• Research in Plant Disease
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• v.27 no.1
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• pp.1-7
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• 2021

In August 2020, necrotic ringspots on leaves were observed on 20 from 143 Plantago asiatica plants in open fields in Eumseong, Chungcheongbuk-do. Eight symptomatic Plantago asiatica plants were subjected to investigation on viral infection by reverse transcription and polymerase chain reaction. Impatiens necrotic spot virus, tomato spotted wilt virus and cucumber mosaic virus were detected from the symptomatic plants. Two impatiens necrotic spot virus (INSV) isolates ('INSV-plantain kr1' and '-plantain kr5') were sequenced and analyzed by comparing L genomic segment, nucleoprotein (N) gene and non-structural protein S (NSs) gene sequences. The nucleotide sequence of 'INSV-plantain kr1' isolate (MW114834) was most closely related to that of a 'Phalaenopsis' isolate (GQ336991) from China in the L genomic segment. 'INSV-plantain kr1' and '-plantain kr5' isolates shared the highest identities with those from 'Pepe' isolate (LC384872) and 'J' isolate (AB109100) in the NSs gene, respectively, and with that from 'YSMi-SH' isolate (FN400773) in the N gene. Phylogenetic analysis based on L genomic segment grouped the INSV-plantain kr1 isolate together with isolates from Korea (LC384870), China (GU112505, GQ336991), and Italy (DQ425094). This is the first report on INSV in P. asiatica from Korea.

• Korean Journal of Environmental Biology
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• v.41 no.3
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• pp.193-203
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• 2023

Ethyl formate (EF) is a naturally occurring insecticidal compound and is used to control pests introduced from abroad, in quarantine, by a fumigation method. In particular, it is mainly used as a substitute for methyl bromide and is less toxic to humans and less harmful to plants. This study aimed to investigate the possible acute toxicity of EF to useful organisms, and how to reduce phytotoxicity in watermelon, zucchini, and oriental melon. After fumigation with EF for 2 h, the LC₅₀ values for earthworms, honey bees, and silkworms were 39.9, 7.09, and 17.9g m^-3, respectively. The degree of susceptibility to EF was in the order of earthworms, silkworms, and honey bees based on the LC₅₀ value, and EF fumigation induced stronger acute toxicity to honey bees. Phytotoxicity was observed in watermelon leaves treated with a concentration of 7.5 g m^-3 EF, and when treated with a concentration of 10.0g m^-3, it was confirmed that the edges of watermelon leaves were charred and seemed to be damaged by acids. Zucchini and melon, and other cucurbits, showed strong damage to the leaves when treated with a concentration of 10 g m^-3, and sodium silicate, at concentrations of 10% and 20%, was used to reduce phytotoxicity. Therefore, acute toxicity towards nontarget organisms and phytotoxicity during the fumigation of EF should be reduced for efficient agricultural pest control.

• Tuberculosis and Respiratory Diseases
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• v.69 no.1
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• pp.16-23
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• 2010

Background: Most lung cancer patients receive systemic chemotherapy at an advanced stage disease. Cisplatin-based chemotherapy is the main regimen for treating advanced lung cancer. Recently, autophagy has become an important mechanism of cellular adaptation under starvation or cell oxidative stress. The purpose of this study was to determine whether or not autophagy can occurred in cisplatin-treated lung cancer cells. Methods: H460 cells were incubated with RPMI 1640 and treated in $5{\mu}M$ or $20{\mu}M$ cisplatin concentrations at specific time intervals. Cells surviving cisplatin treatment were measured and compared using an MTT cell viability assay to cells that underwent apoptosis with autophagy by nuclear staining, apoptotic or autophagic related proteins, and autophagic vacuoles. The development of acidic vascular organelles was using acridine orange staining and fluorescent expression of GFP-LC3 protein in its transfected cells was observed to evaluate autophagy. Results: Lung cancer cells treated with $5{\mu}M$ cisplatin-treated were less sensitive to cell death than $20{\mu}M$ cisplatin-treated cells in a time-dependent manner. Nuclear fragmentation at $5{\mu}M$ was not detected, even though it was discovered at $20{\mu}M$. Poly (ADP-ribose) polymerase cleavages were not detected in $5{\mu}M$ within 24 hours. Massive vacuolization in the cytoplasm of $5{\mu}M$ treated cells were observed. Acridine orange stain-positive cells was increased according in time-dependence manner. The autophagosome-incorporated LC3 II protein expression was increased in $5{\mu}M$ treated cells, but was not detected in $20{\mu}M$ treated cells. The expression of GFP-LC3 were increased in $5{\mu}M$ treated cells in a time-dependent manner. Conclusion: The induction of autophagy occurred in $5{\mu}M$ dose of cisplatin-treated lung cancer cells.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.247-251
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• 2013

