• Molecules and Cells
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• 제38권2호
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• pp.180-186
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• 2015

Escherichia coli AcrAB-TolC is a multidrug efflux pump that expels a wide range of toxic substrates. The dynamic nature of the binding or low affinity between the components has impeded elucidation of how the three components assemble in the functional state. Here, we created fusion proteins composed of AcrB, a transmembrane linker, and two copies of AcrA. The fusion protein exhibited acridine pumping activity, suggesting that the protein reflects the functional structure in vivo. To discern the assembling mode with TolC, the AcrBA fusion protein was incubated with TolC or a chimeric protein containing the TolC aperture tip region. Three-dimensional structures of the complex proteins were determined through transmission electron microscopy. The overall structure exemplifies the adaptor bridging model, wherein the funnel-like AcrA hexamer forms an intermeshing cogwheel interaction with the ${\alpha}$-barrel tip region of TolC, and a direct interaction between AcrB and TolC is not allowed. These observations provide a structural blueprint for understanding multidrug resistance in pathogenic Gram-negative bacteria.

• Biomolecules & Therapeutics
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• 제20권4호
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• pp.393-398
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• 2012

Recently, we reported that defective autophagy may contribute to the inhibition of the growth in response to PP2 (4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine), a selective SFK inhibitor, in multidrug-resistant v-Ha-ras-transformed NIH 3T3 cells (Ras-NIH 3T3/Mdr). In this study, we demonstrated that PP2 induces LC3 conversion via a mechanism that is uncoupled from autophagy and increases apoptosis in Ras-NIH 3T3/Mdr cells. PP2 preferentially induced autophagy in Ras-NIH 3T3 cells rather than in Ras-NIH 3T3/Mdr cells as determined by LC3-I to LC3-II conversion and GFP-LC3 fluorescence microscopy. Beclin 1 knockdown experiments showed that, regardless of drug resistance, PP2 induces autophagy via a Beclin 1-dependent mechanism. PP2 induced a conformational change in Beclin 1, resulting in the enhancement of the pro-autophagic activity of Beclin 1, in Ras-NIH 3T3 cells. Further, PI3K inhibition induced by wortmannin caused a significant increase in apoptosis in Ras-NIH 3T3 cells, as demonstrated by flow cytometric analysis of Annexin V staining, implying that autophagy inhibition through PI3K increases apoptosis in response to PP2 in Ras-NIH 3T3 cells. However, despite the fact that wortmannin abrogates PP2-induced GFP-LC3 punctae formation, some LC3 conversion remains in Ras-NIH 3T3/Mdr cells, suggesting that LC3 conversion may occur in an autophagy-independent manner. Taken together, these results suggest that PP2 induces LC3 conversion independent of PI3K, concomitant with the uncoupling of LC3 conversion from autophagy, in multidrug-resistant cells.

• 한국임상약학회지
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• 제33권4호
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• pp.278-289
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• 2023

Background: Linezolid has been widely used in the treatment for multidrug-resistant tuberculosis. However, there are limitations to use it such as long treatment, because of related side effects, even adequate treatment period has been needed for remission of multidrug-resistant tuberculosis (MDR-TB). Method: The meta-analysis was performed based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. To choose literatures, systematic literature reviews were conducted with databases of PubMed, Web of Science, and EMBASE. Results: Efficacy and safety of Linezolid were determined by 85% (95% CI=79~89%, p<0.05) in the sputum culture conversion and 55% (95% CI=45~64%, p<0.01) in side effects related to linezolid, respectively. In addition, I² was estimated by 72%. In the subgroup analysis, efficacy and safety by dose and region were analyzed. In the subgroup analysis, compared with the linezolid dose in groups greater than 600 mg/day and less than 600 mg/day, this study showed 85% (95% CI 79~90%, p>0.05) in 206 patients and 82% (95% CI 73~89%, p<0.05) in 297 patients, respectively. Also, in the subgroup analysis, adverse effects caused by linezolid occurred more than 50% of treated patients. Conclusion: Therapeutic efficacy of linezolid for MDR-TB patients was confirmed regardless of the initial dose of linezolid, especially for sputum culture conversion and it was recommended that the dose of linezolid has been more effective below 600 mg/day. However, it should be necessary to closely monitored for safety issues since serious side effects possibly occurred by administration of long period treatment.

