• The Korean Journal of Malacology
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• v.25 no.3
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• pp.223-230
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• 2009

Metallothioneins (MTs) play a key role in metallic homeostasis and detoxification in most living organisms. In an attempt to study the biological functions and significance of MT in a snail, we cloned and partially characterized the MT gene from the left-handed snail, Physa acutawhich has been regarded as a potential biomonitering species for fresh water. The complete cDNA sequence of PaMT cDNA was identified from the expressed sequence tag (EST) sequencing project of Physa acuta. The coding region of 180 bp gives 60 amino acid residues including the initiation methionine and termination codon. Clustering and phylogenic analysis of PaMT with other MT amino acid sequences show that it has some identities to Helix pomatia (60%), Arianta arbustorum (58%), Perna viridis (49%), Mytilus edulis (49%), Bathymodiolus azoricus (49%), Bathymodiolus azoricus (48%) and Bathymodiolus sp. FD-2002 (48%). Time dependent induction for PaMT from P. acuta exposed with cadmium (50 ppb) indicated that PaMT was induced at 4-8 hr after exposure. It remains to further develop PaMTas a potential biomarker for water contamination in fresh water.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.4
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• pp.406-413
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• 2018

The emergence of carbapenem resistance among Pseudomonas aeruginosa has become an increasing problem worldwide. In particular, $metallo-{\beta}-lactamases$ (MBLs) are responsible for the high-level resistance to carbapenem. Sequence type 235 (ST235) has been found internationally in a multidrug-resistant clone and is involved in the dissemination of genes encoding IMP-6 and VIM-2. This study examined the prevalence of MBLs and the epidemiological relationship in carbapenem-resistant P. aeruginosa (CRPA) isolates obtained from a tertiary hospital in Daejeon, Korea, between March 2008 and June 2014. The antimicrobial susceptibilities were determined using the disk-diffusion method and PCR and DNA sequencing were used to identify the MBL genes. In addition, an epidemiological relationship was investigated by multilocus sequence typing (MLST). Among the 110 CRPA isolates, 32 isolates (29.1%) were MBL-producers; the major type was IMP-6 (29 isolates, 90.6%). VIM-2 was identified in 3 isolates (9.4%) of ST357. IMP-6-producing isolates were multidrug-resistant (MDR) and belonged to ST235. ST235 (55 isolates, 50.0%) was the clone most frequently detected and has gradually emerged during a seven-year period. To prevent the spread of MDR ST235 P. aeruginosa isolates, the current widespread use of carbapenems needs to be curtailed, and novel continuous monitoring strategies should be developed as soon as possible.

• Korean Journal of Ecology and Environment
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• v.52 no.3
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• pp.221-230
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• 2019

Barbel steed (Hemibarbus labeo) is a small freshwater fish species as semi-bottom dwellers distributed in eastern Asia. We carried out characterization of the cytochrome c oxidase subunit I (COI) gene from the mitochondrial DNA of H. labeo in the Sumjin River to identify the phylogenetic location of H. labeo in the genus Hemibarbus and Cyprinidae. Multiple alignment of the 577 bp COI sequence revealed high sequence homology (99~100%) between Seomjin River H. labeo. The nucleotide sequence similarity between H. labeo (HD1) and H. mylodon was 88.91% and that of H. longirostis was 88.81% among the three species found in Korea. In addition, the nucleotide sequence similarities of H. maculatus, H. meditus, H. umbrifer and H. barbus showed 98.97%, 97.20%, 96.87% and 98.85%, respectively. Phylogenetic analysis on seven species of the genus Hemibarbus showed that the H. labeo collected in this study formed two clades. One of which consisted of Hadong, Imsil, Kangjin. The other one formed a step with HD2, HD8 and HD9 of Hadong and the H. labeo reported in Busan, Asan and Seoul, Korea. Phylogenetic position of the H. labeo among Cyprinidae showed 0.143 for the evolutionary distance from Zacco platypus and 0.006 for the H. maculatus. In addition, the genetic position of the H. labeo among 28 species of Cyprinidae was found to be located in Group I, including Gobioninae fishes. The results of this study will provide key genetic information for the taxonomic comparison in Cyprinidae and study of model fish for pollution monitoring in freshwater environments.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.3
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• pp.217-224
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• 2021

