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Considering the preexisting influence of the process of natural aging on antioxidant enzymes activity and the level of lipid peroxidation, the age of the rats at which D-galactose (D-gal) treatment is started could strongly impact the development of D-gal induced senescence. To evaluate this, we subjected 1, 3 and 15 months old rats to D-gal treatment in parallel with having appropriate placebos (0.9 % saline). Our results showed elevated glutathione peroxidase (GPx) activity and no significant changes in superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) activity or malondialdehyde (MDA) levels in relation to natural aging. In mature and aged senescent livers we observed positive correlation between increased ratio R=SOD/(GPx+CAT) and increased MDA concentration. MDA levels seemed to correlate positively with the age of the animals at which D-gal treatment had started. In the case of 3 and 15 months old rats there was D-gal induced decrease in SOD and GR activity, but this effect of the treatment was not observed in 1 month old rats. Our results imply that the changes in the antioxidant enzyme activities are not only under the influence of the D-gal overload, but also depend on the developmental stage of the rats. According to our results, with regard to enzymatic antioxidant capacity and the level of lipid peroxidation, the best age for induction of senescence is somewhere after the third month.

A multi-class and multi-residue/contaminant method for the determination of veterinary drug and pesticide residues and mycotoxins in bovine meat has been developed and validated. The veterinary drug residues/contaminants included antimicrobials, anabolic hormones, lactones, β-agonists, mycotoxins, and pesticides. Isotopic labeled internal standards were included to compensate residual matrix effects. The calibrators used in the method demonstrated linearity with the R2 > 0.98. The decision limit (CCα) values were in the range from 0.067 to 2103.84 μg/kg, while the range for detection capability (CCβ) was from 0.083 to 2482.13 μg/kg. The limit of detection (LOD) and limit of quantification (LOQ) were in the range from 0.059 to 291.36 μg/kg, and 0.081 to 328.13 μg/kg, respectively. The recovery of analytes ranged from 61.28% to 116.20%. The intra-day coefficient of variation (CV) was from 0.97 to 25.93% and the inter-day CV was 2.30–34.04%. The method has been used for the determination of 49 residues/contaminants in bovine meat. Application of the method in routine analysis in bovine samples, revealed in limited samples the presences of enrofloxacin, oxytetracycline and sulfadiazine at the concentration of 35.22 µg/kg, 27.35 µg/kg, and 36.20 µg/kg, respectively.

The probability of contamination of non-transgenic varieties with genetically modified (GM) products increase as a result of global expansion of areas sown with transgenic crops. DNA-based methods as accurate, efficient and reliable methods are preferable for detection of GM material in raw or highly processed foods. Isolation of high quality DNA with a suitable and efficient DNA extraction protocol is crucial for getting precise results in DNA amplification. In this study, we performed modifications of previously known Sodium dodecyl sulfate (SDS)-based DNA extraction method regarding the incubation period, DNA pellet washing and addition of organic solvent extraction, to improve DNA quality and to reduce costs. Raw corn kernels and roasted soybean seed were used as samples. DNA was extracted following three protocols, modifications of Edwards protocol. The type of detergent used in raw corn sample did not cause significant effects on extracted DNA yield and purity, while in roasted soybean samples the 2% (w/v) SDS lysis buffer gave the highest DNA yield. The additional incubation step raised the DNA yield from raw corn for 121%, while the purest DNA from soybean sample was obtained using organic solvent extraction. Electrophoretic determination of DNA integrity showed varying degree of DNA smearing from roasted soybean. Contrary, all extraction protocols used on raw corn kernels produced a high molecular weight DNA. Thus, our in-house DNA extraction protocol is as efficient but more cost effective compared to commercial kits and can be used for raw corn, while the protocol for roasted soybean needs further improvement.

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