• Molecular & Cellular Toxicology
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• 제1권3호
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• pp.164-171
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• 2005

Toxicological studies have an object of detecting adverse effects of a chemical on an organism based on observed toxicity marker (i.e., serum biochemical markers and chemical-specific gene expression) or phenotypic outcome. To date, most toxicogenomic studies concentrated on hepatic toxicity. cDNA microarray analysis enable discrimination of the responses in animals exposed to different classes of hepatotoxicants. In an effort to further characterize the mechanisms of 2, 3, 7, 8,-Tetrachlorodibenzo-p-dioxin (TCDD or dioxin)-mediated toxicity, comprehensive temporal-responsive microarray analyses were performed on hepatic tissue from Sprague-Dawley rats treated with TCDD. Hepatic gene expression profiles were monitored using custom DNA chip containing 490 cDNA clones related with toxicology. Gene expression analysis identified 26 features which exhibited a significant change. In this study, we observed that the genes related with oxidative stress in rats exposed to Dioxin, such as CYPIIA3 and glutathione S-transferase, were up-regulated at 24hr after exposure. In this study, we carried out to discover novel evidence for previously unknown gene expression patterns related to mechanism of hepatic toxicity in rats exposed to dioxin, and to elucidate the effects of dioxin on the gene expression after exposure to dioxin.

• Toxicological Research
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• 제34권4호
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• pp.291-296
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• 2018

Chemical carcinogenesis is a multistep process. Genotoxic carcinogens, which are DNA-reactive, induce DNA adduct formation and genetic alterations in target cells, thereby generating mutated cells (initiation). Subsequently, preneoplastic lesions appear through clonal proliferation of the mutated cells and transform into tumors (promotion and progression). Many factors may influence these processes in a dose-dependent manner. Therefore, quantitative analysis plays an important role in studies on the carcinogenic threshold of genotoxic carcinogens. Herein, we present data on the relationship between key carcinogenic events and their deriving point of departure (PoD). Their PoDs were also compared to those of the carcinogenesis pathway. In an experiment, the liver of rats exposed to 2-amino-3,8-dimethylimidazo-(4,5-f)quinoxaline (MeIQx) was examined to determine the formation of MeIQx-DNA adducts, generation of mutations at LacI transgene, and induction of preneoplastic glutathione S-transferase placental form (GST-P)-positive foci and tumors (benign and malignant). The PoDs of the above key events in the carcinogenicity of MeIQx were increased as the carcinogenesis advanced; however, these PoDs were lower than those of tumor induction. Thus, the order of key events during tumor induction in the liver was as follows: formation of DNA adducts ${\ll}$ Mutations ${\ll}$ GST-positive foci (preneoplasia) ${\ll}$ Tumor (adenoma and carcinoma). We also obtained similar data on the genotoxic and carcinogenic PoDs of other hepatocarcinogens, such as 2-amino-3,8-dimethylimidazo(4,5-f)quinoline. These results contribute to elucidating the existence of a genotoxic and carcinogenic threshold.

• 한국환경성돌연변이발암원학회지
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• 제16권2호
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• pp.109-116
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• 1996

To study the effect of dietary $\omega 6/\omega 3$ fatty acid ratios on the preneoplastic lesions and lipid peroxidation in rat hepatocellular chemical carcinogenesis, placental glutathione S-transferase(GST-P) positive foci area and numbers, glucose 6-phosphatase(G6Pase) activity, thiobarbituric acid reactive substances (TBARS) were measured. Male Sprague-Dawley rats were fed 5 different diets-low $\omega 6/\omega 3$ ratio with fish oil (Low-F), low $\omega 6/\omega 3$ ratio with perilia oil(Low-P), moderate ratio with perilia oil(Moderate), blend of 10 different commercial fats and oils(High-BL) and high $\omega 6/\omega 3$ ratio(High)-for 8 weeks. Hepatocarcinogenesis was induced by modified Ito model. The area of GST-P positive loci was the lowest in Moderate group and in ascending order of Low-F < Low-P < High-BL < High. But statistically, only Moderate and High groups were significantly different. The number of GST-P positive foci showed the same trend as foci area. The activities of G6Pase, membrane stability marker, were increased as $\omega 6/\omega 3$ ratio decreased. Lipid peroxidation values (TBARS) were the lowest in Low-F group and it is significantly different from Moderate, High-BL and High groups. When dietary $\omega 6/\omega 3$ ratio was moderate(4.06), hepatocarcinogenesis was suppressed compared with high or low $\omega 6/\omega 3$ ratios. Blend fat, commonly consumed among Koreans, did not show any suppressive effect on carcinogenesis because of high ratio(6.7). These results suggest that dietary $\omega 6/\omega 3$ ratio influences hepatocellular chemical carcinogenesis. It is recommended that appropriate $\omega 6/\omega 3$ ratio should be around 4.0. and we recommend to use more $\omega 3$ fatty acid in food preparation to reduce the risk of hepatocarcinogenesis.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.191-191
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• 1994

