Biomedical Engineering Lab.
Yuji OHTA, D. Eng, Ochanomizu University, CV, Publication list
Last update on 2013-04-17
Research themes
Estimation of mechanical prosthetic heart valves
In vivo study: earlier detection of implanted valve malfunction based on the analyses of valve closing sound, ultrasound Doppler signal, high-speed X-ray angiograph, and X-ray cinefilm(->).
In vitro study: development of a circulatory simulator(->), visualization of valve motion by a high-speed CCD camera(->), and early detection of valve malfunction(->).
Development of various assisting devices for independent living/rehabilitation
Man-machine interface system using gazing
Study on the magnetic stimulation for the future neuro prostheses: measurement of the distribution of eddy current induced in the human model
Development of an assisting device for the walk of spinal cord injury patients(->)
Novel Home-based Care Device for Prevention of the Secondary Disease in Paraplegic Persons(->)
Evacuation procedures and drills in case of disasters for disabled children at schools(->)
Artificial Kidney
Water transport model during CAPD(->)
Bioelectrical Impedance Analysis(->)
Computer Aided Surgery System
Navigation system for surgeons using a superimposer(->)
Magnetic Stimulation
Focalization of Induced Current (->)
Scanning Probe Microscopy
Observation of the biological functions using an atomic force microscope(AFM)(->)
AFM visualization of Forssman antigen on sheep erythrocytes by the probe immobilized with antibody(IgM).(->)
AFM for artificial organ research(->)
AFM visualization of sheared red blood cells(->)
Biological measurement
Heart rate measurement based on a time-lapse image(->)
An Image Analysis Algorithm for Kinematics and Morphology Measurement of Cells for the Evaluation of Tissue Construction (->)
Pressure Ulcer Measurement(->)
Research themes(Details)
Measurement of asynchronous motions of the implanted bi-leaflet valves using X-ray cinefilm.
Motions of the implanted bi-leaflet valves, especially with asynchronous motion, were analyzed quantitatively. 6 SJM valves (5 MVR and I AVR) were tested. Using the cinefilm image processing system, asynchronous motion of the two leaflets was analyzed. The maximum angle difference between two leaflets was found to be 11.3 degree. It was also found that any asynchronous motion was not similar to each other. These asynchronous motions could be attributed to valve orientation, atrial fibrillation, thrombus, etc. Though X-ray cinefilms have been used for qualitative inspection in the clinical field, quantitative motion analysis of the implanted heart valves would bring new findings and contribute to the advances in the clinical and research field.
(BACK)
Motion analysis of mechanical prosthetic heart valves at mitral position using a computer-controlled hydraulic mock circulator.
We developed a computer-controlled hydraulic mock circulator to investigate mechanism of motions of mechanical prosthetic heart valves, and studied their in vitro motions under the flow condition controlled with high accuracy. The Omnicarbon valve, the Bjork-Shiley valve and the Medtronic-Hall valve were tested at mitral position. These valves were driven under single- or double-peak flow condition, and were photographed by a high speed CCD camera. Flowrate. BPM and S/D ratio were set as 4.0, L/min, 70 and 0.3, respectively. By analyzing the images of the valves, we found: (1) there was no significant difference in motion among the three tested valves. (2) an unstable motion was observed when inflow rate decreased. (3) a temporary closure of the disc occurred at the least inflow rate between peaks.
KEYWORDS: Mechanical prosthetic heart valve. Hydraulic mock circulator, Double-peak mitral flow. Motion analysis. High speed CCD camera
(BACK)
Nonsymmetric Leaflet Motion of St. Jude Medical Mitral Valves Simulated with a Computer-Controlled Hydraulic Mock Circulator.
Since the introduction of high-performance prosthetic heart valves, particularly bileaflet valves and monoleaflet valves with larger opening angles, we have observed in vivo complex leaflet motions, which have not been simulated through in vitro experiments.Thus, to investigate the leaflet motions of implanted valves, we developed a new computer-controlled hydraulic mock circulator. A high speed CCD camera was used to record the leaflet motion. In the mitral position, a standard St. Jude Medical valve was mounted to be tilted horizontally or vertically. The test valve was driven with single- or double-peaked flow. The flow rate was set as 5.0 L/min at 70 bpm with a systole/diastole ratio of 0.3.As a result, we found:(1) regardless of valve orientation, the valve showed a nonsymmetric leaflet motion. (2) the valve showed unpredictable leaflet motions during the period when flow decreased. (3) the disc closed temporarily between the flow peaks.
Key Words: Quantitative leaflet motion analysis-Bileaflet mechanical prosthetic valve-High speed charge coupled device camera-Hydraulic mock circulator-Mitral flow-Valve orientation.
(BACK)
Analysis of the downstream flow of prosthetic mechanical heart valves by wavelet transform: A trial for the detection of slight valve malfunctions.
Clinically it is important to find malfunctions of mechanical prosthetic heart valves at earlier stage. Actually, the detection of a small thrombus or vegetation around valves is sometimes difficult by conventional clinical methods. In this study, we used the wavelet transform (WT) as a method for the detection of slight malfunctions of valves. The test valve(Bjork-Shiley valve, 25mm) was mounted at the aortic or mitral position of a computer-controlled hydraulic mock circulator, and driven under normal or AF flow condition. The valve tested as a malfunctional model was mechanically restricted with the mobility of an occluder. Using continuous-wave ultrasound Doppler method, mean velocity signals were recorded at 3cm forward from the valve outlet, and were analyzed by Daubechies wavelet. As a result, comparing a thrombosed model with a normal one,there was a significant increase in power in the signal bandwidth (100Hz-1kHz), and it was remarkable during acceleration of flow. The increase in power is thought to be caused by turbulence of downstream flow. These in vitro results indicated that WT was effective for the detection of small malfunctions of valves.
(BACK)
A two-degree-of-freedom motor-powered gait orthosis for spinal cord injury patients.
