• Natural Product Sciences
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• 제25권2호
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• pp.172-180
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• 2019

Infections with Pseudomonas aeruginosa are difficult to treat not only because it is often associated with multidrug-resistant infections but also it is able to form biofilm. The aim of this study was to evaluate the antibiofilm and anti-Quorum Sensing (QS) activities of Thymbra capitata essential oils (EOs) against Beta Lactamase (BL) producing P. aeruginosa and the reference strain P. aeruginosa 10145. GC/MS analysis showed that thymol (23.25%) is the most dominant compound in T. capitata EOs. The MICs of T. capitata EOs against P. aeruginosa (BL) and P. aeruginosa 10145 were 1.11%. At sub MIC (0.041, 0.014 and 0.0046%), the EOs of T. capitata remarkably inhibited the biofilm formation of both strains tested and complete inhibition of the biofilm formation was reported at 0.041%. The EOs of T. capitata were found to inhibit the swarming motility, aggregation ability and hydrophobic ability of P. aeruginosa (BL) and P. aeruginosa 10145. Interestingly, the EOs of T. capitata reduce the production of three secreted virulence factors that regulated by QS system including pyocyanin, rhamnolipids and LasA protease. The potent antibiofilm and anti-QS activities of T. capitata EOs can propose it as a new antibacterial agent to control pseudomonas infections.

• 한국미생물·생명공학회지
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• 제50권1호
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• pp.1-14
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• 2022

Bacteria communicate with each other through an intricate communication mechanism known as quorum sensing (QS). QS regulates different behavioral aspects in bacteria, such as biofilm formation, sporulation, virulence gene expression, antibiotic production, and bioluminescence. Several different chemical signals and signal detection systems play vital roles in promoting highly efficient intra- and interspecies communication. Gram-negative bacteria coordinate gene regulation through the production of acyl homoserine lactones (AHLs). Gram-positive bacteria do not code for AHL production, while some gram-negative bacteria have an incomplete AHL-QS system. Despite this fact, these microbes can detect AHLs owing to the presence of LuxR solo receptors. Various studies have reported the role of AHLs in interspecies signaling. Moreover, as bacteria live in a polymicrobial community, the production of extracellular compounds to compete for resources is imperative. Thus, AHL-mediated signaling and inhibition are considered to affect virulence in bacteria. In the current review, we focus on the synthesis and regulation mechanisms of AHLs and highlight their role in interspecies bacterial signaling. Exploring interspecies bacterial signaling will further help us understand host-pathogen interactions, thereby contributing to the development of therapeutic strategies intended to target chronic polymicrobial infections.

• Journal of Microbiology and Biotechnology
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• 제30권4호
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• pp.571-582
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• 2020

Quorum sensing (QS)-mediated infections cause severe diseases in human beings. The control of infectious diseases by inhibiting QS using antipathogenic drugs is a promising approach as antibiotics are proving inefficient in treating these diseases. Marine fungal (Pestalotiopsis sydowiana PPR) extract was found to possess effective antipathogenic characteristics. The minimum inhibitory concentration (MIC) of the fungal extract against test pathogen Pseudomonas aeruginosa PAO1 was 1,000 ㎍/ml. Sub-MIC concentrations (250 and 500 ㎍/ml) of fungal extract reduced QS-regulated virulence phenotypes such as the production of pyocyanin, chitinase, protease, elastase, and staphylolytic activity in P. aeruginosa PAO1 by 84.15%, 73.15%, 67.37%, 62.37%, and 33.65%, respectively. Moreover, it also reduced the production of exopolysaccharides (74.99%), rhamnolipids (68.01%), and alginate (54.98%), and inhibited the biofilm formation of the bacteria by 90.54%. In silico analysis revealed that the metabolite of P. sydowiana PPR binds to the bacterial QS receptor proteins (LasR and RhlR) similar to their respective natural signaling molecules. Cyclo(-Leu-Pro) (CLP) and 4-Hydroxyphenylacetamide (4-HPA) were identified as potent bioactive compounds among the metabolites of P. sydowiana PPR using in silico approaches. The MIC values of CLP and 4-HPA against P. aeruginosa PAO1 were determined as 250 and 125 ㎍/ml, respectively. All the antivirulence assays were conducted at sub-MIC concentrations of CLP (125 ㎍/ml) and 4-HPA (62.5 ㎍/ml), which resulted in marked reduction in all the investigated virulence factors. This was further supported by gene expression studies. The findings suggest that the metabolites of P. sydowiana PPR can be employed as promising QS inhibitors that target pathogenic bacteria.

• 미생물학회지
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• 제44권2호
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• pp.85-92
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• 2008

