|
|
Effect of Genotoxic 2-Nitrofluorene and Its Metabolites on DNA In Vivo and Possibilities of Investigation of this Effect Using Electrochemical DNA Biosensors In Vitro
Stávková, Klára ; Vyskočil, Vlastimil (advisor) ; Fišer, Radovan (referee)
Presented Bachelor Thesis is targeted on the topic of hazardous 2-nitrofluorene (NF), which is known as one of the markers of the presence of nitrated polycyclic aromatic hydrocarbons. This Thesis summarizes the current knowledge about the formation of this xenobiotic, its occurrence and transport in living and working environment, and about its negative effects on living organisms, especially on their DNA. These findings obtained upon the in vivo investigations are compared in this Thesis with information obtained using electrochemical DNA biosensors, which represent very promising in vitro alternative to the study of processes proceeding in living organisms upon the interaction of their DNA with the xenobiotic. NF is mainly released to the atmosphere through the exhaust gases of diesel and gasoline engines. It is adsorbed onto solid particulate matters, through which it is spread over long distances and can enter the air passages of animals. Through an atmospheric fall-out, NF contaminates waters and soils, where it is transported together with other nutrients and food to plants and animals; by consummation of such organisms, it can finally enter the body of higher animals and the human. It has been shown that NF is a chemically stable substance. On the other hand, it is metabolized intensively...
|
|
|
Molecular mechanism of carcinogenicity of aristolochic acid
Levová, Kateřina ; Stiborová, Marie (advisor) ; Ryšlavá, Helena (referee) ; Souček, Pavel (referee)
Aristolochic acids (AA) are carcinogenic and nephrotoxic alkaloids from Aristolochia species. Aristolochic acid I (AAI), the major component of AA, causes the development of Aristolochic acid nephropathy (AAN) and Balkan endemic nephropathy (BEN). These two diseases cause total renal failure and urothelial malignancies. The fact that these diseases have not been developed in all persons, who have been exposed to their action, might be causd by different activities and protein levels of the enzymes metabolizing AAI. Thus, the identification of enzymes involved in the metabolism, and detailed knowledge of their expression and catalytic specifities is a major importance. Aristolochic acid I (AAI) can be metabolized by several types of reactions. Like most nitroaromatics, the main activation pathway of AAI is reduction of its nitro group to form a cyclic acylnitrenium ion, which can bind to the purine bases, thereby forming AAI-DNA adducts. The detoxication pathway of AAI is its oxidative demethylation by cytochromes P450 forming detoxication metabolite 8-hydroxyaristolochic acid Ia (AAIa). In the present thesis, using rat and human enzymes and as well as several mice models, the metabolism of AAI in vitro and in vivo was investigated. The first model has deleted gene for NADPH:cytochrome P450...
|
|
|
Molecular mechanisms of carcinogenic effects of alcohol
Vepřková, Jana ; Kábelová, Adéla (advisor) ; Novotná, Božena (referee)
Alcohol (ethanol) enters the human body mainly through ingestion of alcoholic beverages and its chronic consumption is considered a worldwide socio-economic problem. Besides others, alcohol consumption increases the risk of development of breast, liver, colorectal and upper aerodigestive tract cancer. In the liver, ethanol is metabolised into toxic acetaldehyde which is the main cause of DNA damage leading to cancer development. Acetaldehyde covalently interacts with nucleotides in the DNA forming DNA adducts such as N2 -ethylidene-2'-deoxyguanosine or S- and R-α-methyl-γ-hydroxy-1,N2 - propano-2′-deoxyguanosine. Acetaldehyde can also interact with proteins and disrupt their function. Ethanol metabolism by cytochrome P450 2E1 leads to production of reactive oxygen species, that subsequently damage cellular molecules such as lipides and DNA. Ethanol also initiates carcinogenesis through aberant DNA methylation or interference with retinoic acid metabolism. In cancer development, alcohol interacts with other environmental and genetic factors, which can increase the risk of developing cancer in predisposed individuals.
|
|
|
The role of mixed function oxidases system with cytochrome P450 in metabolism of drugs and carcinogens
Mrízová, Iveta ; Stiborová, Marie (advisor) ; Levová, Kateřina (referee) ; Hansíková, Hana (referee)
6 Abstract Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole), an alkaloid isolated from Apocynaceae plants, exhibits significant antitumor and HIV activity. This antitumor agent binds to DNA and forms covalent DNA adducts. Enzymes, which are involved in its enzymatic activation, are cytochromes P450 (CYP) and peroxidases. To elucidate the effect of ellipticine on the expression and enzymatic activity of the individual components of the microsomal mixed function oxidase system in different tissues, we used rat model. Simultaneously, the effect of ellipticine and its cytotoxicity on different tumor cell lines was also investigated. Another part of the presented work was targeted on preparation of anti-peptide antibody against orphan cytochrome P450 2S1, which is highly expressed in many human tumours of the epithelial origin, for its detection in these tissues. For better understanding how CYP2S1 can contribute to the metabolism of xenobiotics, the protein was prepared by heterologous expression in E. coli. Furher, its role in metabolism of an antitumor drug ellipticine, a carcinogenic environmental pollutant benzo[a]pyrene (BaP) and its derivate BaP-7,8-dihydrodiol was examined. Utilizing a mouse model, the impact of pulmonary inflammation on the metabolism of an environmental carcinogen was...
