Byunghun Choi

Identification of immunoreactive epitopes of the Porphyromonas gingivalis heat shock protein in periodontitis and atherosclerosis

BACKGROUND AND OBJECTIVE Heat shock protein 60 (HSP60) of Porphyromonas gingivalis, a major periodontal pathogen, might be a trigger molecule linking infectious periodontitis and autoimmune atherosclerosis. The aim of this study was to identify the peptide specificity of anti-P. gingivalis HSP60 monoclonal antibodies and their cross-reactivity with bacterial and human HSPs. Their specific immunoreactivity to periodontal or atherosclerotic lesions was also investigated. METHODS Twenty patients with chronic periodontitis and 20 atherosclerosis patients who had undergone surgical intervention for atheromatous plaques with evidence of ongoing periodontal disease, were selected. Synthetic peptide 19 ((TLVVNRLRGSLKICAVKAPG)-specific T-cell lines were established from inflamed gingiva and atheromatous plaque and the phenotypes and cytokine profiles were characterized. RESULTS Thirty per cent of periodontitis patients and 100% of atherosclerosis patients reacted positively to cross-reactive peptide 19 from both P. gingivalis and human HSP60. The peptide 19-specific T-cell lines demonstrated the phenotype characteristic of helper T cells (CD4(+)) but did not express CD25 or FOXP3. The interleukin-10 levels were elevated significantly in the peptide 19 T-cell line. CONCLUSION Synthetic peptide 19 of P. gingivalis HSP60 is an immunoreactive epitope in the periodontitis-atherosclerosis axis.

Robust Sleep Quality Quantification Method for a Personal Handheld Device

OBJECTIVE The purpose of this study was to develop and validate a novel method for sleep quality quantification using personal handheld devices. MATERIALS AND METHODS The proposed method used 3- or 6-axes signals, including acceleration and angular velocity, obtained from built-in sensors in a smartphone and applied a real-time wavelet denoising technique to minimize the nonstationary noise. Sleep or wake status was decided on each axis, and the totals were finally summed to calculate sleep efficiency (SE), regarded as sleep quality in general. The sleep experiment was carried out for performance evaluation of the proposed method, and 14 subjects participated. An experimental protocol was designed for comparative analysis. The activity during sleep was recorded not only by the proposed method but also by well-known commercial applications simultaneously; moreover, activity was recorded on different mattresses and locations to verify the reliability in practical use. Every calculated SE was compared with the SE of a clinically certified medical device, the Philips (Amsterdam, The Netherlands) Actiwatch. RESULTS In these experiments, the proposed method proved its reliability in quantifying sleep quality. Compared with the Actiwatch, accuracy and average bias error of SE calculated by the proposed method were 96.50% and -1.91%, respectively. CONCLUSIONS The proposed method was vastly superior to other comparative applications with at least 11.41% in average accuracy and at least 6.10% in average bias; average accuracy and average absolute bias error of comparative applications were 76.33% and 17.52%, respectively.

Td92, an outer membrane protein of Treponema denticola, induces osteoclastogenesis via prostaglandin E2‐mediated RANKL/osteoprotegerin regulation

BACKGROUND AND OBJECTIVE Periodontitis is a chronic inflammatory disease of the periodontium that causes significant alveolar bone loss. Osteoclasts are bone-resorbing multinucleated cells. Osteoblasts regulate osteoclast differentiation by expression of RANKL and osteoprotegerin (OPG). Td92 is a surface-exposed outer membrane protein of Treponema denticola, a periodontopathogen. Although it has been demonstrated that Td92 acts as a stimulator of various proinflammatory mediators, the role of Td92 in alveolar bone resorption remains unclear. Therefore, in this study, we investigated the role of Td92 in bone resorption. MATERIAL AND METHODS Mouse bone marrow cells were co-cultured with calvariae-derived osteoblasts in the presence or absence of Td92. Osteoclast formation was assessed by TRAP staining. Expressions of RANKL, osteoprotegerin (OPG) and prostaglandin E(2) (PGE(2) ) in osteoblasts were estimated by ELISA. RESULTS Td92 induced osteoclast formation in the co-cultures. In the osteoblasts, RANKL and PGE(2) expressions were up-regulated, whereas OPG expression was down-regulated by Td92. The addition of OPG inhibited Td92-induced osteoclast formation. The prostaglandin synthesis inhibitors NS398 and indomethacin were also shown to inhibit Td92-induced osteoclast formation. The effects of Td92 on the expressions of RANKL, OPG and PGE(2) in osteoblasts were blocked by NS398 or indomethacin. CONCLUSION These results suggest that Td92 promotes osteoclast formation through the regulation of RANKL and OPG production via a PGE(2) -dependent mechanism.

Robust control allocation with adaptive backstepping flight control

For the enhancement of survivability and maneuverability, modern aircraft systems have redundant control effectors. Control allocation is a useful method for distributing control signals among the individual effectors. In order to implement a control allocation scheme, the control system is designed using two-step procedures. In the first step, the control law is designed by adaptive backstepping control. The second step is to design the control allocator. A robust control allocation method is presented in this paper, which is motivated from the concept of the worst-case robust approximation approach. By assuming uncertainties in the control effectiveness matrix, the worst-case robust control allocation problem is investigated. The proposed robust control allocation technique is compared with weighted least squares control allocation. In particular, nonlinear simulations demonstrate that the proposed robust control allocation method has satisfactory performance and robustness for the assumed uncertainties in the control effectiveness matrix.

