Ryoichi Tashiro

Development of an Electrostatic Generator for a Cardiac Pacemaker that Harnesses the Ventricular Wall Motion.

Abstract A variable-capacitance-type electrostatic (VCES) generator that harnesses ventricular motion was developed with the aim of driving a cardiac pacemaker permanently without a battery. The developed model of the VCES generator was handmade, but it was too large to implant into the thoracic cavity of a laboratory animal. For this reason, to demonstrate its feasibility, a somewhat complicated method that measured the left ventricular wall motion by means of the accelerometer module put on the free wall and reproduced the motion in real time with a vibration mode simulator was used. The VCES generator was vibrated on the simulator, and its generated power was supplied to the cardiac pacemaker, which then stimulated the heart. A mean power of approximately 36 μW was generated, which was enough to drive the cardiac pacemaker. Continuous electric generation and cardiac pacing were performed successfully for more than 2 h in the animal experiment.

Combined use of an epidural cooling catheter and systemic moderate hypothermia enhances spinal cord protection against ischemic injury in rabbits

BACKGROUND Epidural placement of a cooling catheter can protect against ischemic spinal cord injury. With the use of rabbits, we investigated whether this epidural cooling technique, when combined with systemic moderate hypothermia, can protect the spinal cord against ischemic metabolic stress. METHODS New Zealand white rabbits (n = 28) were assigned to 1 of 4 different groups. Animals underwent abdominal aortic occlusion for 30 minutes using a 3F balloon catheter. Group 1 (n = 7) underwent epidural cooling by the catheter and systemic moderate hypothermia (35 °C) induced with a cooling blanket. Group 2 (n = 7) underwent epidural cooling under systemic normothermia (38.5 °C). Group 3 (n = 7) underwent systemic moderate hypothermia (35 °C) without epidural cooling. Group 4 (n = 7) underwent neither epidural nor blanket cooling as a negative control. Neurologic status of their hind limbs was graded according to the modified Tarlov scale at 1, 2, and 7 days after surgery. RESULTS During infrarenal aortic ischemia, epidural temperature was significantly lower in group 1 (18.5 °C ± 0.8 °C) than in group 2 (28.6 °C ± 1.0 °C; P = .0001), group 3 (34.2 °C ± 0.06 °C; P = .0001), or group 4 (38.5 °C ± 0.2 °C; P = .0001). Hind limb function recovery was greater in group 1 (mean Tarlov score, 4.9 ± 0.057) than in group 2 (2.6 ± 0.3; P = .0028), group 3 (2.1 ± 0.34; P = .0088), or group 4 (0.0 ± 0.0; P = .0003). CONCLUSIONS Epidural cooling catheter combined with systemic moderate hypothermia produced additive cooling ability and protected the spinal cord against ischemia in rabbits more effectively than either intervention alone.

A Microactuator Using Phase Transition of Paraffln. Development of an Actuator with Scissors for Surgical Operation.

Our aim is to develop a microactuator to be used for endoscopic surgery. The purpose of this study was to construct cylinder-piston-type microactuators that are actuated by phase transition of material. We use a paraffin as the working material because paraffin has a large coefficient of expansion due to the phase transition in the temperature range of 35 to 45 degrees of centigrade. Firstly, we made a microactuator whose outer diameter was 1.5 mm and the length was 65 mm. The actuator generates the stroke of 2 mm against the load of 1 kg. Secondly, a micro-scissors was attached to the piston of the actuator. It was confirmed that the micro-scissors can cut the paper, string and rubber tube without any trouble. The operation time for one cycle of cutting was approximately 13 secondns.