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Effect of zearalenone on reproductive parameters and the expression of selected genes in mice.
Dvořáková, Eva ; Pěknicová, Jana (advisor) ; Nedvídek, Josef (referee)
A number of chemicals may have a negative impact on the environment and wildlife. Endocrine disruptors (EDs), which can mimic estrogen, interfere with natural hormones in organism and can have a negative effect on the reproductive system. Such substances include zearalenone (ZEA) - mycotoxin, produced by the fungi Fusarium. Despite the non-steriodal structure of its molecule, ZEA and its derivates possess potent estrogenic activity. The influence of ZEA on reproductive parameters and changes in expression of selected genes were tested in the outbred line of mice. This study showed significant effects of ZEA on number of reproductive performances. This effect was observed at lower examined dose, to which are humans normally exposed, and at higher doses, both showed changes in the tested parameters.
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The effect of selected endocrine disruptors on cytochromes P450 1B1 and 3A1/2
Holecová, Jana
Many exogenous and endogenous compounds are referred to as endocrine disruptors (EDCs), as they interfere with natural synthesis, signaling and metabolism of endogenous hormones. Common exogenous endocrine disruptors are benzo(a)pyrene (BaP) and 17α-ethinylestradiol (EE2). Endogenous endocrine disruptor 17β-estradiol (E2) is frequently present in the environment as well. In this thesis, the effect of the mentioned EDCs and their combinations on gene and protein expression of CYP1B1, 3A1 and 3A2 in rat liver, kidney and lung was determined. Protein expression was studied using Western blot method and specific antibodies; gene expression was assessed by quantitative PCR. Moreover, the effect of tested EDCs and their combinations on BaP metabolism and CYP3A specific activity (measured as testosterone 6β-hydroxylation) were studied in liver microsomal samples. It was confirmed, that BaP significantly increases CYP1B1 expression in rat liver and lung both alone and together with EE2 or E2. Pretreatment of rat with E2 and BaP increases the ability of BaP to induce CYP1B1 expression. On the contrary, EE2, E2 and their combination decrease the CYP1B1gene expression. The rate of BaP metabolites formed in liver microsomal samples increases in rats pretreated with BaP and its combinations. In liver, there was...
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Inhibitory effect of 17α-ethinylestradiol on the activity of cytochrome P450 subfamilies 2B and 2C
Knapp, Kryštof ; Dračínská, Helena (advisor) ; Kukačka, Zdeněk (referee)
17α-ethinylestradiol (EE2) is a synthetic derivative of endogenous estrogen 17β-estradiol. It is widely used in pharmaceutics as a ingredient of female oral contraceptives and also in hormone replacement therapy for women with postmenopausal syndrome. Due to its high estrogenic potential together with resistance to the chemical degradation and tendency to bio- accumulate in environment it is considered as an important persistent organic pollutant. In organisms, EE2 is oxidatively metabolised by enzymes from a family of cyto- hromes P450. Some studies show that EE2 is also a potent inhibitor of some isoforms from cytochrome P450 family. In this work, we studied inhibitory effect of EE2 on two human isoforms CYP2B6, CYP2C9 and their rat orthologs CYP2B1 and 2C6, respectively. All studied isoforms exhibited reduced enzyme activity in the presence of EE2. The greatest decrease of enzyme activity was observed with CYP2B1 catalyzing pentoxyresoru n O-depentylation with value of IC50 = 9,6 µM. For hydroxylation of bupropion, selective reaction of CYP2B1 and CYP2B6, EE2 behaved as a more potent inhibitor of CYP2B6 with IC50 = 60 µM. The inhibitory effect of EE2 on rat CYP2B1 for similar reaction conditions was signi cantly lower. With 200µM concentration of EE2, CYP2B1 exhibited still more than 50 % of...
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Inhibition of enzyme activity of cytochromes P450 by endocrine disruptor 17α-ethinylestradiol
Otáhalová, Barbora ; Dračínská, Helena (advisor) ; Ryšlavá, Helena (referee)
17α-ethinylestradiol (EE2) is a synthetic hormone, derivative of the natural hormone estradiol. EE2 is one of the the most prescribed drugs in the world. It belongs to the estrogenic endocrine disrupter chemicals. These compounds are able to alter functions of the endocrine system and cause adverse effects in the organism, offspring and (sub)population. In this thesis, there are observed effects of 17α-ethinylestradiol on enzyme activities of main enzymes involved in phase I of xenobiotic biotransformation, i.e. cytochromes P450 (CYP), in vitro. Isoforms of CYP subfamilies 1A, 2B, 2C, 2E and 3A were studied in rats and humans. Each CYP isoform was incubated with EE2 at two concentrations, 10μM EE2 and the concentration corresponding to the substrate concentration in the specific marker reactions of individual CYP isoforms. The results indicate, that in rat liver microsomes the activity of all studied isoforms except CYP1A2 was decreased in the presence of EE2. When EE2 was added to the incubation mixture at the concentration of the reaction substrate, the greatest decrease in enzyme activity was observed for CYP2C6, with the remaining activity only 36%. In human liver microsomes, the activity of CYP2B6, CYP2C9, CYP2E1 and CYP3A4 was also effected by EE2. As in the case of rat model, CYP2C subfamily...
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Removal of selected pharmaceuticals from the treated wastewater by oxidation processes
Novotný, Hana ; Macsek, Tomáš (referee) ; Hlavínek, Petr (advisor)
The aim of the work is research and summarize the currently available information about micropollutants with a focus on drugs and pesticides. The first part deals with the description, occurrence of micropollutants and their effects on organisms. The second part deals with the possibility of removing selected drugs from wastewater and the application of such methods in practice, and evaluates the effectiveness and economic aspects of O3, O3 + H2O2, O3 + UV and O3 + H2O2 + UV.
