Naruhiro Shiozawa

Electrocardiogram Measurement during Sleep with Wearing Clothes Using Capacitively-Coupled Electrodes

The electrocardiogram (ECG) was measured by non-contact, non-restraint and unconscious method using capacitively-coupled electrodes made of electro-conductive cloth while subjects lay on bed wearing their clothes. These electrodes are very sensitive so measure not only signals but noise. The seat grounded, which arranged under the electrode could suppress noise. Two types of electrode different in length were used, that is long type and short type. Results showed that both electrodes could sense ECG. Noise generated from e.g. commercial power source was almost the same for both electrodes though the length of electrode was longer than the subject for the long type electrode. Setting position was rather serious and noise component changed greatly by the part of body that touches the electrode. Next, ECG was measured on these condition participants lay with supine position, prone position, right lateral position and left lateral position. The ECG was measured on each condition.

Development of a Portable Acceleration Monitor Device and its clinical application for the Quantitative Gait Assessment of the Elderly

In this study, a handy gait assessment system with a tri-axial accelerometer has been developed and its application for a quantitative assessment of gait in the elderly was examined. This assessment system consists of a portable acceleration monitor device and PC analysis software. This portable device was fixed to the lower front of the subject, and the subject was asked to walk around a test course at a voluntary speed. The activities performed on the test course include standing up, normal walking, fast walking, and walking over a barrier. Gaits in 402 elderly people were measured three times every three months. These subjects were under nursing health services, such as expert place nursing, walking training, power rehabilitation, fall prevention training, and pool training. The measured acceleration was converted into relative velocity and relative displacement of the center of gravity of the subject. Four evaluation indices, i.e., physical activity, stability, symmetry, and average speed were calculated. The results reveal that both the physical activity and average speed decreased after six months under nursing services

Reentrant excitation in an analog-digital hybrid circuit model of cardiac tissue

We propose an analog-digital hybrid circuit model of one-dimensional cardiac tissue with hardware implementation that allows us to perform real-time simulations of spatially conducting cardiac action potentials. Each active nodal compartment of the tissue model is designed using analog circuits and a dsPIC microcontroller, by which the time-dependent and time-independent nonlinear current-voltage relationships of six types of ion channel currents employed in the Luo-Rudy phase I (LR-I) model for a single mammalian cardiac ventricular cell can be reproduced quantitatively. Here, we perform real-time simulations of reentrant excitation conduction in a ring-shaped tissue model that includes eighty nodal compartments. In particular, we show that the hybrid tissue model can exhibit real-time dynamics for initiation of reentries induced by uni-directional block, as well as those for phase resetting that leads to annihilation of the reentry in response to impulsive current stimulations at appropriate nodes and timings. The dynamics of the hybrid model are comparable to those of a spatially distributed tissue model with LR-I compartments. Thus, it is conceivable that the hybrid model might be a useful tool for large scale simulations of cardiac tissue dynamics, as an alternative to numerical simulations, leading toward further understanding of the reentrant mechanisms.

Virtual walkway system and prediction of gait mode transition for the control of the gait simulator

A virtual walkway system is proposed in This work. This system consists of a new developed gait simulator and a HMD system to present virtual space to the user. The gait simulator is designed to permit the user to walk straight, change direction, go up and down stairs, etc. Main part of this gait simulator is two foot plates driven by three arms and actuators. Each foot plate follows the foot during swing phase and pulls it back during the stance phase while the user is walking straight However this gait simulator has one weak point, that is, this simulator cannot follow the change of gait mode sufficiently, like the start of walking or the end of walking. To solve this problem it is necessary to predict the change of gait mode to follow the transition perfectly. In this paper we chose the start and the end of straight walking and have tried to measure this transition of gait mode. To do this we paid attention on the anterior bending of the upper trunk. It is expected that the trunk bends forward before the start of walking and bends back before the stop of walking. In the experiment the distance between the upper trunk and the center of gravity (COG) was measured and it was proven that the measurement of this distance showed to be useful to know the transition of straight walking. This result was examined again on the gait simulator. Implanted control algorithm of gait simulator is as follows; two foot plates pull back the feet when the start of walking was predicted and stop when the stop of walking was predicted. Results show that the gait simulator was able to reproduce the start and the end of walking by this prediction algorithm.