The objective of present study was to develop a simultaneous determination method of 5 medical compounds, including beclomethasone, dexamethasone, prednisolone, ketoprofen, phenylbutazone in foods, using LC-MS/MS. To optimize MS analytical condition of 5 compounds, each parameter was established by MRM mode. The chromatographic separation was achieved on a C18 column successfully, with a mobile phase made up of A (0.1% formic acid) and B (0.1% formic acid in acetonitrile), at a flow rate of 0.3 mL/min for 17 min with a gradient elution. LOD and LOQ of 5 compounds were in the range of 0.40~4.60 ng/mL and 0.81~11.46 ng/mL, respectively. As a result of analyzing the three concentrations of the standard mixture added to blank samples, the results showed that the mean recovery rate of 5 compounds was in the range of 81.52~103.83%, and RSD (%) of Intra- and Inter-day assay were 0.52-10.45. Since relatively fine selectivity, accuracy and reproducibility were shown in this qualified experimental method, it could be utilized efficiently to investigating those 5 compounds to see if it is added to food products illegally.

• Journal of Food Hygiene and Safety
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• v.29 no.2
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• pp.131-140
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• 2014

The objective of this study was to develop a simultaneous method of 8 penicillin antibiotics including amoxicillin, ampicillin, cloxacillin, dicloxacillin, nafcillin, oxacillin, penicillin G and penicillin V in meat using LC-MS/MS. The procedure involves solid phase extraction with HLB cartridge and subsequent analysis by LC-MS/MS. To optimize MS analytical condition of 8 compounds, each parameter was established by multiple reaction monitoring in positive ion mode. The chromatographic separation was achieved on a $C_{18}$ column with a mobile phase of 0.05% formic acid and 0.05% formic acid in acetonitrile at a flow rate of 0.2 mL/min for 20 min with a gradient elution. The developed method was validated for specificity, linearity, accuracy and precision in beef, pork and chicken. The recoveries were 71.0~106%, and relative standard deviations (RSD) were 4.0~11.2%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.003~0.008 mg/kg and 0.01~0.03 mg/kg, respectively, that are below maximum residue limit (MRL) of the penicillins. This study also performed survey of residual penicillin antibiotics for 193 samples of beef, pork and chicken collected from 9 cities in Korea. Penicillins were not found in all the samples except a sample of pork which contained cloxacillin (concentration of 0.08 mg/kg) below the MRL (0.3 mg/kg).

• Korean Journal of Environmental Agriculture
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• v.37 no.4
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• pp.283-290
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• 2018

