生体医工学
Online ISSN : 1881-4379
Print ISSN : 1347-443X
ISSN-L : 1347-443X
41 巻, 4 号
選択された号の論文の37件中1~37を表示しています
  • 永岡 隆, 武田 朴, 内山 明彦
    2003 年 41 巻 4 号 p. 239-249
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    We developed a three-dimensional position sensor that can measure the position of a capsule in the digestive tract. For the purpose of inspecting a new position measurement algorithm, we first developed a prototype wired capsule-type sensor that is capable of being swallowed. Our ultimate goal will be to develop a wireless sensor. The current sensor is applicable for medical capsule devices, such as capsule endoscope. The position of the sensor was detected using mutual induction. In order to maintain the electromotive force induced at secondary coils in the sensor constant, the current flowing into the primary coil was regulated using feedback control. The position of the sensor was measured stably using the feedback control, even when the sensor was relatively far from the primary coil. The position of the sensor was determined from the current flowing into the primary coil. As a result of evaluating the accuracy of the wired sensor in vitro, the error was 2.90±2.10 mm (Ave.±S. D. ) in a range of up to 1m from the magnetic field generator. Moreover, using a new position compensation algorithm, we were able to remove distortion caused by the magnetic field.
  • 大脇 崇史, 武田 常広
    2003 年 41 巻 4 号 p. 250-261
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Brain magnetic responses were measured with a 64-channel MEG (magnetoencephalography) system while subjects were engaged in a button-press task in response to random-dot stereogram (RDS) stimuli in order to study the human brain activity related to the depth perception process with high time resolution. Reaction time (RT) was also measured to quantify the temporal properties of subjective depth perception simultaneously. The RDS stimuli were characterized by disparity changes in a rectangular region of the right visual field, and two types of RDS stimuli—crossed disparity stimulus (Stim-C) and uncrossed disparity stimulus (Stim-U) where the disparity changed respectively from zero to crossed and from zero to uncrossed—were used. The button-press task consisted of two conditions: one with the depth judgment of the RDS stimuli and the other without the depth judgment. For the former condition, the subjects had to judge whether the rectangular region appeared in front of (Stim-C) or behind (Stim-U) a screen before pressing a button. From the experimental results, the first MEG peaks were observed between 100 and 180 ms after the onset of the RDS stimuli, and the estimated sources during the latency range were mainly localized in the left occipital lobe. In the depth judgment condition, while the median RT for Stim-C was significantly faster than that for Stim-U, there was no significant difference in the latency of the first MEG peaks between the two RDS stimuli. These results suggest that the first MEG peaks arise from brain activity related to relatively lower visual information processing whose latency does not differ between the two RDS stimuli.
  • 福元 剛智, 神口 達也, 大庭 茂男, 二見 亮弘, 田中 治雄, 星宮 望
    2003 年 41 巻 4 号 p. 262-272
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Acupuncture points have been found in low electrical resistance areas compared to the surrounding tissue. The significance and details of the singular electrical properties of the acupuncture points are not clear at present. In most published studies about the electrical properties of the skin, there have been several problems related to measuring skin impedance. More careful consideration of the electrical properties of the skin and reliable measurements are needed. In this report, in order to improve the reliability of the measurements and clarify the electrical properties of the skin around the acupuncture points, we examined the existence of some parameters of the circular arc law that are little affected by the electrode area. Additionally, we performed multiple and simultaneous measurements of the skin impedance locus around the acupuncture points using the new method we propose. For evaluating the differences in electrical properties of the skin, we estimated the parameters of the circular arc law. As a result, we found that the parameters of the circular arc law (τm, β) are little affected by the electrode area. We also found that the differences of detailed electrical properties of the skin between acupuncture point and non-acupuncture point could be evaluated quantitatively by the parameters of the circular arc law, Z0 and τm. These results suggest that the parameters of the circular arc law, τm, are useful in determining the location of the acupuncture points.
  • 本井 幸介, 田中 志信, 野川 雅道, 山越 憲一
    2003 年 41 巻 4 号 p. 273-279
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    The measurement of physical activity is one of key subjects in fields like rehabilitation and gerontology. Moreover, ambulatory monitoring of changes in human posture in daily life will provide useful information for evaluating results obtained by Holter-type ECGs or ambulatory blood pressure monitors. From this viewpoint, several instruments have been developed which can estimate physical activity in daily life. For example, the Actigraph is a wrist-worn commercially available activity monitor that measures the movement of the subject's hand, and has been widely used for evaluating sleeping disorder. Another example is a system that measures acceleration of the thigh or waist using an accelerometer or gyroscope for rough estimation of a subject's behavior during daily life. However, these instruments have limitations for detailed analysis of posture change and cannot be used for the simultaneous measurement of walking speed, which is a useful index for evaluating the independence of elderly individuals. Taking these factors into consideration, we developed a new sensor system that accurately measures human posture together with walking speed. The system is composed of three accelerometers and one gyroscope. The accelerometers are for posture measurement, and are attached to the subject's waist, thigh and leg, respectively, so as to measure the angle in terms of gravitational direction of each part. The gyroscope measures the change in thigh angle when walking in order to estimate walking speed. The accuracy of the system for posture and walking speed measurements was experimentally evaluated using ten healthy male subjects. According to the results, it was clearly demonstrated that, using the system, human posture in the sagittal plane (±180 deg) and walking speed (0.2 m/s-2.0 m/s) can be measured with reasonable accuracy, and that the system is a useful means for analyzing human activity during daily life.
