• Journal of Microbiology and Biotechnology
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• 제31권1호
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• pp.130-136
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• 2021

Persister cell formation and biofilms of pathogens are extensively involved in the development of chronic infectious diseases. Eradicating persister cells is challenging, owing to their tolerance to conventional antibiotics, which cannot kill cells in a metabolically dormant state. A high frequency of persisters in biofilms makes inactivating biofilm cells more difficult, because the biofilm matrix inhibits antibiotic penetration. Fatty acids may be promising candidates as antipersister or antibiofilm agents, because some fatty acids exhibit antimicrobial effects. We previously reported that fatty acid ethyl esters effectively inhibit Escherichia coli persister formation by regulating an antitoxin. In this study, we screened a fatty acid library consisting of 65 different fatty acid molecules for altered persister formation. We found that undecanoic acid, lauric acid, and N-tridecanoic acid inhibited E. coli BW25113 persister cell formation by 25-, 58-, and 44-fold, respectively. Similarly, these fatty acids repressed persisters of enterohemorrhagic E. coli EDL933. These fatty acids were all medium-chain saturated forms. Furthermore, the fatty acids repressed Enterohemorrhagic E. coli (EHEC) biofilm formation (for example, by 8-fold for lauric acid) without having antimicrobial activity. This study demonstrates that medium-chain saturated fatty acids can serve as antipersister and antibiofilm agents that may be applied to treat bacterial infections.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1293-1316
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• 2021

Using directional antennas in wireless Ad hoc networks has many superiorities, including reducing interference, extending transmission range, and increasing space division multiplexing. However, directional transmission introduces two problems: deafness and directional hidden terminals problems. We observe that these problems result in saturation throughput disparity among the competing flows in directional CSMA/CA based Ad hoc networks and bring challenges for modeling the saturation throughput of the flows. In this article, we concentrate on how to model and analyze the saturation throughput disparity of different flows in directional CSMA/CA based Ad hoc networks. We first divide the collisions occurring in the transmission process into directional instantaneous collisions and directional persistent collisions. Then we propose a four-dimensional Markov chain to analyze the transmission state for a specific node. Our model has three different kinds of processes, namely back-off process, transmission process and freezing process. Each process contains a certain amount of continuous time slots which is defined as the basic time unit of the directional CSMA/CA protocols and the time length of each slot is fixed. We characterize the collision probabilities of the node by the one-step transition probability matrix in our Markov chain model. Accordingly, we can finally deduce the saturation throughput for each directional data stream and evaluate saturation throughput disparity for a given network topology. Finally, we verify the accuracy of our model by comparing the deviation of analytical results and simulation results.

• 대한화장품학회지
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• 제42권4호
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• pp.377-385
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• 2016

본 연구에서는 참깨 추출물의 주름개선 화장품 원료로의 가능성을 확인하기 위하여, 참깨의 70% 에탄올 추출물을 제조하여, 엘라스타제 저해능, 콜라게나제 저해능, matrixmetallopoteinases (MMPs)의 단백질, mRNA 발현 저해 효능을 측정하였다. Elastase와 collagenase 저해활성은 $1000{\mu}g/mL$ 농도에서 각각 37.8%와 45%의 효소 활성을 억제를 나타내었다. 섬유아세포에서 참깨 에탄올 추출물의 세포 생존율을 확인한 결과 $100{\mu}g/mL$ 농도에서 96%의 생존율을 보였다. 참깨 에탄올 추출물을 처리한 섬유아세포에서 matrix metalloproteinase-1 (MMP-1), matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-3 (MMP-3)의 단백질 발현 및 mRNA 발현 억제 효과를 확인한 결과 단백질 발현은 $100{\mu}g/mL$ 농도에서 63%, 43%, 49%의 저해율을 나타내었고, mRNA 발현 억제는 최고농도인 $100{\mu}g/mL$에서 각각 82% 79%, 82%의 저해율을 나타내었다. 이러한 결과로 보아 참깨 70% 에탄올 추출물이 주름개선용 기능성 화장품 소재로서의 응용이 가능할 것으로 판단되었다.

