• Journal of fish pathology
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• v.16 no.1
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• pp.61-68
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• 2003

MICs of 8 chemotherapeutic agents against forty streptococcal isolates were determined. These strains were isolated from diseased olive flounder, Paralichthys olivaceus, and showed 2-5 multiple drug resistance against different antibacterial agents including ampicillin, doxycycline (DOXY), erythromycin, florfenicol, flumequine, norfloxacin, oxolinic acid, and oxytetracycline (OTC). In conjugation experiment, we found transferable R plasmids carrying OTC and DOXY resistance determinant in 3 drug resistance strains analyzed. Six out of 40 isolates showed positive signal in colony hybridization with the R plasmid DNA (pST9) as a probe. It suggests that other types R plasmid different from pST9 is also involving in multiple drug resistance of streptococci isolated from olive flounder.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.11
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• pp.6757-6760
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• 2013

Gastric cancer is one of the most frequently occurring malignancies in the world. Development of multiple drug resistance (MDR) to chemotherapy is known as the major cause of treatment failure for gastric cancer. Multiple drug resistance 1/P-glycoprotein (MDR1/p-gp) contributes to drug resistance via ATP-dependent drug efflux pumps and is overexpressed in many solid tumors including gastric cancer. To investigate the role of MDR1 knockdown on drug resistance reversal, we knocked down MDR1 expression using shRNA in drug resistant gastric cancer cells and examined the consequences with regard to adriamycin (ADR) accumulation and drug-sensitivity. Two shRNAs efficiently inhibited mRNA and protein expression of MDR1 in SGC7901-MDR1 cells. MDR1 knockdown obviously decreased the ADR accumulation in cells and increased the sensitivity to ADR treatment. Together, our results revealed a crucial role of MDR1 in drug resistance and confirmed that MDR1 knockdown could reverse this phenotype in gastric cancer cells.

• Molecules and Cells
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• v.42 no.3
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• pp.237-244
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• 2019

Understanding the mechanisms of cancer drug resistance is a critical challenge in cancer therapy. For many cancer drugs, various resistance mechanisms have been identified such as target alteration, alternative signaling pathways, epithelial-mesenchymal transition, and epigenetic modulation. Resistance may arise via multiple mechanisms even for a single drug, making it necessary to investigate multiple independent models for comprehensive understanding and therapeutic application. In particular, we hypothesize that different resistance processes result in distinct gene expression changes. Here, we present a web-based database, CDRgator (Cancer Drug Resistance navigator) for comparative analysis of gene expression signatures of cancer drug resistance. Resistance signatures were extracted from two different types of datasets. First, resistance signatures were extracted from transcriptomic profiles of cancer cells or patient samples and their resistance-induced counterparts for >30 cancer drugs. Second, drug resistance group signatures were also extracted from two large-scale drug sensitivity datasets representing ~1,000 cancer cell lines. All the datasets are available for download, and are conveniently accessible based on drug class and cancer type, along with analytic features such as clustering analysis, multidimensional scaling, and pathway analysis. CDRgator allows meta-analysis of independent resistance models for more comprehensive understanding of drug-resistance mechanisms that is difficult to accomplish with individual datasets alone (database URL: http://cdrgator.ewha.ac.kr).

• Korean Journal of Food Science and Technology
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• v.42 no.4
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• pp.508-513
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• 2010

Ninety three strains (4.2%) of Vibrio parahaemolyticus were isolated from 2,239 samples of commercial marine products during 2006-2008 in Seoul, Korea. We examined 16 antimicrobial susceptibilities of 93 V. parahaemolyticus isolates. Antibiotic resistance of V. parahaemolyticus was most frequently observed to ampicillin (93.5%), followed by cephalothin (90.3%), streptomycin (87.1%), ticarcillin (55.9%), and amikacin (40.9%). Antibiotic susceptibility was most frequently observed to nalidixic acid, chloramphenicol and ampicillin/sulbactam (100%), followed by trimethoprim/sulfamethoxazole (98.9%), gentamicin and tetracycline (82.8%), and ceftriaxone (63.4%). In addition, the isolates also displayed intermediate resistance to kanamycin (79.6%), ciprofloxacin (64.5%), amikacin (47.3%) and cefoxitin (43.0%). All isolates were resistant to more than two drugs. The most prominent multiple drug resistance was 3 drug resistance (37.6%), followed by 4 drug (24.7%), 5 drug (17.2%), and 6 drug resistance (11.8%). The most prominent multiple drug resistance pattern was the cephalothin-streptomycin-ampicillin resistance pattern (22.6%), followed by cephalothinticarcillin-streptomycin-ampicillin (18.3%) and cephalothin-ticarcillin-streptomycin-ampicillin-amikacin (9.7%). Multiple drug resistance patterns of V. parahaemolyticus from marine products require continuous monitoring.