  • 赤澤 堅造
    2003 年 41 巻 4 号 p. 281
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
  • 片山 俊郎, 佐藤 哲大, 湊 小太郎
    2003 年 41 巻 4 号 p. 282-287
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    This paper proposes two indices in order to quantitatively evaluate the physiological function of the bile acid dynamics of a supplement. We describe the mathematical model for an enterohepatic circulation mechanism of bile acid by conation of the bile acid endurance test. By simulating drifting time course for loading bile acid in the serum using linear differential equations, we extracted the bile acid absorption rate from intestinum tenue and the bile acid uptake rate from portal system in liver as the two indices of the serum bile acid level. We utilized powder tablets of layer as an example of supplements and conducted bile acid endurance tests for 1 wk before and after taking the tablets using six subjects whose serum cholesterol rose an inconsiderable amount. We reviewed the utility of these two indices through detailed experiments. There is a significant difference in the indices between before and after taking the supplement. In addition, after taking tablets, the serum total cholesterol level falls to a clinical normal level. This experiment shows that the indices, which are estimated from simulation of a bile acid endurance test, are useful to quantitatively evaluate the lipid drifting effects of supplements.
  • 海老川 慎, 鈴木 直行, 菅原 俊継, 木村 主幸, 三澤 顕次, 有澤 準二, 五十嵐 治
    2003 年 41 巻 4 号 p. 288-294
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    The nucleic acid amplification test (NAT) has been used as a means for detecting viruses in blood. Using this procedure increases the safety of blood products. However, detection is theoretically impossible if the blood is contaminated with only a minimal viral concentration (less than 102 PFU/mL). As a result, viral infections continue to occur through the use of blood products. A viral detection method with a higher sensitivity than NAT is required to prevent vial infections such as hepatitis B, hepatitis C and acquired immune deficiency syndrome (AIDS) from occurring. We propose in this paper a viral detection method that uses a hollow-fiber membrane made of polypropylene coated with metal. Using this method, the membrane captures the virus and releases genes in the following manner: Herpes simplex virus type 1 (HSV) in samples was captured by the membrane when the samples were aspirated through the membrane. To lyse the capsid covering the viral gene, the membrane was soaked in a lysis solution containing 1% SDS and 10mM NaOH. After that, the membrane was set in an electrophoresis bath as a cathode. An electric field was applied to the membrane and HSV genes were released from the membrane because the genes had a negative charge. These genes were amplified by polymerase chain reaction (PCR). PCR products were detected by electrophoresis. In this paper, we succeeded in detecting a virus from HSV suspensions. The end point for detectable concentration of the virus was 30 PFU/mL. This viral concentration level is not possible using the NAT, which has a detection sensitivity of 102 PFU/mL. Using the method discussed here, it was possible to detect the viral concentration following aspiration. The sensitivity of this virus detection method is higher than that of NAT. We believe that this method has the possibility of reducing the number of viral infections through blood such as hepatitis B virus and so on.
  • Naotaka NITTA, Tsuyoshi SHIINA
    2003 年 41 巻 4 号 p. 295-305
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Ultrasonic tissue elasticity imaging, which displays stiffness distributions such as strain and Young's modulus based on the detection of echo shifts under quasi-static deformation applied to the body surface using an ultrasonic probe, is useful for the detection of lesions, such as cancers, that affect the stiffness of tissue. While the viscoelasticity of tissue makes diagnosis by elasticity imaging difficult, because the image quality depends on the rate of deformation, the differences in viscoelasticity reflect the tissue type and state of degeneration. In this paper, with the aim of achieving tissue discrimination based on viscoelasticity, an ultrasonic imaging technique using the hysteresis parameter (HP), which characterizes the local viscoelastic hysteresis, is investigated. In order to obtain the HP, quasi-static and cyclic loading and unloading to the body surface are applied. As a result of the direct mechanical testing of porcine thigh muscle before and after formalin immersion, the post-immersed HP value decreased to about 46% of the pre-immersed HP value. Moreover, the ability to distinguish tissue components has also been confirmed. Therefore, the sensitivity of the HP in discriminating tissue degeneration and its components is found to be adequate. In the HP imaging experiment involving human breast diagnosed as having a fibroadenoma, while the conventional B-mode and strain images depict the fibroadenoma as circular and homogeneous regions, the HP image depicts these as non-circular and inhomogeneous areas. From these results, HP imaging is proposed as a method for providing different information from that provided by conventional imaging such as B-mode and strain images.
  • 加藤 陽子, 姫野 龍太郎
    2003 年 41 巻 4 号 p. 306-313
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    The shear stress on endothelial cells influences blood vessel disease. This stress depends on blood flow velocity and its distribution near the internal wall of a blood vessel. Blood flow velocity can be measured by the phase contrast method in magnetic resonance imaging, where the phase of the signal reflects the velocity. There are several parameters that influence the accuracy of velocity measurement: dephasing, relaxation time, and sequence parameters. Although the effects of these parameters have been elucidated using measured results at a particular point, the shape of the velocity profile needs to be evaluated in order to identify the shear stress on an endothelial cell. From the results of this study, we propose the parameters that define the velocity profile in the laminar flow regime and evaluate their effects. The results are then applied to evaluate the velocity profile in a U-shaped tube. We then propose the mean and standard deviation at various distances from the center of the tube as the parameters for expressing the velocity profile, because the mean value gives a parabolic distribution and the standard deviation is proportional to the distance from the center in the laminar flow regime. The relaxation time, repetition time, velocity encoding number and oversampling or phase-encoding direction can influence the velocity profile. The velocity encoding number is the velocity when the phase is 180 degrees. Similar effects were observed for the flow in a U-shaped tube. Based on the results for the laminar flow regime, the velocity profile in a U-shaped tube could therefore be evaluated more accurately using the phase contrast method.