본 연구는 D-galactosamine을 이용한 중기발암성 모델에서 세포성면역중의 하나인 natural killer (NK) 세포활성과 c-myc 종양단백의 발현을 알아보기 위하여 실시하였다. 수컷 6주령의 SPF SD랫드 50마리를 3개군으로 각 군당 20마리씩 나누어 배치하였다. 실험 0일에 제 1,2 군에서 DEN을 복강내로 체중 kg당 200mg 1회 투여하여 발암유발을 하였으며 대조군인 제 3군에는 saline을 투여하였다. 제 2주에 제 1군에는 강력한 발암촉진물질인 2-acetylaminofluorene (AAF)을 사료에 0.01% 투여하였으며, 제 2군은 미약한 발암촉진물질인 phenobarbital (PB)을 0.05%로 음수에 6주간 투여하였다 제 8, 15, 36주에 경시적으로 부검하였다. 제 8주에 부검시 GST-P$^{+}$ 병변이 잘 유도되어 전암병변의 유도가 잘 되었음을 확인하였다. 제 15주에 부검시 AAF를 투여한 군에서 glutathione S-transferase placental form (GST-p)에 대한 면역조직화학적 염색에서 AAF와 PB를 투여한 제 1군 및 제 2군의 간장에서는 주위조직과 한계가 명료한 GST-P$^{+}$ 증식성 결절과 병소를 관찰할 수 있었으나 기초 사료만을 투여한 제 3군은 어떠한 GST-P$^{+}$ 증식성 결절 및 병소를 관찰할 수 없었다. 랫드에서 natural killer세포는 사람이나 마우스에서 주로 자연살생능 (natural killing activity)을 보이는 LGL(lure granular lymphocyte)의 형태를 띄고 있었으며 LGL 이라고 부르는 것처럼 특징적으로 세포질 대 핵의 비율이 높고 azurophilic 과립을 세포질내에 함유하고 있으며 일반적으로 신장 형태의 핵을 가지고 있었다. 또한 세포의 크기는 small lymphocyte와 대식세포 (macrophage)의 중간 크기였다. 15주와 시험종료시 정상대조군인 제 3군의 랫드로 부터 분리한 NK 세포활성도 (% cytotoxicity)에 비하여 발암물질 투여군의 NK 활성도는 PB 투여군들의 NK활성도 보다 약간 낮았다. 랫드에서 c-myc 종양단백은 65KD 와 671KD 에서 band가 형성된 것이 관찰되었다. 시험 개시후 15주에 부검한 랫드의 간에서 c-myc 종양단백의 발현은 모든 처리군들이 대조군에 비하여 높게 발현되는. 것이 관찰되었으나 시험개시후 26주에 부검한 랫드의 간에서 c-myc 종양단백의 발현은 대조군에 비하여 차이가 거의 없었다. 따라서 랫드에서 화학적으로 유도한 간암발생 과정에서 NK 세포활성이 현저하게 억제되는 것으로 생각되며, c-myc 종양단백의 발현은 시험개시후 15주에 그 발현이 확실한 것으로 사료되어 진다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1994년도 춘계학술대회 and 제3회 신약개발 연구발표회
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• pp.339-339
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• 1994