Fluoroquinolone (FQ) resistant gram-negative pathogens have emerged worldwide, and the recent increase in FQ resistant Escherichia coli is of great concern in Korea. This study investigated FQ resistance determinants and the epidemiological relationship of 56 ciprofloxacin-resistant E. coli isolated from a tertiary hospital in Daejeon, South Korea from June to December 2018. Molecular epidemiology was investigated by multilocus sequence typing (MLST). Polymerase chain reaction (PCR) and sequence analysis were performed to identify chromosomal mutations in the quinolone resistance determining regions (QRDR) of gyrA, gyrB, parC, and parE and to describe the occurrence of the following plasmid-mediated quinolone resistance (PMQR) genes: aac(6)-Ib-cr, qepA, qnrA, qnrB, qnrC, qnrD, and qnrS. MLST analysis showed 12 sequence types (STs) and the most prevalent ST was ST131 (31/56, 55.4%), followed by ST1193 (13/56, 23.2%), and ST405 (3/56, 5.4%). In 56 ciprofloxacin-resistant E. coli isolates, Ser83→Leu and Asp87→Asn in gyrA and Ser80→Ile and Glu84→Val in parC (51.8%, 29/56) were the most frequent amino acid substitutions and aac(6)-Ib-cr (33.9%, 19/56) was the most common PMQR gene. These results of FQ resistance determinants were more frequently observed in ST131 compared with other clones. Continuous monitoring of the epidemiological characteristics of ciprofloxacin-resistant E. coli isolates and further investigation of FQ resistance determinants are necessary.

• Korean journal of applied entomology
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• v.59 no.4
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• pp.281-293
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• 2020

The Korean thistle (Cirsium setidens) is grown in Gangwon province as a food ingredient called gondre. Based on regular monitoring of Korean thistle cultivation, we detected local outbreaks of a stick insect causing severe damage. Here we report the identification of the stick insect and its ecological characteristics. The survey involved 3 farms located in Jeongeon-gun, Gangwon province and lasted from May 28 to October 1 in 2019. According to morphological and DNA analyses the stick insect was identified as Ramulus koreanus Kwon Ha and Lee. a member of the family Phasmatidae. Its outbreak in the Korean thistle farms was observed from June 11 to August 22 with peak density on July 23. Spatial distribution analyses, using Taylors power law and Greens index showed that R. koreanus was uniformally distributed. Food consumption rate of Korean thistle leaves was estimated as 60.98±4.35 ㎠/day/adult. The main food plants were identified as Juglans mandshurica and Aronia melanocarpa. Further study needs to pursue the mechanism of the outbreak and its possible impact on agricultural and forest ecosystems. Additionally, means to relieve crop damage need to be identified.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.2
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• pp.133-141
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• 2022

Candida is one of the most common causes of bloodstream infections and a leading cause of morbidity and mortality among hospitalized patients. The purpose of this study was to provide important information for formulating empirical treatment plans for candidemia by investigating the antifungal resistance rate of Candida. Among the Candida strains (973 cases) isolated from blood culture tests at the S hospital in 2009~2018, 4.7% (N=44) comprising the Candida spp. (932 strains) showed resistance to fluconazole. The resistant strains included C. albicans, C. parapsilosis, C. tropicalis, and C. glabrata. In addition Candida spp. (947 strains) showed resistance to amphotericin B (N=6, 0.6%), flucytosine (N=23, 2.4%) and voriconazole (N=24, 3.1%). C. albicans was resistant to fluconazole (N=23, 6.9%) and voriconazole (N=21, 6.0%), The statistical analysis showed that C. albicans and non-albicans Candida species were resistant to fluconazole (P=0.039) and voriconazole (P<0.001). A monitoring system to understand the rate of candidiasis infections in a hospital setting is required. It is also important to make the right choice of the antifungal agent based on drug susceptibility patterns. Therefore, an infection surveillance policy that tracks Candida resistance through regular antifungal susceptibility tests is necessary.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.4
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• pp.265-272
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• 2022

The emergence and dissemination of carbapenemase-producing Enterobacteriaceae (CPE), particularly the Klebsiella pneumoniae carbapenemase-2 (KPC-2) producing Klebsiella pneumoniae, has been rapidly increasing worldwide and is becoming a serious public health threat. Since the epidemiology and characteristics of these KPC-2-producing K. pneumoniae vary according to the region and period under consideration, this study investigated the prevalence of carbapenemases and the epidemiological relationship of 78 carbapenem-resistant K. pneumoniae (CRKP) isolated from a tertiary hospital in Daejeon, from March 2017 to December 2020. The antimicrobial susceptibility tests were identified using the disk-diffusion method. PCR and DNA sequencing were used to determine the carbapenemase genes. In addition, molecular epidemiology was performed by multilocus sequence typing (MLST). Among the 78 CRKP isolates, 35 isolates (44.9%) were carbapenemase-producing K. pneumoniae (CPKP) and the major carbapenemase type was KPC-2 (30 isolates, 85.7%). The New Delhi metallo-enzyme-1 (NDM-1) and NDM-5 were identified in 4 isolates (11.4%) and 1 isolate (2.9%), respectively. Multilocus sequence typing (MLST) analysis showed 10 sequence types (STs) and the most prevalent ST was ST307 (51.4%, 18/35). All the ST307 isolates were KPC-2-producing K. pneumoniae and were multidrug-resistant (MDR). In addition, ST307 has gradually emerged during a four-year period. These findings indicate that continuous monitoring and proper infection control are needed to prevent the spread of KPC-2-producing K. pneumoniae ST307.

