The purpose of this symposium is to discuss the significance and the strategy to found the department of bio-medical engineering in Japan. The department of bio-medical engineering has been already established in most of the leading universities in Europe and the United States of America since 1950, while there are a few institutes of the bio-medical engineering in Japan. It is the mandatory issue to be solved in order to grow the young generation up to the international level in the field of biomedical engineering and to strengthen the international competition in medical industry. We would like to show some direction toward the foundation of the department of bio-medical engineering by discussing the current problems and learning the history and the strategy from the founders.
Gelatin has unique properties. The form is changed by temperature. In addition, the melting point is around 37 degree C. For these reasons, gelatin is useful for biofabrication. We are able to fabricate biodevices of biomaterials with cave utilizing gelatin. In this study, we spun gelatin fibers utilizing three methods. We were able to fabricate micro gelatin fibers which diameter was 20~200 μm. Each methods have merits and demerits. Therefore, utilizing three methods, we were able to fabricate complex structures of micro gelatin fibers.
Many studies have been dedicated to the development of scaffold for improving post-traumatic nerve regeneration. Biodegradable chitosan-siloxane porous hybrid membranes were very flexible and have interconnected pores to be excellent cytocompatibility for osteoblastic cells, fibroblastic cells, and nerve cells. In this study, chitosan-siloxane porous hybrid membranes were used to regenerate nerve tissue with or without some cells after crush injury. The regeneration in terms of Schwann cell proliferation, axon elongation and myelination was promoted with the hybrids. Combination with mesenchymal stem cells. The good regenerated nerve improved the the degree of functional recovery such as the extensor postural thrust and the withdrawal reflex latency.
Bone is a natural composite material with anisotropic hierarchical structure predominantly consisting of collagen fibrils and biological apatite (BAp) crystals, where the crystallographic c-axes of the BAp well aligns with the long axis of the collagen fibrils. This anisotropic micro-organization is believed to be responsible for anisotropic mechanical functions which bones exhibit . Indeed, the BAp orientation was proven to be a pivotal determinant of Young's modulus of bone  using regenerating long bones. Therefore, reconstructing and/or maintaining the appropriate BAp/collagen orientation is quite important in bone therapies including orthopedic implantation. In this presentation, we introduce the BAp/collagen orientation analyzed in the normal and regenerated bones, and propose novel implant devices that was developed aiming at maintaining a soundness of bone's anisotropic microstructure.
 T. Nakano et al.: Bone 31, 479-487, 2002.
 T. Ishimoto, T. Nakano et al.: J. Bone Miner. Res. 28, 1170-1179, 2013.
We have developed artificial extracellular matrix (ECM) proteins by genetic engineering. Our constructed ECM proteins were consisted of structural units derived from elastin-like peptides and functional peptides derived from natural ECMs or synthetic peptides. These ECM proteins can be added abilities not only for cell adhesion but also for enhancement of cellular differentiation by combination of several functional peptides. Moreover, to regulate cellular functions, proteins such as growth factors were tethered to our constructed ECM proteins. Recently, we have developed a strategy for induction of cellular differentiation by introduction of transcription factor proteins into cells. Based on this strategy, transcription factor protein tethered ECM was developed. In here, those ECMs tethering proteins for regulation of cellular functions are introduced.
The arterial baroreflex is an important negative feedback system to stabilize arterial pressure (AP). This system can be divided into neural and peripheral arc subsystems. When the neural and peripheral arcs are drawn on a pressure-sympathetic nerve activity (SNA) plane, the intersection yields a baroreflex operating point. We examined the abnormality of AP regulation in chronic heart failure (CHF) using the equilibrium diagram. The slope of the AP response to SNA in the peripheral arc became smaller in CHF. The maximum SNA suppression in the neural arc was attenuated in CHF, suggesting impaired baroreflex function. We examined the effect of chronic intermittent vagal nerve stimulation (VNS) on the baroreflex equilibrium diagram. While VNS significantly restored the magnitude of maximum SNA suppression, it did not affect the peripheral arc significantly. It is concluded that VNS improves the conditions of heart failure mainly by improving the baroreflex-mediated SNA suppression.
