• Molecules and Cells
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• v.42 no.12
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• pp.828-835
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• 2019

PIWI Argonaute proteins and Piwi-interacting RNAs (piRNAs) are expressed in all animal species and play a critical role in cellular defense by inhibiting the activation of transposable elements in the germline. Recently, new evidence suggests that PIWI proteins and piRNAs also play important roles in various somatic tissues, including neurons. This review summarizes the neuronal functions of the PIWI-piRNA pathway in multiple animal species, including their involvement in axon regeneration, behavior, memory formation, and transgenerational epigenetic inheritance of adaptive memory. This review also discusses the consequences of dysregulation of neuronal PIWI-piRNA pathways in certain neurological disorders, including neurodevelopmental and neurodegenerative diseases. A full understanding of neuronal PIWI-piRNA pathways will ultimately provide novel insights into small RNA biology and could potentially provide precise targets for therapeutic applications.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.1
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• pp.33-37
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• 2003

Oxidative damage to mitochondria is a critical mechanism in necrotic or apoptotic cell death induced by many kinds of toxic chemicals. Thioredoxin (Trx) family proteins are known to play protective roles in organisms under oxidative stress through redox reaction by using reducing equivalents of cysteines at a conserved active site, Cys-X-X-Cys. Whereas biological and physiological properties of Trx1 are well characterized, significance of mitochondrial thioredoxin (Trx2) is not well known. Therefore, we addressed physiological role of Trx2 in PC12 cells under oxidative stress. In PC12 cells, transiently overexpressed Trx2 significantly reduced cell death induced by hydrogen peroxide, whereas mutant Trx2, having serine residues instead of two cysteine residues at the active site did not. In addition, stably expressed Trx2 protected PC12 cells from serum deprivation. These results suggest that Trx2 may play defensive roles in PC12 cells by reducing oxidative stress to mitochondria.

• Journal of Korea Game Society
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• v.17 no.3
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• pp.7-20
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• 2017

MMORPG users can create their own identity that they will use to act through in the virtual world utilizing the avatar creation system. The MMORPG customization process, divided into the creation and transformation stages, provides a sandbox for the identity play by users. In this study, analysis of the users' customization attitudes using the Q methodology especially in the transformation stage was conducted. The users' attitudes were found to be categorized into 4 types: 1) fulfilling attitude, 2) customization immersed attitude, 3) customization challenging attitude, and 4) community oriented attitude. Of particular interest are the immersed customization type, where the attitude is driven by the internal motivation of "self-satisfaction" unlike the fulfillment and community oriented attitudes which are driven by instrumental motivation of the avatar, and the continuous desire towards transformation revealed by the challenging customization attitude. This study provides valuable insight in the design perspective for developers in instilling critical immersion elements to the users while preparing to update the level.

• Molecules and Cells
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• v.37 no.4
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• pp.275-285
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• 2014

Macrophages, found in circulating blood as well as integrated into several tissues and organs throughout the body, represent an important first line of defense against disease and a necessary component of healthy tissue homeostasis. Additionally, macrophages that arise from the differentiation of monocytes recruited from the blood to inflamed tissues play a central role in regulating local inflammation. Studies of macrophage activation in the last decade or so have revealed that these cells adopt a staggering range of phenotypes that are finely tuned responses to a variety of different stimuli, and that the resulting subsets of activated macrophages play critical roles in both progression and resolution of disease. This review summarizes the current understanding of the contributions of differentially polarized macrophages to various infectious and inflammatory diseases and the ongoing effort to develop novel therapies that target this key aspect of macrophage biology.

• Biomedical Science Letters
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• v.29 no.4
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• pp.371-375
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• 2023

Natural killer (NK) cells are innate immune cells and play important roles as the first immune cells to recognize and kill cancer. In patients with advanced and terminal cancer, NK cells are often inactivated, suggesting that NK cells may play important roles in cancer treatment. In particular, the proportion of NK cells among immune cells infiltrating tumor tissues is often low, which suggests that NK cells do not survive in tumor microenvironment (TME). In order to overcome these hurdles of NK cells in cancer treatment, it is critical to develop strategies that enhance the proliferation and cytolytic activity of NK cells. We applied Vemurafenib to NK cells and measured the degree of NK cell proliferation and functional activation. We obtained unexpected results of increased NK cell numbers and anti-tumor activity after Vemurafenib treatment. Although further investigation is required to uncover the detailed mechanisms, our results suggest that Vemurafenib is a promising candidate to increase the efficacy of cancer immunotherapy using NK cells.

