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The effects of thiamine (vitamin B1) on the level of spontaneous or radia­tion-induced genetic changes in human lymphocytes in vitro were studied. Cul­tured lymphocytes were exposed to increasing concentrations of thiamine (0-500 Ug/ml) and irradiated with X-rays. The DNA damage was estimated as the frequency of micronuclei and apoptotic or necrotic morphological changes in fixed cells. The results show that thiamine alone did not induce genetic changes. A significant decrease in the fraction of apoptotic and necrotic cells was observed in lymphocytes irradiated in the presence of vitamin B1 at concentrations between 1-100 ug/ml compared to those irradiated in the absence of thiamine. Vitamin B1 at 1 and 10 Ug/ml decreased also the extent of radiation-induced formation of micronuclei. Vita­min B1 had no effect on radiation-induced cytotoxicity as measured by nuclear divi­sion index. The results indicate that vitamin B1 protects human cells from radia­tion-induced genetic changes.
Taxonomic differentiation between Lactococcus sp. and Leuconostoc sp. can sometimes be misleading due to the morphological and biochemical similarities between both genera. Therefore, several molecular techniques have been applied to identify these bacteria. Restriction fragment length polymorphism analysis of PCR-amplified 16S ribosomal RNA gene was used to generate restriction profiles of 9 strains of Lactococcus sp. and 5 of Leuconostoc sp. This method utilizes a set of universal primers for amplification of the 16S rRNA region of typical lactic acid bacteria species. The size of the amplified products was about 1500 bp and the amplicons of the different species could be differentiated from each other with four restriction endonucleases: TaqI, EcoRI, BamHI and HindIII. These restriction enzymes were selected based on nucleotide sequences of 16S rRNA genes for LAB available in databases. Our study demonstrates that DNA of 16S rRNA from strains of Lactococcus sp. contains single restriction site for EcoRI and two restriction sites for TaqI enzymes, 16S rRNA DNA from strains of Leuconostoc sp. contains a single restriction site for each enzyme (HindIII, BamHI) and four restriction sites for TaqI. This result is in good agreement with analysis in silico of 16S rRNA genes published in the National Center for Biotechnology Information (NCBI). These findings led to modify the classification obtained by biochemical methods for five examined strains of lactic acid bacteria. In summary, our study demonstrated that the RFLP analysis applied is a useful method for rapid differentiation between Lactococcus sp. and Leuconostoc sp.
PCR-RFLP analysis of commonly occurring insertion sequences ISS1-type, IS904 and IS982 in Lactococcus sp. and Leuconostoc sp. was used for the genetic differentiation of 17 strains of lactic acid bacteria. ISS1-type and IS982 were found in all analysed strains while 1S904 was present exclusively in strains belonging to Lactococcus sp. Amplification of ISS1-type IS sequences resulted in formation of about 820 bp long amplicons, except of strains Lactococcus lactis ssp. lactis E and Leuconostoc lactis R where extra DNA bands about 370 bp long were observed. Similarly for strains of Leuconostoc lactis M and N, additional DNA bands about 280 bp long were present. TaqI digestion of ISS1-type amplicons revealed that all analysed sequences belonged to the restriction type (ii) or (iii) for which major restriction products were 543 and 147 bp long. Amplification of IS904 from all strains of Lactococcus sp. generated amplicons about 1260 bp long. In three strains of Leuconostoc sp. M, N and R, shorter amplicons about 880 bp were observed whereas strains O and P did not contained IS904. Amplification of IS982 resulted in formation of amplicons about 1000 bp long and no extra bands were observed for all tested strains. TaqI digestion of amplification products showed that for strains C, I and F, G, H, belonging to Lactococcus sp. smaller DNA bands were visible suggesting that they contain two different types of IS9S2.
This study investigates the toxic effect of E(2)nonenal (trans-2-nonenal, T2N) and its conjugate with horse muscle myoglobin (Mb) tested on murine cell line L₉₂₉ and human cell line A₅₄₉, as well as the genotoxic effect of these compounds assayed by measuring of micronuclei in human cells K₅₆₂. It is an aldehyde, which is occurring as the substance responsible for an off flavour in aged beers, but originates also from lipid oxidation in heat processed food. T2N is an aldehyde formed from linoleic acid as a secondary oxidation product. The modification of Mb with T2N was analyzed with the use of SDS-polyacrylamide gel electrophoresis (SDS-PAGE), and electrospray ionization mass spectrometry (ESI-MS). Results from SDS-PAGE suggest that T2N substitutes Mb and additionally causes cross-linking with polymerization of Mb resulting in an insoluble fraction. The ESI-MS spectrum of the soluble fraction used in the toxicity tests, demonstrated that conjugation of T2N with Mb yielded Mb adducts with one residue of trans-2-nonenal per myoglobin molecule as the major fraction and adducts with different numbers of T2N molecules as minor fractions. In the cytotoxicity assay the T2N and its Mb conjugate causes 50 % destruction of cells at the concentration 95-125 pg/ml and 200 pg/ml respectively, when L₉₂₉ and A₅₄₉ cell lines were used, whereas Mb control tested up to 2000 mg/ml was without any cytotoxic effect. In genotoxicity in vitro assay we have observed that the T2N and its Mb conjugate expressed the genotoxicity. The number of micronuclei in human K₅₆₂ cells reac₅₆₂ 26 ± 2.16 promille (MN/1000 cells), comparing to 62 ± 8.64 MN/1000 cells for the reference free T2N, whereas a control value was 10.33 ± 1.25 MN/1000 cells. The studied compounds expressed also the apoptotic effect in K₅₆₂ cells as the number of apoptotic cells increased to 44.67 ±4.92 promille for T2N-Mb, comparing to 168.67 ±37.28 promille for free T2N, whereas a control value was 30.33 ± 1.36 promille for Mb. In these assays the T2N-Mb conjugate is several times more toxic in relation to control protein. Results indicate that T2N adducts with protein are potent to induce various cytotoxic and apoptotic effects when assayed in vitro tests. It suggests that higher level of such aldehyde might create in organism severe potential of toxicity.
 Vitamin D3 (1,25(OH)2D3 (1,25-dihydroxyvitamin D3)) is a hormone playing a crucial role in numerous biological processes in the human body, including induction and control of cell proliferation and differentiation. Numerous data relate the vitamin D3 level with various types of cancer. It has been suggested that SNPs in the vitamin D3 receptor (VDR) gene might influence both the risk of cancer occurrence and cancer progression. The aim of this study was to search for genetic correlations between individual SNPs in the VDR gene and the risk of oral cavity carcinoma. Two SNPs were selected based on the literature and our previous results. Seventy-three patients with squamous cell carcinoma of the head and neck and one hundred control subjects were investigated. Two SNPs in the VDR gene were genotyped in minisequencing reactions followed by capillary electrophoresis. Hardy-Weinberg equilibrium (HWE), the χ2 test and logistic regression were used for statistical analysis. The SNP rs2238135 in the VDR gene displayed statistical differences in frequency between the tested groups (p=0,0007). Furthermore, the G/C genotype of the rs2238135 in the VDR gene was characterized by a 3.16 fold increased risk of oral cavity carcinoma. The obtained results provide evidence for a genetic association between rs2238135 in the VDR gene and the occurrence and risk of oral cavity cancer.
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