• 한국산학기술학회논문지
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• 제6권2호
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• pp.134-143
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• 2005

포유동물에서 중요한 구조단백질인 콜라겐은 다양한 조직내 단백질 조성과 사슬간 복잡한 가교결합의 존재로 인해 그 구조가 복잡하고 다양하여, 직접적으로 분석할 적당한 방법이 없었다. 본 연구에서는 간단한 전처리만으로 다수의 생체분자 시료에 대해 정확한 분자량 측정이 가능한 매트릭스 보조 레이저 탈착/이온화 비행시간 질량분석법(MALDI-TOF MS)을 이용하여 콜라겐과 조각화된 콜라겐을 분석하고 이의 아미노산 서열을 사중극자-비행시간 직렬 질량분석법(Q-TOF MS/MS)으로 확인하여, 시료 중의 콜라겐의 종류에 대한 정보를 확인하여, MALDI-TOF 질량분석을 이용한 콜라겐 분석에서 콜라겐의 종류를 쉽게 예측할 수 있는 방법을 제시하고자 하였다. 쥐의 꼬리에서 분리한 콜라겐을 SDS-PAGE로 분리한 결과 10개의 band를 얻을 수 있었는데, 같은 시료를 MALDI-TOF MS로 확인하여 각 band의 정확한 분자량을 결정할 수 있었다. SDS-PACE상의 10개의 분리된 band에 대해 각각 tryptic digestion후 MALDI-TOF 질량분석을 수행한 결과 4개의 band에서 type I 콜라겐의 $\alpha_1$-chain내의 fragment인 Gly1056-Arg1073을 확인할 수 있었고, 5개의 band에서 type I 콜라겐의 $\alpha_2$-chain내의 fragment인 Gly985-Arg1002을 확인하였다. 잔재한 콜라겐의 가교결합으로 인해 예상되는 fragment중 둘만이 확인되었지만, 확인된 fragment를 통해 적어도 7개의 band에서는 type I콜라겐이 존재함을 확인할 수 있었다. 확인된 두 콜라겐 flagment의 아미노산 서열을 Q-TOF MS/MS로 분석한 결과 MALDI-TOF MS에서의 예측과 일치함을 확인할 수 있었으며, 이를 통해 확인된 두 fragment에 의한 peak을 지문으로 하여 MALDI-TOF MS측정시에 시료내의 type I 콜라겐의 존재를 쉽게 확인할 수 있음을 볼 수 있었다.

• The Korean Journal of Physiology and Pharmacology
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• 제21권2호
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• pp.197-204
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• 2017

In the present study, we tried to examine whether oleanolic acid regulates the activity, secretion and gene expression of matrix metalloproteinase-3 (MMP-3) in primary cultured rabbit articular chondrocytes, as well as the production of MMP-3 in the knee joint of rat to evaluate the potential chondroprotective effect of oleanolic acid. Rabbit articular chondrocytes were cultured in a monolayer, and reverse transcription-polymerase chain reaction (RT-PCR) was used to measure interleukin-$1{\beta}$ (IL-$1{\beta}$)-induced gene expression of MMP-3, MMP-1, MMP-13, a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), ADAMTS-5 and type II collagen. In rabbit articular chondrocytes, the effects of oleanolic acid on IL-$1{\beta}$-induced secretion and proteolytic activity of MMP-3 were investigated using western blot analysis and casein zymography, respectively. The effect of oleanolic acid on in vivo MMP-3 protein production was also examined, after intra-articular injection to the knee joint of rat. The results were as follows: (1) oleanolic acid inhibited the gene expression of MMP-3, MMP-1, MMP-13, ADAMTS-4, and ADAMTS-5, but increased the gene expression of type II collagen; (2) oleanolic acid reduced the secretion and proteolytic activity of MMP-3; (3) oleanolic acid suppressed the production of MMP-3 protein in vivo. These results suggest that oleanolic acid can regulate the activity, secretion and gene expression of MMP-3, by directly acting on articular chondrocytes.

