Recently as one of the medical treatments of the neurogenic bladder, which is due to traffic accidents, labour disasters and other causes, the electrical stimulation of the bladder has been markedly used in the field of rehabilitation. T. Burghele et al. (1959) have reported the new concept of emptying the paralyzed bladder by means of electrically induced detrusor muscle contraction. During the past decade a number of investigators have tested this method. However, this technique is still experimental, and much laboratory and clinical research must be done before this approach is perfected and considered clinically acceptable. The author has improved this method by carring out the experiments on a dog, and has made a new induction implantable bladder pacemaker using high efficiency R. F. energy transport circuit.
This consists of an implantable receiver and a hand-held external transmitter. The receiver is powered by an external high frequency oscillator at 890 kHz, and it demodulates bursts of R. F. into stimulus pulses. The output channel provides stimulus pulses 4 to 10 msec in duration, at an amplitude of 1 to 6 V into a 150 Ω load, and.a repetition rate of 13 to 30 per second. The internal circuitry is encapsulated in epoxy and the electrode leads are protected in a highly flexible implantable silicone.
One of the problems encountered in applications is contraction of the sphincter of urethra during stimulation, so that voiding is considerably impeded or impossible even in the presence of strong bladder contraction and high intravesical pressure.
However in this paper, the author has shown that the new pacemaker can eliminate the leak current and prevents the contraction of the urethral sphincter by using two pairs of electrode, which are electrically isolated from each other.
It was confirmed, by the experiments on the chronic dog, that the leak current to the urethra had so decreased that the micturition with it could be satisfactorily improved.
Also the author has designed a new urine volume detecting apparatus using a tiny magnet and reed switch.

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A new type of valve system for surgical treatment of hydrocephalus has been designed and developed. Results obtained from basic experiments by a scale-up model valve are summarized as follows.
1. Regarding the pressure control of the valve, the opening action of the valve occurs at the critical pressure difference, the flow through the valve begins at the pressure more than this critical one. The increase of the pressure difference along with increase of the flow is comparatively small even of large flow.
2. The prevention of counter flow is almost satisfactory with this valve. 3. With this valve, the cerebrospinal fluid pressure is easily controlled and hence, the valve may be applied to all patients with the abnormal cerebrospinal fluid pressure.
4. A significant advantage of this valve is the existence of the popping pressure, compared with other resistance-type valves.

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The electrical resistance of the urinary bladder which is measured between two electrodes attached on the external bladder wall passing current with frequencies above 100 kHz is proportional to the bladder diameter, if the electrodes are placed at proper positions. Waltz et al. (1971) have reported a sensing device to detect the bladder volume by applying an oscillator whose frequency is modulated by the interelectrode resistance to provide electrical signals proportional to the bladderurine volume; they used this in combination with an electrical bladder stimulator. In this method, however, slight change in urine volume could not be detected.
In this present paper, the author has attempted to improve this method by developing a new concentric disc electrode, which can also be used as a stimulating electrode for the electrical bladder stimulator. Also we have designed a new sensing apparatus. By using these it was confirmed, by experiment on 6 dogs, that the spread of the electric current in the bladder muscle and urine could be prevented and that its dynamic range can be satisfactorily improved. Based on the results the practicability of the device is discussed.

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A reconstruction method of tomographic plane for various depths with sampling tomography is described. Sampling tomography is the method in which X-ray images are taken N times along the trajectory and are shifted and superposed to obtain any sectional image. Other sectional images except tomographic plane in sampling tomography distribute and cause the deterioration of image quality same as blurring in conventional tomograph.
In this paper, the image qualities of sampling tomographs were compared with conventional ones evaluating with the modulation transfer function (MTF) for circular geometry. From this result, we suggest that roughly 10 samples along the trajectory would be reasonable considering the balance between the enhancement of image quality and X-ray damage. We used a computer system for the actual enhancement of reconstructed image quality and discussed about its algorism and filtering techniques by an experiment using a skull fantom with 18 sampled X-ray images. A series of tomographic images of a left maxillary sinus tumor was obtained to prove the usefulness of our method for clinical applications.

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A rhythmic oscillation of force at about 10 Hz called tremor is a well known feature of muscular contraction. The neuronal mechanism by which this is expressed has been extensively investigated and some hypotheses and models have been proposed recently. In this study, an attempt has been made to resolve the neuronal mechanism of tremor from the analysis of interspike intervals of the motor unit discharges.
Finger tremor of the extended second or third digit and bipolar wire electromyograms of the extensor digitorum were recorded. Tremor was measured with force transducer during steady voluntary contractions.
Many motor units displayed double discharges in which short interspike intervals alternated with long interspike intervals. That is, two adjacent spikes of a motor unit were phase-locked with each oscillatory wave of tremor.
When tension exerted by finger was large, motor units displayed intense double discharge firing pattern. But with decrease of tension, number of double discharges decreased and at last double discharges disappeared, that is, each wave of tremor corresponded with one spike. Mean firing frequency also decreased consequently.
Each motor unit showed different discharge characteristics even in the same level of tension. The motor units that displayed intense double discharges had low threshold for recruitment.

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