It has been reported that Indole-3-carbinol (I3C), a naturally occurring compound In cruclferous vegetables, exerts anticarcinogenic activity In several organs In rodents. The modifying effects of I3C were therefore assessed uging a rat multi-organ carcinogenesis model. A total of 100 male Sprague-Dawley rats were divided Into 3 groups. Animals of groups 1 and 2 were sequentially treated with diethylnitrosamine (DEN; 100 mg/kg b.w., i.p.), N-methylnitrosourea (NNU; 20 mg/kg b.w., 4 times for 2 weeks, i.p), and dihydroxy-di-N-propylnitrosauine (DHPN; 0.1% In d.w. for 2 weeks) for 4 weeks (DMD treatment). Animals of groups 1 and 3 were given the diet of 0.25% I3C for 20 weeks after DMD initiation and then were given basal diet for 28 weeks. All animals were sacrificed at week 24 and 52, respectively. I3C has been clearly demonstrated promoting effects on the development of glutathione S-transferase placental form (GST-P) positive hepatic foci at 24 weeks of the experiment. And I3C also exerted promoting potential In the hepatocellular adenoma (4/14; 29%) and the adenoma (7/14; 50%) of the thyroid gland at 52 weeks of the experiment. Therefore, I3C may promote hepatocarcinogenesis and thyroid tumorigenesis in the rat multi-organ carcinogenesis model.

• BMB Reports
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• 제34권1호
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• pp.80-84
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• 2001

The human papillomavirus E7 protein can form a specific complex with a retinoblastoma tumor suppressor gene product (p105-Rb) that results in the release of the E2F transcription factor, which is critical for the growth-deregulation and transforming properties of the viral E7 oncoprotein. In an attempt to apply interaction between the E7 oncoprotein and a target cellular protein Rb for an in vitro screening system for drugs against human papillomavirus infection, we primarily investigated the E7Rb binding through a pull down assay and enzyme-linked immunosorbent assay. The pull down assay showed that both glutathione S-transferase-tagged E7 and His-tagged E7 immobilized on resins specifically produced complexes with bacterially expressed Rb in a dose-dependent manner, as determined by immunoblot analyses. This result coincided with that of an enzyme-linked immunosorbent assay, which is a useful system for the mass screening of potential drugs. Taken together, this screening system (based on the interaction between E7 and Rb) can be a promising system in the development of drugs against cervical cancers caused by human papillomavirus infection.

• BMB Reports
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• 제31권4호
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• pp.370-376
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• 1998

Src-Homology 2 (SH2) domains have a capacity to bind phosphotyrosine-containing sequence context and play essential roles in various cellular signaling pathways. Due to the specific nature of the binding between SH2 domains and their counterpart proteins, inhibitors of SID domain binding have drawn extensive attention as a potential candidate for therapeutic agents. Here, we describe the binding assay system to screen for the ligands or blockers of the SH2 domains with an emphasis on the $p56^{lck}$ SH2 domain. In our assay system, SID domains expressed and purified as fusion proteins to Glutathione-S-transferase (GST) were covalently attached to 96-well microtitre plates through amide bond formation, which were subsequently allowed to bind the biotinylated phosphotyrosine (pY)containing synthetic pep tides. The binding of biotinylated pY peptides was detected by the horseradish peroxidase (HRP)-conjugated streptavidin. Using the various combinations of SH2 domain-pY peptides, we observed that: (1) The binding of pY-peptides to its counterpart SH2 domain is concentration-dependent and saturable; (2) The binding is highly specific for a particular combination of SH2 domain-pY peptide pair; and (3) The binding of Lck SH2-cognate pY-peptides is specifically competed by the nonbiotinylated peptides with expected relative affinity. These results indicate that the established assay system detects the SH2-pY peptide interaction with reproducible sensitivity and specificity and is suitable for screening the specific inhibitors of $p56^{lck}$ SH2 function.