Respiration is determined by the interplay between the controller (arterial PCO2[PaCO2]-minute ventilation[VE] relation) and plant (VE-PaCO2 relation) subsystem elements within the chemoreflex feedback system. Changes in central hemodynamics, exercise stimulus, and regular exercise training modify VE and/or PaCO2 levels at rest and during exercise. These respiratory changes can be quantitatively explained by changes in two subsystem elements on the respiratory equilibrium diagram. This framework should be a powerful tool in understanding the mechanism responsible for respiratory control under specific environments and pathophysiological conditions.
BACKGROUNDS: While hypercapnia activates central chemoreflex and induces sympatho-excitation, its interaction with the baroreflex regulation of sympathetic nerve activity (SNA) has not been quantified. This study aimed to examine the impact of the central chemoreflex on the baroreflex function using an open-loop analysis. METHODS/RESULTS: In 7 anesthetized SD rats, we controlled intra-sinus pressure (CSP, baroreceptor sensed pressure) and recorded SNA and aortic pressure (AP). Hypercapnia was induced by inhalation of 3% CO2 gas. Hypercapnia markedly increased SNA (δSNA=53.4±7.1%, p<0.01) irrespective of CSP, indicating the resetting of the neural arc (CSP-SNA relation). In contrast, the peripheral arc (SNA-AP relation) did not change. The transfer function of the neural arc approximated a high-pass filter, while that of the peripheral arc approximated a low-pass filter. Hypercapnia did not affect either neural or peripheral arc transfer function. CONCLUSION: Chemoreflex activation reset the baroreflex neural arc upward without compromising its dynamic and static function.
Background: Although abnormal respiration during exercise is a powerful predictor of survival in chronic heart failure (CHF), the lack of appropriate animal models which represent respiratory abnormalities limits mechanistic investigations. In this study, we developed an anesthetized rat model of exercise.Methods: We used anesthetized Sprague-Dawley rats with/without CHF. To mimic exercise, we induced muscle contraction by stimulating bilateral sciatic nerves (SNS). We recorded the respiratory change in response to SNS with ramp (5 Hz, 0.01 volts/sec) protocols. Results: SNS significantly increased minute ventilation (VE) in CHF to a greater extent than in that of normal (Normal 66.5±12.8 mL/min vs. CHF 100.9±12.5 mL/min, p<0.05). The VE/VCO2 slope was significantly higher in CHF than Normal (Normal 26.8±12.7 vs CHF 38.5±5.9, p<0.05). CHF shifted the RR-TV relationship rightward indicating the rapid and shallow ventilation. Conclusion: Anesthetized rat exercise model simulated respiratory abnormalities in CHF reasonably well.
The prevention of chronic diseases such as diabetes was important, and it has been shown the effectiveness of the exercise for walks.However, the steps decrease with aging, the motivation to exercise and continuation are not easy.We developed the system that a storage did information such as the activity meter on the cloud for health assistance of the middle aged and elderly persons.The subjects of 1000 healthy middle-aged and elderly persons were participation in this study.All subjects had an activity meter that were analyzed range of activity and quality of activity. As a result, utilization of the supermarket was decrease with advancing age, and utilization of the community plant was increase.It is suggested that the system can be provide support in terms of quantitative analysis, qualitative analysis and time analysis.
Nowadays by advancement of display technology, any contents can be presented to walls, floors and ceilings.
In the near future, people will be able to display favorite contents inside their private house, using this technology.
In this study, we examine the application of this new display technology for healthcare.
Exercise support program was picked as the experimental application, because of urgent needs to reduce medical cost of our society.
To induce motivation for exercise, Microsoft Kinect was used to detect the player's motion and a short focus projector was used for presenting virtual space and balls in front of the player.
The virtual ball is thrown and the player is asked to catch the ball.
Since the ball doesn't fly towards the player, he must move to left or right, and unconsciously the player do exercise. EMG measurement and questionary survey was performed and effectiveness of the application was discussed.