Robust measurement of ocular torsion using iterative Lucas-Kanade

We present a new method to measure ocular torsion using Lucas-Kanade method. After pixels of iris annulus around a pupil have been converted into Cartesian coordinates, 30 features on the iris was selected then the features were tracked using the iterative Lucas-Kanade algorithm to calculate torsional shift. The results show that a precision of the method is higher than those measured by a conventional cross-correlation and by a template matching method. The suggested method showed 0.03 degrees mean error with 0.15 degrees maximum error. Particularly, the method was robust to change of pupil size and misalignment of pupil location. Processing time was also fast enough to be implemented in a real-time system.

Trajectory Optimization Using Virtual Motion Camouflage and Particle Swarm Optimization

This paper investigates a new numerical method to solve a nonlinear constrained trajectory optimization problem. Especially, we consider a problem constrained on the terminal angle and time. The proposed algorithm is based on the virtual motion camouflage VMC and particle swarm optimization PSO and is called VMCPSO. VMC changes the typical full space optimal problem to the subspace optimal problem, so it can reduce the dimension of the original problem by using path control parameters PCPs. If the PCPs are optimized, then the optimal path can be obtained. Therefore, we employ PSO to optimize these PCPs. The optimization results show that the optimal path considering the terminal angle and time is effectively generated using VMCPSO.

Characteristic time scales of electroencephalograms of narcoleptic patients and healthy controls

Sleep electroencephalograms (EEGs) typically showed correlated fluctuations that became random-like oscillations beyond a characteristic time scale. To investigate this behavior quantitatively, the detrended fluctuation analysis (DFA) was applied to EEGs of 10 narcoleptic patients (22.0 ± 4.0 yrs; 6 males) and 8 healthy controls (24.0 ± 2.0 yrs; 5 males). The characteristic time scales of the narcoleptics and controls were estimated as 1.8 ± 0.7 and 4.4 ± 1.2s, respectively (significance level, p<0.01). We further performed DFA of the EEGs segmented into 30s epochs and found that the DFA scaling exponents increased in deep sleep stages. These results were verified with power spectrum and auto-correlation analysis, and reproduced by a mathematical model. We thus concluded that characteristics of EEGs of narcoleptic patients could be differentiated from those of healthy subjects, suggesting a potential application of DFA in diagnosing narcolepsy.

Conflict Management Considering a Smooth Transition of Aircraft Into Adjacent Airspace

A new framework for conflict resolution in air traffic control is studied using air traffic complexity, which ensures conflict avoidance among aircraft and smooth transition of aircraft into adjacent airspace. The air traffic complexity is modeled as deviations in heading angle or speed of the aircraft inside a sector to resolve any conflict induced by the entering aircraft. For conflict management in multisector planning, a two-level hierarchical architecture is proposed. In the higher level, the maneuver constraints of the aircraft are constructed to minimize complexity for the neighboring sectors. In the lower level, the conflict avoidance problem is formulated as a mixed integer linear programming considering the maneuver constraints, which are defined in the higher level. With the two-level hierarchical architecture, the aircraft can find the optimal solution to resolve conflicts among the aircraft and reduce the air traffic complexity of the neighboring sectors. The performance of the proposed conflict management is demonstrated using numerical simulations.

Nonlinear Conflict Resolution and Flow Management Using Particle Swarm Optimization

A new optimization problem to resolve conflicts by allowing aircraft to change both their heading angle and speed is considered. The performance index in the optimization problem is formulated to reduce the variation of the aircraft arrival time that is caused by conflict resolution maneuvers. To achieve both conflict resolution and flow management, metering constraints are introduced together with separation constraints. Even though the performance index and constraints are nonlinear, the optimal solution can be easily obtained by utilizing particle swarm optimization. Numerical simulations are performed to evaluate the performance of the proposed algorithm, and the numerical experimental results showed a significant reduction in the variation of the aircraft arrival time as well as the magnitude of heading angle and speed changes.

Dynamics based motion optimization and operational space control with an experimental rescue robot, HUBO T-100

This paper introduces an experimental rescue robot, HUBO T-100 for a development of a Korean rescue robot with a large load carrying capacity and presents its optimal motion control methods. The mission of the rescue robot is to move and lift patients or soldiers with impaired mobility for the rescue and assistance in the battlefields, hospitals, hazardous and disastrous environments. Another mission includes to dispose and transfer a dangerous object or explosive ordnance. In order to execute these kind of missions, coordinated whole body motions need to be synthesized. We are to make use of a dynamics based motion optimization in the joint space to lift a object with the minimum joint torques while maintaining stability simultaneously. Complex tasks are planned in the operational space and controlled in the multi level hierarchy based on a task primitive priority. Experimental results are to be demonstrated, both in simulations and physical experiments with a humanoid robot, HUBO T-100.