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Study of metabolism air pollutants and mutagens 3-nitrobenzanthrone and 2-nitrobenzanthrone
Čechová, Tereza ; Stiborová, Marie (advisor) ; Martínek, Václav (referee)
Nitroaromatic compounds are mutagenic and carcinogenic substances present in environment. Most of nitroaromatic compounds are potent mutagens in bacterial and mammalian systems. They are also carcinogens causing development of tumors, primarily in the liver, lung and mammary glands. 3-Nitrobenzanthrone (3-NBA, 3-nitro-7H-benz [de] anthracene-7-one) is one of the polycyclic aromatic nitro compounds possesing high toxic effects. 3-NBA is an environmental pollutant present in diesel exhaust and was also detected in soil and in rain water. 2-Nitrobenzanthrone (2-NBA, 2-nitro-7H-benz [de] anthracene-7-one) is an isomer 3-NBA, which also occurs as a pollutant in air. Although the 2-NBA is a weakly toxic substance, its high abundance in air could exhibit a high health risk to humans. This thesis investigates the metabolism of 3-NBA and its isomeric derivate, isomer 2 NBA, under anaerobic and aerobic conditions. To study the metabolism of these compounds, microsomal systems isolated from the liver of rats pretreated with Sudanem I, -naphthoflavone, phenobarbital, ethanol and pregnenolon 16-carbonitrile (PCN), the inducers of cytochromes P450 1A, 2B, 2E1 and 3A, were used. We also used mouse models, a control mouse line (wild type WT) and mice with deleted gene of NADPH:CYP reductase in the liver, thus absenting...
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Study of metabolism air pollutants and mutagens 3-nitrobenzanthrone and 2-nitrobenzanthrone
Čechová, Tereza ; Stiborová, Marie (advisor) ; Martínek, Václav (referee)
Nitroaromatic compounds are mutagenic and carcinogenic substances present in environment. Most of nitroaromatic compounds are potent mutagens in bacterial and mammalian systems. They are also carcinogens causing development of tumors, primarily in the liver, lung and mammary glands. 3-Nitrobenzanthrone (3-NBA, 3-nitro-7H-benz [de] anthracene-7-one) is one of the polycyclic aromatic nitro compounds possesing high toxic effects. 3-NBA is an environmental pollutant present in diesel exhaust and was also detected in soil and in rain water. 2-Nitrobenzanthrone (2-NBA, 2-nitro-7H-benz [de] anthracene-7-one) is an isomer 3-NBA, which also occurs as a pollutant in air. Although the 2-NBA is a weakly toxic substance, its high abundance in air could exhibit a high health risk to humans. This thesis investigates the metabolism of 3-NBA and its isomeric derivate, isomer 2 NBA, under anaerobic and aerobic conditions. To study the metabolism of these compounds, microsomal systems isolated from the liver of rats pretreated with Sudanem I, -naphthoflavone, phenobarbital, ethanol and pregnenolon 16-carbonitrile (PCN), the inducers of cytochromes P450 1A, 2B, 2E1 and 3A, were used. We also used mouse models, a control mouse line (wild type WT) and mice with deleted gene of NADPH:CYP reductase in the liver, thus absenting...
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A use of epidemiology data for a cancer risk assessment and the recautionary principle
Bencko, Vladimír
The traditional approaches and study designs in cancer epidemiology have not been very successful in identifying and evaluating adequately the potential risk and/or protective factors associated with the disease. The main reasons for the failure are often due to small study sample size, and inadequate exposure information. In this paper, issues and approaches relevant to these two challenges are discussed. Multicentre study is proposed as a way to increase study size and to mitigate criticism about meta-analysis of independent studies. A multicentre study of large cohort or case–control studies also offers an exciting opportunity to study the contribution of epigenetic events that may be associated with life-style and environmental risk factors for human health. Optimizing methods for exposure assessment and how to reduce exposure misclassification represent a difficult component in epidemiology studies. A potentially useful approach for improving exposure estimate is to rely on biomarkers of exposures. An example is provided to demonstrate how biomarkers of exposures could provide valuable information in addition to exposure measurements in traditional epidemiological studies. Finally, it is argued that risk assessment and the precautionary principle should not be viewed as conflicting paradigms but, rather, as a complementary approach for developing appropriate policies to address risks posed by exposure to carcinogens and a wide spectrum of other health hazards.
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