Journal of Biomechanical Science and Engineering
Online ISSN : 1880-9863
ISSN-L : 1880-9863
Volume 15, Issue 2
Displaying 1-5 of 5 articles from this issue
  • Akihiro SUZUKI, Kenichi TAKAHASHI, Yasuaki OHTAKI, Kenji KAMIJO, Tadat ...
    2020 Volume 15 Issue 2 Pages 19-00491
    Published: 2020
    Released on J-STAGE: July 15, 2020
    Advance online publication: January 21, 2020

    The rapid increase in the aging population of Japan is becoming a serious social concern, and the number of elderly individuals with dementia is also increasing. The Ministry of Health, Labour and Welfare of Japan has reported that the elderly account for 4.62 million individuals, of which approximately 4 million have mild cognitive impairment (MCI). However, monofunctional disorders, such as those in individuals with MCI, can be treated, with patients recovering 44% of their abilities 2 years after treatment, thereby suggesting that early detection and treatment of dementia is important. It has been reported that individuals who walk slowly or have experienced a significant decline in walking speed with age have a higher risk of developing dementia. In this study, to study movement in individuals aged ≥ 60 years, we focused on walking, a basic activity of daily living. We proposed and evaluated novel methods to estimate cognitive function. Acceleration and angular velocity sensors were attached to the waists of 20 elderly participants who were asked to walk outdoors ordinarily for 5–10 min, during which acceleration and angular velocity were measured. The similarity, standard deviation, and period of the stride were determined from the acceleration waveform and angular velocity waveform during walking. These were used as independent variables, and multiple regression analysis was performed using the Mini-Mental State Examination (MMSE) score as a dependent variable. An MMSE score estimation equation was constructed. The relationship between the estimation formula and the actual test value was R2 = 0.773 (P <0.01), which was good. As a result of cross-validation, the root mean square (RMS) error is low and the error is neither fixed nor proportional. Using the body acceleration and angular velocity information when walking outdoors, we built a very accurate formula for estimating the MMSE score.

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  • Eiji NAKAMACHI, Shohei TANAKA, Koji YAMAMOTO, Yusuke MORITA, Manabu OK ...
    2020 Volume 15 Issue 2 Pages 19-00480
    Published: 2020
    Released on J-STAGE: July 15, 2020
    Advance online publication: January 22, 2020

    Until now, numerous studies on the effects of electrical stimulation on nerve cell activation in a cell culture have been conducted. However, there are very few studies that have used the three-dimensional (3D) culture system to investigate nerve cell axonal extension. In this study, we developed a novel 3D direct current electric field (DCEF) stimulation bioreactor, which can uniformly stimulate cultured nerve cells for a long period. We observed the morphogenesis of PC12 cells using a multi photon excitation fluorescence microscope (MPM) and evaluated DCEF stimulation effects on PC12 cells axonal outgrowth. First, a DCEF stimulation bioreactor was designed using finite element analysis for uniform electric field. We, then, validated the uniform stimulation of PC12 cells using this bioreactor for 24 h. Second, we determined the optimal stimulation condition using the response surface method and adopting objective functions, such as axonal length, the ratio of axonal orientation towards the anode, and design parameters, such as the electric field strength and the duration of the stimulation. We found the optimal condition to be 43 mV/mm and 6.2 h/day for axonal length enhancement. An increase of 20.1% against the condition for the control group (Mann-Whitney’s U test, p<0.05) was obtained. In addition, the 92 % of PC12 cells were oriented toward the anode with 90 mV/mm, 24 h/day condition. However, the axonal formation was suppressed depending on the stimulation duration. Finally, we found the optimal conditions of 70 mV/mm and 7.9 h/day for achieving the enhancement of axonal extension and orientation, simultaneously.

