In this study, we proposed a powder-layered manufacturing process, which is one technique for rapid prototyping, to produce the desired bone shape for a transplantation from a biomaterial powder. In the experiment, we used conventional inkjet-type equipment and orthopedic filling-paste powder (BIOPEX), of which the main component was alpha-tribasic calcium phosphate, as the forming material. To solidify the powder, we used a sodium chondroitin sulfate+dibasic sodium succinate anhydride aqueous solution-the solvent for mixing powder in clinics-as the binder liquid. In the previous report, we formed a geometric model and living bone to examine the formability of artificial bones, and showed that the formation of artificial bones is possible using this technique. In this paper, we investigated porous characteristics, an important condition for artificial bones. In experiments, we formed cylindrical samples (dimensions: 7 mm in diameter, 20 mm in length) by powder-layered manufacturing (PM) and using filling-paste (FP) which is also used in clinical applications. Then we compared the porous characteristics of these samples using mercury porosimetry. The results showed that in the case of PM, porosity was 60%, about three times FP. In addition, we dipped PM samples in water and binder liquid for improving compressive strength by hydration reaction. The compressive strength of two kinds of dipped samples reached about 3 MPa when heated at 90 °C for five hours. Porosity was about 56% when dipped in water, and about 50% when dipped in binder liquid.

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Neuro-physiological measures especially EEG analysis is helpful to understand underlying mechanisms of mental fatigue during sustained mental work. In this research, a work-rest schedule containing mental calculation and music rest break was designed. Neuro-physiological measures were related with subjective evaluation and performance assessment. Individual EEG characteristics and common EEG features were analyzed. It is found that theta and alpha rhythm are highly related with concentration, alertness and drowsy during mental work. Faster EEG frequency bands reflect higher alertness level after taking a rest. Subjective evaluation and performance assessment support EEG findings. The results from subjective evidence and objective evidence indicate that a short break (e.g. 15 min per 2 hrs) in sustained mental work can counteract the accumulation of mental fatigue and improve work efficiency.

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Physiological monitoring was carried out during the motor sport of Racing Kart driving. In addition to highlighting the importance of physiological measurement during motor sports, this study may have social relevance through its potential to contribute to decreasing automobile accidents in overload situations by using appropriate biosignals. The measurement quantities collected in this study were instantaneous heart rate, HR, vector magnitude of acceleration, G, blood pressure, BP, and core body temperature, T_eardrum. After giving informed consent 11 healthy male subjects (34.4 ± 7.7 S.D. yrs) were tested in the racing circuit. We successfully monitored the physiological variables during karting, finding a statistically significant decrease in BP (p < 0.01) and a rise in T_eardrum (p < 0.01) immediately after the driving period. In addition, we have confirmed that HR was maintained at approximately 150bpm, which, by means of time-frequency analysis, could be explained by sympathetic acceleration. Furthermore, it is strongly suggested that the rise in HR could be closely related to the G forces to which the drivers were subjected. These results clearly disclose to us one aspect of the possible physiological responses and the importance of physiological monitoring during motor sports.

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Saliva sampling has some advantages that it is non-invasive, making multiple sampling easy and stress free. The purpose of this study is to evaluate the usefulness of salivary alpha (α) -amylase (sAA) as psychosomatic stress indexes in junior high school students. Seventy healthy (not non-attendance at school) subjects in first-year junior high school students were enrolled (12-13 yr). The sAA in the morning, daytime and early-evening were analyzed for 3 days. General Health Questionnaire (GHQ) -28 and State-Trait Anxiety Inventory (STAI) were conducted as mental health indexes, the all subjects divided two groups; high and low. High stress groups either GHQ-28 (social dysfunction) or STAI (state anxiety) showed significantly high sAA compared with those of low stress groups. The multiple regression analysis using sAA as dependent variable had applied between sAA and both mental health indexes. Although, there was no significance in low stress groups, a causal relationship was found in high stress groups. These results suggested that sAA is useful index for screening of healthy human not having especially psychosomatic stress but havingthe risk before being bad mental conditions such as a state of depression. The sAA might be a useful screening method for preventing to be a non-attendance at school.