  • 荒船 龍彦, 三嶋 晶, 佐久間 一郎, 稲田 紘, 柴田 仁太郎, 中川 晴道, 山崎 正俊, 本荘 晴朗, 児玉 逸雄
    2003 年 41 巻 4 号 p. 314-320
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    It is well known that electrical pacing is used as a method for prevention and termination of arrhythmia such as ventricular tachycardia (VT) or fibrillation (VF). However, many clinical and experimental studies reported that external stimulation resulted in the termination of reentrant activity and also re-initiation of new reentry. The dynamics of interaction of cardiac excitation waves with waves initiated by external pacing are poorly understood. When point stimulation was applied at the cardiac myocardium, a complex depolarization and hyperpolarization pattern called “Virtual electrode polarization” was derived during stimulation. To understand cardiac excitation propagation at defibrillation, we developed a high resolution optical mapping measurement system of action potential propagation and a micro electrical stimulus system to observe a cardiac excitation pattern at the point of stimulation applied during VT. Isolated rabbit hearts, stained with the voltage-sensitive dye, di-4-ANEPPS, were illuminated by high luminance bluish-green LEDs. The emitted fluorescence was long-pass filtered at a wavelength of 600 nm and captured by a high-speed digital video recorder. The recorded image was transferred to a PC and the digital image processed. Our system achieved both spatial resolution (0.11 mm/pixel) and temporal resolution (0.89 msec/frame). The stimulus electrode was a micro platinum wire φ 0.1 mm implanted into a transparent acrylic board and φ 0.04 mm coated copper wiring, so it was able to be measured by an optical mapping system during stimulation. Using this mapping system, we measured the initiation process of virtual electrode induced polymorphous reentrant activity derived by point stimulation during VT with high temporal and spatial resolution.
  • 塩澤 成弘, 岸場 道郎, 有馬 秀一, 牧川 方昭
    2003 年 41 巻 4 号 p. 321-327
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    We developed a gait simulator, which can reproduce various types of walking such as, walking straight, turning, going up and down stairs and other types of motion. The main component of this gait simulator is two foot plates driven by three arms and actuators. For example, each foot plate follows the foot during the swing phase and pulls it back during the stance phase while the user is walking straight. This gait simulator, however, has one weakness in that it cannot sufficiently follow gait mode change in walking start and stop transitions. To solve this problem, it is necessary to predict the change of gait mode to follow the transition perfectly. In this paper, we chose the start and stop of straight walking and tried to measure the gait mode transition. To do this we focused on the anterior bending of the upper body. It was expected that the body bends forward before walking starts and bends back before walking stops. In the experiment, the distance between the upper body and the center of gravity (COG) was measured. The measurement of this distance proved useful in knowing the transition of straight walking. We examined the result again on the gait simulator. The implanted control algorithm of the gait simulator is as follows: It was predicted that when walking starts, two foot plates pull back the feet and when it stops, so do the plates. Results show that the gait simulator was able to reproduce the walking start and stop transition by this prediction algorithm.
  • 藤原 義久, 黒田 征平, 岡田 志麻, 松浦 英文, 安田 昌司, 飯田 健夫, 牧川 方昭
    2003 年 41 巻 4 号 p. 328-334
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    In this paper, chaos analysis was used and examined for the possibility of sleep stage estimation from a nonstationary element included in long time heart rate variability. The experiments were conducted using nine normal, healthy males aged between 21 and 38. Each subject's EEG, EOG, EMG, and ECG were measured during six-hour periods between 12 midnight and 6 a.m. Furthermore, by identifying the sleep stage of each subject based on the international standard, and extracting the most remarkable REM and SWS stages, chaos analysis was conducted from the RRI in each sleep stage. As a result, the max lyapunov exponent and KS entropy in REM increased in a statistically significant manner (p"0.01). In addition, through the results of statistical analysis between all sleep stages and a max lyapunov exponent, KS entropy indicated the possibility of estimating the sleep stage by using a non-stationary element in the heart rate variability. Future work will improve the accuracy of sleep stage estimation using multiple parameters including a non-stationary element in order to realize a sleep stage monitoring device that can be used easily in normal daily life.
  • 塗木 淳夫, 牧原 聡, 湯ノ口 万友
    2003 年 41 巻 4 号 p. 335-341
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Using somatosensory evoked potentials (SEP), we investigated the effects of auditory stimulation and exercise on the human somatosensory area. SEP elicited by the right median nerve stimulation at the wrist of 19 healthy volunteers was recorded from Fpz and P3'. Then the amplitude and latency of N20 and P25 included in the early components of SEP were investigated. In the first experiment, we observed the relationship between sound pressure level and SEP. The sound was composed of nine train pulses with 0.1ms durations. Between the onset of each pulse was 6ms. The sound pressure level ranged from 50 to 100dB (SPL). Auditory stimulation was presented to both ears using headphones. In the second experiment, the effects of auditory stimulation on the early components of median nerve stimulation were examined during 10% maximal voluntary contractions of thenar eminence, and right median nerve stimulation at the wrist was given after auditory stimulation. The interval between auditory stimulation and median nerve stimulation ranged from 0-50ms in 10ms increments. These interstimulus intervals were randomly intermixed with control trials which were without auditory stimulation. Auditory stimulation, which was 50dB higher than the auditory threshold, suppressed the amplitude of N20. During exercise, auditory stimulation strongly suppressed the amplitude of N20 when it preceded the electric stimulation to the median nerve at 20ms. These results show that auditory stimulation that is 50dB higher than the auditory threshold inhibit somatosensory activity. Furthermore, inhibitory action on the somatosensory area by auditory stimulation seems to be associated with gating phenomenon.
