Since 1962, medical and biological application of LASER have been promoted.
The LASER beam is characterized by coherent monochromatic light and is so highly directional that the enormous amount of its energy can be focused even on an extremely small spot.
The diversified effects of LASER irradiation have been observed by numerous investigators in the fields of tumor and cancer therapy, central nervous system, cardiovascular system, microcirculation, photocoagulation and microsurgery of cellular or subcellular components.
On the basis of analysis of a number of given by many authors including ourselves, it is considered that the mechanism of the action involved in LASER irradiation on biological systems consists of the following four factors :
(1) heat effect (2) pressure effect (3) light effect, and (4) effect of electromagnetic field formation.
The accomplishment of a LASER scalpel will enable a surgeon to perform the operations on various subjects ranging from macroscopic tumor to microscopic subcellular component, Moreover, the surgical operation will be performed in the noncontact, aseptic and probably analgesic way.
LASER scalpel will be possible to destroy selectively the only desired area without damages on the other parts, by adjustment of the wavelength of light or application of the suitable dyes, which absorb the LASER energy, to the living tissues.
It may be useful to radiate the internal deep organs by application of optical fibers.
The most interesting method of LASER-spectro-analysis will make it possible, in the future, to give chemically a diagnosis of living tissue in vivo.
The more LASER are widely employed in the industrial or in the other fields, the more carefully it should be treated to prevent a user from unfortunate accident.

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Analysis of correlation function is one of the most important tools in investigation of biological phenomena. Since the analysis should be done, in a short period in most cases of biological phenomena, the estimation of the reliability of the measured values is required.
On the assumption that the process is 1) probabilistic, 2) stationary and 3) Gaussian, the probability density functions of the measured values of the short-term correlation functions and their variance, etc. were calculated, and the procedures of estimating the range of the error were proposed.
For the examination of validity of the methods discussed, some samples from spontaneous E. E. G. were actually processed and a number of short-term autocorrelation functions were obtained.

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To know the aspect of pulsatile blood flow in the arteries, mathematical analysis of motion of viscous liquid in a thin-walled elastic tube has been made. Mode theory of wave propagation in this system was developed. Results of the, analysis showed that the system has only one mode of wave transmission for almost all over the system.

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An automatic cardiac sound analyzer newly developed by authors applying an analog data processing system described.
Outline of the analyzer :
1. In order to identify the first and second heart sounds, and systole and diastole of a cardiac cycle, the carotid arterial pulse was adopted for the reference tracing. The sharp rise in rapid ejection phase and the incisura of the carotid arterial pulse were detected from the second derivative of the pulse tracing, and the detected signals were used for reference of the heart sounds. The time lag between the heart sounds and the reference signals was synchronized by a magnetic delay apparatus.
2. Envelope method was used for pattern analysis of heart sounds and murmurs.
3. Results of the analysis was displayed on an illuminated plastic panel in real time. This analyzer gives answers on the following items ; amplitude of heart sounds, innocent and organic systolic murmurs, respiratory and constant splitting of the second heart sound, physiologic third heart sound and gallop, high and low pitched diastolic murmurs and cardiac rhythm disorders.
Screening of abnormal cadiac sounds
In order to test the function of this analyzer, 159 freshmen of uiversity of Tokyo were selected. The analyzer made quite satisfactory diagnosis with 7 false positive and 1 false negative results. This is compatible with the capacity of non-specialist physician.
This false negative case was reexamined after readjustment of the analyzer, and the correct diagnosis was obtained.

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Clinical charts are very important for medical doctors but the ever-increasing records and films worry us to retrieve and administrate them. We applied the information retrieval system to administration of clinical charts of University of Tokyo. The instrument, called Canon IR system, has been developed by Canon Camera Co. for information retrieval. This. system consists of microfilming system for preservation of information sources and an IR_ computer with magnetic tapes for index memory.
The specifications of this system are :
1. Microfilms for preservation of clinical charts.
2. Duplicated Karvar film for operation film.
3. An IR computer for index retrieval.
4. Magnetic tapes for index memory. (3600 ft. 25000 cases)
5. Extract 254 words index from clinical charts.
6. Connection between microfilm and index with IR reader-printer.
The information retrieval using this system may offer the following benefits :
1. This system eliminates great amount of paperworks and information sources are preserved in microfilm with highest packing density.
2. The retrieved informations are obtained immediately and with accuracy.
3. Maintenance of the system is cheaper than those of other computer systems.
4. Programming is not necessary for retrieval.
5. The utility of the informations stored in clinical charts is be increased by using this system.

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Cardiac catheterization is one of the most important diagnostic aid for heart diseases. Right heart catheterization based on the Fick's principle is a generalized method, and gives various hemodynamic informations such as cardiac output, systemic blood flow, pulmonary blood flow, effective pulmonary blood flow, shunt flow, vascular resistance, ventricular work load, defect area and valve area.
Intracavity electrocardiography is indispensable for the diagnosis of Ebstein's anomaly. Recently intracardiac micromanometry and intracardiac phonocardiography have been available. Indicator dilution method is useful for the external determination of cardiac output, and it is convenient for the detection of a shunt and its site.
The most sensitive diagnostic method for the shunt is the hydrogen electrode method; it may detect a very small shunt.
Ultrasonic intravenous sounding is also useful for the diagnosis of heart diseases. It clearly gives the size of the atrial septal defect and further advancement of this technique is expected.
There are various methods of left heart catheterization, such as direct posterior transthoracic left atrial puncture, transbronchial left atrial puncture, retrograde left heart catheterization, transseptal left heart catheterization and apical left ventricular puncture. But currently the retrograde and transseptal left heart catheterizations the most prevailing methods, and many informaitons obtained from the left side of the heart serve to establish the correct diagnosis of heart disease.

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