• Analytical Science and Technology
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• v.32 no.2
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• pp.35-47
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• 2019

In this study, high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was employed to detect 26 antidiabetic compounds in adulterated dietary supplements using a simple, selective method. The work presented herein may help prevent incidents related to food adulteration and restrict the illegal food market. The best separation was obtained on a Shiseido Capcell Pak(R) C18 MG-II ($2.0mm{\times}100mm$, $3{\mu}m$), which improved the peak shape and MS detection sensitivity of the target compounds. A gradient elution system composed of 0.1 % (v/v) formic acid in distilled water and methanol at a flow rate of 0.3 mL/min for 18 min was utilized. A triple quadrupole mass spectrometer with an electrospray ionization source operated in the positive or negative mode was employed as the detector. The developed method was validated as follows: specificity was confirmed in the multiple reaction monitoring mode using the precursor and product ion pairs. For solid samples, LOD ranged from 0.16 to 20.00 ng/mL and LOQ ranged from 0.50 to 60.00 ng/mL, and for liquid samples, LOD ranged from 0.16 to 20.00 ng/mL and LOQ ranged from 0.50 to 60.00 ng/mL. Satisfactory linearity was obtained from calibration curves, with $R^2$ > 0.99. Both intra and inter-day precision were less than 13.19 %. Accuracies ranged from 80.69 to 118.81 % (intra/inter-day), with a stability of less than 14.88 %. Mean recovery was found to be 80.6-119.0 % and less than 13.4 % RSD. Using the validated method, glibenclamide and pioglitazone were simultaneously determined in one capsule at concentrations of 1.52 and 0.53 mg (per capsule), respectively.

• Biomolecules & Therapeutics
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• v.29 no.5
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• pp.551-561
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• 2021

Thyroid cancer is the most common endocrine malignancy. Patients with well-differentiated thyroid cancers, such as papillary and follicular cancers, have a favorable prognosis. However, poorly differentiated thyroid cancers, such as medullary, squamous and anaplastic advanced thyroid cancers, are very aggressive and insensitive to radioiodine treatment. Thus, novel therapies that attenuate metastasis are urgently needed. We found that both PDGFC and PDGFRA are predominantly expressed in thyroid cancers and that the survival rate is significantly lower in patients with high PDGFRA expression. This finding indicates the important role of PDGF/PDGFR signaling in thyroid cancer development. Next, we established a SW579 squamous thyroid cancer cell line with 95.6% PDGFRA gene insertion and deletions (indels) through CRISPR/Cas9. Protein and invasion analysis showed a dramatic loss in EMT marker expression and metastatic ability. Furthermore, xenograft tumors derived from PDGFRA geneedited SW579 cells exhibited a minor decrease in tumor growth. However, distant lung metastasis was completely abolished upon PDGFRA gene editing, implying that PDGFRA could be an effective target to inhibit distant metastasis in advanced thyroid cancers. To translate this finding to the clinic, we used the most relevant multikinase inhibitor, imatinib, to inhibit PDGFRA signaling. The results showed that imatinib significantly suppressed cell growth, induced cell cycle arrest and cell death in SW579 cells. Our developed noninvasive apoptosis detection sensor (NIADS) indicated that imatinib induced cell apoptosis through caspase-3 activation. In conclusion, we believe that developing a specific and selective targeted therapy for PDGFRA would effectively suppress PDGFRA-mediated cancer aggressiveness in advanced thyroid cancers.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.188-194
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• 2022

