生体医工学
Online ISSN : 1881-4379
Print ISSN : 1347-443X
ISSN-L : 1347-443X
45 巻, 4 号
選択された号の論文の12件中1~12を表示しています
研究
  • 笹倉 祐, 日坂 真樹
    2007 年 45 巻 4 号 p. 235-241
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    Ultrasound-modulated optical speckle measurement in a reflection system has been developed and applied to investigate optical measurement for optical highly scattering media with an acoustically impedance-matched optical absorptive object. A series of pulse ultrasound-modulated backscattered speckle patterns were captured by a charge-coupled device camera with stroboscopic illumination and converted to temporal scalar signals in order to obtain depth distribution. The absorption and scattering dependence of the samples close to biological tissue were experimentally studied and investigated.
  • 吉田 直樹, 白銀 暁, 井野 秀一, 伊福部 達
    2007 年 45 巻 4 号 p. 242-255
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    Relationship between hand positions (HPs) and the corresponding ranges of arm posture (RAPs) was studied computationally for application to rehabilitation using exercise devices which, such as a kind of robot-aided exercise machine, require users to control their HP in 3-dimensional space. A method to calculate the RAP for a HP using a concept of redundant degrees of freedom with a model of upper extremity was shown. The RAPs for 224 HPs sampled from the entire reachable area were obtained by the method. After several RAPs for some example HPs were shown, general characteristics of the joints over all the HPs were investigated using the “allowance ratio” (AR) as an index of controllability of joint. The AR was defined as the ratio of allowable range of a joint for a HP to the full range of the joint. The AR of each joint was calculated for every HP, and the frequent distributions of ARs for all joints were shown. ARs of wrist and forearm (supination/pronation) for most of HPs were over 90%, which suggested these joints might not be controlled. In contrast, ARs of shoulder azimuth and elbow for most of HPs were under 30%. These joints could be controlled better. ARs of both shoulder elevation and rotation were distributed rather widely, but the peaks were in different area; 10-30% for elevation and 80-90% for rotation. These results suggested that at least one degree of freedom of shoulder might be hard to be controlled. Several relationships between HPs and joints were investigated, including those between elbow and shoulder-hand distance, elevation and height of HP, and shoulder azimuth and HP azimuth. Some of the relationships were shown as approximate expressions. The method and results would be useful to design future rehabilitation with the exercise devices.
  • 林 達郎, 周 向栄, 陳 華岳, 原 武史, 藤田 広志, 横山 龍二郎, 桐生 拓司, 星 博昭
    2007 年 45 巻 4 号 p. 256-266
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    The number of osteoporosis patients is increasing every year in Japan. Multi-detector-row CT is widely used in clinical environment including diagnoses of osteoporosis. However, quantitative evaluation of osteoporosis based on CT images is not defined. This paper investigates the distribution of bone mineral density (BMD) values measured in vertebral trabecular bones from the twelfth thoracic vertebra to the first sacral vertebra in Japanese subjects. Using X-ray CT images of 136 subjects, CT number of vertebral trabecular bones in these regions was measured, and BMD values were estimated from CT number using a bone mineral reference phantom. In addition, the relation of BMD values of each vertebra was investigated, and correlation with age, gender, and fusion at lumbosacral portion was shown. The present study showed that there was no statistical significant difference in BMD values of vertebral trabecular bones from the twelfth thoracic vertebra to the fifth lumbar vertebra. Therefore, among these vertebrae, if the CT number of one vertebra is known, the BMD values of the other vertebrae can be estimated based on the relationships shown by our research.
  • 岸 亜由美, 磯山 隆, 斎藤 逸郎, 河野 明正, 小野 俊哉, 杉野 礼佳, 光宗 倫彦, 山口 さち子, 時 偉, 井上 雄介, 中川 ...
