Akihiko Uchiyama

Development of an ECG identification system

The purpose of this paper is to present a new identification engine for an ECG identification system. The system identifies subjects based on a comparison of a patients ECG with previously registered ECG feature parameters. These feature parameters are sampled from the intervals and durations of the electrocardiographic waves extracted using characteristic points appearing on the waveform of the second order derivative and are identified using discriminant analysis. Suitable combinations of feature parameters are selected and the accuracy of the proposed technique verified using ECGs from nine normal subjects.

Information-Power Machine with Senses and Limbs

The WABOT project is aimed at developing an information-power machine to introduce external and internal informations, judge the same by itself and perform a given action autonomously. The WABOT-1 consists of a human-type biped walking machine provided with artificial ears and mouth to receive a vocal command from the operator and make a vocal response, artificial eyes to recognize the position, distance and direction of an object and human-type bilateral hands. Under the control of a mini-computer as the artificial brain and on the basis of external informations received from the visual, auditory and dermal senses, etc., the WABOT-1 performs a given work in linked motions of hands and feet in on-line real time.

Association of microRNA-21 expression with its targets, PDCD4 and TIMP3, in pancreatic ductal adenocarcinoma.

Since the discovery of small non-coding RNAs, the analyses of microRNA (miRNA) expression patterns in human cancer have provided new insights into cancer biology. miRNA-21 has been suggested to be one of the miRNAs that have an important role in the development or biological behavior of a variety of malignancies, including pancreatic cancer. This study was conducted to evaluate the relationship between the expression of miRNA-21 and that of its molecular targets, programmed cell death 4 (PDCD4) and tissue inhibitor of metalloproteinase (TIMP3), in pancreatic ductal adenocarcinoma. The study included 65 pancreatic ductal adenocarcinomas and 5 normal pancreatic tissue specimens for comparison. The miRNA expression profiling of five selected pancreatic ductal adenocarcinomas and five normal pancreatic specimens was performed using a microarray platform, and was evaluated by a hierarchical clustering analysis. The miRNA most highly expressed in pancreatic ductal adenocarcinomas (ie, miRNA-21) was further assessed by quantitative real-time reverse transcription PCR (RT-PCR) assays in the 65 pancreatic ductal adenocarcinoma cases. The expression pattern of its molecular targets (eg, PDCD4 and TIMP3) in pancreatic ductal adenocarcinoma was examined immunohistochemically. In the microarray analyses, 28 miRNAs were upregulated in pancreatic ductal adenocarcinoma compared with normal pancreatic tissue, whereas 48 miRNAs were downregulated. miRNA-21 was the most significantly overexpressed miRNA in the pancreatic ductal adenocarcinomas analyzed, and was also highly expressed in 75% of the 65 pancreatic ductal adenocarcinomas examined by real-time RT-PCR. High miRNA-21 expression was correlated with a worse prognosis in the pancreatic ductal adenocarcinoma patients (P=0.045). The immunohistochemical expression patterns of PDCD4 (reduced nuclear staining pattern) and TIMP3 (downregulated expression) were significantly associated with both the upregulated miR-21 expression (P<0.05) and the poor survival of the patients (P<0.001 and P=0.001, respectively). Our data suggest that an overexpression of miRNA-21 is, therefore, associated with the biological behavior of pancreatic ductal adenocarcinoma via the downregulation of the expression of tumor suppressors, PDCD4 and TIMP3, thus resulting in tumor progression and the adverse clinical course of pancreatic ductal adenocarcinoma.

The distribution and propagation pattern of motor unit action potentials studied by multi-channel surface EMG

We developed the multi-channel surface EMG system using a matrix-type of surface electrode and with the aid of digital signal processing. The subjects were 14 normals (4-50 years) and 2 patients with Duchenne muscular dystrophy (7 and 8 years). The biceps brachii and the tibialis anterior muscles were investigated. The location of the motor end-plates and the measurement of muscle fiber conduction velocity were evaluated by the time shift of bipolar EMG arrays along muscle fibers, or by the distribution map of averaged motor unit action potentials (MUAPs). The lateral extension of a motor unit could be also estimated from the changes of averaged MUAPs amplitudes in the distribution map. Moreover in the biceps of 2 patients with Duchenne dystrophy, the mean muscle fiber conduction velocities were reduced compared to normal subjects, and characteristic propagation patterns of action potentials were obtained. In the 2-dimensional or 3-dimensional distribution map of integrated monopolar EMGs, the high density area agreed with the motor end-plate band.

