National Repository of Grey Literature 50 records found  beginprevious41 - 50  jump to record: Search took 0.00 seconds. 
Role of benzo[a]pyrene in cancer development
Vaňátková, Petra ; Moserová, Michaela (advisor) ; Kubíčková, Božena (referee)
4 ABSTRACT Cancer is nowadays one of the most serious diseases. Tumor development is a multistage process in which the effect of internal and external factors lead to failure of regulatory and defense mechanisms of the organism and to the accumulation of mutations which are generated by these organisms. Chemical carcinogens and also biological and physical factors can be regarded as the main external factors. Polycyclic aromatic hydrocarbons are large group of chemical carcinogens. One of them, benzo[a]pyren is the most studied polycyclic aromatic hydrocarbon. Carcinogenic, mutagenic and teratogenic effects of benzo[a]pyrene had been shown on laboratory animals. Benzo[a]pyrene is considered as the main carcinogen in tobacco smoke and is connected with lung cancer development among smokers. Benzo[a]pyrene is metabolized in activation or detoxication pathways by enzymes of mixed function monooxygenase systeme of cytochromes P450. The most important enzymes involved in the activation of these compounds are CYP1A1 and CYP1B1 with cooperation of epoxide hydrolase. The reactive species generated in its activation pathway are able to form covalent adducts with DNA. The most important carcinogenic product of benzo[a]pyrene is benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide, which can caused irreversible ganges in...
Oxidation of benzo(a)pyrene by cytochrome P450 1A1 expressed in prokaryotic and eukaryotic systems
Kroftová, Natálie ; Stiborová, Marie (advisor) ; Kubíčková, Božena (referee)
Benzo[a]pyrene (BaP) is a human carcinogen, which is metabolized by a variety of enzyms such as cytochrome P450 (CYP) and epoxide hydrolase. The aim of this work was to study BaP metabolism in vitro by the hepatic microsomal system of rats treated with CYP inducers and by human cytochrome P450 1A1 (CYP1A1) expressed in eukaryotic and prokaryotic systems. An eukaryotic expression system consisted of microsomes isolated from insect cells, whereas a prokaryotic expression system was formed by the membrane fragments of E. coli. In the case of recombinant human CYP1A1, we investigated the influence of cytochrome b5, NADPH:cytochrome P450 reductase (CPR) and epoxide hydrolase in BaP oxidation. Isolation and purification of rabbit hepatic CPR was another aim of this work. BaP metabolites were separated by HPLC. The results found in this work demostrate the fact that hepatic microsomal systems of rats treated with an inducer of CYP1A (Sudan I), an inducer of CYP2B (phenobarbital) and an inducer of CYP3A (PCN) exhibit higher efficiency of BaP oxidation than microsomes of control rats. BaP is oxidized by human CYP1A1 expressed in the eukaryotic system to six metabolites (BaP-9,10-dihydrodiol, BaP metabolite with unknown structure, BaP-7,8-dihydrodiol, BaP-1,6-dion, BaP-3,6-dion, BaP-3-ol), whereas by human...
Protein determination - comparison of various methods
Zimmermannová, Jana ; Hudeček, Jiří (advisor) ; Kubíčková, Božena (referee)
The first part of the thesis offers an overview of the literature that deals with the determination of proteins in samples used for the purposes of clinical chemistry. Since proteins are the basic building blocks of life, their determination is an important source of information about the condition of a patient. Proteins, however, build a diverse range of compounds and therefore the protein determination procedure has its difficulties. The second part of the thesis aims to find the correct measurement method for the NanoVue Plus spectrophotometer. This type of spectrophotometer is designed to measure samples of low volumes of just few microlitres. Solutions of potassium dichromate and bovine serum albumin were used in the measurement.