Age-related or disorder-induced changes of the central nervous system and the musculoskeletal system lead an impairment of postural stability. While considerable effort has been provided to archive better recovery from postural disorders, current therapeutic approaches in the rehabilitation field are still insufficient to accomplish this. Our group has been recently developed a real-time postural feedback system in order to establish a novel rehabilitation strategy for the adjustment of the postural control. The developed system can implicitly modulate subject's body sway decreasing (in-phase) or increasing (anti-phase). In this perspective paper, we firstly explain the concept of our newly developed system and its potential effectiveness for the improvement of postural control, and will then, secondly introduce some examples of the clinical attempt to use our system for various type of postural disorders.
Electric stimulation therapy is used to the patient with paralysis in clinical site. Therapist have to gradually raise electrical amount because of subject's physical conditions. It takes time to decide electrical amount. It's needed to develop the system which decide electrical stimulation pattern by using body parameter like Body Mass Index and the position of electrode attached in forearm. We verify the effect of electrical stimulation pattern to the pain and motion. We conducted two experiments. At the first, subject have electrical stimulation to the median nerve in forearm. We set six pattern frequency in the range of 50~2000 Hz and voltage in 50 V. And we evaluate the difference of pain in individual using Visual Analog Scale. Subject have electrical stimulation to the flexor hallucis longus. We set the frequency in 1000 Hz and voltage in 60 V. And we measured displacement of thumb using the clip gauge.
Gait is one of the common motion for human. The purpose of this research is to assess the rehabilitation process for the patient injured right knee by gait measurement using accelerometer. The sensor was attached to lower back of the subject. Subjects were instructed to walk on the hallway with metronome. The metronome was set to 116 bpm. We estimated the center of mass (CoM) after calculating the second integral of the acceleration date obtained from the experiment. Relative displacement fitted regression formula is calculated because integration error noise and drift exude calculated displacement. The result shows the healthy subjects gait drawing a symmetry CoM. The patient gait draws oblique lines, because the patient walked with protecting right knee. The patient gait comes to healthy subject's trajectory because the patient putting weight on right by rehabilitation effects. We could assess the gait improvement by using our proposal method.
In these days, inertial sensors are used to measure body movements, for example joint angles or segment inclination angles. In many reports that refer to angle measurement, results from sensor systems were compared to those from optical motion analysis system to evaluate measurement accuracy. However, the global coordinate systems doesn't match exactly between sensor and motion analysis systems, which cause problem in the accuracy evaluation. In this paper, a method to define standardized coordination system for several measurement systems was developed. At first, two postures were measured with sensor and motion analysis system, and from these measurement data, the standardized coordinate system was defined. Then, difference between the coordination system of sensor system or motion analysis system and the standardized coordination system was calculated. The data measured from each system were recalculated in the standardized coordination, respectively. Therefore, angle measurement accuracy of sensor system was evaluated more precisely.
There are a lot of patients with movement impairment who are paralyzed by brain stroke. Sufficient rehabilitative training is necessary for these patients. Furusho and collaborators developed active type 3D rehabilitation systems EMUL and Serafy (Robotherapisst) at the NEDO Projects. Then, Passive type rehabilitation systems using brakes PLEMO series have been developed by Furusho Lab at the Osaka University and Fukui University of Technology. Development of Upper Limb Rehabilitation System PLEMO-BAT for Stroke Patients Using Bilateral Limb Motion is presented. A brake was used for giving a sense of force and to restrict the motion range of the user's arm to prevent subluxation. The first prototype of the same-side type where a user's right and left hands move in the same direction was developed.J.Furusho, et al.,(Review) Research and Development of Functional Fluid Mechatronics,Rehabilitation Systems, and Mechatronics of Flexible Drive Systems, Journal of Robotics and Mechatronics, Vol.28, No.1, pp.5-16, 2016
Split-belt treadmill walking has been recently used as a tool not only to investigate the process of adaptation during walking but also to improve gait asymmetry in patients post stroke. Previous study used remarkably larger speed ratio more than 1:2, we here use very mild extent of speed ratio about 1:1.2. The purpose of this study was therefore to investigate the effect of split-belt walking on gait asymmetry in stroke patients. In order to determine the extent of speed ratio, we firstly determined the detection threshold when the subject can perceive the changed speed ratio during gradual increment/decrement of each belt speed. Subjects were administrated on two split-belt treadmill walking; (1) affected leg fast and (2) affected leg slow. Results show that the detection threshold is approximately 1:1.2. Stance time symmetry gradually changed to symmetry in affected leg fast. Step length symmetry gradually changed to symmetry in affected leg fast.