• Journal of Yeungnam Medical Science
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• 제37권4호
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• pp.277-285
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• 2020

Tuberculosis (TB) is still a major health problem worldwide. Especially, multidrug-resistant TB (MDR-TB), which is defined as TB that shows resistance to both isoniazid and rifampicin, is a barrier in the treatment of TB. Globally, approximately 3.4% of new TB patients and 20% of the patients with a history of previous treatment for TB were diagnosed with MDR-TB. The treatment of MDR-TB requires medications for a long duration (up to 20-24 months) with less effective and toxic second-line drugs and has unfavorable outcomes. However, treatment outcomes are expected to improve due to the introduction of a new agent (bedaquiline), repurposed drugs (linezolid, clofazimine, and cycloserine), and technological advancement in rapid drug sensitivity testing. The World Health Organization (WHO) released a rapid communication in 2018, followed by consolidated guidelines for the treatment of MDR-TB in 2019 based on clinical trials and an individual patient data meta-analysis. In these guidelines, the WHO suggested reclassification of second-line anti-TB drugs and recommended oral treatment regimens that included the new and repurposed agents. The aims of this article are to review the treatment strategies of MDR-TB based on the 2019 WHO guidelines regarding the management of MDR-TB and the diagnostic techniques for detecting resistance, including phenotypic and molecular drug sensitivity tests.

• Journal of Korean Biological Nursing Science
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• 제14권1호
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• pp.8-15
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• 2012

Purpose: This study was undertaken to identify the knowledge and compliance level of nursing students. It was based on self-administered questionnaires about multidrug-resistant organisms (MDROs). Methods: The test group was 184 nursing students who had contact with MDROs during clinical practice. The study was conducted from May 1 to September 16, 2011. Results: The average knowledge level of MDROs was 16.20 (correct answer rate: 67.5%). The nurses' compliance level of MDROs infection control was on average 40.50 (range: 13-52). "Hand hygiene" ranked highest in the compliance level of MDROs infection control. The lowest level of MDRO infection control was the wearing of disposable aprons or gowns. Conclusion: This study demonstrated the nursing students' knowledge and the compliance level of infection control. We suggest that nursing students receive mandated systematic education of MDROs in the nursing curriculum. And clinical practice experience of MDROs infection control is required in hospitals. These steps will help prevent transmission of MDROs in nursing settings.

• 대한핵의학회:학술대회논문집
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• 대한핵의학회 2001년도 제40차 춘계학술대회 및 연수교육
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• pp.66-75
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• 2001

Although diverse mechanisms are involved in multidrug resistance for chemotherapeutic drugs, the development of cellular P-glycoprotein(Pgp) and multidrug-resistance associated protein (MRP) are important factors in the chemotherapy failure to cancer. Various detection assays provide information about the presence of drug efflux pumps at the mRNA and protein levels. However these methods do not yield information about dynamic function of Pgp and MRP un vivo. Single photon emission tomography (SPECT) and positron emission tomography (PET) are available for the detection of Pgp and MRP-mediated transport. $^{99m}Tc$-sestaMIBl and other $^{99m}Tc$-radiopharmaceuticals are substrates for Pgp and MRP, and have been used in clinical studies for tumor imaging, and to visualize blockade of Pgp-mediated transport after modulation of Pgp pump. Colchicine, verapamil and daunorubicin labeled with $^{11}C$ have been evaluated for the quantification of Pgp-mediated transport with PET in vivo and reported to be feasible substrates with which to image Pgp function in tumors. Leukotrienes are specific substrates for MRP and N-$[^{11}C]$acetyl-leukotriene E4 provides an opportunity to study MRP function non-invasively in vivo. Results obtained from recent publications are reviewed to confirm the feasibility of using SPECT and PET to study the functionality of MDR transporters in vivo.