Lipidic binders in artworks: possible identification of the used drying oils by liquid chromatography
Pecháčková, Soňa ; Hudeček, Jiří (advisor) ; Kubíčková, Božena (referee)
This work is concerned with lipidic substances, in particular vegetable oils, used as pigment binders or as a protective varnishes for finishing artwork. The introduction reviews the recent knowledge of this subject, in particular with respect to the identification of the most used drying oils, and of the methods to study their changes in the course of time. Both can be achieved using determination of the relative representation of fatty acids, most characteristic being the ratio of stearic/palmitic a oleic/palmitic acids. This parameter is changing as the artwork is getting older and the oils are drying. Because of the availability of the instrumentation needed, we have chosen the high- performance liquid chromatography method for further experimental work. The first step was optimalization of the analytical method by standards of fatty acids. For derivatization of fatty acids, reagents 2,4-dinitrophenylhydrazine and 2-nitrophenylhydrazine were examined. Whereas we were unable to get any results with the first one (the method based on the article: Bravo, B. et al., Talanta 64, 1329-1334, 2004) for unknown reasons, good results were obtained with the second one. Derivates of fatty acids have been analyzed by high performance liquid chromatography (HPLC) on column with revesed phase (C18). The...
NADP-dehydrogenases of medicinal plants.
Bartošová, Martina ; Hýsková, Veronika (advisor) ; Kubíčková, Božena (referee)
Medicinal plants usually contain metabolites formed by secondary biosynthetic pathways for example phenylpropanoid and shikimate pathway, which depend on NAPDH availability. In this work total content of phenolic compounds and flavonoids was determined in 10 medicinal plants common for Czech Republic. Activity of enzymes providing NADPH was determined as well. These enzymes were glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49), NADP-isocitrate dehydrogenase (NADP-ICDH, EC 1.1.1.42), NADP-malic enzyme (oxalacetate decarboxylating) (NADP-ME, EC 1.1.1.40). The activity of shikimate dehydrogenase (SDH, EC 1.1.1.25), the main enzyme of shikimate pathway, was also determined. Extraction methods were optimized for each assessment. Applicable source for NADP-dependent enzymes are black radish (Raphanus sativus L. var. niger), garlic (Allium sativum L.) and mint (Mentha piperita L). The highest content of phenolic compounds and flavonoids was determined in sage (Salvia officinalis), lemon balm (Melissa officinalis L.) and Mentha citrata. Extraction with methanol was more effective than extraction with hot water. More extraction methods and studies are necessary for characterization of individual compounds and principals on which they work. Key words: medicinal plants, NADP-dependent enzymes, phenolic...
Biochemical Aspects of Artwork Restoring
Boledovičová, Petra ; Hudeček, Jiří (advisor) ; Kubíčková, Božena (referee)
The following bachelor thesis is focussed on findings on the field of art restoring in connection with its biochemical aspects. In itroduction is resumed brief history of art restoring and generally defined terms of preservation, restoring, art and paint. For better understanding basic paint techniques (aquarelle, gouache, tempera and oil painting), strata sequence and instruments and materials commonly used for art work are mentioned. Most frequently used organic and inorganic pigments are briefly mentioned, however this thesis is mainly focussed on applied organic compounds - lipids, proteins, polysacharides and terpenoids - its composition, characteristics, usagea nd possible interactions. The following thesis is written in czech. Key words: restoring, art work, paint, organic binders, lipids, proteins, polysacharides, terpenoids
Connection between abiotic stress and NADP-dependent enzymes in plants
Plisková, Veronika ; Hýsková, Veronika (advisor) ; Kubíčková, Božena (referee)
Salt stress in plants is accompanied with decreased growth caused by lowered leaf water potential, closed stomata and thus reduced photosynthesis producing NADPH. However, NADPH is indispensable coenzyme for biosynthetic processes (e.g. biosynthesis of osmotically active compounds decreasing influence of stress) and for antioxidant system. In this study it was examined, whether NADP-dependent enzymes: glucose-6- phosphate dehydrogenase (G6PDH), NADP-isocitrate dehydrogenase (NADP-ICDH), NADP-malic enzyme (NADP-ME) and NADP-shikimate dehydrogenase (SDH), producing NADPH are involved in plant defence response against 100 mM NaCl. Three different model plants were used: Pisum sativa L., Phaseolus vulgaris L. and Cucumis sativa L. While in leaves of pea and bean plants salt stress caused rather decreased activities of particular NADP-dependent enzymes (especially of G6PDH and NADP-ICDH), in leaves of cucumber 9th and 11th day of stress condition were found increased activities of all studied enzymes. Simultaneously the Na+ content in salt-stressed plants was analysed by atomic emission spectrometry.