So far, we have proposed the control algorithm to synchronize output of ventricular assist device to native heart cycle without external sensors such as ECG. In the method, heartbeat component in pump rotational speed was regarded as disturbance to controlled rotational speed. Thus the heartbeat signal was calculated as estimation error of rotational speed. Moreover this signal seems to have also information of native heart function. Therefore, the aim of this study is to attempt to estimate cardiac function from the estimated heartbeat signal.The instantaneous pump speed was estimated by an ARX model which inputs were reference speed and current consumption. The parameters of the model were calculated by using recursive identification algorithm.In results, some features of the estimated heartbeat signal have a close relationship with circulatory parameters. Therefore, it was indicated that the proposed method may be able to estimate not only cardiac cycle but function.
Monitoring of flap after transplant surgery is important because occurrence of thrombosis bringing about compromised circulation demands immediate salvage surgery. The risk of thrombosis lasts for one week thus laying heavy burden on staffs. Continuous blood-flow monitoring device not only relieves staffs, but also increases rescue rate of salvage surgery due to its early detection. We propose a flexible sensor array that monitors multipoint flap condition by three quantitative on-site indications: pulse wave, skin color and temperature. Superior to conventional methods with huge devices, we implement small phototransistors and thermistors on flexible substrate which maps large-area flap conditions without disturbing patients. Instead of calculating blood volume, we designed an algorism that assesses blood-flow automatically by observing shift of pulse wave power. Signal obtained from volunteers (5 subjects) during resting-state, ischemia, and congestion demonstrated the effectiveness (p<0.005) of our flap failure detection, and it is expected to judge compromised circulation continuously.
Artificial hearts using rotary blood pumps have the problem of inflow sucking that occurs when drive condition does not match the blood return. When sucking occurs, driving condition should be changed to release the sucking. However, there is no practical sensor to detect inflow sucking. In order to develop an inflow sucking sensor of artificial hearts, we selected flexible conductive silicone rubber. When we install the material in the inflow cannulae or cuffs, its electrical resistance would change with sucking and thus the sucking could be detected. To examine possibility of this material, the cannula in which the conductive silicone was built-in was made and examined with pulsatile flow condition. As a result, in case of more than 30 mmHg of the pulse pressure or 60 mmHg of the diastolic pressure, the change in electrical resistance gave significant differences, showing that such sensor would be available with this material.
This paper reports a conducted interference measured by terminal voltages on an impedance stabilization network connected with a miniaturized externally coupled transcutaneous energy transmission system (ECTETS) for a ventricular assist device. The inverter circuit included in the ECTETS generates electromagnetic interference (EMI). This would cause malfunction to any medical device's as well as the ventricular assist device system itself. In this study, we measured the conducted interference on miniaturized ECTETS based on methods specified by CISPR 11. To reduce the conducted interference, we changed a type of regulator circuit and an EMI filter in the inverter circuit respectively, and this caused the conducted interference on miniaturized ECTETS to be almost below the guidelines of CISPR 11 (Group 2, Class B, Average). However, the interference value does exceed the CISPR 11 guidelines by more than the maximum value of 1.5 dBμV at the frequencies of 3.5−8.4 MHz.
Transcutaneous energy transmission systems (TETS) can transfer energy by electromagnetic induction between two coils placed face-to-face on each side of the abdomen or chest skin. Previously, an AC-AC energy transmission efficiency of TETS has been measured. However, a common-mode current that flows into the ground through the AC source and measuring equipment prevents an accurate efficiency measurement. In this paper, to reduce common-mode current, a common-mode choke coil (CMCC), uninterruptible power supply (UPS), and differential probes were used to measure the efficiency of TETS. The result of the experiment was that the common-mode current was measured to be 133.7 μA and the efficiency was 97.47 % when the transmitting frequency was 989.8 kHz; the theoretical efficiency was 98.13 %. Our results nearly agreed with the theoretical efficiency by reducing enough common-mode current.