• Journal of Life Science
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• 제9권1호
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• pp.40-44
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• 1999

Glutathione S-transferase (GST) is a multifunctional protein that catalyzes the catalyzes the conjugation of glutathione with electrophilic compounds. It exists in a variety of isoenzy-matic froms with a wide range of substrate specificity and plays a pivotal role in detoxification of various drugs. In order to elucidate the GST-${\pi}$'s involvement of multidrug resistance (MDR) in drug-resistant tumor cell lines, we determined GST-${\pi}$ content by "1 step sandwich method". Consequently, adriamycin resistant cells of MCF-7 (MCF-7/ADM) have 7-fold increase of GST-${\pi}$ content than that of MCF-7 cells, while its {TEX}$IC_{50}${/TEX} was 116-fold greater than parent cell line. By northrn blotting, we compared whether MCF-7/ADM cells express GST-${\pi}$ mRNA. The GST-${\pi}$ mRNA expression in these cells was not inducible, but constitutive when treated for 24 h with a concentration of 0, 20, 200, and 2000 nM of adriamycin, respectively. Taken together, these results suggest that GST-${\pi}$ may not be directly associated with multidrug resistance in these human cancer cell lines.ell lines.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1214-1220
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• 2005

Decreased porin-mediated outer membrane penetration of hydrophilic antibiotics is a common mechanism of antibiotic resistance in Gram-negative bacteria. This study was undertaken to determine whether a null mutation in Pseudomonas putida would suppress porin synthesis, and therefore reduce the susceptibility of the organism to streptomycin, norfloxacin, and tetracycline. Inverse PCR amplification and double-stranded DNA sequencing were used to identify chromosomal genes carrying TnphoA'-1 inserts. Genome database available was used to identify putative homologue genes, one of which encodes protein with homology to domains of the MutS of P. putida, suggesting a crucial role in the multidrug resistance. Increased resistance to streptomycin, norfloxacin, and tetracycline might be due to accumulation of compensatory mutations. Either no growth or slow growth was observed in P. putida KH1027 when grown in minimal medium containing gluconate, glucose, or citrate; however, it is not clear whether the growth patterns contributed to the multidrug resistance.

• 한국미생물·생명공학회지
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• 제31권3호
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• pp.230-234
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• 2003

Small multidrug resistance(SMR) family(TC #2.A.7.1)에 속하는 막단백질 중 하나를 coding하는 Bacillus subtilis의 yvaE유전자의 발현을 유도한 결과, 발현된 YvaE단백질에 의해 대장균세포내에서 살균제를 포함한 다양한 양이온 약제에 대한 efflux활성을 촉매하는 것으로 확인되었다. 같은 operon내에 인접한 yaD유전자의 동시발현을 유도한 결과, 이러한 efflux활성은 억제가 되는 것으로 나타났다. Ethidium bromide를 기질로 하여 fluorimeter를 이용한 efflux transport실험결과, YvaE 단백질이 발현된 대장균세포의 경우 vector만을 함유한 대조세포에 비해 현저히 빠른 efflux활성을 보여주었다 따라서 YvaE 막단백질은 multidrug export를 촉매하는 SMR-type efflux pump임을 확인하였다.

• 한국동물위생학회지
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• 제42권4호
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• pp.251-255
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• 2019

Wildlife is a bio-indicator of environmental pollution by antimicrobial resistant bacteria or genes, however, there is no information on antimicrobial resistance in wildlife-origin bacteria. This study aimed to investigate the normal microbiota of staphylococci and their antimicrobial resistance in wildlife that did not take any antimicrobials. After sampling and bacterial isolation/identification, antimicrobial resistance profiles were examined by broth microdilution test, Kirby-Bauer disc diffusion test and mecA genetargeted PCR. Of 90 isolates from wildlife, 83 were coagulase-negative staphylococci while only 7 were coagulase-positive staphylococci. Methicillin-resistance was found in 63 (70%) isolates and 35 of 90 (38.9%) isolates were multidrug-resistant staphylococci. When considering that all of the animals did not take any medication or contacted any medical device before the sampling, the results indicate significantly high prevalence of antimicrobial resistance in wild environments. Further study would be necessary to investigate the transmission route of antimicrobial resistance.