    2007 年 45 巻 4 号 p. 267-273
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    Artificial materials used for artificial organs have sufficient strength and durability. However, their biocompatibility has not been improved yet to the level of tissue-derived biomaterials. On the other hand, there were some problems in artificial organs made of tissue-derived biomaterials; difficulty of forming the desired shapes, insufficiency of strength and durability, and infection control. It is necessary to build arbitrarily-shaped artificial organs that have sufficient strength and durability with tissue-derived biomaterials. In this study, we developed an in-vivo method to make a circle valve leaflet of a jellyfish valve using an insert molding technique. The jellyfish valve is an artificial valve developed at the University of Tokyo, and consists of the valve leaflet and a valve seat. The three types of molds for valve leaflets with different thickness (0.5 mm, 1.0 mm, and 1.2 mm) were made with an acrylic resin. A velour cloth was put inside each mold to ensure strength and durability. Two sets of molds were built; one with only suspended cell and another with both suspended cell and tissue fragments. Three types of molds were implanted under the skin of a goat. The performance and durability of jellyfish valves with tissue-engineered valve leaflets were assessed using a mock circulation circuit after the molds were extracted from the goats and the valve leaflets were fixed with formalin. Moreover, hematoxylin-and-eosin stained sections were observed. The results demonstrated that the valve leaflets covered with connective tissues have sufficient performance and durability of more than one month. In conclusion, we made a tissue-engineered circle valve leaflet with enough strength and durability to be used as heart valves in vivo using the insert molding technique.
生体医工学シンポジウム2007特集
研究
  • 岡田 雄介, 大橋 俊平, 鄭 址旭, 濱田 昌司, 小林 哲生
    2007 年 45 巻 4 号 p. 275-284
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    One of possible problems in fMRI-MEG integrative analysis is mismatches between activated regions detected by fMRI and MEG. These mismatches cause serious degradation of estimation accuracy, especially in the case that fMRI-invisible activities have high temporal correlations to activities detected by fMRI. We proposed a spatial filter which can achieve the accurate reconstruction of MEG source activities even in the case that a priori information of fMRI is insufficient. The proposed filter is based on generalized least square (GLS) estimation method. The GLS method requires to determine the noise covariance matrices, and the proposed filter utilizes measured MEGs for the determination. In the present study, principal component analysis is applied to the measured MEGs to determine the noise covariance matrices. Simulation results with conditions that fMRI-invisible MEG sources are present demonstrated that the proposed filter could reconstruct MEG source activities more accurately than the methods based on both ordinary least square method and minimum variance beamformer. The validities of the proposed method were also discussed, with measured data from the experiment using an apparent motion visual stimulus. The results demonstrated that the proposed method could reconstruct reasonable time courses of activations.
  • 飯島 賢一, 柳田 純一, 関根 正樹, 田村 俊世
    2007 年 45 巻 4 号 p. 285-291
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    The decline of the balance function induces the elderly people to fall and it causes the decrease of daily activity to become bedridden or fear of falling. The fall occurs when sudden external forces such as trips or slips take place. Therefore, it is important to consider a simple evaluation of the posture balance in human to perturbation. In this study, we proposed the measurement system using gyro sensor, and measured the body sway of the pitch direction by the perturbation. The subjects are ten healthy adults and kept upright position on the table. They attached the sensor to an ankle joint, a knee joint and a back near the center of gravity. Then horizontal translation of table to the backward was given as the perturbation. The experiments were performed with 20 patterns of different acceleration from 0.6 m/s2 to 4.4 m/s2 by 0.2 m/s2 randomly. As the result, the feature of three postural control strategies such as ankle strategy, hip strategy and stepping strategy can be confirmed by the angular velocity in the pitch direction. Additionally, the variation of the angular velocity of back for perturbation was larger than those of ankle and knee. Thus, we concluded that the sway in the back greatly influenced to the postural control for horizontal translation to the backward.
  • 疋島 啓吾, 本間 一弘, 早水 紀久子, 相原 雄一, 沼野 智一, 新田 尚隆, 八木 一夫
    2007 年 45 巻 4 号 p. 292-297
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    The goal of this study is to make active or passive electrical characteristics of biological systems visible by magnetic resonance imaging (MRI). As a starting investigation, we visualized a precise flow effected by ionophoresis. We used CuSO4 doped water (25 mM) electrolytes in an ionophoresis cell composed of a pair of horizontal copper electrodes. An evaluation of ion drift, we made by MR diffusion tensor imaging method. The impressed voltage was 0.0-0.5 V, and the current density at that time increased monotonously was 0.00-1.06 mA/cm2. With increasing current density, higher values of drift diffusion coefficient (DDC) induced by the electric field were observed.