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Interaction of selected cosmetic additives with biotransformation enzymes
Bušovská, Radka ; Hodek, Petr (advisor) ; Smrček, Stanislav (referee)
Endocrine disruptors are nowadays very often discussed, due to their negative impact on the human body. They can be found all around us and they've become a parf of our everyday life, even if many people don't even realize it. Cosmetic products and perfumes are part of everyday life and just few of many people realize the consequences of having regular contact with our skin. Perfumes and fragrances are part of all cosmetic products or various commonly used industrial products, that people could not even live without. Perfumes can have a negative effect on the health of the organism and, due to the large number of chemicals they consist of and the interactions with each other and the subsequent interaction with important enzymes such as aromatase, they can belong to the group of hormone-active substances. The aim of this work was to find out by TLC (Thin Layer Chromatography) analytical method whether various perfumes and industrial car smells can disturb the endocrine system by inhibiting the key enzyme, aromatase. Experiments have shown that the commonly used fragrances really interact with aromatase. Keywords: Endocrine disruptors, aromatase, TLC, chromatography, perfumes, industrial fragrances
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Endocrine disruptors in consumer goods
Pařízková, Alžběta ; Šuta, Miroslav (advisor) ; Cajthaml, Tomáš (referee)
The Thesis focuses on the group of specific organic compounds with a potential risk of their endocrine disruptive effect, and appearing as UV filters in various cosmetic products. An extended list of such products was created on the basis of search in drugstores, pharmacies and perfume shops. The products were further grouped as cosmetics for adults, children, and those declared as bio products. The source data collection counted 156 individual products, with origin in 40 drugstores, 20 pharmacies, and 10 perfume shops. The data collection sites were distributed in big cities, their suburb parts, shopping parks, and small towns on many places in the Czech Republic. The products were mostly sun protection creams, oils and emulsions, body creams and emulsions, lips balsams, and hair cosmetics. In these items an occurrence of 7 organic compounds (suspected endocrine disruptors) from the SIN List, used as parts of UV filters, was followed. The compounds of interest were: ethylhexyl methoxycinnamate; benzophenone-1, benzophenone-2, benzophenone-3; 4,4-dihydroxyphenone; 4-methylbenzylidene camphor; 3-benzylidene camphor. Alternative names, product brand names, chemical structures, CAS numbers etc. were also collected from various sources. Of this group only ethylhexyl methoxycinnamate and benzophenone-3...
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The inhibitory effect of estrogenic endocrine disruptors on cytochrome P450 activity
Otáhalová, Barbora ; Dračínská, Helena (advisor) ; Hýsková, Veronika (referee)
Endocrine disruptors are exogenous and endogenous compounds that interfere with the production, signaling and metabolism of natural hormones, thereby disturbing the balance of the endocrine system. Exogenous endocrine disruptors include 17α-ethinylestradiol and endogenous endocrine disruptors include 17β-estradiol. This thesis examinates effects of these endocrine disruptors on the specific activities of rat cytochromes P450 1A1 and 3A1. The enzyme specific activity of CYP1A1 is determined by the marker reaction O-deethylation 7-ethoxyresorufin and the activity of CYP3A1 is determined by the marker reaction 6β-hydroxylation of testosterone. It has been confirmed that both estrogens 17β-estradiol and 17α-ethinylestradiol inhibit activity of CYP1A1 and CYP3A1. The stronger inhibitor of CYP1A1 was 17β-estradiol and of CYP3A1 was 17α-ethinylestradiol. The concentration of estrogens causing 50% inhibition (IC50) of enzymes has been determined, for 17β-estradiol it was 4,6 μM and for 17α-ethinylestradiol 7,9 μM. CYP1A1 is a important enzyme for the biotransformation of carcinogens, it can be said that estrogens can modulate the genotoxicity of CYP1A1 activated carcinogens. The results show that CYP1A1 inhibition increased after pre-incubation of estrogens with NADPH (cofactor of cytochromes P450), that...
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The effects of endocrine disruptors on the expression and the activity of cytochromes P450 2B in laboratory rat as a model organism
Měkotová, Barbora ; Dračínská, Helena (advisor) ; Levová, Kateřina (referee)
Endocrine disrupting chemicals are compounds that interfere with natural hormones and they are responsible for functional changes which may lead to damage of the endocrine system. Their presence in the environment is associated with a number of diseases whose extent is hard to predict. As endocrine disrupting chemicals, a wide range of exogenous and endogenous compounds is present in the environment. Important exogenous endocrine disrupting chemicals include benzo[a]pyrene (BaP) and 17α-ethinylestradiol (EE2); the female sex hormone 17β-estradiol (E2) can act like endogenous endocrine disruptor. In this thesis, the effect of these three compounds and their combinations on the expression and the activity of rat biotransformation enzymes cytochromes P450 2B is studied. The gene expression was determined by quantitative PCR, the expression of the protein itself was studied using Western blot method and consecutive immunodetection. The results show that CYP2B expression is almost unchanged after BaP premedication, whereas estrogenic compounds, E2, EE2, their combination and their combinations with BaP, significantly decrease the expression. The enzyme activity of CYP2B was also studied in rat liver microsomes using the marker substrate 7-pentoxyresorufin. EE2, E2 and their combination decrease the...
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