• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.759-764
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• 2015

Antimicrobial peptides (AMPs) are one of the critical components in host innate immune responses to imbalanced and invading microbial pathogens. Although the antimicrobial activity and mechanism of action have been thoroughly investigated for decades, the exact biological properties of AMPs are still elusive. Most AMPs generally exert the antimicrobial effect by targeting the microbial membrane, such as barrel stave, toroidal, and carpet mechanisms. Thus, the mode of action in model membranes and the discrimination of AMPs to discrepant lipid compositions between mammalian cells and microbial pathogens (cell selectivity) have been studied intensively. However, the latest reports suggest that not only AMPs recently isolated but also well-known membrane-disruptive AMPs play a role in intracellular killing, such as apoptosis induction. In this mini-review, we will review some representative AMPs and their antimicrobial mechanisms and provide new insights into the dual mechanism of AMPs.

• BMB Reports
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• v.38 no.5
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• pp.507-516
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• 2005

Antimicrobial peptides (AMPs) have been isolated and characterized from tissues and organisms representing virtually every kingdom and phylum. Their amino acid composition, amphipathicity, cationic charge, and size allow them to attach to and insert into membrane bilayers to form pores by 'barrel-stave', 'carpet' or 'toroidal-pore' mechanisms. Although these models are helpful for defining mechanisms of AMP activity, their relevance to resolving how peptides damage and kill microorganisms still needs to be clarified. Moreover, many AMPs employ sophisticated and dynamic mechanisms of action to carry out their likely roles in antimicrobial host defense. Recently, it has been speculated that transmembrane pore formation is not the only mechanism of microbial killing by AMPs. In fact, several observations suggest that translocated AMPs can alter cytoplasmic membrane septum formation, reduce cell-wall, nucleic acid, and protein synthesis, and inhibit enzymatic activity. In this review, we present the structures of several AMPs as well as models of how AMPs induce pore formation. AMPs have received special attention as a possible alternative way to combat antibiotic-resistant bacterial strains. It may be possible to design synthetic AMPs with enhanced activity for microbial cells, especially those with antibiotic resistance, as well as synergistic effects with conventional antibiotic agents that lack cytotoxic or hemolytic activity.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1998.03a
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• pp.139-145
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• 1998

기존 AMPS시스템에서는 한정된 채널수 용량의 한계성을 보여왔다. CDMA 의 여러 많은 잇점들로 인하여 서비스로 이미 사용하고 있는 AMPS 의 일정 주파수 대역폭을 CDMA시스템에 할당하여 AMPS와 CDMA가 서로 다른 주파수 대역폭내에서 운용되고 있다. 그러나, CDMA 사용자가 늘어남으로써 이미 AMPS를 위하여 할당된 주파수를 줄이고 CDMA 시스템에 이를 할당하고 있는 실정이다. 그로 인하여 AMPS 에 할당된 대역폭은 차츰 줄어들고 있다. 그러나 CDMA 이용자가 늘어나고 있는 반면에 AMPS 이용자도 같은 추세로 증가하고 있는현실에서 AMPS 의 대역폭으로는 증가하는 이용자의 수를 충족시킬수 없게 되었다. 이 논문에서는 현재 할당되어져 있는 AMPS 시스템의 대역폭 내에 CDMA시스템을 적용시켜 같은 대역폭내에서 동시에 같이 사용하였을 경우, AMPS 시스템에서의 순방향 링크 및 역방향 링크의 용량을 유도한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12A
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• pp.1242-1250
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• 2008

In this paper, we predicted the radiation field strength from the low power radio devices to force the radio interference on the AMPS receiver. The predicted value of 79.13[$dB{\mu}V/m$] is the upper value of radiation against the intermodulation interference emanated from the low power radio devices. To show the validity of the suggested values theoretical analysis on intermodulation and modeling of the AMPS receiver are performed, and also measurements on the AMPS receiver IC are carried out. The resultant numerals show the good match between them within the allowable tolerances.

• Membrane Journal
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• v.6 no.2
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• pp.79-85
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• 1996

This study is undertaken to investigate the effect of positive charge on the premeation characteristics of quaternary ammonium polysulfone (AMPS) membrane. AMPS membrane having a hydrophilic property was less fouled than PSf membrane. AMPS membrane had a positive charge and was thought to be able to expel charged solutes, such as basic dyes, proteins and amino acids, having same sign as the membrane surface.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.2106-2112
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• 1998

In this paper, we propose an antenna sharing scheme between 800 MHz AMPS and CDMA systems using CDMA transmission antenna. We restructured the path of signals such that signals from two systems use AMPS amplifier or CDMA amplifier. The performance of proposed scheme is compared with currently operating system's performance in terms of call connection rate, call completion rate and dropped-call rate after implementing proposed method to the AMPS/CDMA basestation. The results show that the voice quality and call connection of the proposed system is comparable to that of the commercial systems. The number of antenna at the base station can be reduced without performance degradation if the proposed transmission antenna sharing scheme and previously reported receiving antenna sharing technique are used together.