• Structural Engineering and Mechanics
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• v.49 no.4
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• pp.427-448
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• 2014

At present, the time of easy oil and gas is over. Now, the largest part of fossil fuels is concentrated in the deepest levels of tectonic structures and in the sea shelves. One of the most cumbersome operations of their extraction is the bore-hole drilling. In connection with austere tectonic and climate conditions, their drivage every so often is associated with great and diversified technological difficulties causing emergencies on frequent occasions. As a rule, they are linked with drill string accidents. A key role in prediction of these situations should play methods of theoretical modelling. For this reason, there is a growing need for development and implementation of new numerical methods for computer simulation of critical and post-critical behavior of drill strings (DSs). In this paper, the processes of non-linear deforming of a DS in cylindrical cavity of a deep bore-hole are considered. On the basis of the theory of curvilinear flexible rods, non-linear constitutive differential equations are deduced. The effects of the longitudinal non-uniform preloading, action of torque and interaction between the DS and the bore-hole surface are taken into account. Owing to the use of curvilinear coordinates in the constraining cylindrical surface and a specially chosen concomitant reference frame, it became possible to separate the desired variables and to reduce the total order of the equation system. To solve it, the method of continuation the solution by parameter and the transfer matrix technique are applied. As a result of the completed numerical analysis, the critical states of the DS loading in the cylindrical channels of inclined bore-holes are found. It is shown that the modes of the post-critical deforming of the DS are associated with its irregular spiral curving prevailing in the zone of bottom-hole-assembly. The possibility of invariant state generation during post-critical deforming is established, condition of its bifurcation is formulated. It is shown that infinite variety of loads can correspond to one geometrical configuration of the DS. They differ each from other by contact force functions.

• Journal of Korean Society for Quality Management
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• v.29 no.3
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• pp.18-38
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• 2001

This paper attempts to identify variables which affect Korean electronic commerce(EC) venture's strategies for the international market entry decision making. Especially in the perspective of quality management perspective, it is highly relevant question which factors are critical when the industry has high technology driven characteristics such as EC, product quality related factors or environmental factors. Technology competence, operational competence, local marketing competence, psychological barriers, domestic competition level, and local infrastructure level are included to generate the explaining model for international market entry decision. The result is that the higher technology competence and local marketing competence are the significant factors. The higher the perception in these factors, the higher the intention to enter the international market in EC industry. These factors play a pivotal role in determining to go abroad the foreign EC market. Our finding implies that the subjective confidence on quality of EC solution(technology competence) and venture's capability of maintaining it(local marketing competence) are the important factors, when EC ventures make the decisions to enter the foreign markets.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.4
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• pp.7-15
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• 2002

It is of critical importance to understand the characteristics of papermaking additives and their reaction mechanisms to fully utilize the benefits they provide. Among the papermaking additives, retention aids play critical roles in improving productivity, product quality and process economy. Diverse research efforts to understand the reaction mechanisms between cationic polymers and anionic microparticles have been made since microparticle retention systems were introduced into the market. And it is most commonly accepted that flocs formed by the addition of cationic polymers are dispersed by shear force and the broken flocs are reflocculated instantly with the addition of microparticles. There are still many unanswered questions, however, on the reaction phenomena between cationic polymers and anionic microparticles. In this study, several cationic polymers including waxy maize starch, com starch and guar gum were used to investigate their retention efficiency when they were used along with anionic colloidal silica.

• Journal of Navigation and Port Research
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• v.34 no.7
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• pp.559-566
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• 2010

The container port industry has been variously studied by many researchers, because the contemporary container transportation and container port industries play a pivotal role in globalization of the world economy. For container terminals, the productivity, affected by many factors, is an important target in measuring container terminal performance. Under this background, finding the critical factors affecting the productivity is necessary. Regression analysis can be used to identify which independent variables are related to the dependent variable, and explore the relationships of them. The aim of paper is to evaluate the factors affecting the productivity of Chinese major terminals by using a regression statistical analysis modeling approach, which is to establish the variable preprocessing model (VPM) and regression analysis model (RAM), by means of collecting the major Chinese container terminals data in the year of 2008.

• BMB Reports
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• v.48 no.8
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• pp.429-430
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• 2015

Angiogenesis is a complex process involving dynamic interaction of various cell to cell interactions. Endothelial cell interactions regulated by growth factors, inflammatory cytokines, or hemodynamic stress are critical for balancing vascular quiescence and activation. Yes-associated protein (YAP), an effector of Hippo signaling, is known to play significant roles in maintaining cellular homeostasis. However, its role in endothelial cells for angiogenic regulation remains relatively unexplored. We demonstrated the critical role of YAP in vascular endothelial cells and elucidated the underlying molecular mechanisms involved in angiogenic regulation of YAP. YAP was expressed in active angiogenic regions where endothelial cell junctions were relatively loosened. Consistently, YAP subcellular localization and activity were regulated by VE-cadherin-mediated PI3K/Akt pathway. YAP thereby regulated endothelial sprouting via angiopoietin-2 expression. These results provide an insight into a model of coordinating endothelial junctional stability and angiogenic activation through YAP. [BMB Reports 2015; 48(8): 429-430]