不整脈の成因は通常刺激生成異常と刺激伝導異常とに分けて論じられる。しかし最近の知見によれば心電図上, 刺激生成異常と考えられる期外収縮でも, その背後にはむしろ伝導障害による発生機序を考えた方がより合理的に説明できる場合が多く, 両者は画然と分離して論じうる性質のものではなくなっている。しかし不整脈の成因を考えるうえでなお便利であることは否めない。
本稿では不整脈発生を理解する最も基礎的知識として心筋細胞膜の電気生理学的特性を簡単に述べ, 次いで刺激生成異常と刺激伝導異常について解説を進める。

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A flying spot (random access) type x-ray microbeam system with the rating of 150 kV-2 mA has been constructed. By means of a new radiographic method using on-line computer control of x-ray beam scan, observations of the tongue movements have been performed. Also, some pilot experiment on the automatic identification of the bone outline has been conducted.
The method employed here makes it possible to track specific points on a moving organ or to trace outline of an object. The movements of the tongue during speech have been observed by tracking several metal pellets placed on the tongue. Up to 6 pellets have been tracked at the rate of 120 frames/sec. The effective exposure area per frame was 1 cm² and the exposure rate within this area was 100 mR/min, approximately.
Also, identification of the bone outline with restricted scan of a narrow area along it has been successfully performed.
In these experiments, resulting spatial restrictions of exposures combined with the use of highly sensitive scintillation detector achieved a substantial reduction of x-ray dosage.

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Since R. Damadian suggested the detectability of tumors by nuclear magnetic resonance (NMR), the authors have focused their attention on the facts such as the quantities related to the kinds of water and tissues. And at least qualitative information could be non-invasively obtained.
In this paper, in order to clarify the applicabilities of our proposed magnetic focusing method for non-invasive tumor detection, the nuclear magnetic relaxation time (T₁) of transplanted malignant tumor (AH-66) in rat, excised normal and cancerous tissues in man were measured in vitro experiment.
The resultant findings are summarized as followings.
1) Transplanted malignant tumor in rat showed (30-120) % longer value of T₁ than that of the respective normal tissues.
2) In 14 cases of the uterus, breast and stomach in man, the T₁ of cancerous tissues increased (10-150) % than that of their normal portions.
3) When mixed tissue was studied, T₁ changed as the ratio of tumor to normal tissue changed.
4) The longer the time elapsed, the greater the T1 value exhibited by normal and the smaller the T1 measured for cancerous tissue. When both normal and cancerous tissues coexist, T₁ decrement of the tissue is small.

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Dorsal Column electrical Stimulation (DCS) of spinal cord is an effective and non-harmful way for the elimination of chronic or intractable pain. According to the gate control theory proposed by Melzack and Wall, chronic pain can be controlled by means of stimulating the nerve fibers of large diameter in the dorsal column, because the inhibitory neurons in the substentia gelatinosa areactivated by these fibers resulting in the abolition of pain transmission in the afferent system.
For successful stimulation on the dorsal column, electric signals have to be brought into the living body through an adequate interface apparatus. Two types of apparatus are treated in this paper. The first one consists of a pair of coils coupled through the skin and a small dipole electrode which can be inserted on the posterior surface of spinal cord without surgical incision. Electrical signal is applied to the external coil so that the inner coil gives pulses to the dipole and stimulates the dorsal column.
The other apparatus is the multi-channel transcutaneous stimulator having 5 independent outputs, which are to drive 5 pairs of electrodes arrayed on the skin along the dorsal column. With this apparatus, pain spreading over wide area can be treated effectively at rather lower current intensities.
Effects of pain relief using these two types of DCS were clinically tested. Dipole electrodes were inserted on the dorsal column of 4 patients suffering from intractable pain due to advanced carcinoma. The complete pain relief was recognized in 2 and partial pain elimination in 2 patients.
Transcutaneous DCS was applied to 16 patients complaining of chronic pain mainly due to carcinoma. Complete pain elimination was observed in 7 patients (44%), partial elimination in 4 patients (25%), and no effect was noticed in 5 patients (31%). The pain relief continued usually less than 2 hours after cessation of electrical current. Multichannel DCS is suitable for relievingpain spreading over a broad area in patients suffering from advanced carcinoma. Since DCS is no harmful way of controlling pain, it is recommended as first choice of procedure to relieve intractable pain due to cancer.

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心臓は生体の活動を維持するに必要な血流の総和である心拍出量を, 血管抵抗によって発生する動脈血圧に抗して送り出している。心臓はそのエネルギー産生のために酸素を消費している。
心臓の収縮性あるいは収縮の強さは, 実験的あるいは病的には広い範囲に変わるが, 正常な状態では, 動物の種と体重が決まればその収縮性のばらつきは比較的少ない^1～3) 。
与えられた総末梢抵抗に対して一定の心拍出量を送り出す場合, 収縮性の高い心臓では小さい心室容積でもよいが, 収縮性の低い心臓では心室容積が大きくなければならない。すなわち弛緩期末容積ならびに残余容積は, 収縮性の大小に逆比例する⁴⁾ 。
正常な状態において, 心臓の収縮性をばらつき少なく与える機序は何であろうか。この研究では, この問題への第一歩として, 心臓の機械的仕事量とそのための酸素消費量との関係を中心に考察し, 正常な心臓の収縮性は, 酸素消費量が極小となるような値に調節されているのではないかという可能性を指摘した。

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Significant progress of medical engineering in recent years has introduced various kinds of electrical equipment into health and medical care. This situation inevitably involves a danger that medical equipment or installations may not properly be designed or used, thus produce electrical shock hazard. In order to circumvent such a hazardous situation, various schemes have been undertaken, but the author believes that it is necessary to develop an evaluation measure for the extent of safety secured by electromedical equipment and installations. This paper shows an evaluation method in terms of “Figure of protection”, “Multiplicity of protection” and “Protection sensitivity”, which are called “Three figures of merit for protection against electrical shock hazards”. Those figures are useful to (1) analyze a situation from the viewpoint of safety, and to (2) specify the items of testing in periodic inspection of equipment and installations. In addition to these, the figures will serve as guide to improving the equipment and installations by manufacturers, doctors, supporting staffs, hospital engineers and so forth.

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