BACKGROUND: Pesticide residue analysis is an essential activity in order to establish the food safety of agricultural products. Analytical approaches to the food safety are required to meet internationally the guideline of Codex (Codex Alimentarius Commission, CAC/GL 40). In this study, we developed a liquid chromatograph-tandem mass spectrometer (LC-MS/MS) method to determine the herbicide clopyralid in food matrixes. METHODS AND RESULTS: Clopyralid was extracted with aqueous acetonitrile containing formic acid and the extracts were mixed in a citrate buffer consisted of magnesium sulfate anhydrous, NaCl, sodium citrate dihydrate and disodium hydrogencitrate sesquihydrate followed by centrifugation. The supernatants were filtered through a nylon membrane filter and used for the analysis of clopyralid. The method was validated by accuracy and precision experiments on the samples fortified at 3 different levels of clopyralid. LC-MS/MS in positive mode was employed to quantitatively determine clopyralid in the food samples. Matrix-matched calibration curves were inearranged from 0.001 to 0.25 mg/kg with r2 > 0.994. The limits of detection and quantification were determined to be 0.001 and 0.01 mg/kg, respectively. There covery values of clopyralid for tified at 0.01 mg/kg in the control samples ranged from approximately 82 to 106% with relative standard deviations below 2 0%. CONCLUSION: The method developed in this study meets successfully the Codex guideline for pesticide residue analysis in food samples. This, the method could be applicable to determine pesticides in foods produced domestically and internationally.

• 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 Veterinary Service
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• v.43 no.3
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• pp.189-196
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• 2020

This study was conducted to analyze feasibility of monitoring of fluoroquinolnes residual through feather analysis in broilers. The calibration curve showed good linearity (r²≥0.99) within the concentration range of 1~100 ㎍/kg. The limit of detection (LOD) and limit of quantification (LOQ) were validated at ≤0.66 and ≤1.99 ㎍/kg in broiler feather, respectively. The recoveries in feather samples ranged from 94.6 to 114.4% (5.1-15.8% RSD) at the 5 to 20 ㎍/kg spiking levels. The proposed new analytical method proved to be suitable and effective for fluoroquinolnes determination. We also monitored fluoroquinolones residue in 36 samples (broiler that were slaughtered in Gyonggi-do) using this method. Among tested feather samples, enrofloxacin and ciprofloxacin were detected in all samples. In muscle samples, enrofloxacin was detected in 20 (55.6%) samples and ciprofloxacin was not detected.

• Toxicological Research
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• v.11 no.1
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• pp.37-42
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• 1995

Effect of cadmium on the early amphibian development was analyzed through FETAX (Frog Embryo Teratogenesis Assay: Xenopus). Embryos manifested concentration-dependent mortality and realformations; shortage of anterior-posterior axis gut realformation, ocular anomalies, bent notochord, misshapen dorsal fin, and derreal blisters. The treatment with 1.5ppm cadmium solution caused 100% mortality and concentration of lppm did not kill the embryos that caused 100% anomaly. The teratogenic index (TI = LC50 /EC50) was 2.8 indicating that $CdCl_2$ is teratogenic for Xenopus laevis. Embryos that were pulsetreated with at early to late blastula stage (St. 3-9) and mid to late blastula stage (St. 6-10) showed relatively strong resistance to cadmium, but the embryos treated at gastrula stage (St. 10-13) showed high mortality. And the embryos treated at tailbud stage (after St. 25) showed highest mortality of any other early stages. Effects of temperature were studied through pulse- treatment during gastrula stage at $20^{\circ}C$ and $30^{\circ}C$. The embryos treated with 7.5ppm at $30^{\circ}C$ and 15ppm at $20^{\circ}C$ caused 100% mortality respectively, indicating that higher temperature had more severe toxic effect. One of the most peculiar effect of cadmium at gastrulation was distortion of the tail. The probable cause of toxic effect of Cd was discussed.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.6
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• pp.563-569
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• 2002

This paper proposes an inverter for the grid-connected photovoltaic system based on the transformer-less inverter. This system consists of a high frequency DC-DC converter, high frequency transformer, diode bridge rectifiers, a DC filter, a low frequency inverter, and an AC filter. The 20kHz switched high frequency converter is used to generate bipolar PWM pulse, and the high frequency transformer transforms its voltage twice, which is subsequently rectified by diode bridge rectifiers for a full-wave rectified 60 Hz sine wave power output. Even though the high frequency link system needs more power semiconductors, a reduced size, light weight, and saved parts cost make this system more comparative than other power conditioning systems due to elimination of 60Hz transformer.