  • 船瀬 新王, Allan K. BARROS, 大熊 繁, Andrzej CICHOCKI, 八木 透
    2003 年 41 巻 4 号 p. 342-351
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    We have researched saccade-related EEG to investigate the brain function in saccadic eye movement. In previous studies, we analyzed saccade-related EEG using an ensemble averaging method. However, the ensemble averaging method has some problems. First, EEG signals must be recorded repetitively under the same conditions. In addition, the ensemble averaging method can possibly extinguish EEG signals which have unstable latency between a trigger and the peak point of an EEG signal. Therefore, we applied saccade-related EEG to an independent component analysis (ICA). ICA can extract a signal from mixed signals through the assumption that source signals are mutually independent and recorded signals are mixed lineally from source signals. ICA can analyze non-processed signals. Therefore, ICA overcomes the problems of the ensemble averaging method. In this field, many algorithms were proposed. “Fast ICA with Reference signal (FICAR)” was selected, however, because this algorithm can extract a desired signal close to a reference signal. In this experiment, there were two tasks. The first (eye movement task) was that subjects move their eyes toward a visual target (LED) located on the right and left sides. The second (non-eye movement task) was that subjects do not move their eyes toward the visual target when it is turned on. EEG signals were recorded through electrodes arranged according to the international 10-20 method and were analyzed with the FICAR. Reference signals had one peak and each reference signal had a different peak time. EEG signals were analyzed with each reference signal. As a result, in the case of the eye movement task, the FICAR extracted independent components (ICs) which peaked just before saccade. Few ICs were extracted under the non-eye movement task. The features for peak timing, peak amplitude, and dependence on existence of saccade are the same as the features for the ensemble averaging results. The ICs extraction rate is 71.6% under the eye movement task and 25.2% under the non-eye movement task. The ICs were extracted by reference signals which peak just before saccade. Therefore the ICs are related to saccade-related EEG.
  • Phooi Yee LAU, Shinji OZAWA
    2003 年 41 巻 4 号 p. 352-359
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    In clinical applications, medical images are frequently fused together to improve the diagnostic accuracy, treatment planning and aid in surgical procedure. Image registration of medical images from different imaging modality according to diagnostic prescription has played an important role as a diagnostic-assisted tool in supporting diagnosis findings and their accuracy. This paper proposed a novel method for the modality-based medical image registration using multiple classifiers. In our approach, pre-processing is first employed to identify and preview input images by their modality and usage. Three classifiers are then chosen from the current literature: motion estimation, chamfer matching and mutual information. Each classifier is dynamically chosen to improve overall image registration results. The motion estimation (ME) classifier is used to comprehend and recover motion-blurred input images, while the chamfer matching (CM) classifier is used for calculating and improving registration alignment. Next, the mutual information (MI) classifier is selected to improve registration robustness for greater clarity and visibility. Experimental results reveal that using our approach and the combination of the three classifiers yields a robust and accurate registration with respect to motion-blurred and misaligned images for intersubject and intrrsubject study.
  • 星善 光, 斎藤 正男
    2003 年 41 巻 4 号 p. 360-368
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    In order to prevent mistakes, we improved the visibility of the alarm. But, many failures can be missed if the operator doesn't place trust in the machine. In this research, we built a model to increase operator reliability in the machine, thus enabling the detection of more failures. The alarm and machine fail or pass with constant probability. An operator can choose to put trust in the alarm or not as well as, and stop the machine if it is judged that the machine has failed. We calculated the miss rate for the system using the machine and alarm failure rates and the reliability of the operator. As a result, if the failure rate of the machine is small but the failure rate of the alarm and the reliability of the operator are large, then work capacity is decreased due to the misinformation. This, in turn, causes operators to ignore alarms. This problem is an important accident factor related to the reliability of machines used in the medical field.
  • 佐藤 雄亮, 松村 泰志, 中野 裕彦, 松村 憲和, 湊 小太郎, 紀 山枚, 陳 宇峰, 武田 裕
    2003 年 41 巻 4 号 p. 369-376
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    The exchange of patient information between medical institutions via the network is expected to improve the quality of medical services. We built a system which enabled doctors to send patient information extracted from the electronic patient record to doctors in other hospitals using a Web system. The security protection is essential for this system. We use SSL (Secure Socket Layer) to prevent the interpolation of patient information on the net and we authenticate doctors who access the web server by using IDs and passwords. Furthermore, the web server publishes a token called “patient information access ticket” which enables doctors to view patient information. This ticket is used for access control on the web server. A doctor who has a right to receive this ticket can transfer this right to other doctors. As a result, safe and flexible access control to patient information became possible. We built this system in Osaka University Hospital and confirmed the usability of it.
