Left ventricular (LV) pressure, especially LV end-diastolic pressure, is a significant parameter for the clinical diagnosis of heart diseases. And the elastic modulous of the LV wall has an important role in LV function. In this paper, we noninvasively estimate the LV end-diastolic pressure and the elastic modulus of the LV wall. If we obtain the instantaneous mode-2 eigenfrequency of a small vibration and the average radius and thickness of LV, we can noninvasively estimate the LV end-diastolic pressure and the elastic modulous of the LV wall by combing the Mirsky's method, which evaluates the elastic stiffness of the left ventricle, and our proposed method, which evaluates the LV myocardial elasticity. We transcutaneously measure small vibration signals on the LV wall by ultrasound and calculate the LV instantaneous mode-2 eigenfrequency which is determined from time-frequency distribution by applying the short time Fourier tranform (STFT) to the small vibration on the LV wall. We estimate the LV end-diastolic pressure for four patient, (a) 60-year-old, male, mitral incompetence, (b) 57-year-old, male, dilated cardiomyopathy and myocardial ischemia (inferior), (c) 61-year-old, female, dilated cardiomyopathy, (d) 44-year-old, male, dilated cardiomyopathy. The estimated LV pressure, p(t), is compared with the actual pressure, p(t), which is simultaneously measured by the cardiac catheterization. As a result, we confirmed that we can estimate the LV end-diastolic pressure by bias error, -1.6mmHg, and the standard deviation, 3.2mmHg. At the same time, the elastic modulus of the LV wall is estimated from the chest surface by ultrasound. The results of four patients are, (a) 97kPa, (b) 36kPa, (c) 115kPa, (d) 90kPa, respectively. And the LV elastic modulous of (e) 25-year-old, male, normal is 26kPa. The elastic modulus of the LV wall of four patients are higher than that of normal. Although there are several assumptions of our proposed method, we can demonstlate the possibility of noninvasive estimating the LV end-diastolic pressure and elastic modulus of LV wall.

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We have developed an analyzing method to identify the subcomponents (Bereiteschaftspotential; BP, intermediate slope; IS, negative slope; NS') of readiness potentials (RPs) which represent the charging and the discharging processes of neural units in the cascade-type information processing model. In previous studies, parameters of model functions for the subcomponents were set only by the cut-and-try technique which required a great deal of skill. In this study, we proposed a new method to estimate the parameters using a three layered artificial neural network (ANN). Using the back propagating errors, the ANN learned optimal mapping from digitized waveforms of the RPs to initial sets of the parameters for components identification procedure. From these initial parameter sets, we could generate the well fitted components of the RPs with a few efforts. The proposed method greatly contributes to efficient identification of the subcomponents in the RPs.

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Mechanical properties of the healing tissue of incised wound in the rabbit ear were studied after irradiating pulsed high-frequency electromagnetic field for 7, 14, and 28 days. Thirty five rabbits were used for the experiments; 5 rabbits were used to obtain normal data, and 30 animals were used to expose pulsed high-frequency electromagnetic field. In each ear of the 30 animals, a longitudinal skin incision of 300μm in depth and 30mm in length was made at the location between 75mm to 45mm proximal from the tip of the ear, and 20mm from the lateral edge of the ear. A print coil for the irradiation of electromagnetic field was attached onto one of the ears in each animal; the other ear was attached with no coil. The electromagnetic field having a frequency of 10MHz was intermittently burst for 50μsec with a resting time of 50μsec and was irradiated throughout the experimental period. The source current supplied to the coil was 100mA_p-p in 15 animals and 200mA_p-p in the other 15 animals. On the 14th day, thickness of the wound at the irradiated side was significantly less than that at the non-irradiated side. Tensile strength of the healing tissue at the irradiated side was significantly greater than that at the non-irradiated side at 14 and 28 days in the case of 100mA_p-p and at 7 and 28 days in the case of 200mA_p-p. Relative tensile strength, i. e. the ratio of the tensile strength at the irradiated side to that at the non-irradiated side, was greater with 200mA_p-p of supplied current than with 100mA_p-p at 7 and 28 days. These effects indicate that the pulsed high-frequency electromagnetic field enhances the healing of incised wound and that stronger irradiation is more effective for healing.