A number of orthoses have been developed to restore stance and walking in paraplegic subjects. Compliance, however, has been limited mainly due to walking effort. Use of the forces produced by actuators is an effective way to solve the problem of the high efforts required for orthotic gait, or both high muscular loading and high energy expenditure. The purpose of the present study was to investigate the effects of assistance by external actuators on the orthotic gait of spinal cord injury (SCI) patients. Two kinds of linear actuators were developed by using DC motors for assisting the knee and hip joint of a gait orthosis. They were mounted on the knee and hip joint of a commercial ARGO, and a new two-degree-of-freedom externally powered gait orthosis was thus developed. The orthosis was assessed through inter-subject experiments on five male adult SCI patients (complete, T5-12). The motions of the gaits assisted by the linear actuators were measured by a Vicon 370 system, and the general gait parameters and compensatory motions were evaluated. As a result, it was found that: (1) all subjects could walk without falling, assisted by the knee actuator or the hip one. (2) Both the knee and hip joint actuator increased the gait speed and the step length. (3) The knee flexion produced by the orthosis improved the dynamic cosmesis of walking. (4) Lateral compensatory motions as well as vertical ones tended to decrease when the hip joint was assisted, which could contribute to a reduction in walking effort.
(BACK)
Novel Home-based Care Device for Prevention of the Secondary Disease in Paraplegic Persons.
Due to the long term physical inactivity on wheelchair, persons with motor paralysis in lower legs are always at risk for developing the secondary disease around paralysis area, such as muscle atrophy, loss of bone mineral density, and hypo-circulation. These diseases are easy to occur, but hardly curable. Daily stretching exercises are generally approved for the most effective measure for prevention. Actually the patients hardly make practices due to extra effort. We developed an alternative rehabilitation device for individuals with motor disorders. Its aim was to prevent the secondary disease by stretching the ankle joints passively. A pair of linear actuators were mounted under the seat of a wheelchair and connected to each footrest. Because of the simple mechanism the device features easy installation to commercial wheelchairs as well as availability at home. The device has two different exercise modes: a rhythmical planter/dorsiflexion movement and a stretch one. In the former mode, as the neutral position was set at 105 degrees, the range of the reciprocal rotation angle was available between 12 and 24 (+-6 and 12) degrees. The flapping frequency was set at 0.7 Hz based on the normal walking. In this study, we investigated the physiological effect of the former mode at the motion range of 24 degrees. 8 spinal cord injury persons participated in the experiments, and EMG and oxygenation level in the paralyzed muscles were recorded during 10 minutes of passive ankle motion. As a result, we found that the passive ankle motion could induce the rhythmical muscular activity, alteration in the muscle oxygenation level, and enhancement of the blood flow in the calf muscles. These results suggested that the device might be effective for the prevention of the secondary disease, or the facilitation of the neuromuscular function and the peripheral circulation in the paralyzed lower limbs.
Keywords: spinal cord injury, secondary disorders, passive motion, muscle oxygenation, muscle blood flow, electromyographic activity
(BACK)
Evacuation procedures and drills in case of disasters for disabled children at schools.
Evacuation procedure to the handicapped person has not been examined enough up to now. The goal of this research is to develop the evacuation procedures and drills in case of disasters for disabled children at schools, and to verify their effectiveness through trainings. First, the questionnaire survey intended for the teachers is executed, and referring to the evacuation drills by the fire station, the evacuation procedures and instructions currently conducted are investigated. Next, based on the investigation results, an evacuation procedure suitable for the disabled children at each level is developed. Then, to verify the effectiveness, the evacuation drill is going to be executed at the attachment school of Yokohama National University in 2006. Using VR technologies, a handy drill machine for evacuation is developed based on the results of the questionnaire. The VR drill system targets disabled children from slight to middle degree. To evacuate by themselves to some degree, the ability to judge a surrounding situation and to find the escape route is trained. Physical strength for evacuation is also trained. To make the training more concrete and practical, the system has the drawing information of the schoolhouse. Moreover, the contents of the VR display could change according to the earthquake scale. In addition, children's abilities of movement and spatial awareness by the sight are measured through trainings in the VR space, and it is examined to improve their evacuation ability. For heavily disabled children, a device for evacuation is also developed by converting a play equipment routinely used in the class.
(BACK)
Water transport model during CAPD: Determination of parameters.
To minimize the total amount of glucose required for removing the same volume of water as a bolus, a continuous infusion of glucose during CAPD was proposed and studied. Both a computer simulation of water transport through the peritoneal membrane and in vivo assessment with rats were carried out to evaluate the feasibility of the newly proposed mathematical model in which lymphatic drainage of dialysate from the peritoneal cavity to lymphatic system was considered in addition to conventional water transport. Mass transport area coefficients (KA) of 0.041 to 0.063 ml/min/100 g body wt and 0.045 to 0.066 ml/min/100 g body wt were measured for glucose and urea during CAPD with male Wistar rats. Hydraulic conductivity of peritoneal membrane (Lc) was 7.9 x l0~5 to 1.5 x 10~4 ml/min/mm Hg/lOO g body wt, which was calculated by a linear relationship between volume and osmotic pressure. Simulated water transport model using determined parameters indicated that the ratio of lymphatic transport to convective transport would be changeable in CAPD with glucose infusion at varying infusion rates, while up to 16% of the glucose uptake could be reduced compared with that of the common CAPD at the same dwell time.
(BACK)
MEASUREMENT OF TISSUE WATER CONTENT OF RAT KIDNEYS Using BIOELECTRICAL IMPEDANCE TECHNIQUE.
Bioelectrical impedance of rat kidneys which were preserved in the various solutions for three hours were measured using four electrodes made of platinum wire, and the parameters relating extra- and intracellular resistances ( Re, Ri), and membrane capacitance (Cm) were calculated. As a result, linear correlation between tissue specific gravity and Re value could be quantitated by electrical impedance technique. There was a significant difference in Ri among the test kidneys, which corresponded their abilities to prevent edema. A decrease in Re+Ri during cold storage showed the possibility of the gradual development of edema.