  • 東福寺 幾夫, 土橋 康成, 菊池 久和
    2003 年 41 巻 4 号 p. 377-383
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    The objective of telepathology is to realize a pathologist' s diagnosis in observing microscopic images transmitted from remote sites. Telepathology systems require presentation of proper images to achieve correct diagnosis. Presentation of proper images requires two points. The first is that images have to reflect the intention of a remote pathologist in both positioning and magnification to capture images of a specimen. The other is that images should have enough resolution for diagnosis. The former problem was solved by a modeling method for the pathological observation flow. That is an observation methodology model starting at the observation of the entire image of a specimen followed by careful and successive magnifications of particular areas of the specimen. An observation history can be modeled as a tree of observation events, and its root is the entire image of the specimen. The model was useful to construct a telepathology system between different types of terminals. The latter problem, that is, poor resolution of lower magnification microscopic images was pointed out by several telepathologists. We discussed the relationships between the resolution of an objective lens of a microscope and pixel pitch of an imaging device to account for digital images to have the same level of resolution as the naked eye. The result indicates that the ideal pixel pitch of imaging devices should be equal to half the product of the resolution in an objective lens and the magnification ratio of a microscope. We found that the pixel pitch of the actual camera installed in our telepathology system is so big compared with the ideal pitch in lower magnifications that it causes the insufficient resolution. A precise matching between the optical lens system and imaging device can improve the situation.
  • 橋本 真人, 土居 伸二, 熊谷 貞俊
    2003 年 41 巻 4 号 p. 384-391
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    The algebraic reconstruction technique (ART) solves image reconstruction problems, regarding them as simultaneous linear equations. This algorithm applies the sequential projection onto a hyperplane constructed by each equation. The ART is able to reconstruct images even if sufficient projection data is not obtainable. On the other hand, parallel computing algorithms suitable for the recently increasing multiprocessor systems are required. A parallel algorithm using simultaneous projection has been proposed by Censor et al. (2001). However, the original ART algorithm is not suitable for parallel computing because it uses sequential projection. In this study, we propose a new parallel iterative method using the ART algorithm. In this method, we divide the simultaneous linear equations into blocks that contain the equations obtained from one projection. Then we apply the ART algorithm to each block, and calculate the average of the solutions from them. This average is the solution of a simultaneous equation system, (i. e.), a reconstructed image. Evaluating the result of reconstruction simulations with our method, in terms of convergence speed and the quality of reconstructed images, verifies the high efficiency of the new method.
  • 佐藤 哲大, 菅 幹生, 湊 小太郎, 米倉 義晴, 椛沢 宏之
    2003 年 41 巻 4 号 p. 392-398
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    In this paper we propose a new technique for detecting a symmetrical axis in the human brain using two-dimensional MR images. Since MR brain images are non-invasive, they have been widely used in the diagnosis of brain diseases in medicine and the study of human brain functions. In such studies, there are many articles discussing the differences between the left and right hemispheres of the human brain. The purpose of detecting the symmetrical axis is to compare the differences between these two brain hemispheres. However, this symmetry is difficult to detect due to the development of lesions. Conventional methods of detecting the symmetrical axis cannot deal with these kinds of local asymmetry, resulting in false positives. Although prior research on the detection of the symmetrical axis or symmetrical plane of the human brain has been performed, most techniques are intricate, and thus unfavorable. In contrast, we have developed a novel method to find the symmetrical axis of the human brain with local asymmetry. Our method examines the center of gravity of each perpendicular line of the assumed symmetrical axis. If the assumed axis is correct, the center of gravity of each line correctly matches with the axis. On the basis of this idea, using the information derived from these lines, such as mean squared errors of the center of gravity, asymmetric parts are removed selectively by parameters we defined. Then we can determine the symmetrical axis irrespective to local asymmetry. Our method is applied to MR brain images and the results are reasonable regardless of the local asymmetry caused by lesions. We also considered the possible effects of the parameters we defined and conclude that our method is well suited for detecting the symmetrical axis in the human brain.
  • 早見 武人, 樋脇 治
    2003 年 41 巻 4 号 p. 399-404
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Computer simulations were conducted to investigate the relationship between the magnetic field induced by the action of a nerve fiber and the distribution of its source current. The normal component of the magnetic field on a sensing plane produced by an active nerve fiber was calculated. A contour map of the magnetic field showed four peaks. It was found that the interpeak distance orthogonal to the nerve fiber was affected by the distance from the sensing plane to the fiber, and the interpeak distance parallel to the fiber was affected by both the diameter of the fiber and the distance from the sensing plane to the fiber. A procedure to estimate the location and active part of the nerve fiber from the interpeak distances of the contour of magnetic field is proposed.
  • Takayoshi HOSONO, Misato NAKANO, Rie TERAI, Tomoko YAGISHITA, Ryuhei O ...
    2003 年 41 巻 4 号 p. 405-409
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Neuronal signal propagations from the optic nerve to the hypothalamus via the suprachiasmatic nucleus (SCN), which works as the center for generating circadian rhythm in the body, were analyzed using two-dimensional optic recording with a voltage-sensitive dye. When electric stimulation on the optic chiasma (OX) was applied to a slice preparation of rat brain including SCN, signal propagations from the vetrolateral SCN to dorsomedian SCN were successfully recorded by the optical recording system. The signals propagated dorsally along the third ventricle. The optic signals disappeared in the low Ca2+ and high Mg2+ artificial cerebrospinal fluid, which blocks synaptic transmissions. Signal propagation from the SCN to the hypothalamus was synaptically mediated. Application of the NMDA receptor blocker decreased the responses, and the application of a vasoactive intestinal polypeptide (VIP) antagonist also weakened the response. These results indicate that the NMDA receptor and VIP are involved in signal propagation in the SCN.