The skin through cable is used for the energy transmission of artificial heart and is one of the major source of infection. To solve this problem, the transcutaneous energy transfer system (TETS) was developed. TETS are conducted energy transmission by using magnetic coupling between inside coil and outside coil of the body, improving the transmission efficiency is expected by using the magnetic resonance. The same coil for both transmission-side power receiving side is used in the energy transmission using the magnetic resonance. On the other hand, a large outside coil and small inside coil were used for the TETS in order to easily obtain a high transmission efficiency. So the effect of the difference of the coil characteristics of the power transmission side receiving side of TETS is given to the transmission efficiency of the magnetic resonance and energy, were investigated by simulation transmission circuit.
Cells sense external forces and then translate them into biochemical signals that induce various responses. The nucleus itself has been proposed to act as a cellular mechanosensor, and the changes in nuclear shape or its deformation possibly affect the regulation of cell functions. Here we investigated the effects of deformation and trapping of the nucleus on the cellular functions using a PDMS-based micro fabricated substrates with an array of micropillars. Cells spread normally in the space between the micropillars and showed remarkable deformation of their nuclei. Such mechanical trapping of the nuclei inhibited cell migration and DNA synthesis. Interestingly, the mechanical trapping of the nuclei also inhibited the DNA damage in the ultraviolet irradiated cells. These results indicate that mechanical deformation of the nucleus using the micro fabricated substrate would be a powerful tool for regulating many cell functions.
Plasma is called the 4th state of matter, it has been widely used in industrial field.However, in recent years, various applications have been reported in medical field.Especially, atmospheric-pressure plasma effects such as cell proliferation, angiogenesis and vasodilation have been reported, and expectations are growing that it will lead to new disease treatment.In this study, we observed the action of atmospheric-pressure plasma exposure/inhalation on blood vessels, and considered applications for treatment of hypoxic ischemic encephalopathy (HIE) there is no effective treatment method presently.Accordingly first in this study, in order to create a stable HIE model, we performed ligature of the common carotid artery on one side, and then exposure to 8% oxygen to reduce the volume of blood flow to the brain.As a result, we were able to identify the cerebral edema responsible for the ischemia within the specimen.
In this study, we investigated how a reaction of the brain changed according to the understanding, using four different languages. We made 3 subjects listen a sound of short scene in a movie, and we measured a reaction of the brain, using NIRS. Subjects were a Netherlander who has lived in Japan for 10 months, a Salvadoran who has lived in Japan for 13 months, and a Chinese who has lived in Japan for 10 years. The languages of the sound were Dutch, Spanish, Chinese, and Japanese. Subjects listened the sound for 20 seconds, after 20 seconds rest, and they rested 20 seconds after listening. We asked the understanding about the sound at 10 stages after the experiment. As the result of the experiment, the clear difference in the reaction of the brain was admitted between the unknown language and the language which can be understood.
The auditory octave illusion arises when dichotically presented tones, one octave apart, alternate rapidly between the ears. To explore the link between the perceived pitches and brain activity interactions of dichotic tones, the brain activities were recorded to binaural stimuli for the octave illusion with functional magnetic resonance imaging (fMRI). Fifteen healthy subjects participated. We investigated how subjects perceived the binaural dichotic tones prior to the fMRI measurement. The obtained fMRI data were classified according to illusion and non/partial illusion groups. The brain activity in the some regions other than auditory cortex observed significant differences between illusion and non/partial illusion groups. The results suggested the regions other than auditory cortex were related to the octave illusion arises.
An infant-friendly earphone using the cartilage conduction for non-invasive functional brain imaging was developed. The earphone was composed of a piezoelectric vibrator that is firmly glued to a flat round brass panel, with a diameter of 35 mm, to amplify the vibration. The earphone can be attached to the baby head cap, and just mildly touched to baby's pinna. Since sounds are conveyed via both air- and bone-conduction (mainly osseotympanic emission) pathways by the earphone, the enhancement of low frequency component is expected by the occlusion of the ear canal. Clear auditory evoked MEG responses were obtained from awake babies (6-month-old and 8-month-old) as well as adults, using our first prototype flat-panel earphone. Also, the babies did not dislike to wear the developed earphone at all. The earphone enables an experiment of dichotic listening that was quite difficult for awake babies.