(BACK)
Computer Aided Surgery System.
Several types of supporting systems for surgical planning have been reported up to now. We proposed a new surgical supporting device which features image superimposition using a half mirror. By using the device, graphic image of internal organs could be superimposed on the real image of the patient. In order that the device allows surgeons to move around, the position of the user toward the patient was measured consecutively by a small CCD camera placed on the top of a head mounted display (HMD). The CCD camera imaged a patient model with pre-arranged markers on its surface and the position of the model could be measured with accuracy of about 0.5 cm by an image processing software. Based on this position data, three dimensional model data were processed on a workstation to produce graphic image for superimposition. The Image was presented to the user through the HMD which features the "see through" function. The position error in navigation was found to be as large as I cm. This problem has to be solved in the future study.
Key words Image superimposition, Head mounted display, Image measurement, Virtual reality modeling language.
(BACK)
Study on the Functional Magnetic Stimulation: The Focalization of Induced Current Using Implantable Materials.
Magnetic stimulation has the drawback of poor focality of stimulation compared with conventional electric stimulation, because of the dissipation of induced current. That makes it difficult to use magnetic stimulation for deep seated neurons. We made a preliminary study on the focal magnetic stimulation by using an insulator (a small copper ball), which could be expected to increase the density of induced current. The system for measuring the distribution of the current induced in saline solution was developed. It consists of the stimulating coil, the saline solution chamber as a volume conductor, and the induced current probe. The stimulating coil was driven by the sine wave current produced by a function generator,as well as by the mono-phasic pulse current by a commercial magnetic stimulator (Dantec. MagPro). The induced current was measured with/without the insulator. As a result, density of induced current increased nearly 2-5 times in the vicinity of the insulator, which was supported by the computational simulation. In the study, the protocol of the fabrication of human 3D model by using the laser lithography was also established.
(BACK)
Identification of colloidal gold labels with template matching method for atomic force microscopy.
Atomic Force Microscopy has become a powerful tool in the fields of biophysics and biophysical chemistry. Up to now, a number of biological samples have been imaged at high resolution by AFM. One of the problems of imaging biological samples with AFM is the lack of specificity, and the need for a specific labeling technique for AFM has been recognized. For that purpose, we developed a new method using Immuno-gold labels in combination with AFM. However, the colloidal gold labels can hardly be discriminated from the globular protrusions of the cell membrane. In the paper, a numerical template-matching method was developed to discriminate the colloidal gold label from the globular protrusion. By applying this method to sheep erythrocytes labeled with 10 nm colloidal gold conjugated antibody on the surface, the position of the colloidal gold label corresponding to the antigen could be determined. This method would be useful for discrimination of antigens on cell surface by AFM.
(BACK)
Atomic Force Microscopic Visualization of Identical Site on Cell Surface with Different Probes.
For these several years Atomic Force Microscopy (AFM) has been widely used for visualization of biological samples with high resolution on nanometer scale. Whereas any biological information regarding specific reactions, such as immunological function, cannot be detected because of non-specificity of molecular force reacting between a probe and sample surface. The aim of this study is to visualize a function of a cell, in particular, to detect specific reaction on surface of a cell membrane by AFM. The point of our method is subtraction of the data measured by different probes: by subtracting the data measured by an antibody-fixed probe from those by a regular one, immunological reaction can be determined. As a first step, we developed the technique which enabled AFM to visualize the same area on sample surface with different probes.
Keywords: Atomic force microscopy, functional visualization, immunological reaction, subtraction method, red blood cell
(BACK)
The atomic force microscope: a new tool for artificial organ research.
The atomic force microscope (AFM) was developed by modifying the scanning tunneling microscope (STM). It has high resolution on the sub nanometer scale, does not require troublesome preprocessing of the sample, and permits observation of living samples. With these attractive features, the AFM is expected to be a new research tool in the field of artificial organs in the near future.
(BACK)
ATOMIC FORCE MICROSCOPIC VISUALIZATION OF SHEARED ERYTHROCYTE: EFFECT OF PERIODIC FLOW ON THE SURFACE ROUGHNESS.
[Background] Artificial organs assisting for circulation traumatize red blood cell mechanically or chemically due to non-physiologic flow conditions. To make this invasive mechanism clear, a large number of studies have been conducted for these several decades. It is natural that chemical components such as liberated Hb or lipid molecule have been used as main damage-related indices in these studies, because these components, which are normally confined to cell membrane, might be flown out with membrane damage. However, the membrane damage itself cannot be detailed from these indices. The aim of this study is to understand the damage mechanism directly from nano scale biological viewpoint. [Materials &Methods] Sheep erythrocytes were sheared with a conventional rotational viscometer and visualized with the atomic force microscope (AFM). The surface roughness was measured on nanometer scale. Liberated Hb concentration was also measured and compared to the roughness value. Shearing conditions were as follows. The shear rate and the exposure time were set at 1800 (/sec) and two hours. The duty ratio and the frequency of periodic flow (square wave) were set at 50% and 0.005-0.5 Hz. (The number of start/stop flow during the entire exposure time was 3600, 360, and 36 in the case of 0.5, 0.05, and 0.005 Hz.) [Results] The AFM observation showed that the fine structure of the cell surface was changed drastically by the stress. As shown in the table below, it was also found that the roughness value increased with the number of the start/stop flow and correlated with Hb concentration. Visualization and roughness measurement of the sheared erythrocytes with AFM was thought to offer new microbiological viewpoints for membrane damage caused by shear flow.
(BACK)
Heart rate measurement based on a time-lapse image.