• Journal of Microbiology and Biotechnology
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• v.22 no.11
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• pp.1457-1466
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• 2012

Antimicrobial peptides (AMPs) exert antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi, and viruses by various mechanisms. AMPs commonly possess particular characteristics by harboring cationic and amphipathic structures and binding to cell membranes, resulting in the leakage of essential cell contents by forming pores or disturbing lipid organization. These membrane disruptive mechanisms of AMPs are possible to explain according to the various structure forming pores in the membrane. Some AMPs inhibit DNA and/or RNA synthesis as well as apoptosis induction by reactive oxygen species (ROS) accumulation and mitochondrial dysfunction. Specifically, mitochondria play a major role in the apoptotic pathway. During apoptosis induced by AMPs, cells undergo cytochrome c release, caspase activation, phosphatidylserine externalization, plasma or mitochondrial membrane depolarization, DNA and nuclei damage, cell shrinkage, apoptotic body formation, and membrane blebbing. Even AMPs, which have been reported to exert membrane-active mechanisms, induce apoptosis in yeast. These phenomena were also discovered in tumor cells treated with AMPs. The apoptosis mechanism of AMPs is available for various therapeutics such as antibiotics for antibiotic-resistant pathogens that resist to the membrane active mechanism, and antitumor agents with selectivity to tumor cells.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.1
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• pp.75-87
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• 2012

A design paradigm using sequential geometric programming is presented to accurately design CMOS op amps with BSIM3. It is based on new adaptive modeling of transistor parameters through the operating point simulation. This has low modeling cost as well as great simplicity and high accuracy. The short-channel dc, high-frequency small-signal, and short-channel noise models are used to characterize the physical behavior of submicron devices. For low-power and low-voltage design, this paradigm is extended to op amps operating in the subthreshold region. Since the biasing and modeling errors are less than 0.25%, the characteristics of the op amps well match simulation results. In addition, small dependency of design results on initial values indicates that a designed op amp may be close to the global optimum. Finally, the design paradigm is illustrated by optimizing CMOS op amps with accurate transfer function.

• BMB Reports
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• v.49 no.9
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• pp.520-525
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• 2016

We investigated the effects of two antimicrobial peptides (AMPs) isolated from Scolopendra subspinipes mutilans on neutrophil activity. Stimulation of mouse neutrophils with the two AMPs elicited chemotactic migration of the cells in a pertussis toxin-sensitive manner. The two AMPs also stimulated activation of ERK and Akt, which contribute to chemotactic migration of neutrophils. We found that AMP-stimulated neutrophil chemotaxis was blocked by a formyl peptide receptor (FPR) 1 antagonist (cyclosporin H); moreover the two AMPs stimulated the chemotactic migration of FPR1-expressing RBL-2H3 cells but not of vector-expressing RBL-2H3 cells. We also found that the two AMPs stimulate neutrophil migration in vivo, and that this effect is blocked in FPR1-deficient mice. Taken together, our results suggest that the two AMPs stimulate neutrophils, leading to chemotactic migration through FPR1, and the two AMPs will be useful for the study of FPR1 signaling and neutrophil activation.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.7
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• pp.509-517
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• 2013

The purpose of this study is to assess the applicability of device-type stream coagulation process which combines physiochemical, biological processing for efficient improvement of water quality in small, middle-sized urban streams. The stream purification facility of this study is compose of pressure flotation type Micro Bubble Process(MBP) to remove TSS and TP and conduit line type Attached Microbial Pipe System(AMPS) to remove BOD. Test conditions of each device were set by floating stay time and change of ultra fine bubble injection amount of MBP, and change of AMPS stay time. Also, removal efficiency of pollution sources of each process were assess by change of season. As result of continuous operation of each process, MBP showed a maximum of TSS 83.69%, TP 95.15% process efficiency and AMPS showed a maximum of 52.95% TBOD5 removal efficiency. Also as result of circular operation of each process, MBP showed a maximum of TSS 69.75%, TP 70.17% process efficiency and AMPS showed a maximum of 68.58% TBOD5 removal efficiency. Therefore, it is considered that this stream coagulation process is effective in improving the water quality of streams in urban areas.