Portable jogging monitor device and its application for health management

We have developed a portable jogging monitoring device and studied its application for health management. This device is a micro processor based system with some sensors necessary to monitor the health condition of the user during jogging, that is, a heart rate sensor, a GPS sensor and a physical activity sensor. We also have developed PC based health management software, that receives jogging data from the portable device and stores it as a long term jogging trend data. From these long term data it can feedback the distance completion of jogging on the virtual course. Moreover it can show the trend of jogging time, distance, average heart rate and the user can know his/her own health condition.

Panaxatriol derived from ginseng augments resistance exercised–induced protein synthesis via mTORC1 signaling in rat skeletal muscle

Resistance exercise activates muscle protein synthesis via the mammalian target of rapamycin complex 1 (mTORC1) pathway and subsequent muscle hypertrophy. Upstream components of the mTORC1 pathway are widely known to be involved in Akt and extracellular signal-regulated kinase 1/2 (ERK1/2) signaling. Previous studies have shown that ginseng stimulated Akt and ERK1/2 signaling. Therefore, we hypothesized that panaxatriol (PT) derived from ginseng triggers mTORC1 signaling and muscle protein synthesis by activating both the Akt and ERK1/2 signaling pathways, and that PT additively stimulates muscle protein synthesis when combined with resistance exercise. The study included male Sprague-Dawley rats. The legs of the rats were divided into control, PT-only, exercise-only, and exercise + PT groups. The right legs were subjected to isometric resistance exercise using percutaneous electrical stimulation, whereas the left legs were used as controls. PT (0.2 g/kg) was administered immediately after exercise. The Akt and ERK1/2 phosphorylation levels were significantly higher in the exercise + PT group than in the exercise-only group 0.5 hour after exercise. The phosphorylation of p70S6K was significantly increased at both 0.5 and 3 hours after exercise, and it was higher in the exercise + PT group than in the exercise-only group at both 0.5 and 3 hours after exercise. Muscle protein synthesis was significantly increased 3 hours after exercise, and it was higher in the exercise + PT group than in the exercise-only group 3 hours after exercise. Our results suggest that PT derived from ginseng enhances resistance exercise-induced protein synthesis via mTORC1 signaling in rat skeletal muscle.

Fundamentals of Wearable Sensors for the Monitoring of Physical and Physiological Changes in Daily Life

This chapter provides an overview of wearable sensors for the monitoring of physical and physiological change in daily life, their fundamentals, and applications. The following three cases need to be considered for the applications of a wearable biosignal measurement system: continuous and long-term measurement for accident prevention (e.g., an alarm for heart attack), once-daily measuring for the evaluation of health condition, and biosignal monitoring as the machine interface. In long-term monitoring, the biosignal measurement system must be small in size, with minimal power consumption, and portable. However, in the case of sleep monitoring, the biosignal sensors should not be wearable, but incorporated into a bed. This chapter presents several kinds of wearable and ambient sensors for the monitoring of physiological and physical changes in daytime and nighttime.

Tomographical ECG Measurement Using Capacitance Type Multi Electrodes

Recently electrocardiogram measurement with electrostatic capacity type electrode has been researched. Electrocardiogram can be measured by bringing the metal plate close from the outside of the body to the vicinity of the heart and amplifying the voltage. Metal plate is not necessary to be attached to the skin, and this measurement is a complete no contact measurement of an electrical signal in vivo.

Gait analysis of sit-to-walk motion by using portable acceleration monitor device for fall prevention

The purpose of this study is to investigate whether the acceleration of the center of gravity of body during sit-to-walk motion have a relationship with falling or not. In this study, we measured sit-to-walk motion of fall experienced and inexperienced subjects by using a portable acceleration monitor device that we have developed. The result of discriminant analysis by using indexes with a significant difference revealed a 90.3% correct prediction rate for falling. The results indicated possibility of fall prevention by this method.

Hyperthermia System with Thermoseed Set in Abdominal Cavity and AC-Magnetic-Field

We propose a hyperthermia system for cancer developed in abdominal cavity. Local/deep spot heating and its less invasion feature are expected to be realized by thermoseed. This thermoseed is made of ferromagnetic material and it changes AC magnetic field power from outside of body to heat. AC magnetic field frequency is set on the value not to be absorbed to organs or tissues. We made a heat model of thermoseed and in vivo environment. The amount of heat and heat conduction were calculated from the characteristic values of materials and AC magnetic field. Effective shape of thermoseed for hyperthermia can be designed easily from this calculation. Results showed possibility of effective hyperthermia using this system through evaluation experiments.