Using the time-lapse image acquired from a CCD camera, we developed a non-contact and non-invasive device which could measure both the respiratory and pulse rate simultaneously. The time-lapse image of a part of the subject's skin was consecutively captured, and the changes in the average image brightness of the region of interest (ROI) were measured for 30 seconds. The brightness data were processed by a series of operations of the interpolation, 1st-order derivative, low pass filter of 2 Hz, and 6th-order auto-regressive (AR) spectral analysis. Fourteen sound and healthy subjects (22～27 years of age) participated in the experiments. Each subject was told to keep a relaxed seating posture with no physical restriction. At the same time, the heart rate measurement by a pulse oximeter was conducted as well as the respiratory rate measurement by a thermistor placed at the external naris. As a result, through the AR spectral analysis, two clear peaks could be detected at about 0.3 Hz and 1.0 Hz. The peaks were thought to correspond to the respiratory rate and the heart rate. Correlation coefficients of 0.90 and 0.93 were obtained for the measurement of the heart rate and the respiratory rate, respectively.
keywords: respiratory rate , heart rate, time-lapse image, non-contact measurement
(BACK)
An Image Analysis Algorithm for Kinematics and Morphology Measurement of Cells for the Evaluation of Tissue Construction.
Image of cells has been analyzed in the various fields of biomedical engineering, such as evaluation of new drug and research of wound healing process, where the static or transient parameters, such as cell number, position, shape, and area, are usually quantified for small amount of the cells during a limited period. Therefore, the current image analysis techniques are not directly applicable for the analysis of the property of a tissue, which consists of huge number of cells. In this study, aiming at evaluation of tissue construction or reconstruction process, we developed a new image processing algorithm which could analyze the properties of huge number of cells in a tissue. The cultured human peritoneal mesothelial cells were injured mechanically by a scratch and were used as a tissue reconstruction model. The wound healing process in a CO2 incubator was visualized with a phase contrast microscope. The sequential images of the cells were acquired by a CMOS camera at intervals of one minute, and were stored in a personal computer. The stored image was converted into gray-scale image with 256 levels. Based on the cell position in the flame immediately before, the region of the interest (ROI) was set for cell tracing, and the target cell was detected by processing the ROI with the Watershed method. Various parameters of the detected cell, such as centroid, area, surroundings length, circularity, and luminance, were quantified. The cell tracing algorithm was coded by the macro language of the image processing software. Through the preliminary experiments, the algorithm developed in this study could trace 88.4 ± 7.9 % of the cells detected in the initial flame.
Keywords- image analysis, wound healing, tissue, cell tracking, CAPD
(BACK)
Pressure Ulcer Measurement.
Pressure ulcer is clinically defined as “any lesion caused by unrelieved pressure resulting in damage of underlying tissue”. To solve the problems with pressure ulcer, that is, to clarify the formation, progression and treatment of it, lots of engineering studies have been conducted up to now. For reproducible and statistic evaluation, these studies were simply based on a mathematical tissue model or an artificial one. Therefore, the results obtained cannot be directly applied in the clinical situations because of the wide variety of patients’ skin condition. In this study, we thought it was practical to detect rubor (initial pressure sore) at an earlier stage, which was curable in a short term, and examined the detection method by using bioelectrical impedance analysis (BIA). Four healthy adult females participated in the experiments. The ethanol patch test was used to produce the rubor model on the subjects’ left forearm. BIA was conducted for normal and rubefied skin by using a lock-in amplifier. Frequency range of the measurement was set at 0.1 Hz-30 kHz. Based on the electric tissue model consisting of two resistances and membrane capacity (Hayden model), change in one resistance due to vasodilatation was assessed. The data acquired were fitted in the model by the least-square-method and Cole-Cole curve was plotted. As a result, the resistance of the rubefied skin was found to decrease to 83.4±4.4 % of the normal one. Distinction of rubefied skin and normal skin by this method is applied to at other regions of human-body. The impedance is almost symmetry at right and left side of the body. Considering the load of the nursing staff for the pressure sore management, a non-contact method for rubor detection would be required. Therefore BIA without electrodes has to be established by using time-varying magnetic field.
(BACK)
Curriculum Vitae (Yuji OHTA) (2013)
Yuji OHTA, D. ENG., Prof.
born April 2, 1962, Nagoya, Japan.
Address:
Faculty of Human Life and Environmental Sciences, Ochanomizu University
2-1-1 Otsuka Bunkyou-ku Tokyo 112-8610 Japan
Academic Education and Appointments
1985 BE, Tokyo University, Tokyo, Japan
1987 ME, Tokyo University, Tokyo, Japan
1988 Assistant, Tokyo University, Tokyo, Japan
1992 Doctor Degree (D. Eng) (Tokyo University)
1992 Lecturer, Tokyo University, Tokyo, Japan
1993 Associate professor, Tokyo University, Tokyo, Japan
1994 Associate professor, Toyo University, Kawagoe, Japan
2001 Associate professor, Ochanomizu University, Tokyo, Japan
2011 Professor, Ochanomizu University, Tokyo, Japan
(TOP)
Publication list (Yuji OHTA)（2013）
Review paper
Ohta Y, Dohi T, Funakubo H, Sakuma I. Development of a Portable Artificial B-Cell. Precision Machinery, Vol.2, 201-209, 1989.
Tada Y, Horiuchi T, Ohta Y, Dohi T. A new approach for the Filtrate Regeneration System in the Wearable Artificial Kidney. Artificial Organs 14(6), 405-409,1990.
Dohi T, Ohta Y, Suzuki M, Chinzei K, Horiuchi T, Hashimoto D and Tsuzuki M. Computer Aided Surgery System (CAS): Development of Surgical Simulation and Planning System with Three Dimensional Graphic Reconstruction. First Conference on Visualization in Biomedical Computing, 458-462, 1990.
Ohta Y, Horiuchi T, Dohi T, Sugaya K, Matsumoto H, Ide H. Development of Computer-Aided Motion Analyzing (CAMA) System for Radiopaque Implanted Tilting Disk Heart Valves. Artificial Organs 14(6):449-453, 1990.
Horiuchi T, Ohta Y, Tada Y, Dohi T, Azuma N, Matsugane T, Sakurai H, Mizumura H and Suzuki M. Measurement of Peritoneal Dialysate Volume by CT. T. ASAIO, 37(3), M156-M158, 1991.
