Multi-residue analytical method for detecting pesticides, veterinary drugs, and mycotoxins in feed using liquid- and gas chromatography coupled with mass spectrometry.

Modified QuEChERS and triple quadrupole mass spectrometry (LC and GC-MS/MS) technology were used to sequentially analyze pesticides, veterinary drugs, and mycotoxins in feed. In order to analyze the harmful substances that may remain or occur in the feed, we performed optimization experiments for sample preparation and LC-MS/MS and GC-MS/MS conditions. Optimized sample preparation involves extracting 5 g of sample with 15 mL of 0.25 M EDTA and 10 mL of acetonitrile. And some extracts were diluted 10-fold with 100 mM ammonium formate aqueous solution and analyzed by LC-MS/MS, and some extracts were purified through 25 mg PSA and analyzed by GC-MS/MS by adding an analyte protectant. We confirmed the matrix effect of feed ingredients and compound feeds, and added a dilution process after extraction to increase on-site efficiency. Matrix-matched calibration was applied for quantification. Method validation was performed for 197 pesticides, 56 components for veterinary drugs, and 5 components for toxins. All the components showed good linearity (r2 ≥ 0.98) in the developed analytical method. For most compounds, the limit of quantitation was 0.05 mg/kg. The recovery rate experiment was repeated three times at three concentrations including LOQ in feed ingredient, compound feed for livestock, and compound feed for pets. The recovery rate was 70.09-119.76% and relative standard deviations were ≤ 18.91%. And the accuracy and precision were further verified through cross-validation between laboratories. The developed analytical method was used to monitor 414 domestically distributed and imported feeds.

Effect of atmospheric pressure plasma on inactivation of pathogens inoculated onto bacon using two different gas compositions.

Atmospheric pressure plasma (APP) is an emerging non-thermal pasteurization method for the enhancement of food safety. In this study, the effect of APP on the inactivation of pathogens inoculated onto bacon was observed. Sliced bacon was inoculated with Listeria monocytogenes (KCTC 3596), Escherichia coli (KCTC 1682), and Salmonella Typhimurium (KCTC 1925). The samples were treated with APP at 75, 100, and 125 W of input power for 60 and 90 s. Two gases, helium (10 lpm) or a mixture of helium and oxygen, (10 lpm and 10 sccm, respectively) were used for the plasma generation. Plasma with helium could only reduce the number of inoculated pathogens by about 1-2 Log cycles. On the other hand, the helium/oxygen gas mixture was able to achieve microbial reduction of about 2-3 Log cycles. The number of total aerobic bacteria showed 1.89 and 4.58 decimal reductions after plasma treatment with helium and the helium/oxygen mixture, respectively. Microscopic observation of the bacon after plasma treatment did not find any significant changes, except that the L∗-value of the bacon surface was increased. These results clearly indicate that APP treatment is effective for the inactivation of the three pathogens used in this study, although further investigation is needed for elucidating quality changes after treatment.

Gliotoxin enhances radiotherapy via inhibition of radiation-induced GADD45a, p38, and NFkappaB activation.

The purpose of the study was to elucidate the mechanism underlying the enhancement of radiosensitivity to 60Co gamma-irradiation in human hepatoma cell line HepG2 pretreated with gliotoxin. Enhancement of radiotherapy by gliotoxin was investigated in vitro with human hepatoma HepG2 cell line. Apoptosis related proteins were evaluated by Western blotting. Annexin V/PI and reactive oxygen species (ROS) were quantified by Flow Cytometric (FACS) analysis. Gliotoxin (200 ng/ml) combined with radiation (4 Gy) treated cells induced apoptosis. Cells treated with gliotoxin (200 ng/ml) prior to irradiation at 4 Gy induced the expression of bax and nitric oxide (NO). The gliotoxin-irradiated cells also increased caspase-3 activation and ROS. Gadd45a, p38, and nuclear factor kappa B (NFkappaB) activated in irradiated cells was inhibited by Gliotoxin. Specific inhibitors of p38 kinase, SB203580, significantly inhibited NFkappaB activation and increased the cytotoxicity effect in cells exposed to gliotoxin combined with irradiation. However, SB203580 did not suppress the activation of Gadd45a in irradiated cells. Gliotoxin inhibited anti-apoptotic signal pathway involving the activation of Gadd45a-p38-NFkappaB mediated survival pathway that prevent radiation-induced cell death. Therefore, gliotoxin, blocking inflammation pathway and enhancing irradiation-induced apoptosis, is a promising agent to increase the radiotherapy of tumor cells.