• Bulletin of the Korean Chemical Society
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• 제34권11호
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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.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제15권2호
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• pp.63-73
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• 2012

Development of antiviral resistance to lamivudine is the most important factor for the treatment failure. It is necessary to establish proper guidelines to overcome drug resistance for children with chronic hepatitis B. Primary treatment with lamivudine should be considered if patients are in immune-clearance phase and have persistently elevated ALT levels more than twice the upper limit of normal value. Before initiating the therapy, careful consideration of the patient's status is required to exclude abnormal liver function tests due to other causes. The treatment option should be carefully decided to suppress the viral replication effectively. To obtain good compliance, clinicians should educate patients and their parents. Appropriate monitoring for virologic breakthrough and genotypic resistance is important in deciding to change the treatment plan. Sequential monotherapy should be avoided and a combination of drugs in other categories is recommended. New antiviral agents, such as entecavir and tenofovir, which have high potency and high genetic barrier, are soon expected to be available for use with children.

• 대한수의학회지
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• 제29권4호
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• pp.487-492
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• 1989

The capsular serogroupes and drug susceptibility of 111 isolates of Pasteurella multocida from pigs with atrophic rhinitis and pneumonic lesions were investigated. Of the 111 P multocida isolates, 42 were from lung lesions, 47 from nasal turbinate lesions and the remaining 22 from the nasal swabs. P multocida isolates were typed for capsular serogroupes A by hyaluronidase inhibition of capsule and D by acriflavine auto-agglutination. Most isolates(64.9%) were type A, 23.4% were type D and the remaining 11.7% were untypable. Resistance to triple sulfa(97.3%) was most frequent, followed by resistance to tiamulin(71.2%), tylosin(56.8%), streptomycin(36.9%), and neomycin(36.0%). The majority of the organisms were susceptible in order of prevalence to baytril(100%), ampicillin(98.2%), linsmycin(97.3%), colistin(97.3%), cephalothin(94.6%), gentamicin(93.7%), amikacin(92.3%), tetracycline(91.9%), trimethoprim/sulfamethoxazole(91.0%), and kanamycin(90.1%). No differences in drug resistance in relation to capsular serogroupes of P multocida and the origin of lesions were noted. A high prevalence of multiple drug resistance was observed and the most common resistant patterns were Sss, Tm, Ty(12.6%) and Sm, Sss, Tm, Ty(8.1%) patterns.

• 한국식품과학회지
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• 제42권4호
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• pp.508-513
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• 2010

2006년부터 2008년까지 3년간 시판 수산물 2,239건에서 분리한 V. parahaemolyticus에 대한 항생제 감수성 결과는 다음과 같았다. 어류 789건을 검사하여 42주(5.3%)의 V. parahaemolyticus가 분리 동정되었으며, 패류 735건 중 27건(3.7%), 연체류 387건 중 12건(3.1%), 기타 수산물 328건 중 12건(3.7%), 총 93건(4.2%)에서 V. parahaemolyticus가 분리 동정되었다. 내성률이 높은 항생제는 ampicillin 93.5%, cephalothin 90.3%, streptomycin 87.1%, ticarcillin 55.9%, 그리고 amikacin 40.9%이었으며, 감수성률이 높은 항생제는 nalidixic acid, chloramphenicol 및 ampicillin/sulbactam trimethoprim/sulfamethoxazole 98.9%, gentamicin 및 tetracycline 82.8%, ceftriaxone 63.4%이었다. 중등도 내성률은 kanamycin 79.6%, ciprofloxacin 64.5%, amikacin 47.3%, cefoxitin 43.0%순이었다. 항생제 내성양상은 3제 내성이 37.6%, 4제 내성 24.7%, 5제 내성 17.2%, 6제 내성 11.8%, 2제 내성6.5%, 7제 내성 2.2% 순이었으며, 가장 많은 내성 양상은 AM-CF-S의 3제 내성(22.6%), AM-CF-S-TIC 4제 내성(18.3%), AM-AN-CF-S-TIC 5제 내성(9.7%) 순이었다.

• Biomolecules & Therapeutics
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• 제24권5호
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• pp.482-488
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• 2016

Cancer stem cells (CSCs) are a subset of tumor cells, which are characterized by resistance against chemotherapy and environmental stress, and are known to cause tumor relapse after therapy. A number of molecular mechanisms underlie the chemoresistance of CSCs, including high expression levels of drug efflux transporters. We investigated the role of the antioxidant transcription factor NF-E2-related factor 2 (NRF2) in chemoresistance development, using a CSC-enriched colonosphere system. HCT116 colonospheres were more resistant to doxorubicin-induced cell death and expressed higher levels of drug efflux transporters such as P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) compared to HCT116 monolayers. Notably, levels of NRF2 and expression of its target genes were substantially elevated in colonospheres, and these increases were linked to doxorubicin resistance. When NRF2 expression was silenced in colonospheres, Pgp and BCRP expression was downregulated, and doxorubicin resistance was diminished. Collectively, these results indicate that NRF2 activation contributes to chemoresistance acquisition in CSC-enriched colonospheres through the upregulation of drug efflux transporters.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.167.2-168
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• 2003

