• Parasites, Hosts and Diseases
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• 제31권1호
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• pp.21-30
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• 1993

간흡충은 담관암 발생의 원인적 요소로 알려졌다. 그러나 간흡충이 담관암을 일으키는 병리 기전은 자세하게 알려져 있지 않다. 본 연구는 15 ppm의 dimethylnitrosamine(DMN)을 먹는 물로 투여한 햄스터에 간흡충을 감염시켜 담관암의 발생여부를 알아보고 담관암의 병리조직학적 변화를 관찰하고자 하였다. DMN을 투여하고 간흡충을 감염시킨 챔스터에서 11주 후에 8마리 중 6마리가 육안적 혹은 조직학적으로 담관암(cholangiocarcinoma)의 소견을 보였으며 나머지 2마리는 담관종(cholangiofibroma)으로 진단할 수 있었으나 부분적으로 악성적인 모습도 관찰 할 수 있었다. 담관암의 병리조직학적 소견은 담관상피세포가 선종상 혹은 유두상의 증식을 나타내고 높은 이형성을 보였으며 점액세포화생과 괴사소를 보이고 있었다. DMN 만을, 혹은 간흡충만을 투여하거나 감염시킨 햄스터들에서는 담관암이 전혀 발생되지 않았다. 본 .실험은 DMN을 투여한 햄스터에 간흡충감염으로 담관암이 발생하는 과정에서 DMN과 간흡충의 협동작용(synergism)을 보여준 것으로 추정한다.

• Toxicological Research
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• 제17권
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• pp.79-82
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• 2001

The infection of liver flukes, Clonorchis sinensis (CS) and Opisthorchis viverrini (OV), has been known as a risk factor to induce cholangiocellular carcinoma (CCC) in human living in the endemic area, providing promoting effect on the liver initiated by chemical carcinogens. The present study evaluated the relationship between the dosage level of dimethylnitrosamine (DMN) and the infection load of CS in the neoplastic development by histopathological examination of the treated hamsters. To evaluate the effects of DMN, different doses of DMN ranging from 0 to 25 ppm were administered to hamsters with 20 CS metacercariea. For the risk assessment of the infection load, 0, 5, 15, 50 CS metacercariae were respectively infected with 12 ppm DMN. The mortality was closely related to the infection load rather than the concentration of DMN. The infection of CS clearly promoted the induction of CCC even at dose level of 6 ppm DMN. Only five metacercariae were enough to promote CCC induction at the concentration of 12 ppm DMN.

• 정보과학회 논문지
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• 제44권1호
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• pp.51-56
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• 2017

질의응답 문제를 인공지능 모델을 통해 해결하는 연구는 메모리 네트워크의 등장으로 인해 방법론의 변화를 맞이하고 있으며, 그 중 동적 메모리 네트워크(DMN)는 인간 기억 체계에 착안하여 신경망 기반의 주의 기제를 적용하면서, 질의응답에서 일어나는 각 인지 과정들을 모듈화 했다는 특징들을 갖는다. 본 연구에서는 부족한 학습 데이터를 확장 시키고, DMN이 내포하고 있는 시간 인식의 한계를 개선해 정답률을 높이고자 한다. 실험 결과, 개선된 DMN은 1K-bAbI 문제의 테스트 데이터에서 89.21%의 정답률과, 95%를 질의응답 통과의 기준의 정답률으로 가정할 때 12개의 과제를 통과하는 성능을 보여 정확도 면에서 기존의 DMN에 비해 13.5%p 만큼 더 높고, 4개의 과제를 추가로 통과하는 성능 향상을 보여주었다. 또한 뒤이은 실험을 통해, 데이터 내에서 비슷한 의미 구조를 가지는 단어들은 벡터 공간상에서 강한 군집을 이룬다는 점과, 일화 기억 모듈 통과 횟수와 근거 사실 수의 성능에 큰 영향을 미치는 직접적인 연관성을 발견하였다.