  • ―口蓋形状適応性―
    辻竜 之介, 松村 雅史, 野原 幹司, 舘村 卓, 和田 健
    2003 年 41 巻 4 号 p. 410-418
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    In the oral cavity, movement of the tongue in relation to palatal shape is important for smooth speech and swallowing activities. The present study analyzed adaptation of tongue force in relation to palatal shape based on measurements of tongue force (amount of force exerted by the tongue against the palate) and its action point (center of contact pressure). As a first step, methods for estimating the amount of tongue force and its action point were investigated based on palatolingual contact pressure as measured by a force-sensor-mounted palatal plate. Next, tongue force and its action point were measured in six healthy adults with an essentially symmetric palatal shape and with no speech or swallowing disorders. Results showed that during speech and swallowing, the action point of tongue force corresponded to the central aspect of palatal shape. Furthermore, palatolingual contact pressure was measured using a different force-sensor-mounted palatal plate that caused midline asymmetry in palatal shape. During speech, the action point of tongue force corresponded to the central aspect of the asymmetric palatal shape, but during swallowing, tongue force differed between symmetric and asymmetric palatal shapes at 107 and 341 gw, respectively. These findings show that the tongue moves in relation to the central aspect of palatal shape during speech and swallowing in order to adapt to changes in palatal shape, but that tongue force adaptation differs between speech and swallowing activities.
  • 山代谷 真之, 奥野 竜平, 赤澤 堅造
    2003 年 41 巻 4 号 p. 419-424
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    It is important to study the dynamic properties of a muscle both for understanding the motor control of limbs and for simulation experiments using a muscle model. However, the properties have unclear points in the case when significantshortening displacement is applied to the muscle or muscle length is longer than its natural length Lo (descending limb of tension-length relation). Thus, the purpose of this study was to make clear the muscle's dynamic properties on a descending limb by methodically measuring tension response of frog semitendinosus muscles to forced shortening. By measuring isometric tetanus tension at various values of muscle length, the relation between tension and muscle length was derived. We measured tension response on a descending limb after shortening the muscle using various displacements and velocities. The obtained results were as follows: When the amount of shortening was between 1mm to 5mm, the final tension value after shortening Pe (please enter definition of Pe) was smaller than the isometric tension of muscle length after shortening but larger than the isometric tension before shortening. Pe also increased in proportion to the amount of shortening of the muscle and decreased when the amount was over a certain value. In addition, the muscle length at which maximum Fe occurred was longer than Lo. Furthermore, when shortened to 3mm, Pe increased according to the increase of shortening velocity. This study showed that Pe, after stretching or shortening, depended on both the initial and final length of the muscle under the condition that an electric stimulus was constantly provided to the muscle. That is, in constructing a muscle model that deals with large displacements, it is necessary to represent muscle tension as a function of the past state of muscle.
  • 中島 淳, 古市 浩隆, 塗木 淳夫, 湯ノ口 万友
    2003 年 41 巻 4 号 p. 425-430
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Recently, magnetic stimulation is being used as a new technique for nerve functional diagnosis as a replacement of electric stimulation in the clinical field. However, the focality of magnetic stimulation has not yet improved. On the other hand, magnetic stimulation has been applied in the rehabilitation field. The authors have previously studied the effect of pulsed magnetic stimulation on recovery from fatigue. In this paper, the recovery effect of pulsed magnetic stimulation on peripheral muscle fatigue on the forearm was quantitatively examined. As a result, an improvement in movement performance was proven by performing pulsed magnetic stimulation for fatigue.
  • 奥野 竜平, 赤澤 堅造, 吉田 正樹
    2003 年 41 巻 4 号 p. 431-439
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Surface electromyograms (EMG) have been widely utilized as an index of muscle activity in the biomedical field because they can be measured noninvasively without any special difficulty. The quantitative investigation of surface EMGs has been attempted to analyze the dynamic relation between torque, joint angle and muscle activity in voluntary limb movements. The location of the electrode is very important for monitoring EMG correctly and accurately. There have been some reports on estimating the innervation zone of upper limb muscles. However the innervation zone projected on the skin surface changes during movement, because muscle and skin are shortened independently. When the electrode is located on an innervation zone, the amplitude of the EMG becomes small. The measured EMG does not reflect the activity of the muscle. Electrodes need to be put on a region not influenced by the innervation zones in order to measured EMG accurately. The purpose of this study was to determine the surface electrode location forelbow flexor and extensor muscles, applicable to dynamic movements as well as isometric contraction. Five flexors and two extensor muscles of four male subjects were studied. At first, the innervation zones of the individual muscles were estimated as follows. A seven-channel electrode array was put on the skin surface of each muscle and the EMGs were measured during isometric contraction. The innervation zones were detected by watching motor unit action potential waveforms. These experiments were repeated while varying the electrode location on the same muscle and changing the elbow angle. It was shown that the detected innervation zones changed as the elbow angle changed. We decided an area outside of the innervation zone as the optimum electrode pasting position. Secondly, the EMG signals were measured with bipolar disk electrodes put on the determined area. This allowed us to measure reliable EMGs.