• The Journal of the Korean Society for Microbiology
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• v.15 no.1
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• pp.19-32
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• 1980

Besides the benefits of antimicrobial agents in the control of various infectious diseases, widespread and prolonged use of particular antimicrobial agents has brought about the increase of drug-resistant strains in a community and the profound changes in the pattern of infectious diseases. In Korea, there are some remote villages where no clinics and drug stores are available and the residents in those areas are assumed to have fewer chances to contact with antimicrobial agents. In the present study, the differences in susceptibilities to 14 antimicrobial agents between the isolates from rural areas(R) and Seoul National University Hospital(SNUH, H) were studied. The isolates and their numbers were Staphylococcus aureus, R;55, H;68), Enterococci(R;28, H;30), Escherichia coli(R;40, H;40), Enterobacter aerogenes(R;25, H;21) and Klebsiella pneunoniae(R;58, H;67). Minimal inhibitory concentrations(MIC's) of penicillin, ampicillin, carbenicillin, cephalexin, tetracycline, oxytetracyline, doxycycline, minocycline, gentamicin, kanamycin, streptomycin, erythromycin, troleandomycin and co-trimoxazole were determined by agar dilution method. I. Comparison of MIC's and resistant strain proportions between isolates from SNUH and rural areas. MIC's and/or resistant strain proportions of the isolates from SNUH were significantly higher than those of the isolates from rural areas in the cases of 1. S. aureus to doxycycline, streptomycin and kanamycin. 2. E. coli to penicillin, ampicillin, carbenicillin, tetracycline, oxytetracycline, doxycycline, minocycline, streptomycin, kanamycin, erythromycin and co-trimoxazole. 3. E. aerogences to carbenicillin, tetracycline, oxytetracycline, doxycycline, minocycline, streptomycin, kanamycin, genaamicin and co-trimoxazole. 4. K pneunoniae to penicillin, ampicillin, tetracycline, oxytetracycline, doxycycline, monocycline, streptomycin, kanamycine, gentamicin and co-trimoxazole. However, the mean MIC and resistant strain proportion of S. aureus to tetracycline were higher in isolates from rural areas than in those from SNUH and Enterococci showed no differences in susceptibilities to the antimicrobial agents between isolates from rural areas and from SNUH. Therefore, in general, differenes in susceptibility to these antimicrobial agents between the isolates from rural areas and SNUH were remarkably greater and broader in gram negative enteric bacteria. II. Multiple drug resistance pattern. Patterns and incidences of multiple drug resistance were studied with penicillin, ampicillin, tetracycline, cephalexin, gentamicin, streptomcin, kanamycin and co-trimoxazole in Enterococci, E. coli, E. aeroges and K. pneumoniae. There appeared significant differences in the incidence of multiply drug-resistant strains and multiple drug resistance patterns between the isolates from SNUH and rural areas in Enterococci, E. coli, E. aerogenes and K. pneumoniae. However, there was no difference in the incidence of multiply drug-resistant strains between isolates of S. aureus from SNUH and rural areas but the pattern of multiple resistance of the SNUH strains of S. aureus was diverse, while that of the rural strains was predominantly confined to penicillin-tetracycline combination. The incidence of multigly drug-resistant strains and diversity of their patterns were the highest in E. coli strains isolated from SNUH and there were no multiply drug resistant strrains in Enterococci and K. pneumoniae strains isolated from rural areas. The number of drug-resistance determinants was also different between the isolates from rural areas and SNUH. Most of the multiply drug-resistant strains of E. coli, E. aerogenes and K. pneumoniae isolated from SNUH were resistant to more than 3 kinds of antimicrobial agents, most frequently to ampicillin, tetracycline and streptomycin, while multiply drug-resistant strains from rural areas were resistant to 2 kinds of antimicrobial agents among ampicillin, tetracycline and streptomycin. With drug-resistant E. coli strains, resistance to tetracycline which was used most widely since 1951 was most frequently involved as a part of mutliple drug-resistance, followed by resistance to ampicillin and streptomycin. This strongly suggests that emergence of drug-restant strains in a community is directly dependent on the selective pressure exerted by the antimicrobial agent used. III. Cross resistance. Cross resistance of bacteria was studied among tetracycline penicillin, aminoglycoside and macrolide derivatives by analyzing correlation coefficients of sucseptibilities using the least square method. In this study, there were high correlations among the susceptibilities to related derivatives. It appears that the relatively low correlations in susceptibilities present in some cases are due to intrinsic resistance of E. aerogenes to penicillin, Enterococci to aminoglycoside and E. coli E. aerogenes and K. pneumoniae to macrolide derivatives.