• 폴리머
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• 제25권1호
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• pp.25-32
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• 2001

${\circ}C$ 범위에서 아연과 망간촉매를 사용하여 에스테르 교환반응시켜 반응속도를 살펴보았다. 반응은 반회분식 반응기에서 비등온 조건으로 진행되었고 반응온도와 메탄올 유출량으로 반응성을 평가하였다. 반응모델로서는 관능기 모델과 분자종 모델을 적용하여 상호 비교하였다. 아연촉매를 사용할 경우 DMN과 EG의 반응속도는 methyl hydroxyethyl naphthalate(MHEN)와 EG의 반응속도에 비해 1.4배정도 였으나 망간촉매를 사용할 경우 4.3배정도로 촉매 종류에 따라 반응성이 크게 차이가 있음을 알 수 있었다. 아연촉매의 경우 DMN 및 MHEN과 EG의 반응에 대한 촉매농도의 반응차수는 1보다 작았으나, 망간촉매의 경우 오히려 1보다 컸다. 활성화에너지는 DMN과 MHEN의 분자종 차이에 관계없이 아연과 망간촉매의 경우 각각 25000, 28750 cal/mol이었다. 두 가지 반응모델을 비교하여 본 결과 분자종 모델이 반응현상을 잘 표현함을 알 수 있었다.

• Biomolecules & Therapeutics
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• 제16권3호
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• pp.243-248
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• 2008

In the present study, we investigated activity change of sphingomyelin anabolic enzymes such as sphingomyelin synthase and ceramide synthase. Sprague-Dawley male rats treated with 10 mg/kg of DMN intraperitoneally were used as a hepatic fibrosis model. Sphingomyelin synthase and ceramide synthase activities were measured in 1-week, 2-week, 3-week and 4-week DMN-treated rats along with respective control group rats. We found the increased sphingomyelin synthase activity in 4-week DMN-treated liver but not in kidney. Ceramide synthase activity was significantly increased in DMN-treated kidney after 2-week treatment and in DMN-treated liver after 3-week treatment. Although further investigation is necessary to elucidate meanings of sphingolipid metabolites during the liver fibrosis, activity change of sphingolipid anabolic enzymes may imply that sphingolipid metabolism and sphingolipid metabolites could be involved in liver fibrosis especially under oxidative stress.

• 생약학회지
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• 제34권1호통권132호
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• pp.60-64
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• 2003

Solanum lyratum(Solanaceae) has been used as a traditional analgesic, antipyretic and hepatoprotective agents in Korea. In this study, we investigated the hepatoprotective effect of ethylacetate extract of Solanum lyratum (SL) on the dimethylnitrosamine (DMN)-induced liver damage in rats. Oral administration of SL (150, 300 mg/kg daily for 4 weeks) into the DMN-treated rats remarkably prevented the elevation of serum alanine transaminase, aspartate transaminase and alkaline phosphatase levels. SL also increased serum protein level and reduced the hepatic level of malondialdehyde in DMN-treated rats. Furthermore, DMN-induced elevation of hydroxyproline content was reduced by the treatment of SL. In conclusion, these results demonstrated that SL exhibited in vivo hepatoprotective effect against DMN-induced liver injury, and suggest that SL may be useful in the prevention of liver damage.

• 생약학회지
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• 제28권4호
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• pp.215-224
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• 1997

Gamijiyu-tang (GJT) described originally in the Dong Eui Bo Gam, a traditional reference for oriental medicine in the Korea, has been clinically used for treatment of chronic liver disease. In order to evaluate scientifcally a hepatoprotective effect of GJT in the liver fibrotic disease, the present study investigated how GJT improves a hepatic function in the dimethylnitrosamine (DMN)-treated rat. DMN treatment caused a significant increase of relative liver weight to the body at 28 days after DMN induction. Administration of with a clinical dose decreased significantly the sAST level $(158.8{\pm}7.76\;IU/L)$ elevated by DMN in jection (p<0.01). A similar phenomenon was also observed at change of both Salt and Salt level in the GJT and/or DMN-treated animal (p<0.01, p<0.05, respectively). A remarkable increase of hydroxyproline was observed by treatment of DMN with comparing to the normal rat $(361.9{\pm}7.35\;vs.\;1278.1{\pm}52.9\;{\mu}g/g\;tissue,\;p<0.01)$. This was significantly reduced by a simultaneous treatment of GJT with DMN for 21 days (p<0.05), but not recovered completely to its normal value. In addition. GJT administration ameliorated conspicuously the DMN-induces histopathological changes of liver such as hemorrhage. Cell necrosis and fibrosis. Tak'en together, results described here demonstrated scientifically in first the medicinal efficacy of GJT by using in vivo animal model, indicating that GJT improves the DMN-induced hepatic injury through reducing an excessive accumulation of collagen and histopathological changes. The decreased collagen content may be a pivotal process for GJT to improve hepatic function in the DMN-induced liver fibrosis. The present study suggests that GJT may be useful for and applicable to the treatment of hepatic fibrosis in chronic liver disease.

