• Journal of Food Hygiene and Safety
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• v.37 no.3
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• pp.136-142
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• 2022

The research aims to develop a rapid and easy analytical method for methoprene using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A simple, highly sensitive, and specific analytical method for the determination of methoprene in livestock products (beef, pork, chicken, milk, eggs, and fat) was developed. Methoprene was effectively extracted with 1% acetic acid in acetonitrile and acetone (1:1), followed by the addition of anhydrous magnesium sulfate (MgSO₄) and anhydrous sodium acetate. Subsequently, the lipids in the livestock sample were extracted by freezing them at -20℃. The extracts were cleaned using MgSO₄, primary secondary amine (PSA), and octadecyl (C₁₈), which were then centrifuged to separate the supernatant. Nitrogen gas was used to evaporate the supernatant, which was then dissolved in methanol. The matrix-matched calibration curves were constructed using 8 levels (1, 2.5, 5, 10, 25, 50, 100, 150 ng/mL) and the coefficient of determination (R²) was above 0.9964. Average recoveries spiked at three levels (0.01, 0.1, and 0.5 mg/kg), and ranged from 79.5-105.1%, with relative standard deviations (RSDs) smaller than 14.2%, as required by the Codex guideline (CODEX CAC/GL 40). This study could be useful for residue safety management in livestock products.

• Korean Journal of Poultry Science
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• v.42 no.2
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• pp.109-116
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• 2015

Ogye rooster sperm chromatin status can be detected using well established sperm assays. In this paper, a simple and fast method to monitor rooster sperm chromatin status could be employed in field for assessment of chicken sperm quality. Using standard bright field microscope, Diff-Quik stains can be reproducibly, easily and routinely monitored with simple staining. The presence of abnormal chromatin staining of rooster sperm was determined by darker stain in head. In the fresh semen, the viabilities of three tested Ogye spermatozoa were 93.53%, 82.42% and 90.63% and normal chromatin rates were 87.96%, 74.25% and 85.10% respectively. However, after freezing, the rates of viability of thawed semen were reduced to 69.58%, 61.98% and 72.20% and normal chromatin rate also reduced to 58.91%, 48.49% and 63.34%. A significant correlation between live sperm and normal sperm nuclei was 0.875 in fresh semen and 0.513 in frozen semen. After incubation of sperm at $37^{\circ}C$ for 5min, the rates of viability, chromatin normality and sperm head activity were shown as $90.63{\pm}1.28%$, $82.44{\pm}8.09%$ and $66.68{\pm}10.29%$ in fresh semen. However, the rates of thawed semen were reduced to $67.92{\pm}7.55%$, $56.92{\pm}12.15%$ and 47.32{\pm}5.02%, respectively. The relationship between chromatin normality and sperm head movements in fresh and thawed semen were 0.564 and 0.540, respectively. With these results, the chicken sperm normality could be assessed by the Diff-Quik staining that could be used for chromatin status of sperm head and activated morphology of live spermatozoa, as a simple and rapid staining method.

• Clinical and Experimental Reproductive Medicine
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• v.33 no.4
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• pp.237-243
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• 2006

Objective: The aim of this study was to evaluate the efficacy of frozen-thawed ET in poor prognosis patients such as the old age (38~44 years; OA group) and the patients who did not achieve clinical pregnancy with the first fresh ET cycle (non-pregnant patients; NP group). Methods: Laboratory and clinical data were collected from fresh and frozen-thawed ET cycles of OA and NP group. Controlled ovarian hyperstimulation (COH) and conventional insemination or ICSI, in vitro culture and ET were performed by routine procedures. Supernumerary embryos were frozen by the slow freezing method, and frozen embryos were thawed by the rapid thawing method. Embryo development, pregnancy and implantation rates were statistically analyzed by Student t-test and chi square test Results: Mean ages were similar between fresh ET ($40.0{\pm}1.8$ years, n=206) and frozen-thawed ET ($39.9{\pm}1.9$ years, n=69) cycles in OA group. However, the clinical pregnancy and implantation rate of subsequent frozen-thawed ET significantly higher than those of fresh ET cycles (29.0% and 11.2% vs. 16.5% and 7.0%, p<0.05). In NP group, there was no difference in the mean age between fresh ET ($31.2{\pm}2.3$ years, n=40) and frozen-thawed ET ($31.9{\pm}3.1$ years, n=119) in subsequent cycles. The clinical pregnancy and implantation rates were similar between the subsequent fresh ET (42.5% and 22.6%) and the frozen-thawed ET (40.3% and 18.8%). Conclusion: In old age patients, higher pregnancy rate of frozen-thawed ET compared to fresh ET cycles in this study. It may be related that better uterine environments for implantation in frozen-thawed ET cycles than that of non-physiological hormonal condition in uterus of fresh COH cycles.