• Korean Journal of Clinical Laboratory Science
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• v.54 no.4
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• pp.249-255
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• 2022

Alzheimer's disease (AD) represents a major public health concern and has been identified as a research priority. Clinical research evidence supports that the core cerebrospinal fluid (CSF) biomarkers for AD, including amyloid-β (Aβ42), total tau (T-tau), and phosphorylated tau (P-tau), reflect key elements of AD pathophysiology. Nevertheless, advances in the clinical identification of new indicators will be critical not only for the discovery of sensitive, specific, and reliable biomarkers of preclinical AD pathology, but also for the development of tests that facilitate the early detection and differential diagnosis of dementia and disease progression monitoring. The early detection of AD in its presymptomatic stages would represent a great opportunity for earlier therapeutic intervention. The chance of successful treatment would be increased since interventions would be performed before extensive synaptic damage and neuronal loss would have occurred. In this study, the importance of developing an early diagnostic method using cognitive decline biomarkers that can discriminate between normal, mild cognitive impairment (MCI), and AD preclinical stages has been emphasized.

• Journal of Food Hygiene and Safety
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• v.38 no.4
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• pp.246-254
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• 2023

V. parahaemolyticus causes waterborne and foodborne disease such as acute diarrhea. In this study, V. parahaemolyticus isolates from seawater, fish tanks, and distributed fishery products in Jeju were investigated for potential toxin or species-specific genes (tdh, trh, tlh, and toxR) using RT-PCR and their genetic characteristics were analyzed using Pulsed-field gel electrophoresis (PFGE). Overall, V. parahaemolyticus of 90 strains (36.7%), including 33 strains from seawater, 8 strains from fish tanks, and 50 strains from fishery products, were isolated from 245 samples. All V. parahaemolyticus strains did not detect the tdh gene, whereas all strains detected tlh or toxR genes. In addition, trh genes were detected in 3 strains from seawater and 1 strain from fishery products. Monthly quantitative testing of seawater revealed that V. parahaemolyticus was positively correlated with water temperature. The 90 strains of V. parahemolyticus obtained in this study showed by gene homology between types, ranging from 64.0-97.3%. Among these, thirteen types showed 100% homology between genes. These results indicate that continuous monitoring is needed to facilitate food poisoning epidemiological investigations because some isolated V. parahaemolyticus strains harbored toxin genes and V. parahaemolyticus strains isolated from seawater, fish tanks, and distributed fishery products showed genetic similarity.

• Journal of Preventive Medicine and Public Health
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• v.55 no.3
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• pp.280-288
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• 2022

Objectives: One of the most widely used pesticides today is chlorpyrifos (CPF). Cytochrome P450 (CYP)2B6, the most prominent catalyst in CPF bioactivation, is highly polymorphic. The objective of our study was to evaluate the role of CYP2B6^*6, which contains both 516G>T and 785A>G polymorphisms, in CPF toxicity, as represented by the concentration of 3,5,6-trichloro-2-pyridinol (TCPy), among vegetable farmers in Central Java, Indonesia, where CPF has been commonly used. Methods: A cross-sectional study was conducted among 132 vegetable farmers. Individual socio-demographic and occupational characteristics, as determinants of TCPy levels, were obtained using a structured interviewer-administered questionnaire and subsequently used to estimate the cumulative exposure level (CEL). TCPy levels were detected with liquid chromatography-mass spectrometry. CYP2B6^*6 gene polymorphisms were analyzed using a TaqMan^® SNP Genotyping Assay and Sanger sequencing. Linear regression analysis was performed to analyze the association between TCPy, as a biomarker of CPF exposure, and its determinants. Results: The prevalence of CYP2B6^*6 polymorphisms was 31% for ^*1/^*1, 51% for ^*1/^*6, and 18% for ^*6/^*6. TCPy concentrations were higher among participants with CYP2B6^*1/^*1 than among those with ^*1/^*6 or ^*6/^*6 genotypes. CYP2B6^*6 gene polymorphisms, smoking, CEL, body mass index, and spraying time were retained in the final linear regression model as determinants of TCPy. Conclusions: The results suggest that CYP2B6^*6 gene polymorphisms may play an important role in influencing susceptibility to CPF exposure. CYP2B6^*6 gene polymorphisms together with CEL, smoking habits, body mass index, and spraying time were the determinants of urinary TCPy concentrations, as a biomarker of CPF toxicity.