Thesis (M.Sc. (Biochemistry)) --University of Limpopo, 2004 / Refer to the document / National Research Foundation (NRF) and the UNlN Research Commitee

No / Ethylmethanesulphonate (EMS), benzidine (BZD) and benzo[a]pyrene (B[a]P) were assayed for ability to induce mutation at the hprt locus of wild-type L5178Y mouse lymphoma cells. EMS was assayed in the absence of metabolic activation, B[a]P in the presence of metabolic activation (S-9 mix) and BZD both in the absence and presence of S-9. Treatment with EMS minus S-9 and B[a]P plus S-9, especially when the S-9 content of the incubation was 2% (v/v), produced strong dose-related increases in mutant frequency. BZD failed to induce mutation at the hprt locus, either in the absence or presence of S-9.

<p>Generation of DNA damage is regarded to be an important initial event in the development cancer. Consequently, a battery of tests have been developed to detect different types of genotoxic effects in order to be able to predict the potential genotoxicity and mutagenicity of chemicals, including both pharmaceutical drugs and various types of environmental and occupational agents, as well as dietary factors. The aim of this thesis was to evaluate whether the combination of the comet assay and the extended-term cultures of human lymphocytes (ETC) can be used as an alternative <i>in vitro</i> system to more commonly used transformed mammalian cell lines, and primary cell cultures from humans, when testing the potential genotoxicity of chemicals. </p><p>Using the comet assay, a panel of reference compounds showed that the ETC were found to detect the DNA-damaging effects with no remarkable difference to what has been reported in other cell types. Moreover, in comparison with a well-established rodent cell line, the mouse lymphoma L5178Y cells, the ETC showed similar sensitivity to the DNA damaging effects of the genotoxic agents hydrogen peroxide and catechol. Although there was an interindividual variation in induced DNA damage and the subsequent repair when using ETC from different blood donors, it did not seem to be of crucial importance for the identification of DNA-damaging agents. The demonstrated difference in sensitivity to catechol-induced DNA damage between freshly isolated peripheral lymphocytes and ETC may very well be due to their different proliferative status but despite this difference, both <i>in vitro</i> systems were able to identify catechol as a DNA-damaging agent at the same concentration.</p><p>Based on these results, it is proposed that the ETC and the comet assay are a useful combination when testing for the potential DNA damaging effects of chemicals. Representing easily cultivated cells possessing the normal human karyotype, where one blood sample can be used for numerous experiments performed over a long time, extended-term cultures appear to be a useful alternative, both to transformed mammalian cell lines, and primary cell cultures from humans. In fact, the extended-term lymphocytes, with or without S9 and/or lesion specific DNA repair enzymes, should be used more frequently when screening for the potential genotoxicity of chemicals.</p>

Generation of DNA damage is regarded to be an important initial event in the development cancer. Consequently, a battery of tests have been developed to detect different types of genotoxic effects in order to be able to predict the potential genotoxicity and mutagenicity of chemicals, including both pharmaceutical drugs and various types of environmental and occupational agents, as well as dietary factors. The aim of this thesis was to evaluate whether the combination of the comet assay and the extended-term cultures of human lymphocytes (ETC) can be used as an alternative in vitro system to more commonly used transformed mammalian cell lines, and primary cell cultures from humans, when testing the potential genotoxicity of chemicals. Using the comet assay, a panel of reference compounds showed that the ETC were found to detect the DNA-damaging effects with no remarkable difference to what has been reported in other cell types. Moreover, in comparison with a well-established rodent cell line, the mouse lymphoma L5178Y cells, the ETC showed similar sensitivity to the DNA damaging effects of the genotoxic agents hydrogen peroxide and catechol. Although there was an interindividual variation in induced DNA damage and the subsequent repair when using ETC from different blood donors, it did not seem to be of crucial importance for the identification of DNA-damaging agents. The demonstrated difference in sensitivity to catechol-induced DNA damage between freshly isolated peripheral lymphocytes and ETC may very well be due to their different proliferative status but despite this difference, both in vitro systems were able to identify catechol as a DNA-damaging agent at the same concentration. Based on these results, it is proposed that the ETC and the comet assay are a useful combination when testing for the potential DNA damaging effects of chemicals. Representing easily cultivated cells possessing the normal human karyotype, where one blood sample can be used for numerous experiments performed over a long time, extended-term cultures appear to be a useful alternative, both to transformed mammalian cell lines, and primary cell cultures from humans. In fact, the extended-term lymphocytes, with or without S9 and/or lesion specific DNA repair enzymes, should be used more frequently when screening for the potential genotoxicity of chemicals.

No description available.