Hashimoto D, Dohi T, Tsuzuki M, Horiuchi T, Ohta Y, Chinzei K, Suzuki M and Idezuki Y. Development of a computer-aided surgery system: Three-dimensional graphic reconstruction for treatment of liver cancer. Surgery, 109, 589-596, 1991.
Chinzei K, Dohi T, Horiuchi T, Ohta Y, Suzuki M, Yamauchi Y, Hashimoto D and Tsuzuki M. Quantitative Integration of Multi-modality Medical Images. Visualization in Biomedical Computing 1992, 187-195, 1992.
Horiuchi T, Tada Y, Ohta Y and Dohi T. Water transport model during CAPD: Determination of parameters. Kidney International, vol.44, 700-707, 1993.
Masutani Y, Yamauchi Y, Suzuki M, Ohta Y, Dohi T, Tsuzuki M, Hashimoto D. Development of interactive vessel modeling system for hepatic vasculature from MR images. Medical and Biological Engineering and Computing, 33, 97-101, 1995.
Ohta Y, Okamoto K, Sonderegger M, Dohi T, Matsumoto H, Horiuchi T. Non-symmetric leaflet motion of St. Jude Medical mitral valves simulated with a computer-controlled hydraulic mock circulator. Artificial Organs 21(4), 335-339, 1997.
Naemura K, Ohta Y, Fujimoto T, Umezu M, Matsumoto H, Dohi T. Comparison of the closing dynamics of mechanical prosthetic heart valves. ASAIO J 43(5), M401-M404, 1997.
Naemura K, Sonderegger M, Matsumoto H, Dohi T, Izumi K, Fujimoto T, Umezu M, Ohta Y. Study of the effect of atrial contraction on mitral prosthetic valve by high speed video camera, Artificial Organs 21(4), 300-305,1997.
Hayashi K, Ohta Y, Kumano K, Horiuchi T. Changes in peritoneal permeability due to chemical fibrosis. J Artificial Organs, 1(2), 76-79, 1998.
Ohta Y, Kikuta Y, Shimooka T, Mitamura Y, Yuhta T, Dohi T. Effect of the sinus of Valsalva on the closing motion of bi-leaflet prosthetic heart valves. Artificial Organs 24(4), 308-312, 2000.
Okamoto H, Ohta Y, Okuda T. Identification of colloidal gold labels with template-matching method for Atomic Force Microscopy. Bioimages 8 (4), 121-127, 2000.
Okamoto H, Kobayashi T, Okuda T, Ohta Y. Detection of the binding sites on a cell membrane using atomic force microscopy with tip modification combined with background subtraction. Bioimages 9 (3-4), 123-130, 2001.
Ohta Y, Okamoto H, Kanno M, Okuda T. Atomic force microscopic observation of mechanically traumatized erythrocytes. Artificial Organs 26(1), 10-17, 2002.
Ohta Y, Otsuka C, Okamoto H. Changes in surface roughness of erythrocytes due to shear stress: atomic force microscopic visualization of the surface microstructure. J Artificial Organs, 6, 101-105, 2003.
Horiuchi T, Miyamoto K, Miyamoto S, Fujita M, Sano N, Minamiyama K, Fujimura Y, Nagasawa K, Otsuka C, Ohta Y. Image analysis of remesothelialization following chemical wounding of cultured human peritoneal mesothelial cells: The role of hyaluronan synthesis, Kidney International, 64(6), 2280-2290, 2003.
Horiuchi T, Ohta Y, Beavis MJ, Craig KJ, Williams JD, Topley N, Morgan LW, Wieslander A, Davies M. Glucose degradation products (GDP) retard remesothelialization independently of d-glucose concentration. Kidney International, 64(5), 1854-1866, 2003.
Kawashima N, Yano H, Ohta Y, Nakazawa K. Stretch reflex modulation during imposed static and dynamic hip movements in standing humans. Exp Brain Res, in press, 2006.
Ohta Y, Yano H, Suzuki R, Yoshida M, Kawashima N, Nakazawa K. A 2-DOF motor-powered gait orthosis for spinal cord injury patients. Journal of Engineering in Medicine: Proceedings of the Institution of Mechanical Engineers Part H. 221(6): 629-639, 2007.
Uchiyama T, Ishigame S, Niitsuma J, Aikawa Y, Ohta Y. Multi-frequency bioelectrical
impedance analysis of skin rubor with two-electrode technique. J Tissue Viability, 17, 110-114, 2008.
Otaki Y, Otaki M, Pengchai P, Ohta Y, Aramaki T. Micro-components survey of residential indoor water consumption in Chiang Mai. Drinking Water Engineering and Science, 1, 17-25, 2008．
Horiuchi T, Matsunaga K, Banno M, Nakano Y, Nishimura K, Hanzawa C, Miyamoto K,
Nomura S, Ohta Y. HPMCs induce greater intercellular delocalization of tight junction- associated proteins due to a higher susceptibility to H2O2 compared with HUVECs. Peritoneal Dialysis International, 29, 217-226, 2009.
Shimba S, Kawashima N, Ohta Y, Yamamoto SI, Nakazawa K. Enhanced stretch reflex
excitability in the soleus muscle during passive standing posture in humans. J
Electromyography & Kinesiology, 20, 406-412, 2010.
Urayama M, Aizawa S, Ohta Y and Aikawa Y. Simplified Model for Cardiovascular System and its Regulation. Okubo J. Journal of the Japanese society of balneology, climatology and ohysical medicine, 73(2)，109−121，2010．
Okubo J, Noguchi N, Kimura H, Koizumi T, Urayama M, Aizawa S, Ohta Y, Aikawa Y. Electrochemical Measurement of Filiform Needle Surface Condition. J Materials Science Society Japan, 47(6), 299-303, 2010.
Saito M, Nakajima K, Takano C, Ohta Y, Sugimoto C, Ezoe R, Sasaki K, Hosaka H, Ifukube T, Ino S, Yamashita K. An in-shoe device to measure plantar pressure during daily human activity. Med Eng Phys. 2011, 33(5):638-45.
