Protein carbonyls and traditional biomarkers in pigs exposed to low-dose γ-radiation.

Response of pigs to irradiation manifested by production of protein carbonyls and adaptable enzymes was studied in two experiments. In one experiment, 10 mixed-sex pigs were exposed to 0.5 Gy whole body (60)Co irradiation. In the other experiment, another batch of 10 pigs was exposed to 1.0 Gy half-body irradiation. Unlike those exposed to half-body irradiation, the pigs exposed to whole-body irradiation showed significant increase in protein carbonyls by 73%, and a decrease in cholesterol by 25.7%, compared to the control group. In both cases of dose-dependent irradiation exposure, pigs showed a decrease in alanine aminotransferase activity compared with the control group. At the dose of 1 Gy, ALT activity decreased significantly by 27.7%. Aspartate aminotransferase activity in pigs after half-body irradiation decreased significantly by 65.5%. Although low doses of ionizing radiation were applied, monitoring of the above biochemical parameters helped define the pigs' biological response.

Liquid chromatography tandem mass spectrometry determination of maduramycin residues in the tissues of broiler chickens.

Maduramycin is a polyether ionophoric coccidiostat used to prevent coccidiosis in poultry at a prescribed concentration over a certain time interval. Due to public health concerns about the presence of coccidiostat residues in poultry, the aim of the present study was to determine the level of maduramycin residues in the tissues of broiler chickens fed commercially produced feed containing 5 mg kg(-1) of maduramycin in complete feed throughout the 5-day withdrawal period (WP). The residues were investigated by liquid chromatography (LC) coupled with electrospray ionisation (ESI) tandem mass spectrometry (MS/MS). The limit of detection (LOD) and limit of quantification (LOQ) of the method were 0.3 and 0.8 microg kg(-1), respectively. The average recovery based on matrix-fortified calibrations for chicken tissues was 90%. Maduramycin was found to be rapidly distributed in all tissues. The highest concentrations of maduramycin residues were found in the heart followed by the skin, liver, gizzard, kidneys and, finally, muscle (thigh and breast). On day 5 of the WP, residue concentrations of maduramycin did not decline below the LOQ of the method. Our results emphasize the need to establish a maximum residue limit (MRL) for maduramycin to control its residue levels in edible tissues from chickens before slaughter.

Evaluation of three different microbial inhibition tests for the detection of sulphamethazine residues in the edible tissues of rabbit.

The aim of the present study was to evaluate three microbial inhibition tests (MIT) based on inhibition of growth of the test organisms: (a) four plate test (FPT) containing Bacillus subtilis BGA, (b) screening test for antibiotic residues (STAR) containing Bacillus stearothermophilus var. calidolactis_ATCC 10149 and (c) the Premi(R)Test containing Bacillus stearothermophilus var. calidolactis. The tests were used to determine sulphamethazine (SMZ) residues in edible tissues of rabbit after oral administration up to day 15 of the withdrawal period (WP). A solvent extraction procedure was used to enhance the capability of the tests to detect SMZ residues at or below the maximum residue limit (MRL). Para-aminobenzoic acid (PABA) was employed to previously identify SMZ residues in the first stage of the residue screening. The presence of SMZ residues in the samples was confirmed and quantified by a validated HPLC method. The Premi(R)Test detected SMZ residues in the muscle and heart tissue up to day 9 of the WP, and in the liver, lungs and kidneys up to day 10 of the WP. The STAR detected SMZ residues in the edible organs of rabbits up to day 8 of the WP. The kidneys were positive up to day 5 of the WP, the liver until day 4 of the WP and the lungs until day 3 of the WP. No SMZ residues were detected in the muscle and heart. By using the solvent extraction procedure, SMZ residues were detected in the muscle extract up to day 10 of the WP and the muscle was positive until day 6 of the WP. No detection sensitivity was observed using the FPT. After solvent extraction, SMZ residues were detected in the muscle extract until day 8 of the WP and the muscle was positive until day 3 of the WP. No positive results were detected after the addition of PABA into/onto the agar medium. PABA at a concentration of 10 microg ml(-1) completely reversed the inhibitory activity of SMZ and enabled reliable identification of SMZ in the examined samples. Using HPLC, SMZ was detected in the muscle samples until day 10 of WP (0.02 mg kg(-1)) and in the liver until day 12 of the WP (0.09 mg kg(-1)). The results obtained by the HPLC method and the limit of detection (LOD) of screening tests for SMZ (FPT 0.4 microg ml(-1), STAR 0.2 microg ml(-1), Premi(R) Test 0.05 microg ml(-1)) allowed us to state that the most suitable screening tests for the detection of SMZ residues in the edible tissues of rabbits at level corresponding to the MRL of 0.1 mg kg(-1), established for sulphonamides, are the Premi(R)Test and STAR in conjunction with the solvent-extraction procedure.

Determination of lipid oxidation level in broiler meat by liquid chromatography.

An assay was conducted for the determination of malondialdehyde (MDA) levels in broiler meat. The method involves extraction of tissues with trichloroacetic acid (TCA) and reaction of the TCA extract with 2,4-dinitrophenylhydrazine (DNPH). After separation of the MDA-DNPH complex using a solid-phase extraction C18 column, samples were eluted with 1 mL acetonitrile. Aliquots of 20 microL acetonitrile were analyzed by liquid chromatography on reversed-phase C18 column (3 microm) with UV detection. The products were eluted isocratically with the mobile phase containing acetonitrile-water-acetic acid (39 + 61 + 0.2, v/v/v). The retention time for MDA-DNPH was 6.5 min, and the detection limit was 3.5 microg/kg. Two extraction methods (cold and hot) were also used in the study. The results showed that hot extraction increased results about 55.8% and recovery from samples spiked with 116.6 microg/kg was lower (74.6%) in comparison with cold extraction (94.7%).