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The effects of pulsed high-frequency electromagnetic field on the healing of open wound were studied in the rabbit ear by the measurement of the defect area and blood flow of the healing tissue during a period of 28 days. In each ear of 6 rabbits, circular open wounds were made using a 6mm diameter surgical biopsy punch at two sites; the centers of the wounds were located at 52.5mm and 67.5mm proximal from the tip of the ear and 20mm from the lateral edge of the ear. A print coil for the irradiation of electromagnetic field was attached onto one of the ears in each animal; the other ear was attached with no coil to obtain data for comparison. The electromagnetic field having a frequency of 10MHz was intermittently burst for 50μsec with a resting time of 50μsec and was irradiated throughout the experimental period. The source current supplied to the coil was 200mA_p-p. Every 7 day after making wound, defect area in each wound was measured with an image analyzer, while blood flow in the healing tissue was measured using a laser Doppler flowmeter having the illuminating area of 2mm in diameter. The defect area was significantly smaller at the irradiated side than at the non-irradiated side at 14 and 21 days. In addition, on the 21st day, the areas at the proximal site were significantly smaller than those at the distal site regardless of irradiation or non-irradiation. The blood flow was highest at the irradiated side both at the distal and proximal sites on the 7th day. In addition, the blood flow at irradiated side of both sites on the 7th day, and of proximal site on the 21st day, were significantly higher than those at the non-irradiated side. These effects indicate that the pulsed high-frequency electromagnetic field enhances the healing of wound due to the increased blood flow in the healing tissue.

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Heart rate variability data contains well-defined rhythms which have been shown to contain physiological information. The spectral components of heart rate variability data can be used clinically to assess the autonomic nervous system. The FFT, MEM and AR methods are used for calculating power spectral density functions, and, a stationary time series is needed for several minutes. These methods cannot analyze the transient change in frequency information. The wavelet transforms shows good time and frequency resolution, especially for the analysis of non-stationary signals. In wavelet transforms, a time series for 20 or 30 seconds is necessary. Therefore, frequency information is not obtained for 20 or 30 seconds from the starting point of the measurement. Moreover, the frequency information around the transient change is the average value before and after the change. We proposed a method for extracting accurate frequency information from the starting point of the measurement or from the part of transient change, when the heart rate variability is analyzed using wavelet transforms. The effectiveness of this method was confirmed by applying our results to the simulation data and R-R interval time series data. The proposed method determined the transitional change in the frequency information, which is not possible using classical methods. The transitional change in the autonomous nerve function were estimated using our method.

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An implantable stimulation unit for multichannel functional electrical stimulation (FES) system applied to the restoration of motor functions has been developed. The stimulation unit implanted in the body is externally controlled and powered by an encoded carrier radio frequency of 1.23MHz and a continuous frequency of 123kHz, respectively. A new type of RF coil utilizing amorphous magnetic fibers was introduced to realize high efficiency of power transmission. Using this RF coil, electric power of 370mW can be transmitted at an efficiency of about 55% at a coil space of 10mm. The maximum power consumption of the implanted unit is about 300mW, and the transmitter supplied with four cells of 1200mAH Ni-Cd battery can operate continuously for more than 10 hours. The information is transmitted through a pair of twisted coil which prevents magnetic interference by power transmission frequency. Up to 16 independently controlled stimulus output channels are provided, with output channel selection and stimulus pulse amplitude controlled externally by the information transmitted in a packet style. The information to check operating states of the implanted unit is also returned. This bi-directional communication system can increases reliability and safety of the implantable FES system. Miniaturization of the implanted unit has been realized by using MCM (Multi-Chip-Module) for analog circuit and FPGA (Field Programmable Gate Array) for digital circuit, respectively. The size of the packaged unit is 50mm×65mm×11mm.

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The usefulness of a remote monitoring system that uses a PHS (Personal Handy-phone System) and a GPS (Global Positioning System) for artificial heart-implanted patients was investigated. The PHS has several advantages: high-speed data transmission, and little electromagnetic interference with medical devices, etc. In our system, patients have the PHS and a mobile computer for data transmission control between an implanted controller and a host computer in the hospital, and also a GPS receiver for location of patients. Information on motor rotational angle and motor current of the implanted motor-driven heart is fed into the mobile computer from the implanted controller according to 32-bit command codes from the host computer. Motor current and motor rotational angle data from inside the body are framed together by a control code (frame number and parity) for data error checking and correcting at the receiving site, and the data are sent through the PHS connected to the mobile computer. GPS positioning data and battery data from the mobile computer are also sent to the host computer with control codes. The host computer calculates pump outflow and arterial pressure from the motor rotational angle and motor current values and displays the data in real-time waveforms. The host computer also displays patient's position on the map and batteries' condition. The results of this study showed that accurate data could be transmitted from the subjects while they were walking or driving a car to the host computer at a data transmission rate of 32kbps, and that driving condition of the artificial heart and subject's position could be remotely monitored on the host computer. This system is useful for remote monitoring of patients with an implanted artificial heart.

