• 한국독성학회:학술대회논문집
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• 한국독성학회 2001년도 International Symposium on Signal transduction in Toxicology
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• pp.169-169
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• 2001

The phthalates have been shown to produce hepatic peroxisome proliferation and certain peroxisome proliferators (PPs) are also known to increase the incidence of liver tumors in rodents. In this study we investigated the correlation between oxidative injury, changes in peroxisomal and microsomal enzymes and tumor formation in PP-treated rats.(omitted)

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1993년도 제2회 신약개발 연구발표회 초록집
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• pp.71-71
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• 1993

Carboxylesterase is widely distributed in the tissues of vertebrates, insects, plants and mycobacteria. Among various tissues of animals and humans, the highest esterase activity with various substrates is found in the liver. Kidney has moderate carboxylesterase activity in the proximal tubules. Considerable esterase activity is also found in the small intestine epithet elial cells and serum of mammals. Besides these tissues, carboxylesterase has been found in the lung, testis, adipose tissue, nasal mucosa and even in the central nervous system. Hepatic microsomal carboxylesterase catalyzes the hydrolysis of a wide variety of endogenous and exogenous compounds such as carboxylester, thioester and aromatic amide. Since carboxylesterases are important for metabolic activation of prodrugs and detoxification of xenobiotics, differences in substrate specificity and immunological properties of this enzyme are important in connection with choosing a suitable laboratory animal for the evaluation of biotransformation and toxicity of drugs. On the other hand, liver, kidney, intestine and serum were found to contain multiple forms of carboxylesterases in animal species and humans. In fact, we have purified more than fifteen isoforms of carboxylesterases from microsomes of liver, kidney and intestinal mucosa of nine animal species and humans. and characteristics of these isoforms were compared each other in terms of their physical and immunochemical properties. On the other hand, we have reported that hepatic microsomal carboxylesterases are induced by many exogenous compounds such as phenobarbital, polycyclic aromatic hydrocarbons, Aroclor 1254, aminopyrine and clofibrate. Later, we showed that some isoforms of hepatic carboxylesterase were induced by glucocorticoids such as dexamethasone and 16 ${\alpha}$-carbonitrile, but other isoforms were rather inhibited by these compounds. These findings indicate that involvement of carboxylesterases in the metabolism and toxicity of drugs should be explained by the isoforms involved. Since 1991, we have carried out detailed research investigating the types of carboxylesterases involved in the metabolic activation of CPT-11, a derivative of camptothecin, to the active metabolite, SN-38. The results obtained strongly suggest that some isoforms of carboxylesterase of liver microsomes and intestinal mucosal membrane are exclusively involved in CPT-11 metabolism. In this symposium, the properties of carboxylesterase isoforms purified from liver, kidney and intestine of animal species and humans are outlined. In addition, metabolism of CPT-11, a novel antitumor agent, by carboxylesterases in relation to the effectiveness will also be discussed.

• Archives of Pharmacal Research
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• 제21권4호
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• pp.363-369
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• 1998

Glutathione S-transferase placental form (GST-P) positive foci development and its expression in liver exposed by nongenotoxic carcinogens phenobarbital (PB) and clofibrate (CF), and genotoxic carcinogen 2-amino-3-methylimidazo[4,5-f] quinoline (IQ) were investigated as a measure of carcinogenic potential of these chemicals. Male F344 rats were initially given a single intraperitioneal injection of diethyinitrosamine (200 mg/kg), and 2 weeks later, animals were fed diets containing 0.03% IQ or 0.5% CF or 0.05% PB or basal diet as a control for 6 weeks. All rats were subjected to two-thirds partial hepatectomy (PH) at week 3. Sequential sacrifice of rats was performed at 8 weeks or 52 weeks, and liver tissues were examined for immunohistochemical staining of GST-P positive foci. The numbers (No./$cm^2$) and areas ($mm^2$/ $cm^2$) of GST-P positive foci were increased by IQ or PB, but were decreased by CF compare to the control. Consistent with the development of GST-P positive foci, a time-related increase in the expression of GST-P mRNA was found in the rats treated with IQ, whereas CF decreased it. The incidence of hepatocellular carcinoma at 52 weeks was increased by all three chemicals. These results show that PB and IQ induced GST-P positive foci, but the peroxisome proliferator CF did not, which suggest that the prediction of carcinogenic potency based on the development of prenoplastic foci may cause false negative in a particular category compounds like peroxisome proliferators.

• 한국식품과학회지
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• 제30권1호
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• pp.206-212
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• 1998

본 연구는 식용으로 사용되는 어패류의 화학오염지표로서 glutathione S-transferase (GST)의 활성을 사용 할 수 있는 가를 검토하기 위하여 수행하였다 어류의 간췌장 및 패류의 소화선에서 기초적 GST 효소활성은 시험한 동물종에 따라 차이를 보였다. 시험한 어패류 중 큰이랑 피조개에서의 활성이 가장 높았으며 메기 및 홍합이 그 다음이었다. 백합 및 이스라엘 잉어에서는 낮은 기초적 활성을 보여 주었다. 큰이랑 피조개를 전형적인 PAH물질인 3-methylcholanthrene에 1주일간 노출 시켰을 경우 GST의 활성은 약 30% 감소하였으며 노출중단 2주경에는 회복되었다. 다른 대부분의 동물종에서는 GST의 활성이 3-MC에 의하여 증가하였다. 홍합의 경우 기초 활성의 약 200%수준으로 증가하여 노출중단 후에도 1주일간 지속되다가 서서히 감소하였다. 이스라엘 잉어에서도 홍합과 유사한 반응이 관찰되었다. Phenobarbital은 홍합 및 이스라엘 잉어에서 GST활성을 증가시켰다. Clobibrate, butylated hydroxyanisole 및 oxolinic acid 등은 효소활성의 변화를 유발하지 아니하였다. 한편 phenol은 이스라엘 잉어에서 활성을 감소시켰다. 이 결과를 종합하면 식용 어패류의 정상적 GST활성은 동물종에 따라 큰 차이가 나며 화학물질 오염에 따른 변화도 증가, 감소 및 불변으로 다양한 것으로 관찰되었다. 따라서 이 효소의 활성을 측정함으로서 PAH나 phenol과 같은 환경 오염물질에 의한 오염정도를 추정할 수 있는 지표로의 사용이 가능하리라고 본다.