Horiuchi T, Masamune K, Iwase Y, Ymashita H, Tsukihara H, Motomura N, Ohta Y, Dohi T. Endoscope system with plasma flushing and coaxial round jet nozzle for off-pump cardiac surgery. Surg Endosc. 2011, 25(7):2296-301.
Takafumi Takebayashi, Takashi Horii, Hiromi Denno, Nobutoshi Nakamachi, Keiko Otomo, Saki Kitamura, Keiichi Miyamoto, Takashi Horiuchi, and Yuji Ohta. Human mesenchymal stem cells differentiate to epithelial cells when cultured on thick collagen gel. Bio-Medical Materials and Engineering, 23, 2013, 143–153.
Hiromi Akahira, Yuko Yamaguchi, Kimitaka Nakazawa, Yuji Ohta, and Noritaka Kawashima. Effect of dynamic knee motion on paralyzed lower limb muscle activity during orthotic gait: A test for the effectiveness of the motor-assisted knee motion device. Journal of Novel Physiotherapy（for Special issue "Advances in Neurorehabilitation Techniques")(on-line journal)
Yuji Ohta and Miki Uchida. Non-Contact Pulse Monitoring Using Live Imaging. (Technological Advancements in Biomedicine for Healthcare Applications. Ed. Jinglong Wu, Published by IGI Global(USA). 2012, 240-246)
(TOP)
Conference Proceedings
Ohta Y, Dohi T, Funakubo H, Sakuma I, Yasuda H, Niwa H, Oka H. Development of an open-loop type artificial B-cell. Pros. 2nd ISBMRE, 311-318, 1986.
Dohi T, Tsuzuki M, Hashimoto D, Idezuki Y, Ohta Y, Suzuki M and Horiuchi T. Development of computer aided surgery system(CAS): Three dimensional graphic reconstruction and surgery simulation. 1989 Korea-Japan Joint Conference on MBE, 15-18, 1989.
Horiuchi T, Ohta Y, Tada Y, Dohi T. A new approach for the filtrate regeneration system in the wearable artificial kidney. Artif. Organs, 13(4), 308, 1989.
Dohi T, Horiuchi T, Ohta Y and Matsumoto H. Development of computer aided motion analysis (CAMA) system for implanted tilting disk valve. Artif. Organs, 13(4), 295, 1989.
Ohta Y, Horiuchi T, Matsumoto H, Ide H and Dohi T. Development of computer aided motion analyzing (CAMA) system for implanted tilting disk valve. Pros. 4th ISBMRE, vol. 1, 49-52, 1990.
Ohta Y, Sako T, Horiuchi T, Dohi T. Eye motion communication system for the bedridden patients. Med. & Biol. Eng. & Comput., Vol. 29, Supp., 798, 1991.
Ohta Y, Horiuchi T, Dohi T, Matsumoto H and Umezu M. Integration of in vivo motion analysis and in vitro hemodynamic study on heart valve prostheses. Artif. Organs. 15(4), 322, 1991.
Dohi T, Horiuchi T, Ohta Y, Chinzei K, Masutani Y, Yamauchi Y, Suzuki M, Hashimoto D, Tsuzuki M. Development of semi-automatic data acquisition for vessel model reconstruction in computer aided surgery. Med. & Biol. Eng. & Comput., Vol. 29, Supp., 451, 1991.
Dohi T, Horiuchi T, Ohta Y, Chinzei K and Fujiki T. Development of assisting manipulator for bed-ridden patients. Med. & Biol. Eng. & Comput., Vol. 29, Suppl., 796, 1991.
Dohi T, Horiuchi T, Ohta Y, Yamauchi Y and Horii A. Development of the multifunction bed for the severely handicapped. Med. & Biol. Eng. & Comput., Vol. 29, Suppl., 800, 1991.
Dohi T, Horiuchi T, Ohta Y, Yamauchi Y and Narahara H. Development of a speech training system for hearing impaired children considering man-machine interface. Med. & Biol. Eng. & Comput., Vol.29, Suppl., 153, 1991.
Dohi T, Horiuchi T, Ohta Y, Horii A, Tsuzuki M, Miyata K, Kakimoto A and Sekiguchi Y. Development of a laser scanning system for excimer laser corneal surgery. Med. & Biol. Eng. & Comput., Vol. 29, Supp., 1250, 1991.
Horiuchi T, Ohta Y, Dohi T, Matsugane T, Azuma N and Suzuki M. Non-invasive measurement of peritoneal dialysate volume and distribution by the X-ray CT. ASAIO 37th annual meeting abstracts, 107, 1991.
Horiuchi T, Ohta Y, Dohi T, Tanaka Y, Yada I and Matsumoto H. Is asynchronous motion of the bi-leaflet valve relating to hemolysis episode? ASAIO 37th annual meeting abstracts, 35, 1991.
Horiuchi T, Ohta Y, Hashimoto K, Dohi T, Uechi M and Watanabe T. Machine perfusion of isolated kidney at 37 C using pyridoxalated hemoglobin-polyoxyethylene (PHP) solution, UW solution and its combination. Biomaterials, Artif. Cells, & Immobilization Biotech., Vol.19, No.2, 400, 1991.
Horiuchi T, Ohta Y, Ohtani S, Dohi T and Saito K. Study on peritoneal dialysate regeneration system (PDRS) using newly developed positively charged membrane. Artif. Organs, 15(4), 331, 1991.
Ohta Y, Suzuki M, Dohi T and Horiuchi T. Development of double pulse magnetic stimulator. Proc. 5th ISBMRE, Vol. 2, 17-20, 1992.
Yamauchi Y, Ohta Y, Dohi T, Tanikawa T and Iseki H. A Stereoscopic Image Integration System for Neurosurgery. Proc. 5th ISBMRE, Vol. 2, 13-16, 1992.
Yamauchi Y, Ohta Y, Dohi T, Kawabata K, Kawarazaki H and Tsuzuki M. An Interference Assessment of Geometric Model of Transplanted Organ in Computer Aided Surgery. Intl Symp. Advanced Computing for Life-Science, 161-163, 1992.