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Damage of central nervous system caused by a stroke or spinal cord injury usually brings about motor paralysis and increase of muscle tone, spasticity. Excessive spasticity disturbs smooth and coordinated voluntary movement. In this study, we investigated the change of motion parameters during walking in the spastic paraplegic patients and hemiparetic stroke patients before and after application of therapeutic electrical stimulation (ES) . Five spastic paraplegics and seven spastic hemiparetics participated in this study. Eight were male and mean age was 46.3 ± 13.8 (16∼61) years. With regard to the stroke patients, all had left hemiparesis. Stimulation parameters were pulse width of 0.3 msec and frequency of 20 Hz. For the spastic paraplegic patients, stimulation was given to right and left leg alternately during 15 min with 10 s on and 5 s off interval. For the spastic hemiparetic patients, stimulation was only given to the side of paralysis with same duration and interval as the paraplegics. The data of more-spastic side of paraplegics and paralyzed side of hemiparetics were treated as one group (severe side). As for severe side, mean motion range of knee joint was significantly increased after ES (p < 0.05) . Mean motion range of hip joint showed a tendency to increase after stimulation (p < 0.1). Physiological and kinesiological mechanism on the effect of ES providing the change of some motion parameters is complicated. Usually, therapeutic ES for a muscle brings about spasticity inhibition of the antagonist muscle and facilitation of the target muscle. In the present study, ES for rectus muscle possibly suppressed the tone of hamstrings and elicited voluntary action of rectus. Hamstrings have actions as a knee flexor and a hip extensor. Consequently, the motion range of knee and hip joint may have been easily expanded during walking. The results in the present study suggest ES during 15 min can improve gait performance.

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Optical imaging based on intrinsic signals has been widely used in the studies on the functional organization of cortex. Due to the poor temporal resolution of the signal which is caused by the property of the cortical tissue, the temporal information of the cortical intrinsic signal has been largely untouched. In this study, we proposed a method based on the temporal correlation between the presentation of stimulus and the cortical optical responseto visualize the dynamics of neuronal activity, and applied the method in the study of cat primary visual cortex. With the help of the proposed method, we have successfully mapped the metabolic changes associated with the stimulus-driven activity of underlying cortical neurons, and furthermore succeeded in revealing the temporal relation across various cortical areas. The results approved the usefulness of the proposed method and demonstrate the dynamics of optical signals evoked by the presentation of the visual stimuli.

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MR images of human prostate gland are lightly affected motion artifact from the patient's free-breathing. MR images are superior to Computed Tomography Images at contrast resolution in pelvic region. We measured prostate gland capacity from 20 volunteers (average age: 23.08 years old) who had no symptoms related to the prostate. We recalculated the MR imaging by the Chapman method. We created two cross-sectional images from prostate's MR images at the following; Coronal Oblique plane (follow the shape of the ejaculatory duct and distal urethra segment), Double Oblique plane (vertically-directed coronary plane from distal urethra segment), which is defined from zonal anatomy which proposed by McNeal JE. For 20 volunteers' studies, the average capacity of the prostate is 15.72 cc. The almost same volume was calculated from both Coronal Oblique plane and Double Oblique plane.

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The objective of our research is to develop brain-computer interface (BCI) for cognitive P300 event-related potentials (ERPs) in a bone-conduction (BC) and air-conduction (AC) auditory oddball paradigm. The utilization of BCI for the severe physical limitation persons will assist them in their communication and enable them to interact with the outside world, which is our final research goal. In order to target communication support for severe neuromuscular disease patients including children, we reconsidered the current state of the communication support in clients with amyotrophic lateral sclerosis (ALS) over the last seven years and examined the possibility of clinical application of BCI technology. Compared to previous P300 BCI system using AC auditory oddball paradigm, our study aims at the possibility of using BC auditory oddball paradigm by arbitrary distinction of the tone burst sound stimulation at different frequencies. The optimal condition for deriving the P300 ERPs wave by AC stimulation using standard headphones was compared with BC stimulation using headphones in contact with both sides of the temporal bone in healthy subjects. It was necessary to examine the transmission characteristics to the auditory pathway such as loudness, pitch and degree of mental load, between AC and BC stimulation methods. It was also necessary to examine auditory processing in the cortex as well as auditory cognitive processes, among others, involved in the P300 ERPs potential selective attention task for our BCI system. Such a BCI system is clinically useful as a communication-assistive technology for patients with severe neuromuscular diseases.