This work presents a non-destructive and straightforward approach to assemble a large-scale conductive electronic film made of a pre-treated single-walled carbon nanotube (SWCNT) solution. For effective electron transfer between the immobilized enzyme and SWCNT electronic film, we optimized the pre-treatment step of SWCNT with p-terphenyl-4,4"-dithiol and dithiothreitol. Glucose oxidase (GOx, a model enzyme in this study) was immobilized on the SWCNT electronic film following the positively charged polyelectrolyte layer deposition. The glucose detection was realized through effective electron transfer between the immobilized GOx and SWCNT electronic film at the negative potential value (-0.45 V vs. Ag/AgCl). The SWCNT electronic film-based glucose biosensor exhibited a sensitivity of 98 ㎂/mM·cm². In addition, the SWCNT electronic film biosensor showed the excellent selectivity (less than 4 % change) against a variety of redox-active interfering substances, such as ascorbic acid, uric acid, dopamine, and acetaminophen, by avoiding co-oxidation of the interfering substances at the negative potential value.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.34 no.1
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• pp.4-14
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• 2023

This study aimed to discuss mental health services for children and adolescents that are being implemented as initiatives of the Korean government and to review the functions and roles of these projects during the COVID-19 pandemic. Three government departments are in charge of providing mental health services for children and adolescents: Ministry of Education, Ministry of Gender Equality and Family, and Ministry of Health and Welfare. The Ministry of Education has implemented several policies to facilitate the early detection of mental health issues among school students (from preventive interventions to selective interventions for high-risk students). The Ministry of Gender Equality and Family additionally serves out-of-school children and adolescents by facilitating early identification of adolescents in crises and providing temporary protection or emergency assistance (as required) through the Community Youth Safety-Net Project. Furthermore, the Ministry of Health and Welfare operates relevant mental health agencies for individuals of all ages including children and adolescents. Any high-risk students who have been screened through the projects of the Ministry of Education are supported through referrals to the following institutions for appropriate treatment of their symptoms: specialized hospitals, the Youth Counseling and Welfare Center operated by the Ministry of Gender Equality and Family, the National Youth Healing Center, the Mental Health Welfare Center operated by the Ministry of Health and Welfare, the Suicide Prevention Center, and the Child Welfare Center. To assist students who are facing any psychological difficulties because of the COVID-19 pandemic, the Ministry of Education has established a psychiatric support group for providing emergency mental health care; furthermore, schools are promoting psychological surveillance (e.g., provision of non-face-to-face counseling services that are centered around the Wee Center). The Ministry of Education, Ministry of Gender Equality and Family, and Ministry of Health and Welfare have provided varied mental health support services in order to address the challenges faced by children and adolescents during the pandemic. Nevertheless, the mental health services operated by each ministry do show some limitations because their service provision system is insufficiently collaborative. The present study discussed the positive effects of each initiative as well as its limitations; furthermore, it suggested improvements for facilitating the healthy development of children and adolescents' mental health.

• Analytical Science and Technology
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• v.19 no.1
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• pp.107-114
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• 2006

Early diagnosis and medical intervention are critical for the treatment of patients with metabolic disorders. A rapid analytical method was developed for simultaneous quantification of organic acids and amino acids in urine without labor-intensive pre-extraction procedure showing high sensitivity and specificity. A new method consisted of simple two-step trimethylsilyl (TMS)-trifluoroacetyl (TFA) derivatization using GC/MS-selective ion monitoring (SIM). Filter paper urine specimens were dried under nitrogen after being fortified with internal standard (tropate) in a mixture of distilled water and methanol. Methyl orange was added to the residue as indicator reagent. Silyl derivative of carboxylic functional group was followed by trifluoroacetyl derivative for amino functional group. N-methyl-N-(trimethylsilyl-trifluoroacetamide) and N-methyl-bistrifluoroacetamide were consecutively added and heated for 15-20 min at $65^{\circ}C-70^{\circ}C$, for TMS-TFA derivative, respectively. This reactant was analyzed by GC/MS-SIM. Linear dynamic range showed 0.001-50 mg with the detection limit of (S/N=3) 10-200 ng, and the quantification limit of 80-900 ng in urine. Correlation coefficient of regression line was 0.994-0.998. When the method was applied to the patients 'urine, it clearly differentiated the normal from the patient with metabolic disorder. The study showed that the developed method could be the method of choices in rapid and sensitive screening for organic aciduria and amino acidopathy.