|
|
|
Molecular mechanism of carcinogenicity of aristolochic acid
Levová, Kateřina ; Stiborová, Marie (advisor) ; Ryšlavá, Helena (referee) ; Souček, Pavel (referee)
Aristolochic acids (AA) are carcinogenic and nephrotoxic alkaloids from Aristolochia species. Aristolochic acid I (AAI), the major component of AA, causes the development of Aristolochic acid nephropathy (AAN) and Balkan endemic nephropathy (BEN). These two diseases cause total renal failure and urothelial malignancies. The fact that these diseases have not been developed in all persons, who have been exposed to their action, might be causd by different activities and protein levels of the enzymes metabolizing AAI. Thus, the identification of enzymes involved in the metabolism, and detailed knowledge of their expression and catalytic specifities is a major importance. Aristolochic acid I (AAI) can be metabolized by several types of reactions. Like most nitroaromatics, the main activation pathway of AAI is reduction of its nitro group to form a cyclic acylnitrenium ion, which can bind to the purine bases, thereby forming AAI-DNA adducts. The detoxication pathway of AAI is its oxidative demethylation by cytochromes P450 forming detoxication metabolite 8-hydroxyaristolochic acid Ia (AAIa). In the present thesis, using rat and human enzymes and as well as several mice models, the metabolism of AAI in vitro and in vivo was investigated. The first model has deleted gene for NADPH:cytochrome P450...
|
|
|
An acellular genotoxicity assay of complex mixtures of organic compounds bound on size segregated aerosols.
Fikejzlová, Monika ; Rössner, Pavel (advisor) ; Machala, Miroslav (referee)
The main aim of this work was to compare the genotoxicity of organic extracts from different size fractions of aerosol particles (1-10 µm, 0,5-1 µm, 0,17-0,5 µm) collected by high volume cascade impactors in various localities of the Czech Republic differing in the extent of the environmental pollution (Březno - strip mine, Dobré Štěstí - highway, Praha - city center, Láz - background station). Genotoxicity was determined in acellular assay of calf thymus DNA (CT-DNA) with and without S9 metabolic activation by analysis of DNA adducts induced by extractable organic matter (EOM) from the particulate matter (PM) by 32 P-postlabeling and the ability of extracts to induce oxidative DNA damage was evaluated using the competitive ELISA test. The main finding of this work is that most of the observed genotoxicity is connected with fine particles (<1 µm). The concentration of carcinogenic polycyclic aromatic hydrocarbons (c-PAHs) in EOMs indicate that fine fractions bound the highest amount of c-PAHs in all sampling sites. This fact might be related to a higher specific surface of this fraction as compared with a course fraction and a higher mass as compared with a condensational fraction. As for aerosol mass, both fine and condensational fractions are effective carriers of c-PAHs. Similarly, the DNA...
|
|
|
Effect of Genotoxic 2-Nitrofluorene and Its Metabolites on DNA In Vivo and Possibilities of Investigation of this Effect Using Electrochemical DNA Biosensors In Vitro
Stávková, Klára ; Vyskočil, Vlastimil (advisor) ; Fišer, Radovan (referee)
Presented Bachelor Thesis is targeted on the topic of hazardous 2-nitrofluorene (NF), which is known as one of the markers of the presence of nitrated polycyclic aromatic hydrocarbons. This Thesis summarizes the current knowledge about the formation of this xenobiotic, its occurrence and transport in living and working environment, and about its negative effects on living organisms, especially on their DNA. These findings obtained upon the in vivo investigations are compared in this Thesis with information obtained using electrochemical DNA biosensors, which represent very promising in vitro alternative to the study of processes proceeding in living organisms upon the interaction of their DNA with the xenobiotic. NF is mainly released to the atmosphere through the exhaust gases of diesel and gasoline engines. It is adsorbed onto solid particulate matters, through which it is spread over long distances and can enter the air passages of animals. Through an atmospheric fall-out, NF contaminates waters and soils, where it is transported together with other nutrients and food to plants and animals; by consummation of such organisms, it can finally enter the body of higher animals and the human. It has been shown that NF is a chemically stable substance. On the other hand, it is metabolized intensively...
|
|
| |
guest ::
