• IMMUNE NETWORK
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• v.6 no.2
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• pp.76-85
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• 2006

Background: Chemotaxis is one of the cardinal functions of leukocytes, which enables them to be recruited efficiently to the right place at the right time. Analyzing chemotactic activities is important not only for the study on leukocyte migration but also for many other applications including development of new drugs interfering with the chemotactic process. However, there are many technical limitations in the conventional in vitro chemotaxis assays. Here we applied a new optical assay to investigate chemotactic activities induced in differentiated HL-60 cells. Methods: HL-60 cells were stimulated with 0.8% dimethylformamide (DMF) for 4 days. The cells were analyzed for morphology, flow cytometry as well as chemotactic activities by a time-lapse videomicroscopic assay using a chemotactic microchamber bearing a fibronectin-coated cover slip and an etched silicon chip. Results: Videomicroscopic observation of the real cellular motions in a stable concentration gradient of chemokines demonstrated that HL-60 cells showed chemotaxis to inflammatory chemokines (CCL3, CCL5 and CXCL8) and also a homeostatic chemokine (CXCL12) after DFM-induced differentiation to granulocytic cells. The cells moved randomly at a speed of $6.99{\pm}1.24{\mu}m/min$ (n=100) in the absence of chemokine. Chemokine stimulation induced directional migration of differentiated HL-60 cells, while they still wandered very much and significantly increased the moving speeds. Conclusion: The locomotive patterns of DMF-stimulated HL-60 cells can be analyzed in detail throughout the course of chemotaxis by the use of a time-lapse videomicroscopic assay. DMF-stimulated HL-60 cells may provide a convenient in vitro model for chemotactic studies of neutrophils.

• Bulletin of the Korean Mathematical Society
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• v.57 no.5
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• pp.1269-1297
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• 2020

In this paper, we consider a two-species parabolic-parabolic-elliptic chemotaxis system with weak competition and a fractional diffusion of order s ∈ (0, 2). It is proved that for s > 2p₀, where p₀ is a nonnegative constant depending on the system's parameters, there admits a global classical solution. Apart from this, under the circumstance of small chemotactic strengths, we arrive at the global asymptotic stability of the coexistence steady state.

• The Microorganisms and Industry
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• v.12 no.2
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• pp.14-18
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• 1986

Barcterial chemotaxis is a transient response of an organism in a situation where environmental homogeneity has been disturbed by certain chemical compounds. The phenomenon has been described in motile bacterial species including enteric bacteria, Gram-positives(14), Spirochaetes (6) and even Archaebacteria (8). However, most comprehensive studies have been done with Escherichia coli and Salmonella typhimurium. Two analogies to higher eucaryotic sensory phenomena are provided by the study of bacterial chemotaxis. First, bacterial chemotaxis is similar to the stimulus-response of neuronal, immune and sperm cells. Second, studies of individual components involved in the bacterial sensory pathway can contribute to the understanding of the function of receptors, controling signals and molecular comparators in transmembrane signalling system. The bacterial sensory transducer, a chemoreceptor in a broad sense, is a unique entity for studying sensory function in which sensory reception, signalling and adaptation are integrated (7,18).

• Journal of the Korean Mathematical Society
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• v.57 no.1
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• pp.215-247
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• 2020

In this paper, we deal with a two-species chemotaxis-Stokes system with Lotka-Volterra competitive kinetics under homogeneous Neumann boundary conditions in a general three-dimensional bounded domain with smooth boundary. Under appropriate regularity assumptions on the initial data, by some L^p-estimate techniques, we show that the system possesses at least one global and bounded weak solution, in addition to discussing the asymptotic behavior of the solutions. Our results generalizes and improves partial previously known ones.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.790-792
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• 2005

함수 최적화는 주어진 자원의 한도 내에서 최대의 이익 흑은 최소의 손실을 내는 최선의 결정을 내리는 것을목표로 한다. 본 논문은 $M{\ddot{u}}ller$의 연구를 바탕으로 박테리아의 주화성을 형상화한 'Chemical Sensing Bacteria Chemotaxis'라는 알고리즘을 제안한다. 이 알고리즘은 multimodal 환경에서의 전역 탐색을 목표로 한다. 또한 실험을 통해, 제안 알고리즘의 타당성을 분석하고, 결과적으로 제안 알고리즘이 기존의 자연계 기반의 알고리즘에 비해 경쟁력이 있음을 입증하였다.

