The source localization of various arrhythmias has become more important since catheter ablation has been introduced to clinical antiarrhythmic therapy. Magnetocardiography (MCG) is thought to be useful for non-invasively localizing foci of the various arrhythmias. The accuracy in the source localization is important in such application. However the accuracy by MCG is still unclear. To make the accuracy clear, the MCG of a subject with the WPW syndrome was measured using a 7-channel first order DC-SQUID gradiometer system. The site of the accessory pathway was estimated using the single dipole model assuming the body to be the semi-infinite conductor. An electrophysiological study (EPS) was also carried out for the localization. The difference in distance of the accessory pathway sites estimated by MCG and EPS was less than 7mm. The location of accessory pathway was confirmed by an epicardial mapping in the surgical treatment. It is concluded that non-invasive MCG is a very helpful method for catheter ablation in localizing the site of focus in various kinds of the arrhythmias.

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We developed an image processing method to estimate an instantaneous 2-dimensional blood flow distribution using cineangiograms (CAG). This method will be useful for in vivo study of blood flow. Two-dimensional blood flow velocity was estimated from the flow of contrast medium between two sequential CAG frames. Each frame was divided into overlapping block areas whose size was determined by consideration of the maximum flow velocity. Then we made a cost function including smoothness constraint term. The apparent interframe movement of the contrast medium between blocks was determined by minimizing the cost function. A 2-dimensional blood flow velocity could be, consequently, estimated. By introducing overlapping block areas, a spatially dense distribution of blood flow velocity was obtained. We tested this method with an experiment using a pulsatile flow through a curved pipe. A time sequence of 2-dimensional flow velocities in the curved pipe was estimated with this method, and a time sequence of spatially averaged flow velocities in the pipe was calculated. The calculated average flow velocity showed excellent agreement with electromagnetic flow measurements (γ=0.960, n=47). Furthermore, the estimated flow velocity profile in the curved pipe showed that the maximum flow velocity shifted towards the outer wall. This result is consistent with a visual inspection of the CAG frames. To evaluate not only averaged flow velocity but also flow velocity profile, we also made a computer simulation study. We simulated steady fluid flow in a straight pipe. By this method, parabolic flow velocity profile in the straight pipe could be estimated within small enough error. Finally we applied this method to clinical data. The application to an abdominal aorta with an aneurysm showed a vortex flow in the abdominal aneurysm. The application to a left ventricle showed not only the blood flow in the left ventricle but also the left ventricular wall motion. These results were consistent with visual inspection of CAG frames.

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An unconstrained ECG and heart rate monitor is designed using ECG measured at bathtub. The apparatus is consisted of an analog and a digital parts. In the analog part the ECG wave from electrodes which are fixed inside bathtub is amplified approximately 4000 times. In the digital part the heart rates are calculated from the R-R interval of ECG pulse and the calculated data are stored in random access memory. The stored data in this apparatus are transferred to a personal computer by the RS-232C interface and analyzed by the personal computer. The heart rates obtained from bathtub ECG agreed with those obtained from body surface ECG. In measurement of bathing water with several concentrations of sodium chloride solution, the amplitude of ECG wave form decreased as an increase of electrical conductivity. Using this apparatus the heart rate can be obtained easily and noninvasively. Thus this developed monitor can be used as a home health monitor.

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In the single sweep record of ERP (event-related potential), peak latency of P300, which is one of the most prominent positive peaks in the ERP record, might fluctuate according to the recording conditions of the subject during the recording time. It is important to investigate whether the fluctuation of the peak latency (measurement fluctuation) is caused by physiological factor (physiological fluctuation) or by the noise of background EEG (noise fluctuation). In this paper, we proposed a method for extracting the physiological fluctuation of the peak latency of P300 from the measurement fluctuation. We clarified the relationship between the SN ratio of the single sweep ERP and the noise fluctuation based on the models which represented the features of the P300 and the background EEG appropriately. The noise fluctuation can be estimated by using the relationship, and the physiological fluctuation is extracted by subtracting the estimated noise fluctuation from the measurement fluctuation. In order to evaluate the proposed method, we estimated the physiological fluctuation in simulation data in which the true value of the physiological fluctuation was already known, and were able to obtain the accurate estimation value of the physiological fluctuation of the peak latency. Furthermore, the proposed method was applied to actual ERP data of eleven healthy adults, and the physiological fluctuation of the peak latency was extracted.