Pseudomonas aeruginosa는 기회 감염성 병원균으로, Cystic fibrosis, 미생물 감염성 각막염,화상 부위 2차 감염 등의 다양한 질병을 초래한다. 정족수 인식(쿼럼 센싱)이라고도 알려져 있는 세포간 신호전달 기전이 이러한 감염에서 중요한 역할을 하기 때문에 P. aeruginosa의 정족수 인식 시스템들이 집중적으로 연구되어 왔다. P. aeruginosa의 정족수 인식 시스템들을 소개하는 많은 문헌들이 주로 두 개의 주요 acyl-homoserine lactone (AHL) 계열 정족수 신호물질들인 N-3-oxododecanoyl homoserine lactone (3OC12)과 N-butanoyl homoserine lactone (C4)에 초점을 맞추어 설명하고 있지만, 실제로는 몇 가지 새로운 신호물질들이 발견되어져 왔고, 그들이 P. aeruginosa의 병독성과 신호전달에 중요한 역할을 할 수 있음이 제안되어져 왔다. 그 중 하나가 PQS(Pseudomonas quinolone signal; 2-heptyl-3-hydroxy-4-quinolone)인데, 이 물질은 현재 P. aeruginosa의 잘 규명된 주요 신호물질로 인식되고 있다. 이에 더하여, 최근의 연구들은 또 다른 가능성 있는 P. aeruginosa신호물질들을 제안해 왔는데, diketopiperazines (DKPs)과 pyocyanin이 그들이다. DKPs는 환형 dipeptide로써 이를 구성하는 아미노산의 종류에 따라 다양한 구조를 가진다. P. aeruginosa의 배양액에서 검출된 몇몇 DKPs들이 기존에는 AHL에만 특이적으로 반응한다고 알려졌던 Vibrio 랸�N갸 LuxR biosensor를 활성화 시킬 수 있다는 것이 발견되어 새로운 신호물질로 제안되었다. Pyocyanin (1-hydroxy-5-methyl-phenazine)은 P. aeruginosa가 생산하는 여러 phenazine 화합물들 중의 하나로써, 특징적인 청록색을 띄는 산화-환원 활성물질이다. 이 물질도 정체 성장기 동안 일부 정족수 인식의 조절을 받는 유전자들의 발현을 증가시키는 최종 신호 인자로 최근 제안되었으며, 그 신호는 또 다른 전사 조절 인자인 SoxR에 의해 매개된다고 제안되었다. 본 논문에서는 P. aeruginosa에서 새롭게 발견, 제안되고 있는 이들 신호 전달 물질들에 대해 자세히 다루어 보기로 한다.

• 한국미생물·생명공학회지
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• 제43권4호
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• pp.357-366
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• 2015

쿼럼센싱은 세포 간의 의사소통 방법이며 박테리아의 병원성과 관련된 유전자들의 조절메커니즘이다. 박테리아는 다양한 생리학적 과정들을 제어하기 위해 이 쿼럼센싱 시스템을 활용한다. 본 연구에서 석류(Punica granatum L.) 껍질 추출물이 바이오 리포터 균주인 Chromobacterium violaceum 과 C. violaceum CV026에서 쿼럼센싱 억제능을 갖는 것으로 1차 선별되어 식중독균인 Y. enterocolitica에서 편모에 의한 운동능과 바이오필름형성 억제능에 대한 석류껍질 추출물의 효과에 대한 다음 실험을 수행하였다. 추가로 N-acylhomoserine lactones (AHLs)의 합성(yenI and yenR)과 편모 레귤론(fliA, fleB and flhDC) 에 관련된 특정유전자의 발현변화를 역전사 중합효소연쇄반응법으로 평가하였다. 결과는 석류껍질 추출물이 C. violaceum CV026에서 쿼럼센싱으로 제어되는 바이오레신 생산을 78.5%까지 억제하였으며, Y. enterocolitica에서는 세포의 성장에 영향을 주지 않고 바이오필름 형성과 편모 운동성을 현저히 감소시키는 것을 확인할 수 있었다. 이러한 억제 효과는 AHLs의 합성과 운동성에 관여하는 유전자 발현을 down-regulation 하는 결과와도 일치하였다. 본 연구의 결과는 석류껍질 추출물의 임상 적용을 위하여 생체 내 특성에 대한 추가적인 연구가 필요하다는 것뿐 아니라 석류껍질 추출물이 사람의 위장관염을 방지하기 위한 잠재적인 치료제가 될 수 있다는 것을 보여준다.

• NEWSLETTER 전기공업
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• 97-1호통권170호
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• pp.17-44
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• 1997

• 한국통신학회:학술대회논문집
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• 한국통신학회 1998년도 추계종합학술발표회 논문집(상)
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• pp.1051-1054
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• 1998

• 광학세계
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• 제5권6호통권28호
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• pp.9-17
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• 1993

• Journal of Chest Surgery
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• 제19권2호
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• pp.238-242
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• 1986

The prognosis of patients with VSD and pulmonary hypertension is at least partially related to the reversibility of pulmonary hypertension after surgery. To predict postoperative pulmonary arterial pressure, immediate postbypass values were compared with preoperative hemodynamic data in 18 surgically closed VSD patients aged 6 to 80 months. The following results were obtained. 2] There was a good correlation between preoperative PP/PS and postoperative PP/PS in patients aged over 24 months [r=0.685, p<0.05], and in patients whose QP/QS were over 2.0 [r=0.686, p<0.01]. 3] There was also a good correlation between pump time and postoperative PP in total patients [r=0.697, p<0.005]. 4] Direct correlations were found between preoperative PP/PS and immediate postbypass PP/PS in patients aged over 24 months and in patients whose QP/QS>2.0, but the effect of CPB would participate in some degree. So it may be necessary to reevaluate their relationship after the effect of CPB have been disappeared.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2000년도 춘계학술대회
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• pp.139-147
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• 2000

This paper studied two factors for the manufacturing companies whose number of employee are under three hundred. One is the effect of the observation of quality system under the CEO's interest degree of quality management. First, most of company answered acquiring certificate ISO 9000 is very helpful for the company management .therefore the company have competence for the change of economic environment of domestic and international economy. Second, after acquiring the certificate ISO 9000, there were many improvements in company culture, quality control and business process productivity. As a result, acquisition of certificate of ISO 9000 system makes the company culture preparing the future to become a world first class company.