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  • Tianyang XIAO, Hao LIU
    2020 Volume 15 Issue 2 Pages 20-00001
    Published: 2020
    Released on J-STAGE: July 15, 2020
    Advance online publication: February 10, 2020

    While rovers are of importance for Mars exploration in terms of various surveillance, surface rovers may encounter great challenges due to rough terrain and complex turbulent environment on Mars partly because aerial vehicles have difficulties to stay airborne due to the extremely low atmospheric density. Flights of surface rovers on Mars share the aerodynamic similarity with insect flights on earth in terms of low Reynolds number flow regime. Motivated by that insects can achieve remarkable flapping-wing aerodynamic performance in force production, flight stability and maneuverability under highly unsteady environments, we here proposed a bumblebee-inspired flapping-wing design for Mars surface rovers. We developed a power-efficient aerodynamic model by combining a surrogate model and a bioinspired dynamic flight simulator for hovering flight in a parametric space comprising wing shape and wing kinematics to explore feasible design points and some optimal solution with the power output minimized. Our results indicate that an enlarged wing model inspired by bumblebees is capable of sustaining hovering flight on Mars with a set of aspect ratios and wing kinematics and an optimal design point is found to correspond with a power output of 0.0509W, which may provide a novel and feasible biomimetic design for flapping-wing aerial vehicles on Mars.

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    ★Graphics of the Year 2020

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  • Kensaku KAWAKAMI, Takahiko NAKAMURA, Katsumi HAMA, Koichi KOBAYASHI, M ...
    2020 Volume 15 Issue 2 Pages 19-00616
    Published: 2020
    Released on J-STAGE: July 15, 2020
    Advance online publication: May 26, 2020

    In clinical practice, motion analysis can be challenging due to lack of space. Therefore, we propose a method of using one-way frontal video that can be executed easily in a small area. As it has been suggested that gait analysis using one-way frontal video can be used to analyze dynamic changes to knee joint alignment, the purpose of this research was to evaluate this method of motion analysis and examine the accuracy of this technique compared with that of a 3D motion analysis system. Twelve healthy subjects wearing optical reflective markers participated in this gait analysis study that involved the simultaneous use of one-way frontal video and a 3D motion analysis system. The femoral tibial angle (FTA) and the distance between the lower limb mechanical axis and the center of the knee joint were analyzed. The mean absolute error (MAE) of the results from the one-way frontal video and the 3D motion analysis system was calculated and the accuracy of the one-way frontal video method was evaluated. As a result, the patterns of change in knee alignment index obtained from the one-way frontal video all qualitatively matched those observed using the 3D motion analysis system. The MAE was 0.8 degrees in the FTA and the distance between the lower limb mechanical axis and the center of the knee joint was 2.5 mm. The MAE of knee joint alignment was sufficiently small compared to the alignment change associated with abnormal motion in patients with osteoarthritis. Therefore, the evaluation of knee joint alignment using the one-way frontal video method offers sufficient levels of accuracy to be used in diagnoses of abnormal movement.

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  • Masashi YAMAZAKI, Hiromichi FUJIE, Hiromi MIYOSHI
    2020 Volume 15 Issue 2 Pages 20-00083
    Published: 2020
    Released on J-STAGE: July 15, 2020
    Advance online publication: May 28, 2020

    Mechanical forces transduced to the nucleus that affect intranuclear organization are critical regulators for directing the differentiation of mesenchymal stem cells (MSCs). The supraphysiological dose of a mechanical cue, which is from the stiff surface of the substrate like standard tissue culture polystyrene, biases the MSCs toward osteogenic differentiation with irreversible nuclear retention of an osteogenic master transcription factor, RUNX2. To study the mechanism underlying the loss of lineage plasticity and robustness of the irreversible osteogenic differentiation in human MSCs due to the mechanotransduction, we investigated how RUNX2 was retained in the nucleus focusing on the dynamic shuttling of a mechanotransducer, yes-associated protein (YAP), intranuclear chromatin organization, and their regulation by the actin cytoskeleton using pharmaceutical inhibitors to perturb the mechanical properties of chromatin and actin cytoskeleton. YAP and RUNX2 were localized in the nucleus of MSCs during the expansion culture on the polystyrene surfaces followed by 24 hours culture on the glass surface, at the time point just before the inhibitor treatments. The nuclear RUNX2 was diffused into the cytoplasm by chromatin decondensation through the inhibition of histone deacetylase. In contrast, RUNX2 localization was unaffected from the perturbations to the actin organization through the inhibition of actin polymerization and that of Rho kinase activity under the condition that chromatin condensation was maintained, although YAP was released from the nucleus to the cytoplasm. These findings suggest that RUNX2 is stably retained in the nucleus by its engagement with specific DNA and/or nucleoskeletal structures coexisting with the robustly condensed chromatin, in the MSCs biased toward an irreversible osteogenic differentiation.

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