• Applied Biological Chemistry
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• 제36권1호
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• pp.64-69
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• 1993

참잉어에 대한 해독효소 활성을 협력작용을 갖는 농약을 공시하여 조사하였고 잉어의 각 조직별 효소활성도 조사하였다. 협력작용을 갖는 약제의 독성증가에 따른 효소활성은 carboxylesterase와 GST 모두 준치사 농도에서는 활성의 증가를 보였으나 독성이 증가함에 따라 활성이 감소하였다. Carboxylesterase의 활성은 IBP와 isoprothiolane과의 협력작용으로 인해 현저한 감소를 보였으며 GST 활성 또한 isoprothiolane의 IBP, cartap과의 협력작용으로 인해 감소를 나타냈다. 한편 각 조직별 효소활성의 경우, carboxylesterase는 단일약제 처리시 공시어의 간(肝)에서, 혼합약제 처리시 장(腸)에서 그 활성이 높았으며 GST의 조직별 활성은 약제의 처리양상과는 관계없이 다양한 효과를 보였다. HPLC 방법에 의한 LDH의 활성은 isoprothiolane 단일처리구에서 활성이 가장 높았고 isoprothiolane+cartap 혼합처리구와 cartap 단일처리구에서는 가장 낮았다.

• 한국식품위생안전성학회지
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• 제13권3호
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• pp.258-267
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• 1998

해혈 및 진동 효과를 가진 APAP는 과량 복용시 CYP-450에 의해 독성 유발 물질인 NAPQI로 대사되어 간장과 세포막을 붕괴시켜 세포 내 calcium 유입을 증가시킴으로서 간세포의 괴사를 일으킨다. DIL은 CYP-450 작용을 억제하는 것으로 알려진 칼슘채널차단제이다. 따라서 본 연구에서는 APAP 300mg/kg을 경구 투여한 후 3, 6. 9 및 12시간에 DIL을 복상내로 투여하여 DIL이 APAP의 독성에 미치는 영향을 조사하였다. APAP 투여 12시간후 DIL 투여군에서 혈청과 간조직의 생화학 분석과 조직학적 관찰에서 간손상의 개선 효과가 확인되었으며, 이는 세포내로의 calcium 유입과 지질과산화의 억제 및 GST의 활성도 증가에 기인한 것으로 보인다. 그러므로 APAP 과량 복용 12시간 후의 DIL 투여는 간손상의 억제에 효과적일 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제28권8호
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• pp.1194-1201
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• 2015

This study investigated the effect of oxidized soybean oil in the diet of young chickens on growth performance and intestinal oxidative stress, and indices of intestinal immune function. Corn-soybean-based diets containing 2% mixtures of fresh and oxidized soybean oil provided 6 levels (0.15, 1.01, 3.14, 4.95, 7.05, and $8.97meqO_2/kg$) of peroxide value (POV) in the diets. Each dietary treatment, fed for 22 d, had 6 replicates, each containing 30 birds (n = 1,080). Increasing POV levels reduced average daily feed intake (ADFI) of the broilers during d 1 to 10, body weight and average daily gain at d 22 but did not affect overall ADFI. Concentrations of malondialdehyde (MDA) increased in plasma and jejunum as POV increased but total antioxidative capacity (T-AOC) declined in plasma and jejunum. Catalase (CAT) activity declined in plasma and jejunum as did plasma glutathione S-transferase (GST). Effects were apparent at POV exceeding $3.14meqO_2/kg$ for early ADFI and MDA in jejunum, and POV exceeding $1.01meqO_2/kg$ for CAT in plasma and jejunum, GST in plasma and T-AOC in jejunum. Relative jejunal abundance of nuclear factor kappa B ($NF-{\kappa}B$) P50 and $NF-{\kappa}B$ P65 increased as dietary POV increased. Increasing POV levels reduced the jejunal concentrations of secretory immunoglobulin A and cluster of differentiation (CD) 4 and CD8 molecules with differences from controls apparent at dietary POV of 3.14 to $4.95meqO_2/kg$. These findings indicated that growth performance, feed intake, and the local immune system of the small intestine were compromised by oxidative stress when young broilers were fed moderately oxidized soybean oil.