Anticancer drug resistance occasionally occurs in malignant hematologic diseases such as acute myelocytic leukemia (AML) treated with chemotherapy and is a major problem to complete remission. Malignant cells primarily induce intrinsic resistance to treatment of anticancer drug, but gradually obtain acquired resistance to cytotoxic activities of chemotherapy. In this study, we monitored the expression profiles of doxorubicin resistance-related genes in AML-2/DX100, a doxorubicin-resistant human acute myelocytic leukemia cell line. (omitted)

• Tuberculosis and Respiratory Diseases
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• 제78권3호
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• pp.168-174
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• 2015

Drug-resistant tuberculosis (TB) is still a major threat worldwide. However, recent scientific advances in diagnostic and therapeutic tools have improved the management of drug-resistant TB. The development of rapid molecular testing methods allows for the early detection of drug resistance and prompt initiation of an appropriate treatment. In addition, there has been growing supportive evidence for shorter treatment regimens in multidrug-resistant TB; and for the first time in over 50 years, new anti-TB drugs have been developed. The World Health Organization has recently revised their guidelines, primarily based on evidence from a meta-analysis of individual patient data (n=9,153) derived from 32 observational studies, and outlined the recommended combination and correct use of available anti-TB drugs. This review summarizes the updated guidelines with a focus on the medical management of drug-resistant TB.

• Journal of Microbiology and Biotechnology
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• 제31권5호
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• pp.733-739
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• 2021

Acinetobacter strains are widely present in the environment. Some antimicrobial-resistant strains of this genus have been implicated in infections acquired in hospitals. Genetic similarities have been reported between Acinetobacter strains in nosocomial infections and those isolated from foods. However, the antimicrobial resistance of Acinetobacter strains in foods, such as meat, remains unclear. This study initially aimed to isolate Campylobacter strains; instead, strains of the genus Acinetobacter were isolated from meat products, and their antimicrobial resistance was investigated. In total, 58 Acinetobacter strains were isolated from 381 meat samples. Of these, 32 strains (38.6%) were from beef, 22 (26.5%) from pork, and 4 (4.8%) from duck meat. Antimicrobial susceptibility tests revealed that 12 strains were resistant to more than one antimicrobial agent, whereas two strains were multidrug-resistant; both strains were resistant to colistin. Cephalosporin antimicrobials showed high minimal inhibitory concentration against Acinetobacter strains. Resfinder analysis showed that one colistin-resistant strain carried mcr-4.3; this plasmid type was not confirmed, even when analyzed with PlasmidFinder. Analysis of the contig harboring mcr-4.3 using BLAST confirmed that this contig was related to mcr-4.3 of Acinetobacter baumannii. The increase in antimicrobial resistance in food production environments increases the resistance rate of Acinetobacter strains present in meat, inhibits the isolation of Campylobacter strains, and acts as a medium for the transmission of antimicrobial resistance in the environment. Therefore, further investigations are warranted to prevent the spread of antimicrobial resistance in food products.

• Journal of Ginseng Research
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• 제31권2호
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• pp.74-78
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• 2007

Multi-drug resistance (MDR) is a major problem in cancer chemotherapy and has often ended up with termination of the therapy. The aim of this study was to identify any fractions of Korean red ginseng that would be effective in modulating for MDR. Although ginsenosides have been reviewed as possible MDR modulators, the MDR modulation activity of the other component is unknown. Therefore, a red ginseng was extracted with methanol, ether, ethylacetate, and n-butanol, followed by several fractionations by silica gel chromatography. And the activity of MDR modulating for these fractions was examined via sulforrhodamine B assay. We have found that several ether fractions, as nonsaponin components are effective on MDR modulation. We have expect that these results helpful to improvement of cancer chemotherapy.

• 통합자연과학논문집
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• 제4권1호
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• pp.23-30
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• 2011

Multidrug resistance (MDR) is one of the main obstacles in the chemotherapy of cancer. MDR is associated with the over expression of P-glycoprotein (P-gp), resulting in increased efflux of chemotherapy from cancer cells. Inhibiting P-gp as a method to reverse MDR in cancer patients has been studied extensively, but the results have generally been disappointing. First-generation agents were limited by unacceptable toxicity, whereas second-generation agents had better tolerability but were confounded by unpredictable pharmacokinetic interactions and interactions with other transporter proteins. Third-generation inhibitors have high potency and specificity for P-gp. Furthermore, pharmacokinetic studies to date have shown no appreciable impact on drug metabolism and no clinically significant drug interactions with common chemotherapy agents. Third-generation P-gp inhibitors have shown promise in clinical trials. The continued development of these agents may establish the true therapeutic potential of P-gp-mediated MDR reversal.