We have recently developed the implantable stimulator producing burst stimuli for electrical training of the skeletal muscles. We implanted the stimulator in the dogs to evaluate its basic performance. The stimulator consisted of two parts. The main body of the stimulator had dimensions of 60×40×22mm, weight, 150g. The battery part had dimensions of 55×47×21mm, weight, 56g. The stimulator was programmed with a burst frequency of 30Hz, pulse width, 210μs, burst number, 6 beats, amplitude, 5V, and rate, 80bpm. These stimulation parameters were fixed in this series of the stimulator. Six stimulators of this type were implanted in 6 adult mongrel dogs to stimplate the latissimus dorsi muscles for electrical training. Five of six stimulators were stopped to operate in between 10 to 35 days after the implantation, but one was allowed to operate over 84 days after implantation. The poor waterproof technique for the joint between the stimulators and the electrodes were all caused the stimulator to stop the operation. In the ATPase staining, the ratio of type I fiber of preconditioned latissimus dorsi muscles was 71±21%, which was increased compared to that (39±13%) of opposite unconditioned latissimus dorsi muscles. Despite the problems of waterproof technique, miniaturization and soon, from our study, it was suggested that this type of stimulator would be useful for the electrical training of the skeletal muscles.

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In order to evaluate the effect of total artificial heart replacement on autonomic nervous system, power spectrum analysis of the hemodynamic parameters and sympathetic nerve activity in TAH animal was performed using the fast Fourier transform and maximum entropy methods. Two pneumatically actuated sac type ventricular assist devices were connected as biventricular bypass (BVB) in 7 mongrel dogs, and sympathetic outflow were recorded at the renal sympathetic nerve. After the BVB pumping, natural heart was electrically fibrillated to constitute a BVB type of TAH model. In arterial pressure waveform of the animal with TAH, respiratory waves were not significantly changed, though Mayer waves were significantly decreased compared with that of natural heart. And Mayer wave fluctuation were significantly increased during prosthetic circulation. These results suggest that autonomic nervous system want to increase the Mayer wave component in the hemodynamic
parameters during artificial circulation.

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The study was carried out to define the relationship between the surface roughness of cellulose acetate beads and the tumor necrosis factor (TNF) inducing activity. The effective induction of TNF was obserbed when the cellulose acetate beads with a plenty of roughness on the surface was incubated with human blood. However, it was scarcely obserbed with the smooth surface beads. Electron microscopic findings demonstrated that leukocytes on beads with rough surface overlaid the roughness as phagocytised foreign bodies. From these results, the cellulose acetate beads with rough surface is an inducer of endogenous TNF and the surface roughness is speculated to be responsibile for TNF induction following leukocyte-activation.

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Left heart bypass and cardiopulmonary bypass with Sarns centrifugal pump were used for the operation of the thoracic aneurysm. The total number of patients were 57 at 7 medical centers. Left heart bypass were in 48 cases and CPB were in 9 cases. Sarns centrifugal pump had many benefits for the operation of the thoracic aneurysm, such as hemolysis, thromboemborism and lower priming volume, but low dose heparinization was needed for prevention of thromboembolism due to low flow bypass. Intraoperative complications by using left heart bypass were hypothermia in 13 cases (27%), hypoxia in 2 cases (4.2%), and hypercapnia in 8 cases (16.7%). Postoperative complications were respiratory failure in 7 cases (12.3%), bleeding in 6 cases (10.5%), renal failure in 5 cases (8.8%), MOF in 2 cases (3.5%), paraplegia in 2 cases (3.5%) and cerebrovascular attack in 2 cases (3.5%). Hospital deaths were 6 cases (10.5%). Autologus transfusion systems decreased transfusion and its complications. CPB using Sarns centrifugal pump and small membrane oxygenator (MENOX) with heat exchanger by low dose heparinazation made good surgical results and decreased complications.

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