The accidents such as a stumble by the tangle of the foot, a fall, the fall from a bed are happened just after getting up in an elderly person and may lead to a serious injury.It is thought that the decrease of the brain cognizance function just after the getting up causes problems such as the tangle of the foot.Subjects had oddball task just after the getting up in early morning. And we based on the P300 components in the normal condition and judged the presence of the decrease of the brain cognizance function. We set the electrodes to the position of Cz and Pz from the international 10-20 method to measure the P300 component. As the result, we could confirm the difference with the wave pattern just after the getting up compared with normal condition.
Responses to a periodic visual stimuli called steady-state visual evoked potentials (SSVEPs) play important roles in applications of brain--computer interfaces (BCIs) as well as understanding of visual information processing mechanism. The measurement of the responses to the periodic stimuli from electroencephalography (EEG) involves accurately estimating its frequency and phase. This paper introduces a novel approach to recognition of the frequency and the phase of SSVEPs that can achieve high performance in BCI applications. The proposed method exploits multiset canonical correlation analysis (Mset CCA) to enhance SSVEP components in EEG recordings. An experiment of the simultaneous recognition of the frequency and phase was conducted to compare performance of the proposed method with the previous work. The proposed method achieved the ITR of 126.74 bits/min when analyzing a very short time window of 500 ms in the EEG signal, which was significantly higher than the state-of-the-art.
It is thought that quadrupedal gaits are assumed to be generated by the central pattern generators (CPGs) which is hypothesized to exist in the spinal cord. We have modeled, using electronic circuits and hardware modules, a hard-wired network composed of eight CPGs (Z4×Z2 symmetry) that was originally proposed by Golubitsky et al. from the theoretical approach. Furthermore, we reproduced switching phenomena between quadrupedal locomotion patterns by manipulating the only one parameter (externally inputted DC voltage). In this study, we clarify the switching phenomena from the viewpoint of the necessary energy to change the locomotion patterns. Hoyt et al. experimentally examined that horses selected the gaits (locomotion patterns) so as to minimize the oxygen consumption per unit distance. We examined the relation between the switching phenomena in the hardware model and the necessary electric power, by using the circuit simulator, LT Spice IV.
Recently, there are numerous studies about two-dimensional cell patterning that enables to make a cell chip. However, to simulate in vivo condition on the chip, three-dimensional cell patterning technique is required for the reconstruction of complicated cellular organization in vitro. In this study, to develop three-dimensional cell organizing technique and apply it for a neural cell chip, we focus on micro-injection method which could control the three-dimensional position of cells in hydrogel. This three-dimensional cell drawing technology was consisted of micro injector and automatic positioning stage. Using our novel device, PC12 cells were located and patterned three-dimensionally in collagen gels. The width of drawn cells, length of neurite outgrowth, and the continuity of cell-network were evaluated. As the results, PC12 cells were located and positioned three-dimensionally in the collagen gel. The cells in gel extended their neurites and connected to each other.
Myelination is essential for cognitive development. However, little is known about the association of myelin-related protein expression with regulation of axonal conduction velocity. The aim of this study is to develop a culture system which evaluates the alteration in axonal conduction velocity during myelination process. As a source of myelinating cells, Schwann cells were cultured and purified. Immunocytochemical analysis revealed the ratio of Schwann cells to all cells was more than 95%. Also, Schwann cell and dorsal root ganglion (DRG) neuron co-culture was maintained for 5 weeks. As a next step, DRG neurons were cultured in a microfabricated device and were electrically stimulated. Evoked responses recorded from multiple electrodes had a constant delay, suggesting that axonal conduction velocity could be evaluated. These results suggest that development of DRG neuron and Schwann cell co-culture on this device would be a useful culture system for evaluating myelin-regulated changes in axonal conduction velocity.