Enzymes metabolizing drugs
Škodová, Petra ; Stiborová, Marie (advisor) ; Kubíčková, Božena (referee)
Mixed function oxidase system (MFO) is one of the most effective systems of enzymes of the first phase of biotransformation of xenobiotics. Cytochromes P450 seem to be the most important part of the MFO system, which also contains other components such as NADPH:CYP reductase and membrane lipids. Cytochromes P450 function as a terminal oxidase of the mixed function oxidase (MFO) system. Many xenobiotics, including drugs, are the substrates of these enzymes. Endogenous substances can serve as the substrates of these enzymes as well. Peroxidases are a group of enzymes which are able to metabolize drugs. The function of cytochromes P450 can be substituted by peroxidases. Both groups of enzymes are able to potentiate the effect of the drugs by activating them or they form deactivated metabolites, which are excreted from the organism. The action of cytochromes P450 and peroxidases is shown on the metabolism of the drug ellipticine. Ellipticine has anticancer effects. The advantage of this drug is its low number of side-effects. The oxidation of ellipticine by cytochromes P450 and peroxidases leads to its metabolic activation or detoxification. Carbenium ions are generated by spontaneous cleavage of two active metabolites, 12-hydroxyellipticine and 13-hydroxyellipticine. Carbenium ions then form adducts...
Biochemical aspect of investigation of the natural-origin binders and varnishes in the paint layer of old paintings
Pecháčková, Soňa ; Kubíčková, Božena (referee) ; Hudeček, Jiří (advisor)
The subject of this work are choosen bioanalytical methods, used for the identification of organic binders and varnishes in coloured layer of ancient paintings. In the past, the plant and animal substances were used as a binders and varnishes. To those materials belong proteins, oils, polysacharide gums and resins. Succesful analysis in the history of using binders and varnishes demands a good knowledge of their chemical qualities and reactivity during the process of aging. Nowadays are prefered the methods and technics, which don?t destruct the sample and which are non-invasive towards the whole artwork. Recently, the imunofluorescence technics have been started to use as the alternative methods of classical and easier microchemical tests. The spectroscopic methods are widely used in material investigation of ancient artworks. The main is infrared spectometry (FTIR) and Raman spectroscopy. The methods of nuclear magnetic resonance are significant mainly for studying changes of connective and isolating material during the process of aging. To indentify mainly protein binders, the technic of mass spectrometry (MALDI-TOF) is widely used. Due to the progress of technic the paper and thin-layer chromatography were replaced by very effective high performance liquid chromatography (HPLC), gas chromatography (GC)...
Modulation of activities and expression of enzymes metabolizing ellipticine by histone deacetylase inhibitor trichostatin A
Kopejtková, Barbora ; Kubíčková, Božena (referee) ; Stiborová, Marie (advisor)
Histone deacetylase inhibitor trichostatin A (TSA) increases cytotoxicity of antineoplastic agent ellipticine to human neuroblastoma cells. Its mechanism of action has not yet been explained. One of the possible mode of action is conformational change in chromatin, which leads to changes in DNA that is more accessible to covalent modification and intercalation. The aim of this work is to study another mode of action, which can explain this phenomenon. The question is, if TSA can increase cytotoxicity of ellipticine to human neuroblastoma cells by modulation of activities and expression of cytochromes P450 and peroxidases. These enzymes are responsible for cytotoxicity of ellipticine to human neuroblastoma cells. TSA has no effect on oxidation of ellipticine mediated by cytochromes P450 leading to metabolites responsible for formation of ellipticine-DNA adducts and detoxication metabolites. TSA increases formation of ellipticine dimer, which is a detoxication metabolite, forming during its oxidation by peroxidases. TSA has no effect on activities of CYP1A1, CYP1A2, CYP3A, which significantly participate in oxidation of ellipticine. TSA modulates expression of enzymes oxidizing ellipticin in human neuroblastoma cells. TSA in the presence of ellipticine increases expression of CYP1A1 a CYP3A4 in...

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7 KUBIČKOVÁ, Barbora
7 Kubičková, Barbora
7 Kubíčková, Barbora
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