<p>Opisane&nbsp; su&nbsp; sinteze&nbsp; novih&nbsp; liganada&nbsp; bis(ftalazin-1hidrazon)-2,6-diacetilpiridna&nbsp; (Hz₂DAP&middot;2HCl),&nbsp; bis(3-hlorpiridazin-6-hidrazon)-2,6-diacetilpiridina (Hp₂DAP),&nbsp; 3-hlorpiridazin-6-hidrazon&nbsp; di(2-piridil) ketona&nbsp; (HpDPK),&nbsp; ftalazin-1-hidrazon&nbsp; di(2-piridil)<br />ketona&nbsp; (HzDPK)&nbsp; i&nbsp; ftalazin-1-hidrazon&nbsp; piridin-2-karbaldehida&nbsp; (HzPY).&nbsp; Zajedničko&nbsp; svojstvo&nbsp; dobijenih liganada&nbsp; je&nbsp; &scaron;to&nbsp; sadrže&nbsp; piridinski&nbsp; i&nbsp; diazinski&nbsp; prsten&nbsp; i sadrže&nbsp; samo&nbsp; donorne&nbsp; atome&nbsp; azota.&nbsp; Tokom&nbsp; nastajanja kompleksa dolazi do deprotonacije liganada. Svi ligandi su&nbsp; okarakterisani&nbsp; elementalnom&nbsp; analizom, termoanalitičkim&nbsp; metodama&nbsp; i&nbsp; metodom&nbsp; IR spektroskopije,&nbsp; dok&nbsp; neki&nbsp; i&nbsp; metodom&nbsp; NMR spektroskopije&nbsp; kao&nbsp; i&nbsp; rendgenskom&nbsp; strukturnom analizom.Za&nbsp; sintezu&nbsp; koordinacionih&nbsp; jedinjenja&nbsp; primenjeni&nbsp; soli Co(II),&nbsp; Ni(II),&nbsp; Cu(II)&nbsp; i&nbsp; Zn(II).&nbsp; Dobijeni&nbsp; kompleksi su okarakterisani&nbsp; elementalnom&nbsp; analizom, konduktomerijskim&nbsp; i&nbsp; magnetnim&nbsp; merenjima,&nbsp; IR spektroskopijom i termoanalitičkim metodama. Barem jedan&nbsp; kompleks&nbsp; iz&nbsp; svake&nbsp; serije&nbsp; je&nbsp; okarakterisan&nbsp; i rendgenskom strukturnom analizom. Urađena&nbsp; su&nbsp; i&nbsp; ispitivanja&nbsp; antimikrobne&nbsp; aktivnosti odabranih&nbsp; jedinjenja&nbsp; prema&nbsp; predstavnicima&nbsp; grampozitivnih i gram-negativnih bakterija i kulturu kvasca. Pored&nbsp; toga,&nbsp; urađena&nbsp; su&nbsp; i&nbsp; ispitivanja&nbsp; citotoksične,antiproliferativne&nbsp; i&nbsp; inhibitorne&nbsp; aktivnosti&nbsp; jedinjenja prema&nbsp; roditeljskim&nbsp; i&nbsp; multirezistentnim&nbsp; T-limfomnim ćelijama&nbsp; kancera.&nbsp; Utvrđeno&nbsp; je&nbsp; da&nbsp; neka&nbsp; jedinjenja pokazuju&nbsp; izrazito&nbsp; mikrobicidno,&nbsp; citotoksično, antiproliferativno i inhibitorno dejstvo.</p> / <p>The synthesis of new ligands dihydrochloride salt of 2,6-diacetylpyridne&nbsp;&nbsp; bis(phthalazine-1hydrazone) (Hz₂DAP&bull;2HCl),&nbsp; 2,6-diacetylpiridine&nbsp; bis(3- chloropyridazine-6-hydrazone)&nbsp; (Hp₂DAP),&nbsp; di(2-pyridyl)ketone&nbsp; 3-chloropyridazine- 6-hydrazone (HpDPK),&nbsp; di(2-pyridyl)ketone&nbsp; phthalazine-1-hydrazone&nbsp; (HzDPK)&nbsp; and&nbsp; &nbsp; pyridine-2-carbaldehide phthalazine-1-hydrazone&nbsp; (HzPY)&nbsp; have&nbsp; been described. All the ligands contain pyridine and diazine core and all of them have only nitrogen donor atoms. During the complex formation the deprotonation of ligands takes&nbsp; places.&nbsp; All&nbsp; of&nbsp; the&nbsp; ligands&nbsp; have&nbsp; been characterized&nbsp; by&nbsp; elemental&nbsp; analysis,thermoanalytical&nbsp; methods&nbsp; and&nbsp; IR&nbsp; spectroscopy.&nbsp; In some&nbsp; cases&nbsp; also&nbsp; by&nbsp; NMR&nbsp; spectroscopy&nbsp; and&nbsp; X-ray structural analysis.Co(II), Ni(II), Cu(II) and Zn(II) salts were&nbsp; used for the synthesis&nbsp; of&nbsp; the&nbsp; coordinational&nbsp; compounds.&nbsp; The obtained complexes were characterized by elemental analysis,&nbsp; molar&nbsp; conductivity&nbsp; and&nbsp; magnetic measurements,&nbsp; IR&nbsp; spectroscopy&nbsp; and thermoanalytical&nbsp; methods.&nbsp; At&nbsp; least&nbsp; one complex&nbsp; of each&nbsp; series&nbsp; were&nbsp; characterized&nbsp; by&nbsp; X-ray&nbsp; structural analysis.The antimicrobial activity of some of the compounds toward&nbsp; Gram-positive/Gram- negative&nbsp; bacteria furthermore,&nbsp; the&nbsp; cytotoxic,&nbsp; antiproliferative&nbsp; and inhibitory&nbsp; activity&nbsp; toward&nbsp; sensitive&nbsp; parental&nbsp; andmultiresistant&nbsp; T-lymphoma&nbsp; cancer&nbsp; cells&nbsp; have&nbsp; also been carried out. It&nbsp; can&nbsp; be&nbsp; concluded&nbsp; that&nbsp; some&nbsp; of&nbsp; the&nbsp; compounds exhibit&nbsp; outstanding&nbsp; antimicrobial,&nbsp; cytotoxic, antiproliferative, and inhibitory activity.</p>