It is important to grip an object accurately and recognize the shape of the objects for the potential future robot hand. We have developed the multichannel flexible tactile sensor having finger print applicable for an artificial robot hands. The tactile sensor was consisted of four pneumatic sensors and a flexible plastic cap with a finger print structure that was made of silicone resin and was separated from four air spaces. We evaluated the slipping characteristics of the tactile sensor. Evaluation tests showed that the multiple soft tactile sensors detected the friction between the tactile sensor and the object, and the results that the objects were easy to slip or not.
Tactile presentation of various hardness/softness feeling of complicated multilayered anatomical structures has been required for the medical robots, because the relationship between psychological and physical multilayer hardness/softness has not been clarified. In this study, the threshold of psychological and physical multilayer hardness/softness was investigated by validating the prediction from the previous study using the psychological engineering approaches and the physical Young's modulus of multilayer. Eleven subjects' fingers touched to both 3.75%(softer) and 5.0%(harder) concentration single-layer gelatin jellies and touched to 5 double layer gelatin jellies of which upper layer was 3.75% and 5.0% jelly, and lower layer were 10.0%, 12.5%, 15%, 20%, and 25% jellies, respectively. After that, subjects were answered whether the specimen had multilayer tactile. The results showed that the threshold of multilayer hardness/softness was consistent with the prediction of the previous research.
Finger manipulation is a basic action of human in our daily lives. The measurement of finger manipulation is important to know person's behavior and support the work. In our study, we estimate stroking manipulation by measuring propagated wave in their finger. During stroking manipulation, load center between the finger and object changes. In this paper, we investigated relationship between the load center and stroking direction. The figure showed the measured load center by pressure sensor. The result of ANOVA and multiple comparison showed a significant difference in the average position.
Electromyogram (EMG) is recorded electrical muscle contraction, mechanomyogram (MMG) indicates cross-sectional area change of muscle, reflect mechanical muscle contraction. By simultaneously measuring both signals, it is possible to multifaceted evaluation of muscle contraction. However, MMG measurement at voluntary movement was difficult. Therefore, the authors developed MMG / EMG hybrid transducer capable of simultaneous measurement of MMG and EMG. This study evaluated MMG and EMG of rectus femoris (RF) and hamstrings using recumbent bicycle of easy load regulation. As result, dMMGbase (baseline of displacement MMG) indicated cross-sectional area change of muscle at pushing down and pulling up of pedal. In addition, EMG and dMMGbase increased with pushing down of pedal in RF, dMMGacc (acceleration dMMGbase) showing muscle contraction force was output simultaneously. Each signal of hamstrings had output that antagonize RF. By simultaneously measuring MMG and EMG at recumbent bicycle pedaling, it was possible to evaluate muscle contraction of voluntary movement.
The aim of this study was to evaluate muscle stiffness during one cycle of pedaling exercises. Electrical stimulation was applied to the vastus lateralis muscle at various clank angles in a resting state and during pedaling exercises. The angles were -30, +30, and +90 deg. The angle of 0 deg corresponds to top center of the pedal, and the clockwise direction is positive. A mechanomyogram (MMG) was measured with a capacitor microphone. The MMG system was identified using a singular value decomposition method and the poles of the transfer function were calculated. The poles and mass of the vastus lateralis muscle were used to estimate the muscle stiffness. The muscle stiffness increased as the muscle activity increased. In conclusion, it was suggested that muscle stiffness during pedaling exercises changes depending on muscle activity.
The cardiac Na+/Ca2+ exchanger (NCX1) is the primary transport system that extrudes Ca2+ after the rise in cytoplasmic Ca2+ during contraction. Previously, we showed that the recovery of depressed NCX1 activity by inducing NCX1 expression prevents heart failure (HF) progression. In this study, we analyzed effects of inducing NCX1 expression on the microstructure in cardiomyocytes during progression of HF. Transverse aortic constriction (TAC)-surgery caused severe HF with the disorganization of T-tubule membrane and sarcomere structures after 16 weeks. Junctophilin-2 connecting the sarcoplasmic reticulum (SR) with T-tubule membrane showed abnormal localization, suggesting that SR/T-tubule junctions were disrupted. In contrast, cardiomyocytes inducing NCX1 overexpression after TAC-surgery showed no abnormalities in T-tubule membrane, sarcomere structures and junctophilin-2. Thus, inducing NCX1 expression during HF progression was found to prevent the collapse of myocardial microstructure under prolonged pressure-overload conditions. These results suggest that Ca2+ clearance by NCX1 is important in maintaining the myocardial microstructure.