Control of Wavelength Dispersion of Birefringence for Oriented Copolycarbonate Films Containing Positive and Negative Birefringent Units

The wavelength dispersion of birefringence for uniaxially oriented copolycarbonate films containing positive and negative birefringent units has been examined by polarization-modulated transmission spectro-ellipsometry, as a function of copolymerization ratio and stretching parameters. The copolymers were synthesized from 2,2-bis(4-hydroxyphenyl)propane (BPA), 9,9-bis(4-hydroxy-3-methylphenyl)fluorene (BMPF) and phosgene by interfacial polycondensation. The films indicate reverse dispersion in the region of BMPF volume fraction from 0.65 to 0.80. The wavelength dispersion is controlled by the copolymerization ratio. The dispersion change of the 70 mol% BMPF copolycarbonate films as a function of stretching parameters is negligible. These behaviors are explained by the birefringence equation for a multicomponent system of the copolymer.

Simulator for virtual surgery using deformable organ models and force feedback system.

This paper describes a real-time surgery planning system using virtual reality techniques. This system allows us to simulate incision of skin and organs which respond as elastic objects with surgical tools in virtual space. Inner structures such as blood vessels and lesions can be seen and manipulated in the simulation. In addition to these functions we attempted to add a feedback function that responds to the operators hands. We developed a force feedback device to manipulate the elastic organ model based on pressure from the operators fingers.

Evaluation of a Multifunctional Hand Prosthesis System Using EMG Controlled Animation

In this communication, we present an on-line real-time simulation system used to evaluate a new method of controlling a multifunctional hand prosthesis. The system employs two computers. Acquisition, analysis, and classification of EMG signals are performed by a minicomputer, and the animation model of the hand prosthesis which is displayed on a monitor TV is controlled by a microcomputer. From three EMG signals picked up from the most suitable muscles of the forearm, three amplitude and three frequency components are derived. Six voluntary movements are then classified by the use of a pattern recognition technique based on the linear discriminant analysis method. Besides the six basic motions, the model can also make eight combined motions using the method of selecting control signals. The experimental results tested on healthy adults indicated that recognition rate was above 90 percent, and nearly 100 percent in some of the better cases. Then the subjects could easily operate the model on the TV screen.

Analysis of Extraordinary Birefringence Dispersion of Uniaxially Oriented Poly(2,6-dimethyl 1,4-phenylene oxide)/Atactic Polystyrene Blend Films

The birefringence dispersion of uniaxially oriented poly(2,6-dimethyl 1,4-phenylene oxide) (PPO)/atactic polystyrene blend films has been investigated by polarization-modulated transmission spectro-ellipsometry measurements. The films show reverse birefringence dispersion in the region of PPO volume fraction from 0.21 to 0.29, where the birefringence is negative and close to zero, indicating ordinary refractive index dispersion. The reverse birefringence dispersion can be explained by the birefringence equation of a multicomponent system based on the preconditions that the intrinsic birefringence of each component in the blend is not changed and the form birefringence is ignored. Furthermore, it has been found that the orientation functions change depending on the volume fractions by the new method for obtaining orientation functions from birefringence dispersion.

Development of Three-Dimensional Endoscopic Ultrasound System with Optical Tracking

We have developed a new three-dimensional (3D) endoscopic ultrasound system (EUS) with convex scanning echoendoscope to diagnose and navigate by using 3D image. We use an optical tracking system which is shaped like a ribbon to detect the position of the probe and to monitor the shape of the scope inside the body. The optical tracking system can measure bends and twists at each position along with the echoendoscope. Then, the position of the tip of the echoendoscope is allotted to a 2D image, and the system can reconstruct and visualize a 3D image in real-time. We have reported results of our experimental studies using phantom and 3D images of vessels in animal studies.

Development of a small wireless position sensor for medical capsule devices

Medical capsule devices such as video capsule endoscopes are finding increasing use in clinical applications. At present, technologies capable of measuring capsule position in the digestive tract have not yet been established. The present study aims to develop a small wireless position sensor capable of measuring capsule position based on the phenomenon of mutual induction. Currents into primary coils are adjusted to maintain electromotive force induced in secondary coils at a constant level. Electromotive forces induced in the secondary coils are modulated to FM signals using an astable multivibrator, and the signals are passed directly through living tissue at low current and then demodulated by detectors on the surface of the body. A prototype wireless sensor was developed and evaluated in vitro. The sensor was capable of accurately measuring capsule position up to 500 (mm) from the primary coils with an accuracy of 5 (mm). Miniaturization of the sensor is necessary for commercialization.