Ohta Y, Okamoto K, Tada Y, Chinzei K, Dohi T and Horiuchi T. In vitro simulation of non-harmonic motion of bi-leaflet prosthetic heart valves. ASAIO 39th annual meeting abstracts, 26, 1993.
Ohta Y, Okamoto K, Tada Y, Dohi T, Horiuchi T. Development of a hydraulic mock circulatory simulator for motion analysis of prosthetic heart valves. Proceedings of 2nd Far Eastern Conference on Medical and Biological Engineering, 113, 1993.
Tada Y, Kuwahara Y, Ohta Y, Dohi T and Horiuchi T. Water transport modeling for minimizing glucose usage in CAPD. ASAIO 39th annual meeting abstracts, 113, 1993.
Yamauchi Y, Suzuki M, Ohta Y, Dohi T, Kawamura H, Tanikawa T, Iseki H, Takakura K. Needle insertion manipulator system for stereotactic neurosurgery. Proceedings of 2nd Far Eastern Conference on Medical and Biological Engineering, 332, 1993.
Suzuki M, Nozaki H, Hashimoto H, Ji L, Ohta Y, Dohi T, Honma K. Development of an assisting system for Indoor- transportation of elderly people. Proc. 4th Intl. Conf. on Rehabilitation Robotics, 133-136, 1994.
Ohta Y, Dohi T, Matsumoto H, Horiuchi T. Motion analysis of bi-leaflet mechanical prosthetic heart valves at mitral position using a computer-controlled hydraulic mock circulator. X World Congress of the International Society for Artificial Organs, Abstract volume, 182, 1995.
Naemura K, Matsumoto H, Dohi T, Izumi K, Fujimoto T, Umezu M, Ohta Y. Study on the effect of atrial contraction on mitral prosthetic valve by high speed video camera. X World Congress of the International Society for Artificial Organs Abstract Volume, p.160, 1995.
Ohta Y, Okamoto H, Dohi T, Matsumoto H, Horiuchi T. Analysis of down stream of in vitro mechanical prosthetic heart valve for an early detection of valve malfunction. The International Journal of Artificial Organs, 19(9), 537, 1996.
Ohta Y, Ohmukai T, Okamoto H, Dohi T, Matsumoto H, Horiuchi T, Development of a hydraulic mock circulator for the quantitative analysis of leaflet motion of mechanical prosthetic heart valves., Waseda Intl. Congrs. Modeling and Simulation Technol. for Artif. Organs. Proc., 87-88,1996.
Horiuchi T, Hayashi K, Sumida Y, Ohta Y. Bioelectrical impedance analysis (BIA) for assessing water distribution in chronic dialysis patients. The International Journal of Artificial Organs, 19(9), 503, 1996.
Naemura K, Ohta Y, Fujimoto T, Umezu M, Matsumoto H, Dohi T. X-ray high speed video camera for measurement of the motion of the implanted mechanical heart valve prostheses. The International Journal of Artificial Organs, 19(9), 537, 1996.
Naemura K, Ohta Y, Fujimoto T, Umezu M, Dohi T, Measurement of the prosthetic valve motion by X-ray high speed video camera, Waseda Intl. Congrs. Modeling and Simulation Technol. for Artif. Organs. Proc., 51-52, 1996.
Ohta Y, Okamoto H, Kanno M, Yuhta T, Shimooka T, Mitamura Y, Dohi T. Effect of the sinus of Valsalva on the closing motion of bi-leaflet prosthetic heart valves. Third world congress of biomechanics, Abstracts, 358, 1998.
Ohta Y, Okamoto H, Kanno M, Dohi T, Matsumoto H. Analysis of the downstream flow of prosthetic mechanical heart valves by wavelet transform: A trial for the detection of slight malfunction of valves under in vitro condition. The 4th International Conference on biomedical engineering, Proceedings, pp.27-28, 1998.
Ohta Y, Okamoto H, Kanno M, Okuda T. Morphological changes of sheep red blood cell by loading with shear stress: imaging by atomic force microscope in nanometer scale. the XXVth ESAO (European Society for Artificial Organs) Congress. International Journal of artificial organs, 21(10), 598, 1998.
Ohta Y, Okamoto H, Kanno M, Dohi T, Matsumoto H. Turbulent analysis of the down stream flow of prosthetic mechanical heart valves using wavelet transform. the XXVth ESAO (European Society for Artificial Organs) Congress. International Journal of artificial organs, 21(10), 646, 1998.
Okamoto H, Kanno M, Ohta Y, Okuda T. Imaging of the spectrin network of red blood cells by an atomic force microscope. Third world congress of biomechanics, Abstracts, 488, 1998.
Ohta Y, Okamoto H, Okuda T, Horiuchi T. The atomic force microscope: a new tool for artificial organ research. J Artificial Organs 2(1), 131-134, 1999.
Ohta Y, Kataoka H, Masamune K, Sakuma I, Dohi T, Iseki H, Takakura K. Development of a supporting device for surgical planning using superimposition of images. IMEKO-XV World Congress, volume I, 213-216, 1999.
Ohta Y, Kanno M, Okamoto H, Okuda T. Measurement of surface roughness of erythrocyte using Atomic Force Microscope for the estimation of the damage caused by shear stress. Artificial Organs, 23(7), 624, 1999.
Ohta Y, Okamoto H, Okuda T, Horiuchi T. Visualization of biological samples using the atomic force microscope: a new tool for biomedical research. Proceedings of the 5th International conference on biomedical engineering, 21-24, 1999.
Okamoto H, Ohta Y, Kanno M, Okuda T. Measurement of surface roughness of erythrocyte using Atomic Force Microscope for the estimation of the damage caused by shear stress. IMEKO-XV World Congress, volume I, 217-220, 1999.
