
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• 제21권1호
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• pp.4-15
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• 2021

Recently, endoscopic screening systems have enabled the diagnosis of gastric cancer in the early stages. Early gastric cancer (EGC) is typically characterized by a shallow invasion depth and small size, which can hinder localization of EGC tumors during laparoscopic surgery. Here, we review nine recently reported tumor localization methods for the laparoscopic resection of EGCs. Preoperative dye or blood tattooing has the disadvantage of spreading. Preoperative 3-dimensional computed tomography reconstruction is not performed in real time during laparoscopic gastrectomy. Thus, they are considered to have a low accuracy. Intraoperative portable abdominal radiography and intraoperative laparoscopic ultrasonography methods can provide real-time feedback, but these methods require expertise, and it can be difficult to define the clips in some gastric regions. Despite a few limitations, intraoperative gastrofibroscopy provides real-time feedback with high accuracy. The detection system using an endoscopic magnetic marking clip, fluorescent clip, and radio-frequency identification detection system clip is considered highly accurate and provides real-time feedback; we expect a commercial version of this setup to be available in the near future. However, there is not yet an easy method for accurate real-time detection. We hope that improved devices will soon be developed and used in clinical settings.

• Journal of Gastric Cancer
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• 제22권1호
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• pp.24-34
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• 2022

Purpose: Total gastrectomy (TG) with lymph node (LN) dissection is recommended for early gastric cancer (EGC) but is not indicated for endoscopic resection (ER). We aimed to identify patients who could avoid TG by establishing a scoring system for predicting lymph node metastasis (LNM) in proximal EGCs. Materials and Methods: Between January 2003 and December 2017, a total of 1,025 proximal EGC patients who underwent TG with LN dissection were enrolled. Patients who met the absolute ER criteria based on pathological examination were excluded. The pathological risk factors for LNM were determined using univariate and multivariate logistic regression analyses. A scoring system for predicting LNM was developed and applied to the validation group. Results: Of the 1,025 cases, 100 (9.8%) showed positive LNM. Multivariate analysis confirmed the following independent risk factors for LNM: tumor size >2 cm, submucosal invasion, lymphovascular invasion (LVI), and perineural invasion (PNI). A scoring system was created using the four aforementioned variables, and the areas under the receiver operating characteristic curves in both the training (0.85) and validation (0.84) groups indicated excellent discrimination. The probability of LNM in mucosal cancers without LVI or PNI, regardless of size, was <2.9%. Conclusions: Our scoring system involving four variables can predict the probability of LNM in proximal EGC and might be helpful in determining additional treatment plans after ER, functioning as a good indicator of the adequacy of treatments other than TG in high surgical risk patients.

• Journal of Gastric Cancer
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• 제24권2호
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• pp.199-209
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• 2024

Purpose: Long-term outcomes of patients with positive lateral margins (pLMs) after endoscopic submucosal dissection (ESD) for early gastric cancer (EGC). This study aimed to evaluate the remnant cancer and survival rates of patients with pLMs compared with those who underwent curative resection. Materials and Methods: A retrospective analysis was performed on consecutive patients with pLMs as the only non-curative factor of expanded indication who underwent ESD for EGC with a follow-up duration of 5 years or more. The rates of remnant cancer, recurrence, and survival were analyzed and compared to those of control patients who underwent curative resection by propensity score matching. Results: Among 3,515 patients treated with ESD between 2005 and 2018, 123 non-curative EGCs were retrospectively analyzed. A total of 108 patients were followed up without endoscopic or surgical resection for 8.2 years. The control group was matched in a 1:1 ratio with patients with EGC who underwent curative resection after ESD. The observation group with pLMs had a higher incidence of remnant cancer (25.9%; 28/108) compared to that in the curative resection group (0/108; P=0.000). The remaining tumors were treated with surgical or endoscopic resection, and no additional recurrences were observed. The overall survival analysis demonstrated no significant difference between the observation and curative resection groups (P=0.577). Conclusions: No difference was observed in the overall survival rate between observation and curative resection groups. Therefore, observation may be a possible option for incomplete ESD with pLMs if continuous follow-up is performed.

• Journal of Gastric Cancer
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• 제1권1호
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• pp.55-59
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• 2001

Purpose: Several studies of an endoscopic mucosal resection(EMR) have been reported, but reports about benign protruding lesions that arise at the scar of EMR for early gastric cancer (EGC) or a gastric adenoma are rare. The purpose of this study was to elucidate endoscopic and histological characteristics of benign protruding lesions which arise at the scar of an EMR for EGC and a gastric flat adenoma. Materials and Methods: In 101 lesions (73 gastric flat adenomas and 28 EGCs) from 96 patients, 16 lesions developed new protruding lesions that arose at the scar of the EMR. We retrospectively analyzed the endoscopic findings of initial and protruding lesions, and several other clinical factors (H. pylori infection, eradication therapy, and proton pump inhibitor (PPI) or H2-blocker use). Results: 1. The mean duration until detection of the protruding lesion was 8.9 months ($1.5\∼27$). Protruding lesions arose at the scar of the EMR in 1 of 28 EGCs ($3.6\%$) and from 15 of 73 gastric flat adenomas ($20.5\%$). All of the patients were men. 2. With respect to the endoscopic findings, the shapes of the protruding lesions were as follows: 10 Yamada (Y) I, 4 Y-II, 1 Y-III, and 1 flat lesion. Histological examination of the protruding lesions revealed regenerating hyperplasia in 5 lesions, intestinal metaplasia in 5, and both in 6. 3. The incidence of these lesions was higher in cases of tubular adenomas with focal high-grade dysplasia than in cases of tubular adenomas without dysplasia (p<0.05). 4. The incidence of H. pylori infection was higher in patients ($81.7\%$) who developed a protruding lesion than in those ($51.8\%$) who did not develop (p=0.029); also, the incidence of use of PPI was higher in those patients (p=0.045). However, eradication therapy for H. pylori and duration of use of PPI or H2-blocker showed no difference between groups. Conclusions: It may be possible that the potential hyperplasia that may reside in normal mucosa surrounding EGC or a gastric adenoma might awaken during the healing process of the EMR ulcer and develop to benign protruding lesions. And, H. pylori and PPI might also be related to the development of the protruding lesions.