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It has been conceived that the appearance of spiral waves in the heart is one of the main causes of fatal reentrant arrhythmia such as tachycardia and fibrillation; generation and sustenance of spiral waves in the heart correspond to tachycardia and their breaking up is regarded as the transition of tachycardia to fibrillation. In this study, in order to clarify the mechanisms of functional reentrant tachyarrhythmia, we investigated the dynamics of spiral waves in three dimensional homogeneous media model by computer simulations. The model is composed of one million cells. Each cell is described by FHN equations and is connected each other in cubic lattice. As a whole, the medium forms a simple rectangular parallelepiped or a shape of human ventricle. Refractory period and conduction velocity were selected as parameters to characterize the dynamics of spiral waves. It was shown that, in the case of two dimensional homogeneous media, the spiral waves sustain stably, while the spiral waves in three dimensional media show three types of behavior such as sustaining, vanishing and breaking up by the model parameters. We discussed the dynamics of three dimensional spiral waves by examining the critical thickness of the model media for breaking up and the behavior of filament which is three dimensionally connected two dimensional cores. It was also shown that even in the homogeneous media, reversing the direction of rotation of spiral waves which is observed on the surface of the heart and the difference of potential patterns between the epicardium and the endocardium could be explained by the property of snaking phenomena of filaments. Finally, we studied the process of excitation propagation on the surface and in the interior of the ventricle using the ventricular shaped model and it turned out that the dynamics found in the simplified shape model is preserved in the complex ventricular model.

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We demonstrated a simultaneous measurement of refractive index n and thickness t of biological tissue by the low-coherence interferometry. Using the object scanning method, refractive index and thickness measurement were successfully performed for a chicken tissue, human tooth and a nail with an accuracy of ≤1%. Especially, refractive index of an enamel and a dentin are measured separately. We suggest that this method is applicable for simultaneous measurement of n and t of multiple layers. Simultaneous measurement of n and t of a crab skin with multiple layers are also demonstrated.

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Muscles not only have contractile function but also viscous elastic like property. The viscous elastic like property was observed as the force in response to stretching the contracting muscle. While there are many reports concerning stretch reflex or stiffness, the viscous elastic like property originated from the contractile mechanism itself has not been studied enough. The purpose of the present study is to investigate the relation between EMG (electromyogram), isometric force and stretch evoked force. Three normal male subjects were instructed to change isometric contractile force of their thumb tracking a visible target displayed on an oscilloscope. Sinusoidal oscillation of the target was presented to the subjects. While the subject was tracking the target, length perturbation of short duration was applied to the thumb at random time. The thumb was extended with constant velocity 0.15m/s for 20ms, maintained for 30ms at the extended position and then returned to the previous position. The position and flexing force of the thumb and the EMG of flexor pollicis longus muscle were measured. By subtracting both isometric force and the force of passive components from the measured force response to stretch, the stretch evoked force generated by viscous elastic components was calculated. The stretch evoked force at 15ms after the onset of length perturbation was examined; the force at this time did not contain the force increased by the stretch reflex. The stretch evoked force followed the IEMG with a short latency when the isometric force varied sinusoidally. It was shown that the viscous elastic property of muscles did not depend on the isometric force.

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This paper describes a method for detection of breast carcinoma regions from hematoxylin and eosin (HE)-stained breast tumor images using artificial organisms. In this model, the artificial organisms can survive, obtain energy and produce offspring in the carcinoma regions. Organisms in other regions lose energy by the movement and die during searching. As a result, carcinoma regions are detected by the collective behavior of artificial organisms. The artificial organisms have the differentiation of function between “self” and “non-self” which is inspired by the biological immune system. The texture features of nuclei regions in normal mammary gland and those of breast carcinoma regions in malignant tumors are treated as “self” and “non-self”, respectively. This model consists of two stages of operations for detecting carcinoma regions, the learning and searching stages. At the learning stage, the nuclei regions are roughly detected and each organism's texture feature values are treated as candidates of antibodies. At the searching stage, each organism's environment, whether the target region is “non-self” (carcinoma) or not, is investigated using the texture features of antibodies and those of “self”. The method developed was applied to 11 cases of test images and discrimination between malignant and benign tumors by the artificial organisms was successful in all cases. The proposed method has the following advantages: the candidates of antibodies for the evaluation of carcinoma regions are decided automatically at the learning stage in every input image. Therefore, this model can successfully detect carcinoma regions without affecting the variance of color tones in stained images which depends on the tissue condition and the degree of malignancy in each breast tumor case.

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