• The Korean Journal of Physiology and Pharmacology
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• v.26 no.5
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• pp.307-312
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• 2022

It is well known that dopamine transmission from the ventral tegmental area (VTA) modulates motivated behavior and reinforcement learning. Although dopaminergic neurons are the major type of VTA neurons, recent studies show that a significant proportion of the VTA contains GABAergic and type 2 vesicular glutamate transporter (VGLUT2)-positive neurons. The non-dopaminergic neurons are also critically involved in regulating motivated behaviors. Some VTA neurons appear to co-release two different types of neurotransmitters. They are VGLUT2-DA neurons, VGLUT2-GABA neurons and GABA-DA neurons. These co-releasing neurons show distinct features compared to the neurons that release a single neurotransmitter. Here, we review how VTA cell populations wire to the other brain regions and how these projections differentially contribute to motivated behavior through the distinct molecular mechanism. We summarize the activities, projections and functions of VTA neurons concerning motivated behavior. This review article discriminates VTA cell populations related to the motivated behavior based on the neurotransmitters they release and extends the classical view of the dopamine-mediated reward system.

• Progress in Superconductivity and Cryogenics
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• v.9 no.4
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• pp.46-49
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• 2007

This paper describes the sensitive cooling performance change of J-T refrigerator for cryosurgical probe due to its working fluid. The analytical results of using 50 bar nitrous oxide are compared with the case of 300 bar argon. Bio-heat equation is numerically solved to investigate the effect of the probe temperature and the cooling power of the J-T refrigerator. The refrigerator using 50 bar nitrous oxide has larger cooling power above 185 K than the one with 300 bar argon, which enables fast cooling at early stage of cryosurgery, but the biological tissue away from the probe tends to be cooled slowly after the probe reaches its lowest operating temperature. When the repeated freeze-thaw cycle is employed for main tissue destruction mechanism, using high pressure nitrous oxide is more advantageous than argon if the freezing operation is within 2-3 minutes. The probe with high pressure argon is more suitable for the case of longer freeze-thaw cycle with fewer repetitions.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.159-164
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• 2023

Ferroptosis is a type of regulated cell death recently discovered, characterized by the accumulation of iron-dependent lipid peroxides in the cell membrane, and it involves a complex network of signaling pathways, including iron metabolism, lipid peroxidation, and redox regulation. The dysregulation of these pathways can lead to the induction of ferroptosis and the development of liver diseases, such as alcoholic liver disease, non-alcoholic fatty liver disease, viral hepatitis, and liver cancer. Studies have demonstrated that targeting key molecules involved in iron metabolism, lipid peroxidation, and redox regulation can reduce liver injury and improve liver function in different liver diseases by inhibiting ferroptosis. Thus, modulation of ferroptosis presents a promising therapeutic target for treating liver diseases. However, further research is required to gain a more comprehensive understanding of the mechanisms underlying the role of ferroptosis in liver diseases and to develop more effective and targeted treatments.

• BMB Reports
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• v.47 no.8
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• pp.417-423
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• 2014

MicroRNAs (miRNAs) are a large family of post-transcriptional regulators, which are 21-24 nt in length and play a role in a wide variety of biological processes in eukaryotes. The past few years have seen rapid progress in our understanding of miRNA biogenesis and the mechanism of action, which commonly entails a combination of target degradation and translational repression. The target degradation mediated by Argonaute-catalyzed endonucleolytic cleavage exerts a significant repressive effect on target mRNA expression, particularly during rapid developmental transitions. This review outlines the current understanding of the mechanistic aspects of this important process and discusses several different experimental approaches to identify miRNA cleavage targets.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1137-1147
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• 2004

In this paper, we proposed two types of adaptive control mechanism which is named HIA(Humoral Immune Algorithm) PID and CMIA(Cell-Mediated Immune Algorithm) controller based on biological immune system under engineering point of view. The HIA PID which has real time control scheme is focused on the humoral immunity and the latter which has the self-tuning mechanism is focused on the T-cell regulated immune response. To verify the performance of the proposed controller, some experiments for the control of AGV which is used for the port automation to carry container without human are performed. The experimental results for the control of steering and speed of an AGV system illustrate the effectiveness of the proposed control scheme. Moreover, in that results, proposed controllers have better performance than other conventional PID controller and intelligent control method which is the NN(neural network) PID controller.

• Journal of Biomedical Engineering Research
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• v.2 no.2
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• pp.127-140
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• 1981

This paper describes the mechanism of information processing in the nervous system through neuron pool model which is consisted of six single neural models. In the neuron pool model, summation characteristic of stimulus satisfies those of real nervous system and output impulse rate increases linearly to the input stimulus. Occlusion phenomena of the neuron pool model is approached to those of real nervous system and also if the threshold potential within sutlirninal fringe is increased, facilitation phenomena appreared. Therefore, the results of this study suggest that we can construct large neuron pool with many single neural models and verify the mechanism of information processing in the wide part of nervous system.

• BMB Reports
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• v.30 no.3
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• pp.229-233
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• 1997

Indolicidin has been known to have a broad spectrum of antimicrobial activities against Gram negative and positive bacteria. Its eight analogues were chemically synthesized. The analogue design was based on the analysis of sequence to elucidate the role of some residues in the antibacterial mechanism of indolicidin. Bactericidal activities were assayed against Escherichia coli and Proteus vulgaris, and the membrane perturbing abilities of the peptides were assayed using a dye containing liposome. Among the eight analogues, $[Gly^4, Gly^6]-Indo,\;[Ile^6,Ile^8]-Indo,\;[Lys^{12}]-Indo$ and $[Thr^2,Tyr^9]-Indo$ showed enhanced antibacterial activities. These results suggest that proline and cationic residues are important in the bactericidal activity of indolicidin. We tried to describe the antimicrobial mechanism of indolicidin with these results.

• Toxicological Research
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• v.29 no.3
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• pp.149-155
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• 2013

G protein-coupled receptors (GPCRs) are membrane receptors; approximately 40% of drugs on the market target GPCRs. A precise understanding of the activation mechanism of GPCRs would facilitate the development of more effective and less toxic drugs. Heterotrimeric G proteins are important molecular switches in GPCR-mediated signal transduction. An agonist-activated receptor interacts with specific sites on G proteins and promotes the release of GDP from the $G{\alpha}$ subunit. Because of the important biological role of the GPCR-G protein coupling, conformational changes in the G protein upon receptor coupling have been of great interest. One of the most important questions was the interface between the GPCR and G proteins and the structural mechanism of GPCR-induced G protein activation. A number of biochemical and biophysical studies have been performed since the late 80s to address these questions; there was a significant breakthrough in 2011 when the crystal structure of a GPCR-G protein complex was solved. This review discusses the structural aspects of GPCR-G protein coupling by comparing the results of previous biochemical and biophysical studies to the GPCR-G protein crystal structure.

• Microbiology and Biotechnology Letters
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• v.44 no.4
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• pp.420-431
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• 2016

The complement system comprises a set of essential molecules that bridge the innate and adaptive immune responses. Research has focused on how the complement system's destructive mechanism could potentially be harnessed for cancer treatment. However, cancer subverts the complement system to avoid immunosurveillance. In addition, a complement-triggered biological mechanism that contributes to cancer growth has been identified. Thus, drugs should be designed to homeostatically maintain a normal concentration of complement. This review explores three types of complement-related anti-cancer drugs: therapeutic antibodies, complement inhibitory drugs, and anti-complement regulatory drugs.

• 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.