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Isometric force response curve by electrically stimulated skeletal muscle contraction of twitch is important in order to judge the ability of the skeletal muscle and to distinguish disease state. In this report, we introduce a new mathematical model of the isometric force response curve, in order to estimate the muscle contraction behavior accurately. The new mathematical model of force response curve was expressed by a difference of fundamental function which was expressed by products of a step response function and a logistic function. The mathematical model was applied to the force response curve by electrically stimulated muscle contraction of twitch, using the rat gastrocnemius muscle (GC), intermediate vastus muscle (VI) and soleus muscle (SOL) . The results indicate new mathematical model showed better agreement with the force response curve of twitch than previous mathematical model in the rat skeletal muscle which has different muscle fiber type only changes the model parameters.

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It is desirable to move on feet with a supporting tool even when a patient is injured in the leg. In this research, a three-point gait with an axillary crutch was focused on, because it has stability and portability. Untrained patients tend to use an axillary crutch unsuitably and this may cause their falling. Therefore, an axillary crutch walking trainer for untrained patients was developed. Developed trainer can warn immediately the patient against the inadequate usage, that is, the axillary crutch is leaned more than the threshold angle. Inexperienced subjects could acquire a skill of axillary crutch walking through trainings with the developed trainer.

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Salivary gland function is primarily evaluated by observing biopsy tissue and by measuring the saliva collected by gum test and saxon test. However, biopsy is an invasive method of evaluation for the salivary gland. In addition, neither the gum test nor the saxon test can specify the disordered parts, as saliva of the parotid or submandibular gland is difficult to separate from the collected saliva, meaning that function of the salivary gland other than overall saliva secretion cannot be adequately evaluated. As an imaging method, salivary scintigraphy is one method for evaluating function. However, radiation exposure is unavoidable with this modality, as radionuclides are used. Magnetic resonance imaging (MRI) is noninvasive and requires no exposure to radiation. In addition, this modality can obtain morphological, biochemical and physiological information with high spatial resolution for soft tissues using magnetism and electromagnetic waves. We examined the utility of equivalent cross-relaxation rate (ECR) imaging (ECRI) for functional evaluation of the parotid gland to detect minute changes in organization and molecular structure, offering information reflecting interactions with water molecules and biomacromolecules using MRI. A total of 15 patients with head-neck cancer underwent both salivary scintigraphy and MRI. ECR values were compared between non-and post-radiated parotid glands. In addition, ECR value was compared with maximum uptake rate (MUR), a functional parameter obtained by salivary gland scintigraphy. A correlation was detected between ECR values and MUR. Moreover, ECR values were significantly elevated in the post-radiated parotid gland. ECRI is thus useful for detecting changes in organization and molecular configuration and for evaluating function of the parotid gland after radiotherapy.

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The final goal of this study is to develop a total implantable biosignal monitoring device which monitors biosignals inside body for long time. For such device transcutaneous digital communication and energy transmission is indispensable. This paper describes a noncontact transcutaneous digital communication using Bluetooth and long distance energy transmission system using core coil. We have developed an implantable biosignal monitoring device equipped with an acceleration sensor, an ECG amplifier, a temperature sensor, a flash memory, a Bluetooth module, a transcutaneous energy receiving coil and a lithium ion battery. We performed an implant test using a cow and transcutaneous digital communication at a distance of 2,700 mm and energy transmission at a distance of 150 mm through the skin were confirmed.