  • Masanori OHMOTO, Yuuki WATANABE, Masako OHNO, Tsuyoshi FUKUDA, Junichi ...
    2003 年 41 巻 4 号 p. 440-448
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    The aim of this study was to construct a physiologically based pharmacokinetic (PBPK) model based on the Nonlinear Mixed Effect Model (NONMEM) using venlafaxine pharmacokinetic data obtained from human subjects, and to investigate the effect of CYP2D6 polymorphisms with varying hepatic intrinsic clearance (CLint, h). Eight compartments of the human body were considered in our PBPK model. CLint, h was estimated to evaluate the contribution of CYP2D6 polymorphism to the first-pass effect and systematic metabolism of venlafaxine in the PBPK model. The PBPK model was confirmed to be functionally similar to a pharmacokinetic one-compartment model by frequency analysis. In addition, the influence of CLint, h on gain and cut-off frequency was evaluated, because the frequency characteristics reflected the transient response of venlafaxine concentration. The results of CLint, h (CYP2D6*1/*1, 259.7 L·hr-1) and the liver-to-plasma partition coefficient (48.4) suggested that venlafaxine is sufficiently distributed and ultimately metabolized by the liver. Both CLint, h in CYP2D6*1/*10 and CYP2D6*10/*10 could be estimated as 106 and 51 L·hr-1, respectively, based on the value of CLint, h in CYP2D6*1/*1. We found that there was limited metabolic capacity of CYP2D6*1/*10 and CYP2D6*10/*10 in the liver compared to that of CYP2D6*1/*1. In conclusion, the PBPK model was a useful tool in evaluating the contribution of CYP2D6 polymorphism to the hepatic metabolism of venlafaxine.
  • 佐藤 克也, 西島 尚吾, 安達 泰治, 冨田 佳宏
    2003 年 41 巻 4 号 p. 449-457
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Bone responds to change in mechanical environment and adaptively remodels the internal structure and external shape. Therefore, for bone cells, such as bone-forming osteoblasts, a mechanical stimulus as well as biochemical signaling plays an important role in the regulation of their activities. Many studies on various osteoblastic responses to mechanical stimulus have been reported; however, the mechanosensory mechanism by which cells sense the stimulus and translate it to biochemical signaling is not clearly understood. Cytoskeletal actin fibers have been proposed as one of the candidates playing an important role in the mechanosensory mechanism. In this study, we hypothesize that the organized network structure of actin fibers is essential in the mechanosensory mechanism. Three groups of osteoblast-like cells with different amounts of controlled actin fiber structure were prepared by controlling polymerization time after treatment with cytochalasin D. By applying mechanical stimulus to a single osteoblast-like cell, as localized deformation of the cytomembrane by direct indentation with a glass microneedle, a calcium signaling response to thestimulus was observed using a fluorescent calcium indicator, Fluo 4, under a confocal laser-scanning microscope. As aresult, cells responded more sensitively to the applied deformation with a larger amount of actin fiber structure, and afew cells without an organized structure responded to stimulus as well. These results suggest that the organized actin fiber structure is not necessarily essential in the mechanism by which the mechanical stimulus is transduced into a calcium signaling response, but plays a supporting role indirectly, such as improving the efficiency of transmitting the stimulus to the cell or amplifying the stimulus itself.
  • 生田 幸士, 山田 章, 新倉 史智
    2003 年 41 巻 4 号 p. 458-465
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    We have developed a novel three-dimensional microfabrication method for biodegradable materials. Unlike conventional processes, our process satisfies high-resolution and high-speed requirements. The system design allows the processing of micro-level forms by stacking up melted polymers from the nozzle. We adopted a batch process to supply materials in order to eliminate the prior process that employed toxic solvents. In addition, it is possible to handle almost all biodegradable thermoplastic resins by adopting this system. A single layer from the piled-up layers of extruded lines can be observed using SEM images to evaluate the resolution. The lateral and depth resolutions attained are 70μm and 40μm, respectively. Poly (lactide) (PLA) enables millimeter-sized structures such as micro-pipes, micro-bends, and micro-coil springs to be processed in less than 10min. The biocompatibility of the newly fabricated device was evaluated using a cell line (PC 12). For this purpose, a small vessel with a transparent base was fabricated and the cells cultivated in it. The results were then compared with the results obtained using the standard method. Our system renders it possible to produce toxic-free, as well as transparent and leakage-free devices. The shape of the structures can be easily changed and quickly modified. Our system is expected to have potential applications in optimum design and fabrication of implantable devices.
  • 平澤 宏祐, 白松 直樹, 山本 知仁, 原田 久, 三宅 美博
    2003 年 41 巻 4 号 p. 466-474
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    In radiotherapy, it is essential to focus the radiation on the affected parts of the internal organs, like lung, liveretc., while minimizing the exposure to healthy tissues. Although methods that apply the beam to affected parts in synchronization with the patients' breathing have been used extensively, irradiation accuracy is not sufficient when the respiratory status of the patient is unstable. In this paper, we propose a new irradiation system that features (1) stabilizing the patients' respiration by synchronizing the rhythm of his/her breathing with that of music being played, and (2) controlling the timing of the irradiation based on the predicted respiratory phase instead of the measured phase that has been used widely. From experimental results using 12 subjects, it is possible to clarify that deviation of the beam irradiation position from the targeted point has been decreased to one-third as compared to conventionalmethods, resulting in a dramatic improvement in the accuracy of the irradiation system.