• 터널과지하공간
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• 제13권1호
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• pp.20-32
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• 2003

균열암반에서 콜로이드를 동반한 방사성 핵종의 이동을 핵종붕괴사슬과 주변암반으로제한적 분자확산을 고려하여 모사하였다. 암반 내 핵종 이동을 모사하기 위한 핵종이동 시스템과 지배 방정식 및 초기/경계 조건을 설정하여 반 해석해를 도출하였으며, 수치적 라플라스 역변환을통하여 반해석해의 검증을 실시하였다. 유사콜로이드의 반응상수가 균열 내에 미치는 영향과 콜로이드의 여과작용이 핵종이동에 미치는 영향 그리고 주변 암반으로 제한적 확산이 핵종이동에 미치는 영향에 대하여 알아보았다. 지하수 내에 존재하는 유사 콜로이드의 양이 많아질수록 균열 내 방사성 핵종이동의 가속현상이 크게 나타났으며 여과 계수가 모든 핵종에 대하여 $10^{-3}$ (m$^{-1}$)보다 클 경우 여과에 의한 핵종 지연을 무시할 수 없었다. 콜로이드 존재로 인한 핵종가속과 더불어, 주변암반으로 방사성핵종의 분자확산이 제한적일 경우에 예측된 핵종가속현상은 확산깊이가 적을수록 더 커지는 것을 알 수 있었고, 이때 가속에 영향을 주는 유효확산깊이가 존재하는 것을 발견할 수 있었다. 또한 주변암반의 저지계수가 클수록 제한적 확산깊이에 따른 핵종들의 가속범위의 증가를 볼 수 있었다.

• Industrial Engineering and Management Systems
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• 제8권3호
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• pp.194-200
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• 2009

This study provides a heuristic algorithm to solve the locating problem of repair service centers (RSCs). To enhance the customer service level with more satisfaction and quicker responsiveness, the locating problem of RSCs has become one of the important issues in reverse supply chain management. This problem is formulated as a zero-one mixed integer programming in which an exiting distributor will be considered to be an un-capacitated repair service center for the objective of cost-minimizing. Since logistical costs are highly interrelated with the multinational location of distributors and RSCs, the fixed cost for setting a repair service center, variable cost, transportation cost, and exchange rates are considered in this study. Recognizing the selection of un-capacitated RSCs' locations is a combinatorial optimization problem and is a zero-one mixed integer programming with NP-hard complexity, we provide a heuristic algorithm named as incremental cost matrix procedure (ICMP) to simplify the solving procedure. By using the concise and structural cost matrix, ICMP can efficiently screen the potential location with cost advantage and effectively decide which distributor should be a RSC. Results obtained from the numerical experiments conducted in small scale problem have shown the fact that ICMP is an effective and efficient heuristic algorithm for solving the RSCs locating problem. In the future, using the extended ICMP to solve problems with larger industrial scale or problems with congestion effects caused by the variation of customer demand and the restriction of the RSC capacity is worth a further investigation.

• Journal of Korean Neurosurgical Society
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• 제55권5호
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• pp.237-243
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• 2014