• Food Science and Biotechnology
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• v.15 no.3
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• pp.339-340
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• 2006

The pattern of drug resistance and incidence of R-factors were studied in Shigella sonnei as food-borne pathogen strains isolated from chicken meat in Iran. In this study we examined for transferring R-factors of S. sonnei to sensitive Escherichia coli $k_{12}{\bar{F}}(\lambda)$. The results showed that 19 out of 57 strains (33.3%) were resistant to one or more drugs and multiple drug resistance was more common than single drug resistance. The most predominant pattern of resistance observed was Tetracycline (Tc), Chloramphenicol (Cm), Streptomycin (Sm), and Sulfonamide (Su). 100% of the strains from the Caspian littoral transferred at least a part of their resistance pattern to sensitive E.coli $k_{12}{\bar{F}}(\lambda)$.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3345-3349
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• 2013

Hsp90 shows great promise as a therapeutic target due to its potential to disable multiple signaling pathways simultaneously. In this study, we discovered that a natural product, butein moderately inhibited the growth of drug-resistant cancer cells (A2780cis and H1975), and brought about the degradation of oncogenic Hsp90 client proteins. The study demonstrated that butein would be a therapeutic lead to circumvent drug-resistance in cancer chemotherapy. The structure-based screening, synthesis, and biological evaluation of butein are described herein.

• Journal of fish pathology
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• v.19 no.3
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• pp.267-276
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• 2006

Seventy-five streptococci were isolated from diseased olive flounder, Paralichthys olivaceus in Jeju. Their drug susceptibility and transferable multiple drug resistance were characterized. All isolates were resistant to flumequine (AR) and oxolinic acid (OA) and 26 isolates (34.7%) showed 4～6 multiple resistance of ampicillin (ABPC), AR, doxycycline (DOXY), erythromycin (EM), norfloxacin(NOR), OA and oxytetracycline (OTC) in various combinations. pST9 of a transferable R plasmid was detected from a multiple drug resistance strain, Streptococcus sp., ST9 originated from diseased flounder in Jeju, previously. We performed DNA hybridization to know the distribution of plasmid with the same DNA structure as pST9 in streptococci. Thirteen out of 60 isolates analyzed were positive in colony DNA hybridization and the part of bacteria isolated from raw meal was also hybridized with pST9. It suggested that raw meal is one of the origin of the resistance plasmid and R plasmid with DNA structure differing from pST9 is also involving in multiple drug resistance of the streptococci. In conjugation experiment, we found transferable R plasmid carrying OTC, DOXY and/or EM resistance determinant in the 13 resistance strains. all of the streptococci carrying the transferable R plasmid were similar in RAPD patterns. However, pST -type R plasmid was rare in S. iniae most frequently appearing in flounder farm.

• Biomolecules & Therapeutics
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• v.5 no.3
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• pp.265-271
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• 1997

Since the advent of chemotherapy, certain types of cancer have been particularly resistant to chemotherapeutic treatment. One of the most well-studied types of resistance is resistance to multiple struc-turally dissimialr hydrophobic chemotherapeutic agents, or multidrug resistance (MDR). We found that MDR cells (KBV20C, KB7D) being highly resistant to colchicine, etoposide, and vincristine were found to have very low level of putrescine and low level of spermidine than the drug sensitive parental cells (KB) but they had almost same level of spermine as the drug sensitive cells. Although both MDR and drug sensitive cells had almost same rate of polyamine uptake, MDR cells were much more sensitive to an inhibitor of polyamine synthesis, methylglyoxal-bis guanylhydrazone (MGBG), suggesting that MDR cells might be defective in polyamine synthesis. These results also suggest that HGBG can be used for treatment of MDR in vivo.

• Korean Journal of Veterinary Service
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• v.16 no.1
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• pp.41-50
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• 1993

This study was undertaken the bioserotype and drug resistance of Salmonella and Escherichia coli isolated from feces for the prevention and treatment of salmonellosis and colibacillosis in zoological animals. The results obtained from the research were as follows 1. Salmonella were isolated 19, or 4.7% from 408 samples and E. coli were isolated 12, or 40.0% from 30 diarrheal samples. 2. The biotypes in 19 Salmonella were Subspecies 1. 3. The serogroups of Salmonella isolated were 47.4% in B group, 31.6% in C, 5.3% in D and 15.8% in other, and serotype of E. coli was 100% in 0127a. 4. The antibiotic resistance of Salmonella and E. coli isolated were 13, or 68.4% and 7, or 58.3% strains, respectively 5. The multiple resistant patterns of antibiotics in Salmonella were 2drugs- and 3 drugs-resistance 30.8%, respectively, and those in E. coli were mono drug-, 2 drugs- and 7 drugs-resistance 28.6%, respectively. 6. The transferred rate of resistance to recipients (E. coli ML 1410 NA$^{r}$ ) in Salmonella was 38.5%, but that in E. coli was 71.4%.