• Advances in robotics research
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• v.2 no.1
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• pp.1-11
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• 2018

To monitor the environment and determine the source of a pollutant gradient using a multiple robot swarm, we propose a hybrid algorithm that combines two bio-inspired algorithms mimicking chemotaxis and pheromones of bacteria. The algorithm is implemented in virtual robot agents in a simulator to evaluate their feasibility and efficiency in gradient maps with different sizes. Simulation results show that the chemotaxis controller guided robot agents to the locations with higher pollutant concentrations, while the pheromone marked in a virtual field increased the efficiency of the search by reducing the visiting redundancy. The number of steps required to reach the target point did not increase proportionally as the map size increased, but were less than those in the linear whole-map search method. Furthermore, the robot agents could function with simple sensor composition, minimum information about the map, and low calculation capacity.

• Molecules and Cells
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• v.40 no.3
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• pp.163-168
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• 2017

Microglia are the primary resident immune cells of the central nervous system (CNS). They are the first line of defense of the brain's innate immune response against infection, injury, and diseases. Microglia respond to extracellular signals and engulf unwanted neuronal debris by phagocytosis, thereby maintaining normal cellular homeostasis in the CNS. Pathological stimuli such as neuronal injury induce transformation and activation of resting microglia with ramified morphology into a motile amoeboid form and activated microglia chemotax toward lesion site. This review outlines the current research on microglial activation and chemotaxis.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.392-400
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• 2008

This paper proposes a novel optimization algorithm inspired by bacteria behavior patterns for foraging. Most bacteria can trace attractant chemical molecules for foraging. This tracing capability of bacteria called chemotaxis might be optimized for foraging because it has been evolved for few millenniums. From this observation, we developed a new optimization algorithm based on the chemotaxis of bacteria in this paper. We first define behavior and decision rules based on the behavior patterns of bacteria and then devise an optimization algorithm with these behavior and decision rules. Generally bacteria have a quorum sensing mechanism that makes it possible to effectively forage, but we leave its implementation as a further work for simplicity. Thereby, we call our algorithm a simple bacteria cooperative optimization (BCO) algorithm. Our simple BCO is tested with four function optimization problems on various' parameters of the algorithm. It was found from experiments that the simple BCO can be a good framework for optimization.

• Tuberculosis and Respiratory Diseases
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• v.43 no.3
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• pp.359-366
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• 1996

Background : Eosinophilic leukocytes are prominent cellular participants in the pathogenesis of allergic disease and asthma. Chemotaxis is still a very useful method in evaluating the response of human eosinophil to novel modulators. Degranulated mast cells and activated T lymphocytes are responsible for the pathophysiology of asthma and tryptase is one of most important proteases released after activation of mast cells. The purpose of this study was to investigate the actions of trypsin and chymotrypsin on eosinophils in terms of chemotaxis and activation. Method : Eosinophils were isolated by negative immunoselection from the peripheral blood of atopic donors. Chemotaxis was studied by using micro-Boyden chambers and ECP release was assayed by fluoroimmunoassay. Results : Eosinophil showed a chemotactic response to trypsin. Maximal chemotactic response was with $1000{\mu}g/ml$ trypsin ($56.52{\pm}14.50$/HPF) which was comparable to PAP. But chymotrypsin showed no significant chemotactic response to eosinophils. Trypsin at the concentration of 10, 100, $1000{\mu}g/ml$ induced secretion of ECP, which at the concentration of $10{\mu}g/ml$ represented about 2.7 times of the spontaneous rate of release. Soybean protease inhibitor reduced trypsin induced ECP release. Conclusion : Trypsin can induce chemotactic response to eosinophils and activation of eosinophils that can induce secretion of ECP. On the contrary, chymotrypsin showed no direct effect on eosinophils. We propose a role of trypsin on the chemotaxis and activation of eosinophils.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.241-244
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• 2007

본 논문에서는 박테리아의 주화성에 기초한 Bacteria Cooperative Optimization(BCO) 알고리즘을 소개한다. BCO는 Ant Colony Optimization (ACO)처럼 자연계에 존재하는 생명체의 행동양식을 모방하여 만든 최적화 알고리즘으로 크게 초기화, 측정, 행동결정, 이동으로 구성된다. 우리는 먼저 BCO 알고리즘을 설명하고 2차원 함수 최적화 문제를 이용하여 BCO알고리즘과 Genetic Algorithm(GA) 그리고 Bacterial Foraging for Distributed Optimization(BFO)의 성능 측정 결과를 기술한다. 실험 결과 BCO의 성능이 GA나 BFO보다 우수함을 보였다.