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Electric characteristics of a Millipore-DOPH membrane composed of a Milliporefilter whose pores are adsorbed with a synthetic lipid analogue, dioleylphosphate (DOPH) have been investigated. The oscillation phenomenon of the membrane resistance produced by a pressure stimulus is simulating a part of a mechanoreceptor membrane. It is difficult, however, to maintain changes of the resistance more than 3 days, because the DOPH embedded in the Millipore filter that serves as a supporting body dissolves easily in a salt solution. In this study, a PVC (polyvinylchloride)-DOPH new artificial membrane which used a high-polymer PVC instead of the Milliporefilter was made. Durability of the membrane improved in this substitution for a long period more than 120days. An electric equivalent circuit of a cell membrane is simply shown by an electric resistance and capacitance. The Millipore-DOPH membrane had characteristics of a Ca²⁺ion sensor in the former study. This paper experimentally makes it clear that the electric resistance and capacitance of the new PVC-DOPH membrane changed with Ca²⁺ion as observed in the Millipore-DOPH membrane, and that this characteristic of the PVC-DOPH membrane was kept for long. Futhermore, responses of the electric resistance and capacitance to the concentration of five basic taste substances, in addition to Ca²⁺ion, i. e., a sucrose (sweetness), a NaCl (saltiness), a HCl (sourness), a quinine (bitterness) and a mono-sodium L-glutamate (umami) were investigated by the new artificial membrane. These results suggest that the PVC-DOPH membrane had a possibility to be applied to a taste sensor material which is excellent in durability.

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We have developed a portable measurement system for automatic transcutaneous blood-glucose monitoring by adopting the Suction effusion fluid (SEF) as sample. The SEF is transcutaneously sampled by sucking in a corneous layer-stripped skin with a slight invasive procedure. The glucose concentration in the SEF shows good correlation with that in serum. This automatic system consists of a main body and a suction apparatus. Each parts are easily fixed on waist and arm with belt for human usage. Glucose concentration in the SEF was measured with a miniature Ion Sensitive Field Effect Transistor (ISFET) glucose sensor. This sensor can continually measure glucose concentration in a very small amount sample. A rotary valve for 5μl sampling, a sensor apparatus with an ISFET glucose sensor and a stirring unit, and small, low-power pumps were originally developed. They realized this automatic and portable system. The present system was applied to white rabbits during glucose loading. The glucose concentration in SEF was automatically measured every 15 minutes for about 3 hours with this automatic system, then compared with that from a different position on the same rabbit with manual suction apparatus. The each result with these procedures showed almost the same. This automatic system is expected to achieve a great contribution to managing glucose monitoring in human, such as diabetic pacients.

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In recent years, the number of bone marrow donors for bone marrow transplants has been increasing in advanced nations. Mainly, the Lymphocyte Citotoxicity Test (LCT) is used for the typing of HLA class I for many these volunteers. However there are two problems with LCT. (1) HLA typing with LCT requires a high technician skill. Therefore, LCT takes much money and labor, and cannot come into wide use. (2) If it is suggested that Complement do not act on some HLA immune complexes, LCT would have the disadvantage of not being adaptable for the multi type character of HLA class I. In order to realize an automatic HLA class I analyzer, we have developed an experimental equipment using following technologies. a. Auto separating leukocyte from peripheral blood. b. Positive Lymphocyte segregation in stead of using Complement. c. Positive Lymphocyte counting instead of using Microscope. d. Computer programming of HLA typing theory. Examination by an experimental equipment showed that HLA type of major sample Leukocyte went together the result of LCT. However there were some disparity of HLA type each another between the experimental equipment and LCT. These results suggest that an possibility of realizing of HLA Auto Typing Equipment will be approved, never the less above some disparity.

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We have been developing a flexible infrared optical fiber for CO₂ laser, and studying applications of CO₂ laser for dentistry. This paper contains two sections, developing a hollow waveguide, outer diameter is smaller than 0.6mm, for endodontics and its application for 4 types of oral bacteria. We developed a new 50% transmittance tip by the hollow waveguide, 20mm length, 0.5mm inner dimeter, polished and Au-coated inside. By simulating the bactericidal effect, we used this laser tip to irradiate energy of 5 to 40J with 5W*10ms pulses. The results indicated that the reducing rate of all oral bacteria was depend on the irradiated energy. Above 15J energy, the reducing rate of each bacteria was more than 90%, and over 25J, it was more than 99%. Our results suggest CO₂ laser has a superior bactericidal effect and the laser has a possibility for endodontics use. However, when we apply the laser therapy for the root canal, it is also necessary to clarify the thermal effect against the surrounding tissue.

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We are developing an electrolarynx of implant type controlled by the EMG of the sternohyoid muscle. In this paper, first of all, we researched the possibility that speech functions such as pitch frequency and voiced and unvoiced sounds can be voluntarily controlled by the EMG of the sternohyoid muscle. In addition, we developed an electrolarynx controlled by the EMG of the sternohyoid muscle, and examined the properties of the electrolarynx. For this purpose, we performed three experiments to test the physical properties of the EMG of the sternohyoid muscle assuming the following conditions. First, the on/off control of the vibrator of the electrolarynx is synchronized with the activity of the sternohyoid EMG. Second, the higher pitch frequency of the electrolarynx is produced according to the lower amplitude of the sternohyoid EMG, and vice versa. Third, the period of firing or not firing of the sternohyoid EMG corresponds to the period of voiced sound or unvoiced sound of the electrolarynx. As a result of the experiments, we found that the on/off of the vibrator, the pitch frequency and the voiced/unvoiced sounds of the electrolarynx can be controlled by using the sternohyoid muscle. Then, we performed the same three experiments using the developed electrolarynx. We found that the electrolarynx controls the on/off of the vibrator and the pitch frequency and may control the voiced/unvoiced sounds. This study may aid the development of an implant type electrolarynx in the future.

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