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The repair of the oxidative DNA damage and its relationship to the cytotoxic effect of the oxidants.
Havlínová, Alena ; Herink, Josef (advisor) ; Hochmann, Jiří (referee)
H2O2 is a strong oxidant and therefore affects all cell structures. Especially the oxidative damage of DNA is known as being very severe. It is considered to be contributing cause of carcinogenesis, mutagenesis and aging. Our work is focused on the relationship between cytotoxic effect of H2O2 and the repair of oxidative DNA damage caused by H2O2. We also studied the effects of epigallocatechin gallate (EGCG). Several studies have already proven its protective activity on DNA in particular concentrations. In our experiments we used the test of cytotoxicity to demonstrate the colony forming inhibition and the comet assay test which measures the number of single strand breaks (SSB) in 109 daltons of DNA. Generally we used cells of line AA8 and in one experiment also NER deficient cells of line UV-20. We found out that EGCG in concentrations of 12,5 and 25 μg/ml significantly protects the cells against cytotoxic effects of H2O2. When we followed the repair of the oxidative DNA damage, we have found that EGCG did not affect the repair of direct DNA breaks, but the repair of oxidised pyrimidines and purines was accelerated. And this acceleration is probably largely responsible for the protection against cytotoxic effect of H2O2. However, the EGCG function of free radical scavenger and iron ions chelator...
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The repair of the oxidative DNA damage in Chinese hamster cells deficient in nucleotide excision DNA repair.
Strejčková, Lada ; Hochmann, Jiří (advisor) ; Polívková, Zdeňka (referee)
Nucleotide excision repair (NER) is one of the mechanisms of how to repair DNA damaged by the external influences. First of all, it plays the role when removing the results caused by UV radiation. The damaged bases in the form of pyrimidine dimers are enzymatically splitted out from DNA as part of oligonucleotides. The effect of the UV light on DNA is however manifested also indirectly, by oxidation of the bases. In our experiment we tried to find out whether the cells deficient in nucleotide excision repair are able to repair the damages induced only by oxidative agent. We stated the extent of DNA damages in the cells in vitro and the ability of their re- paration after treatment with the dilution of hydrogen peroxide in different concentrations. During the experiments we used the cell lines of a Chinese hamster, namely the parental cell line AA8 and their derivative UV-20, which is defective in gene ERCC1. This gene takes part in creation of nucleases participating in NER. For measuring of DNA lesions we used the method of alkaline comet assay, the ba- sis of which is alkaline single-cell gel electrophoresis. The principle of this method consists in the detection of DNA strand breaks originating in the damaged alkali-labile sites. We evaluated the number of DNA single-strand breaks. We detected...
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Influence of the age and other factors on the cytosol concentration of steroid receptors in breast cancer.
Hanáková, Tereza ; Hochmann, Jiří (advisor) ; Filip, Stanislav (referee)
2 Summary Tereza Hanáková Influence of the age and other factors on the cytosol concentration of steroid receptors in breast cancer Diploma assay Charles university in Prague, Faculty of Pharmacy in Hradec Králové Pharmacy In our diploma thesis we analyzed statistically the cytosolic results of estrogen and progesterone receptors (ER a PR) of patients with the breast cancer diagnosis, which we got from the laboratory in Pardubice and Hradec Králové. We compared ER and PR concentrations of premenopausal and postmenopausal patients with the use of different methods of evaluation of age dependence of ER and PR. We used predominantly the methods that exploited the calculations of great number of medians of the neighbouring - mutually overlapping groups of patients. First we marshalled the results in the (programme Excel) table according to the age of patients and we constituted the groups for calculation of the medians from the patients in the mutual neighbourhood. These groups were constituted using the similarity of the patients' age or - on the contrary - by such manner which uses the same number of patients in the groups for medias - the age of which was also similar - but not constantly. The age differences in these groups were greater in such age in which there was the small frequency of arising of such...
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Influence of contraceptives and hormonal substitution therapy on the receptors of sex steroid hormones
Krasulová, Hana ; Hochmann, Jiří (advisor) ; Tošner, Jindřich (referee)
The thesis deals with questions about levels of estrogen and progesteron receptors (ER and PR) in normal breast tissue and in tumorous tissue and explains their changes. The aim of our effort was to find the publications which deal with possibilities of false positivity or negativity in a breast cancer and clarify the time period after which we can expect relevant results of the receptor levels after contraception therapy or hormonal substitution therapy and which concentration of hormones we can expect in serum. First we listed contraception therapy and hormonal therapy. We focused on physiological concentrations of estradiol and progesterone in serum and their potential affection by contraception and hormonal substitution therapy. We found that most of contraceptives contain now such dose of ethinylestradiol to reach such concentration in the serum which are nearly physiological. In postmenopauzal women the estradiol levels decreases in comparison with premenopausal women. The doses of ethinylestradiol during substitution therapy are essentially higher than during contraception therapy. Subsequently we searched for the releationship between levels of ER and PR and their potential affection by contraception or hormonal substituonal therapy. As the Czech literature does not include this questions -...
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