• 분석과학
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• 제7권2호
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• pp.165-171
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• 1994

화학 발암제인 dimetylnitrosamine(DMN)을 Hamster에 구강투여하였을 때 간의 아미노산 조성에 미치는 영향을 규명하기 위하여 reversed phase liquid chromatography법으로 아미노산을 정량하였다. DMN을 투여한 실험군의 간에서의 아미노산의 농도는 대조군에 비해 aspartic acid, glycine, glutamine, histidine, proline, tyrosine, leucine 등은 약 2배, valine, tryptophan은 약 3배, phenylalanine은 약 10배 증가하였고, threonine은 23%로 감소하였으며, serine, alanine, arginine, methionine, isoleucine, lysine은 큰 변화가 없었다.

• Toxicological Research
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• 제26권3호
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• pp.193-201
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• 2010

Hepatic fibrosis represents the main complication of most chronic liver disorders and, regardless of its etiology, is characterized by excessive deposition of extracellular matrix components. In this study, we examined that 1-O-Hexyl-2,3,5-Trimethylhydroquinone (HTHQ), a potent anti-oxidative agent, could prevent experimental hepatic fibrosis induced by dimethylnitrosamine (DMN) in male SD rats. Except for vehicle control group, other groups were induced hepatic fibrosis by intraperitoneal injection with DMN (10 mg/ml/kg) on 3 consecutive days weekly for 4 weeks. During the same 4 weeks, control and DMN groups were given vehicle and HTHQ 50, 100 and 200 groups were orally administered HTHQ (50, 100, 200 mg/kg respectively). In HTHQ 100 and 200 groups, relative liver weight and serum chemistry level improved significantly. HTHQ reduced hydroxyproline (p < 0.05) and malondialdehyde (p < 0.05) level in the liver. Histopathological examination of H&E, Masson's trichrome stain showed the reduced fibrotic septa in HTHQ 100 and 200 groups. HTHQ administration showed reduced mRNA level of PDGF (Platelet-derived growth factor), $\alpha$-SMA ($\alpha$-smooth muscle actin) and TGF-$\beta$ (transforming growth factor-$\beta$) than DMN-induced hepetic fibrosis animals in the liver tissue. In this study, we showed that HTHQ improves against DMN-induced liver fibrosis in male SD rats.

• 대한불안의학회지
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• 제14권2호
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• pp.63-70
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• 2018

It has been suggested that aberrant self-referential processing (SRP) is one of the important components of the explanatory models of social anxiety disorder (SAD). The default mode network (DMN), which reflects intrinsic brain functions, is known to play a critical role in SRP. Recently, resting state functional magnetic resonance imaging (fMRI) research on the functional connectivity in the brain network has gained greater attention as a tool to elucidate the neurobiological basis of various psychiatric disorders. We reviewed resting state fMRI studies that investigated the resting state functional connectivity (RSFC) of the DMN in SAD. Despite of the heterogeneity of the analytic methods and occasional negative findings, most studies consistently reported abnormalities of RSFC within the DMN, suggesting that the DMN may be significant neural correlates of aberrant SRP in SAD. Also, changes in RSFC of the DMN are associated with clinical improvements of therapeutic interventions. Moreover, emerging findings provide the basis for potential use of RSFC as a complementary method in diagnosis of SAD. Ongoing and future research to investigate RSFC of the DMN could broaden our understanding regarding the neurobiological basis of SAD, and contribute to the development of novel treatments for SAD.