  • 酒井 智仁, 中本 将彦, 鍵山 善之, 佐藤 嘉伸, 菅野 伸彦, 西井 孝, 赤澤 堅造, 多田 幸生, 田村 進一, 吉川 秀樹
    2003 年 41 巻 4 号 p. 475-482
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    In total hip replacement, the fitting of the femoral stem, which is a component of the hip joint implants, to the femoral canal is important for stability of the stem. A surgeon determines the parameters such as the size, position and orientation of the stem based on a visual assessment of the relationship between the stem and femoral canal surface. However, visual assessment depends on a surgeon's subjectivity. Our work focuses on the development of an automated method for determining placement of the stem in the femoral canal, which is intended to emulate the expertise of an experienced surgeon. The proposed method is based on stem fitness, which is the measure of shape difference between the stem and femoral canal surface. The combinations of the size, position and orientation of the femoral stem, which provide the local maxima for stem fitness, are determined by exhaustive searching. We applied the automated method developed to four cases of patient data sets, and compared the results obtained from the automated method with those of an experienced surgeon. The results obtained were generally close to those of the experienced surgeon, and the difference from the experienced surgeon was 1.6mm and 1.3 degrees in the best case. These results suggest the feasibility of using the proposed method in clinical practice.
  • 酒井 健作, 持丸 正明, 横山 和則
    2003 年 41 巻 4 号 p. 483-492
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    During surgery using local anesthesia, the skills to infer and keep the patient's philological and mental condition under control are important to the surgeon. However, acquiring these skills is diflicult in the training period as they are acquired only during actual surgery. From this viewpoint, we are developing a model which can represent a patient's philological and mental responses to surgical procedures. This model is expected to be used during training, where trainee doctors can experience the behavior of the patient and acquire the skills mentioned above. Measurements were taken during actual surgery. The heart rate, breathing rate and amplitude, and complaints of pain were recorded as the patient's response. The endoscopic view and scene in the operating room were recorded in order to determine the factors that cause each patient's response. To develop the model, the causal relationship between surgical procedures and patients' responses was investigated. It became clear that the patient's response is dependent on the surgical phase, movement of surgical area and the type of surgical tool. We constructed a model of this behavior using a Bayesian network.
  • 岡田 志麻, 藤原 義久, 松浦 英文, 安田 昌司, 水貝 浩二郎, 牧川 方昭, 飯田 健夫
    2003 年 41 巻 4 号 p. 493-497
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    Sleep is very important to keep our physical condition healthy. Many studies have been devoted to clarify the mechanism of sleep and to monitor the sleep all night. In this study, we paid attention to heart activity during sleep and have developed a nonrestraint monitoring method of heart activity using an acceleration sensor set inside the coverlet. This method is easy for the use of sleep monitoring at home in daily life. An acceleration sensor was set inside the coverlet as it opposing to subject's left chest. Subjects were asked to lie in supine position and the coverlet with an acceleration sensor was put on the subject. Mechanical vibration from heart activity expected to be carried to the acceleration sensor through the coverlet. As a result, periodic vibration was measured successfully and this vibration was proved to be in high correlation with the R wave of ECG in six subjects. The same results were obtained even in case of lying in right and left lateral decubitus position.
  • 保坂 良資, 山下 和彦, 西村 千秋
    2003 年 41 巻 4 号 p. 498-503
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    The utilization of information systems is spreading in the nursing environment. However, the ordinary QWERTY-type personal computer (PC) keyboard is necessarily required for personal computer novices. In this study, the performance of a mobile phone-type interface is estimated. In the experiment, 10-character texts and 100-character texts were input from a mobile phone interface and a PC keyboard. Input time length and error rate were measured in the experiment. The results revealed that it is clear that the mobile phone interface is an effective means for beginner PC users from the viewpoint of input time length in each one-key stroke. From the viewpoint of error rate, the rate for mobile phone interfacing is minimal. It is no more than 1.79%. It is believed that the beginner PC users in thenursing environment are able to use the computer, even if the mobile phone interface is realized as a input device.
  • 四宮 葉一, 小澤 尚久, 王 碩玉, 浜岡 隆文, 勝村 俊仁, 木目 良太郎, 佐藤 祐造
    2003 年 41 巻 4 号 p. 504-509
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
    A new type of passive exercise training equipment has been developed that allows persons with knee joint osteoarthritis and NIDDM (non-insulin dependent diabetes mellitus) to participate in exercise training. The idea of “passive exercise training” was applied to equipment so that trainees are induced to exercise caused by physical stimulation without voluntary effort. The apparatus is equipped with a seat, and in order to induce muscle contraction in the leg by utilizing the user's own weight, the seat can be alternately inclined toward the user's knee joints of each leg so that the user's center of gravity moves from around his/her hip to his/her foot. In addition, the apparatus has foot-plates on which the user's foot is placed. In order to cope with knee joint pain, the height of the foot-plates canbe automatically controlled to keep the angle of the user's knee joint. By conducting a laboratory experiment using near infrared spectroscopy, it was indicated that the muscle oxygenation in the femur was promoted and that knee joint pain was less than that experienced walking on a flat surface as determined from a subjective evaluation by persons with knee joint osteoarthritis.
  • 窪田 ひろみ, 西村 泉, 根岸 正
    2003 年 41 巻 4 号 p. 510-512
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
  • 2003 年 41 巻 4 号 p. 513-518
    発行日: 2003/12/10
    公開日: 2011/09/05
    ジャーナル フリー
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