It is well known that maximum voluntary torque, produced by skeletal muscles is lower during concentric contraction and higher during eccentric contraction compared with isometric contraction. The steady state property defined by its isometric strength is commonly used. We focus on isometric contraction in detail. The purpose of this study is to measure maximum isometric strength both at active and passive conditions and to examine the condition-related contribution of neural and force mechanics to the force. Six healthy subjects participated in this study. The strength of their elbow flexors and electromyogram (EMG) were measured during the two conditions. As results, the passive condition led to stronger force in maximal isometric significantly while EMG did not show significant changes. In other words, we can sustain stronger force enduring external forces rather than exerting one's maximal voluntary forces against a fixed object.
Recently, attention has been directed to the study on biohybrid robots utilizing biotic muscle tissue as an actuator. However, biohybrid robots reported previously was fabricated by manually assembling muscle tissue onto a structure. It is necessary to develop the technique for automatically assembling cells or tissue onto a structure in the culture medium. We already proposed a three-dimensional cell assembly method using the Magneto-Archimedes effect and succeeded in bridging of myoblast aggregation between micropillars by the method. In this study, we aim at inducing differentiation of myoblast aggregation and maintaining differentiated tissue by perfusing culture medium. First, myoblast aggregation bridged between micropillars. Then, the medium for magnetic assembly was replaced with differentiation medium and was kept perfusing using peristaltic pumps. Perfusion culture enabled us to maintain the muscle tissue for a long term. Establishment of perfusion culture would contribute to the industrial production of biohybrid robot.
It is said that a myocardial tissue does not regenerate because it has low capability to self restore. Therefore, regenerative medicine using the multi-layer cell sheet is gathering attention. Generally, the cell sheet is made without using a scaffold, however, the method using carbon nano-tube (CNT) as a scaffold was examined in this study, for supplementing the adhesive property of the cell sheet. Futher examination related to the cell adhesiveness is necessary for CNT as a scaffold of the cell sheet. So we investigate the cell adhesiveness of CNT. Experimental results, CNT surfaces had the tendency of lower cell adhesiveness in comparison with the normal culture vessel surface. Therefore, we will be described in this report a plasma activation (P-A) treatment to CNT was carried out to improve cell adhesiveness.
How and to what degree do the slight differences in the attachment positions of the sensors influence the values of photoplethysmographic measures? To address this question, we measured pulse rate (PR) and alternating current-to-direct current ratio (AC/DC) from the tips of the index fingers of 12 subjects under rest condition, using a sensor geometry having one light source and three photo detectors. The analysis revealed that the values of the intraclass correlation coefficient, an index of internal consistency, for PR and AC/DC across geometries were 1.00 and 0.90, respectively. The mean values of PR from the three photo detectors remained the same whereas those of AC/DC did not. These findings indicate that the internal consistency of PR and AC/DC across geometries are high, which implies that they can be used irrespective of the slight differences in the sensor attachment positions.
[Purpose] Wave-Intensity (WI) is one of the useful hemodynamic indices of the cardiovascular system. However, effects of vascular stiffness on WI waveform are not well known. In this study, we developed a cardiovascular model that includes an elastic tube as a model of a vessel, and measured WI of the elastic tube. [Methods] We made the cardiovascular model composed of pulsatile pump and circulation circuit. The model of elastic vessels were prepared using styrene-based elastomer material (Aronkasei Co., LTD), which were putted in the circulation circuit. We measured the blood vessel stiffness β(β=ln(Ps/Pd)/[(Ds-Dd)/Dd])and WI (WI=(dP/dt)(dU/dt)) using the ultrasonic diagnostic apparatus. [Results] We were able to measure the blood pressure waveform and blood flow velocity waveform. The calculated β was 46.9 and W1 is 1990mmHg×m/s3, which were far from human data (β was higher and W1 was lower than healthy subjects). [Conclusion] Lower β vessel model required to make biological model.