Kobayashi T, Okamoto H, Ohta Y, Okuda T. Atomic force microscopic visualization of identical site on cell surface with different probes for the detection of specific reaction force. Proceedings of 4th symposium on bio-nano electronics, 103, 1999.
Okamoto H, Ohta Y, Okuda T. Identification of cell surface antigens using atomic force microscopy ﾐ immuno-gold labeling combined with pattern matching. Proceedings of 4th symposium on bio-nano electronics, 102, 1999.
Ohta Y, Kobayashi T, Okamoto H, Okuda T. Atomic force microscopic visualization of identical site on cell surface with different probes. Technical proceedings of the third international conference on modeling and simulation of microsystems, 245-248, 2000.
Ohta Y, Okamoto H, Saito F, Okuda T. Atomic force microscopic visualization of sheared erythrocytes: Effect of the periodic flow on the surface roughness. 10th International Conference on Biomedical Engineering, 83-84, 2000
Kobayashi T, Okamoto H, Ohta Y, Okuda T. Detection of the specific reaction force by the differential method with Atomic Force Microscopy. Proceedings of 5th Symposium on Bio-Nano Electronics．124，2000．
Ohta Y. Applications of atomic force microscopy in the field of life science. The 3rd Joint Forum of EWU, JWU, and Ochanomizu University for the Promotion of Education and Research in Science for Women in the 21st Century. 83-86, 2001 Nov 9 at Ochanomizu University.
Okamoto H, Ohta Y, Okuda T. Identification of colloidal gold labels with template-matching method for Atomic Force Microscopy. Tokyo-2001: Scanning probe microscopy, sensors, and nanostructures Abstracts, p.58, May 27-31, 2001.
Okamoto H, Kobayashi T, Ohta Y, Okuda T. Detection of the binding sites with differential method for Atomic Force Microscopy. Tokyo-2001: Scanning probe microscopy, sensors, and nanostructures Abstracts, p.113, May 27-31, 2001.
Ohta Y. Applications of atomic force microscopy in the field of life science. The 3rd Joint Forum of EWU, JWU, and Ochanomizu University for the Promotion of Education and Research in Science for Women in the 21st Century. 83-86, 2001 Nov 9 at Ochanomizu University.
Ohta Y, Yoshida M, Shinoya Y, Matsumoto A, Kawashima N, Nakazawa K, Yano H. A gait orthosis for paraplegics with a motor-driven knee joint. 4th World congress of Biomechanics, in CD-ROM, 2002.
Ohta Y, Yoshida M, Kawashima N, Nakazawa K. A gait orthosis for paraplegics with a motor-driven hip joint. International Society for Posture and Gait research, XVIth Conference, 142, 2003.
Ohta Y, Kawashima N, Nakazawa K, Development of a powered gait orthosis for spinal cord injury patients. 2nd International Conference on Biomechanics of the Lower Limb in Health Disease and Rehabilitation, 30-31, 2003.
Takano C, Ohta Y. Simultaneous Measurement of Respiration and Heart Rate Using Live Image. The First International Conference on Complex Medical Engineering-CME2005, 24, 2005.
Suzuki R, Ohta Y, Nakazawa K, Ohtsuka H, Kawashima N. Novel Home-Based Care Device for Prevention of the Secondary Disease in Paraplegic Persons. World Congress on Medical Physics and Biomedical Engineering 2006(WC2006, August 27 to September 1, 2006 in Seoul, Korea) in CD-ROM.
Gessei T, Ohtsuka C, Banno M, Miyamoto K, Ohta Y, Horiuchi T. An Image Analysis Algorithm for Kinematics and Morphology Measurement of Cells for the Evaluation of Tissue Construction. World Congress on Medical Physics and Biomedical Engineering 2006(WC2006, August 27 to September 1, 2006 in Seoul, Korea) in CD-ROM
Uchiyama T, Ohta Y. Bioelectrical Impedance Analysis of Skin Rubor for Early Detection of Pressure Ulcer. World Congress on Medical Physics and Biomedical Engineering 2006(WC2006, August 27 to September 1, 2006 in Seoul, Korea) in CD-ROM
Uchiyama T, Ishigame S, Ohta Y, Niitsuma J. Measurement of skin rubor by using Bioelectric impedance method: detection of initial pressure ulcer. EPSM-ABEC 2007 Conference (Engineering and Physical Sciences in Medicine and The Australian Biomedical Engineering Conference 2007), 238, 2007.
Tanaka M Ohta Y, Matsumiya K, Masamune K, Dohi T, Iimura A, Matsuse M, Kobayashi Y. An evacuation drill system using virtual reality technology for children with mental retardation. EPSM-ABEC 2007 Conference(Engineering and Physical Sciences in Medicine and The Australian Biomedical Engineering Conference 2007) 237, 2007.
Saito M, Ruijia Z, Ohta Y, Takano C, Sugimoto C, Ezoe R, Sasaki K, Hosaka H, Ifukube T, Ino S, Yamashita K. A wireless device for foot pressure measurement: prevention of fall for the elderly. EPSM-ABEC 2007 Conference(Engineering and Physical Sciences in Medicine and The Australian Biomedical Engineering Conference 2007), 233, 2007.
Hasegawa K, Ohtsuka C, Miyamoto K, Horiuchi T, Ohta Y. Quantitative anlysis of cell kinematics in the wound restoration process: distance dependency from wound area. The 2nd International Federation for Artificial Organs, CD-ROM, 2007.
Ohta Y, Motooka N, Siio K, Tsukada K, Kambara K. An approach for real life monitoring in a ubiquitous computing house. Ubiqutous healthcare 2009, Oct 22-24, Osaka, p.15-17, 2009.
Kanako NAKAJIMA, Michiko SAITO, Miyuki KODAMA, Yumi IWAKAMI, Shuichi INO, Tohru IFUKUBE, Kazuhiko YAMASHITA, Yuji OHTA. Evaluation of ambulatory function by using the shoe device. EUROPEAN IFMBE MBEC, 868-871, 2011.
(TOP)
For more information, please contact Y Ohta ohta.yuji@ocha.ac.jp