    The diffusion tensor ellipsoid in current density of 1.06 mA/cm2 was successfully visualized as the effects of ion drift induced by the electric field. By applying this method to biological systems, it has a possibility to make functional electrical characteristics visible.
  • —模擬血管内拍動血流の管断面内流速分布の測定—
    郡 慎平, 田地川 勉, 大場 謙吉
    2007 年 45 巻 4 号 p. 298-306
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    For measurement of local blood velocity, a less invasive miniaturized fiber-optic LDV (laser Doppler velocimetry) sensor which was directly inserted into a blood vessel was developed as a monitoring device for clinical use and in vitro testing equipment. By using the process of a chemical etching with a HF-NH4F buffer solution, a convex lens-like surface was formed on the fiber tip having a core of 50 μm. Laser beam emitted from the fiber tip was focused and formed measuring volume. In the authors' previous studies, the local velocity of a steady blood flow was successfully measured using a same type of the present fiber-optic LDV sensor. In order to measure local velocity in a pulsatile flow, the optical system and the curvature of the fiber sensor tip were improved. The fiber sensor was inserted at an insertion angle of 120 deg. through an injection needle into a flow duct of an acrylic pipe in which an opaque fluid as a model of whole blood was pulsatingly flowing. The waveform of the flow rate was modeled after the human middle cerebral arterial flow. In this experiment, the local flow velocity and velocity profile across the duct were measured in a pulsatile flow of a dense suspension of a white pigment. The results measured by this sensor were compared both with that by a fringe-mode LDV and with that calculated on the basis of Womersley's oscillatory flow theory. As a result, it was found that the local velocity and its profile across the duct in the pulsatile flow were successfully measured by the present fiber-optic LDV sensor, which proved the capability of the sensor as a diagnostic device.
  • 玉城 祐二, 大塚 明香, 栗城 眞也
    2007 年 45 巻 4 号 p. 307-312
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    A neuromagnetic response, N1m, is elicited in the auditory cortex at around 100 ms after onset of input sound. The amplitude of the N1m response reflects acoustic properties of sounds such as spectral characteristics, loudness and frequency overlap with the preceding sound. On the other hand, the auditory cortex elicits an N1m-like response when a sound is mentally imagined or expected at a certain timing. We studied effects of such endogenous factors on the modulation of N1m response to chords that are musically unfolded in sequence. We observed that the N1m response was significantly larger when the chord sequence was unfolded to be musically closed as compared to the control chords presented sequentially but not in form of musical progression. We infer that the N1m response was augmented as a result of listeners' expectation for the final chord that closes the sequence musically.
研究速報
  • 増子 知也, 渡邉 高志, Achmad ARIFIN, 吉澤 誠
    2007 年 45 巻 4 号 p. 313-318
    発行日: 2007/12/10
    公開日: 2008/09/12
    ジャーナル フリー
    A fuzzy controller based on the cycle-to-cycle control method for FES-induced gait was tested experimentally in controlling maximum knee extension angle with normal subjects in our previous study. Although the controller performed it well, error was increased in some trials because many cycles were needed to compensate the change of muscle response. This was considered to be caused by fixed parameter values of the controller for suppressing oscillating response. In this paper, an automatic adjustment method of maximum output value of the fuzzy controller based on the error of the previous cycle was tested. The experimental results of the maximum knee extension angle control with normal subjects showed that the automatic adjustment method was effective in reaching the target value with the small number of cycles and in controlling after reaching the target compensating changes of property of electrically stimulated muscles. The increase of error caused by the change of muscle response was not observed. However, in some trials, the maximum knee joint angle was not detected correctly for a few cycles and oscillating responses were observed. It is necessary for clinical applications to compensate oscillating response and to improve the maximum knee joint angle detection method.
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