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By regarding skeletal muscle as an actuator, it has good features, excellent frexibility and efficiency, and these features are not able to obtain by using another artifical actuators like electric motors or mechanical engines. We have started to culture skeletal muscle to use it as a miniaturized bio-actuator. To culture myoblast and to develop skeletal muscle, stimulation is very important. The purpose of this study is to clear the importance of the mechanical stimulation to differentiate myoblast into myotube. We have developed a mechanical stimulation apparatus and new designed flexible scaffolds for cultivation. C2C12 cells were cultured under the condition to be stimulated mechanically to one direction, continuously or periodically. After cultivation, it was observed that the cultivated and stimulated cells were fused into myotube. In addition, the cultivated cells were observed to contract by applying voltage pulses. The conclusion was that it was very important to stimulate or stress to myoblast for the development of skeletal muscle.

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The aim of our research is to establish a virtual educational program of MR imaging technique with a computer-based simulation system. A fast simulation method of MR imaging is required for efficient learning of the relationship between imaging parameter settings and the generated MR images. In our research, MRI signal intensity equations are applied for fast MR imaging. Our previous research evaluated a T2 estimation method and simulation accuracy for spin echo pulse sequence. This time, the study shows an evaluation of simulation accuracy for SPGR sequence and IR sequence. Also, T1 is estimated by using image data of SPGR sequence. The T2 estimation method used is the same as our previous research. Results showed that an effective simulation of MR imaging is possible with the similar imaging parameter settings applied to real image data for T1 estimation. On the other hand, large simulation error of the IR sequence is obtained.

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Recent study had demonstrated that the medial gastrocnemius (MG) muscle fiber during upright standing moved as paradoxical relative to the anatomical demands, and suggested that the predictive neural activities were important for the postural sway. In this respect, we estimated the changes in the length of the muscle fiber (MFL) of MG while upright standing tasks in which the changes of center of mass (COM) and the length of moment arm were different. The aim of this study was to estimate the relationship of the behavior of MFL and the length of moment arm under three muscle fiber movements in vivo revealed by time series of the ultrasound images; 1) subjects swayed their body voluntarily in an anterior-posterior direction, 2) standing on their tiptoe or heels which could induce the same angle of the ankle plantar-and/or dorsi-flexion compared with those of bodily swaying in anterior-posterior direction, and 3) treadmill walkingat 3.0 and 4.0 km/h. The hip, knee and ankle angular displacements were recorded by goniometers. The center of pressure and the angle of ankle had used as a visual feedback signal in two postural tasks. The MFL of MG shortened when the position of the COM located in front of the ankle joint, and lengthened when the position of the COM located behind the ankle joint. These results suggested that the changes in the MFL of MG were determined by the COM position relative to the ankle joint.

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This study aimed to investigate the laterality and influence of contraction time during low-intensity isometric contraction (20% maximum voluntary contraction) in the case of upper limb physiological tremor (PT) . The PT signal was measured in 9 healthy and right-handed males by using an acceleration sensor. The maximum entropy method was used to compare the contraction time and laterality among these subjects. The amplitude of PT was found to increase with the contraction time. This increase was mainly influenced by components measuring < 12 Hz. Further, the amplitude of PT was greater in the left limb than in the right limb. During the first half of the contraction (0 to 30 sec), the standard deviation of amplitude (SD) significantly correlated with components measuring ranging from 8 to 12 Hz (r = 0.81 (right), r = 0.75 (left) ) ; however, in the latter half (30 to 60 sec) of the contraction, the SD significantly correlated with components measuring < 4 Hz (r = 0.91 (right), r = 0.71 (left) ) and those ranging from 8 to 12 Hz (r = 0.88 (right), r = 0.89 (left) ) . These results suggest that PT is influenced by a superspinal mechanism at the onset of contraction; however, with an increase in the contraction time, PT is influenced by both a superspinal mechanism and stretch reflex. Furthermore, PT is influenced by not only the contraction time but also laterality.

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