• Analytical Science and Technology
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• v.20 no.1
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• pp.84-90
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• 2007

To determine levels of 11 sulfonamides for animals in food, simultaneously, a selective method of high performance liquid chromatography with UV detector has been applied. The targets were sulfachlorpyridazine (SCP), sulfadiazine (SDZ), sulfadimethoxine (SDM), sulfisoxazole (SSX), sulfamerazine (SMZ), sulfamethazine (SMT), sulfamethoxazole (SMX), sulfamethoxypyridazine (SMP), sulfamonomethoxine (SMM), sulfaquinoxaline (SQX) and sulfathiazole (STZ). Food samples were beef, pork, chicken, milk and whole egg that were collected at the main 6 cities in Korea as Seoul, Busan, Daejon, Incheon, Mokpo and Gangneung. After homogenizing food samples with sodium phosphate solution and acetonitrile, it was extracted with n-hexane. The mobile phase gradient was a mixture of 5 mM potassium phosphate (pH 3.25) and methanol with a gradient ratio from 100:0 to 30:70. The UV wavelength was 270 nm. The overall recoveries were ranged from 75% to 95% and the limit of detection was minimum 0.004 mg/kg for SMT, and 0.007 mg/kg for STZ at signal/noise > 3, respectively. As results, sulfonamide drugs were not detected in most of the selected food samples, however, sulfamonomethoxine was detected in meat. The determined level of sulfamonomethoxine were 0.03 and 0.06 mg/kg for beef that were below the MRLs.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.10
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• pp.1343-1356
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• 2008

The evaluation of microbiological quality for school food samples collected from 19 selected middle and high schools located in Seoul was undertaken. Eighty-nine food samples consisting of 38 non-pretreated vegetables, 13 pre-washed and cut vegetables, 9 meats and poultry, 3 fish and shellfish, 7 dried fish, and shellfish and 20 processed foods were collected. Aerobic plate count, total coliforms, and Escherichia coli (E. coli ) were detected using $Petrifilm^{TM}$, and the food-borne pathogens were screened by multiplex PCR with species-specific primer sets. Sequentially, the quantitative and confirmative test of the food-borne pathogens were carried out with the selective media and biochemical kits. The contamination of coliform counts was observed on the pre-washed vegetables ($3.4{\sim}4.3\;log\;CFU/g$) and meats ($2.2{\sim}4.3\;log\;CFU/g$). Also, the cooked foods were heavily contaminated with coliform, ranging from 1.0 to $5.5\;log\;CFU/g$. E. coli counts were found in 16 raw and cooked food samples, exceeding the microbiological standards for the guideline of safety management for school foods. Through PCR detection, B acillus cereus was detected in 32 raw and cooked foods, and quantitatively found in pre-washed carrot, radish, and pan-broiled dried shrimp and filefish ranging from $2.3{\sim}3.6\;log\;CFU/g$, respectively. E. coli O157:H7 was detected on frozen pork sample and was confirmed with API kit. Campylobacter jejuni was found in 3 ready-to-eat type vegetables. Vibrio parahaemolyticus were found in 4 pre-washed vegetables and 2 cooked foods, indicating unsatisfactory quality based upon the microbiological standards of ready-to-eat vegetables and cooked foods by Korea Food and Drug Administration. Salmonella spp. was detected in frozen chicken sample and confirmed by API kit and latex antisera agglutination.