Objective : Symptomatic disc degeneration develops from inflammatory reactions in the annulus fibrosus (AF). Although inflammatory mediators during annular inflammation have been studied, the roles of matrix metalloproteinases (MMPs) and their inhibitors have not been fully elucidated. In this study, we evaluated the production of MMPs and tissue inhibitors of metalloproteinase (TIMPs) during annular inflammation using an in vitro co-culture system. We also examined the effect of notochordal cells on annular inflammation. Methods : Human AF (hAF) pellet was co-cultured for 48 hours with phorbol myristate acetate-stimulated macrophage-like THP-1 cells. hAF pellet and conditioned media (CM) from co-cultured cells were assayed for MMPs, TIMPs, and insulin-like growth factor (IGF)-1 levels using real-time reverse-transcriptase polymerase chain reaction and enzyem-linked immunosorbent assay. To evaluate whether notochordal cells affected MMPs or TIMPs production on annular inflammation, hAF co-cultured with notochordal cells from adult New Zealand White rabbits, were assayed. Results : MMP-1, -3, -9; and TIMP-1 levels were significantly increased in CM of hAF co-cultured with macrophage-like cells compared with hAF alone, whereas TIMP-2 and IGF-1 levels were significantly decreased (p<0.05). After macrophage exposure, hAF produced significantly more MMP-1 and -3 and less TIMP-1 and -2. Interleukin-$1{\beta}$ stimulation enhanced MMP-1 and -3 levels, and significantly diminished TIMP-2 levels. Co-culturing with rabbit notochordal cells did not significantly influence MMPs and TIMPs production or COL1A2 gene expression. Conclusion : Our results indicate that macrophage-like cells evoke annular degeneration through the regulation of major degradative enzymes and their inhibitors, produced by hAF, suggesting that the selective regulation of these enzymes provides future targets for symptomatic disc degeneration therapy.

• 대한한방내과학회지
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• 제37권1호
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• pp.16-25
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• 2016

Objectives: Gilgyung-tang (GGT) has been used as one of the main multi-herb formulas to treat “Peo-ong” (lung abscess). In this study, we investigated the inhibitory effects of water extracts of GGT on cell migration and invasion, two critical cellular processes that are often deregulated during metastasis, in human bladder cancer 5637 cells.Methods: Effects on cell viability were quantified using an MTT assay. To analyze the anti-metastatic effects, we conducted a wound healing migration assay, an in vitro invasiveness assay, and a measurement of the transepithelial electrical resistance (TER). The expression of protein and mRNA were measured by Western blotting and real-time polymerase chain reaction (RT-PCR), respectively.Results: GGT markedly inhibited the cell motility and invasiveness of 5637 cells within the concentration range that was not cytotoxic. The inhibitory effects of GGT on cell invasiveness were associated with tightening of the tight junctions (TJs), which was demonstrated by an increase in the TER. The RT-PCR and Western blotting results indicated that GGT decreased the levels of claudin proteins. GGT also inhibited the activity and expression of matrix metalloproteinase (MMP)-2 and -9 and simultaneously increased the levels of tissue inhibitor of metalloproteinase-1 and -2.Conclusions: Our findings suggest that GGT reduces both the migration and the invasion of 5637 cells by modulating the activity of TJs and MMPs.

• Archives of Plastic Surgery
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• 제42권5호
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• pp.544-551
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• 2015

Background Changes in the composition of the extracellular matrix (ECM) occur between the proliferating and involuted phases of infantile hemangiomas (IH), and are associated with angiogenic growth. We examined the composition of the ECM in proliferating and involuted IHs and assessed correlations between the composition of the ECM and whether the IH was in the proliferating or the involuted phase. Methods We evaluated IH samples from a cohort of patients who had five proliferating IHs and five involuted IHs. The following ECM molecules were analyzed using enzyme-linked immunosorbent assays and immunohistochemistry: laminin, fibronectin, collagen type I, collagen type II, and collagen type III. Results The involuted IHs had higher levels of deposition of collagen type III than the proliferating IHs. The median values (interquartile ranges) were 1.135 (0.946-1.486) and 1.008 (0.780- 1.166) (P=0.019), respectively. The level of laminin was higher in involuted IHs than in proliferating IHs, with median values (interquartile ranges) of 3.191 (2.945-3.191) and 2.479 (1.699- 3.284) (P=0.047), respectively. Abundant collagen type III staining was found in involuted IHs. Laminin ${\alpha}4$ chain staining was clearly present within the basement membrane adjacent to the blood vessels, and was significantly more intense in involuted IHs than in proliferative IHs. Conclusions Involuted hemangiomas showed extensive deposition of collagen III and laminin, suggesting that differences in the composition of the ECM reflect stages of the development of IHs. This pattern may be due to the rapid senescence of IHs.