• Journal of Food Hygiene and Safety
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• v.33 no.4
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• pp.266-271
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• 2018

The Ministry of Food and Drug Safety (MFDS) is amending its test methods for health-functional foods (dietary food supplements) to establish regulatory standards and specifications in Korea. In this regard, we continue our research on developing analytical methods for the items. Octacosanol is the major component of polycosanol and is a high-molecular-mass primary fatty alcohol, obtained from sugar cane wax. Previous researchers have shown that octacosanol can lower cholesterol and has antiaggregatory properties, cytoprotective uses, and ergogenic properties for human health. Recently, octacosanol products have been actively introduced into the domestic market because of their functional biological activity. We have developed a sensitive and selective test method for octacosanol that the TMS derivatives by means of gas-chromatographic-tandem mass spectrometry (GC-MS). The trimethylsilyl ether derivative of the target analyte showed excellent chromatographic properties. The procedure was validated in the range of $12.5{\sim}200{\mu}g/L$. Standard calibration curves presented linearity with the correlation coefficient ($r^2$) > 0.999, and the limits of detection (LOD) and limits of quantitation (LOQ) were $4.5{\mu}g/L$ and $13.8{\mu}g/L$, respectively. The high recoveries (92.5 to 108.8%) and precision (1.8 to 2.4%) obtained are in accordance with the established validation criteria. Our research can provide scientific evidence to amend the octacosanol test method for the Health-Functional Food Code.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.388-394
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• 2014

BACKGROUND: Aclonifen is used as a systemic and selective herbicide to control a wide spectrum broad-leaf weeds by inhibition carotenoid biosynthesis, and then its MRLs(Maximum Residue Limits) will be determined in onion and garlic. In this study, a new official method was developed for aclonifen determination in agricultural products to routinely inspect the violation of MRL as well as to evaluate the terminal residue level. METHODS AND RESULTS: Aclonifen was extracted from crop samples with acetone and the extract was partitioned with dichloromethane and then purified by silica solid phase extraction(SPE) cartridge. The purified samples were detected GC using an ECD detector. Limits of detection(LOD) was 0.001 mg/kg and quantification(LOQ) was 0.005 mg/kg, respectively. For validation purposes, recovery studies were carried out at three different concentration levels (LOQ, $10{\times}LOQ$, $50{\times}LOQ$, n=5). The recoveries were ranged from 74.3 to 95.0% with relative standard deviations(RSDs) of less than 8%. All values were consistent with the criteria ranges requested in the Codex guidelines(CAC/GL 40). CONCLUSION: The proposed analytical method was accurate, effective and sensitive for aclonifen determination and it will be used to as an official method in Korea.

• Journal of Life Science
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• v.19 no.2
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• pp.277-283
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• 2009

Biogenic amines are generally formed through the decarboxylation of specific free amino acids by exogenous decarboxylases released by microbial species associated with the fish products and fermented feeds. This study was conducted to investigate the properties of e tuna waste regarding the control of degradation of biogenic amines (histamine, tyramine, tryptamine, putrescine, and cadaverine) that might be related with the anti-nutritional factor of the tuna waste that is used for manufacturing domestic fish meal. The values of pH and the salt content were 6.51, 3.35% in tuna waste and 5.58 and 5.83% in tuna fish meal, respectively. The strains and dominant bacteria tested in the tuna waste sample were 9.20, 9.29, 5.67, 7.82 and 7.58 log CFU/g of total bacteria, aerobic plate count (APC), total coliform (TC), Lactobacillus spp. and Bacillus spp., respectively. The main histamine forming-bacteria (HFB) in tuna waste were detected by silica gel thin-layer chromatography (TLC) and 7 histamine-forming bacterial species were isolated among microbes grown in selective medium. The histamine concentration was determined by detection of fluorescence of ο-phthaldialdehyde (OPA) derivatives using HPLC and the date were used to reconfirm the identities of the amine-producing bacteria. The 15 histamine- forming bacteria strains grown in trypicase soy broth (TSB) supplemented with 1% L-histidine (TSBH) were identified as Lactococcus(L.) lactis subsp. lactis, Klebsiella pneummonlae, L. garvieae 36, Vibrio olivaceus, Hafnia alvei and L. garvieae which were main dominant amine - producing strains, and Morganella morganii identified by 16S ribosomal RNA (rRNA) sequencing with PCR amplification. A Phylogenetic tree generated from the 16S rRNA sequencing data showed different phyletic lines that could be readily classified as biogenic amine forming gram-positive and negative bacteria.