Cycling wheel chair (C-W/C) is a useful tool to provide a chance of physical exercise for the patients with severe impairment in lower extremities. We developed a new C-W/C with a round shaped steering system and examined the change of physical function before and 4weeks after training with this C-W/C for the patients with unilateral impairment of lower extremity. All of the patients could drive it and continue training during 4weeks. Maximum walking speed (MWS). score of Barthel index and driving speed of C-W/C (DS) significantly increased after training though grip strength and knee extension strength did not. Increment of MWS and DS during 4weeks (ΔMWS, ΔDS) and mean driving distances per week correlated each other. Furthermore, ΔDS correlated with the increment of cardio-respiratory fitness evaluated by metabolic equivalents. Physical training during 4weeks with C-W/C has a possibility to improve physical function through reinforcement of reciprocation in the lower extremities and efficient use of physical fitness.
This paper addressed issues related to the initial stability of stem fixation after implantation of the cementless shaft type hip stem. The study investigated whether a plate is useful to obtain initial fixation between the stem and bone tissue. The specimen was a characteristic stem with a proximal plate. Two type finite element models were constructed for the computer simulation. Stress distribution and micromotion in the movable plate stem model was compared to that in the fixed-plate stem model. Boundary and initial conditions were (i) Rigid contact of the distal end of the model femur with the rigid base. (ii) Walking load of 1800 N was applied to the proximal top of the stem. (iii) Muscle force was pulled from the greater trochanter of the femur. As a result, it was found that the representative von Mises stress in a movable plate stem model was lower than that of the fixed-plate stem model. The movable plate is useful to avoid excessive stress concentration and loosening. We judged that the slight mobility of a plate was useful for primary stem fixation.
We have developed an imaging system adopting the combination of coded excitation and synthetic aperturefocusing technique. Using this system, wecan obtain theultrasound imageby a high framerate. However, when the orthogonalization of the code system is imperfect, the artifact is generated. In this paper, the moving ultrasound image is considered as multidimensional images. From the multidimensional space, the feature enhanced image can be extracted using tensor voting. Through the simulation, it is shown that the image enhancement of ultrasound image by tensor voting is feasible.
Contraction of the heart is controlled by electrical excitations of cardiac cell membranes. The electrical excitations of the cells and their propagation within the heart tissue provide a basis of the physiological function of the heart through the cardiac excitation-contraction coupling mechanism. A large number of studies have been carried out using mathematical models of the cardiac excitation in order to understand normal and abnormal dynamics of the heart. However, simulating the dynamics of a tissue or organ model with a large number of cellular models requires an immense amount of computational time. Here, in order to reduce the computational time required for the simulation, we developed an analog-digital hybrid model of the electrical excitation of cardiac cells based on Luo-Rudy phase I (LR1) model for the action potential generation in a mammalian cardiac ventricular cell. The hybrid model includes analog circuits and a dsPIC microcontroller that could reproduce time-dependent and time-independent nonlinear current-voltage characteristics of six-type of ionic currents in LR1 model. The analog circuits were used to implement the ionic currents either of timeindependent or with relatively short time constants, and the dsPIC was used to implement the ionic currents with long time constants, connecting in parallel with a model of the membrane capacitance. The constructed model could realize real-time simulation of the action potential generation that was quantitatively comparable with the cardiac excitation of LR1 model. In particular, we showed that response characteristics of the hybrid model to periodic trains of impulsive current stimulation were also comparable with those of LR1 model.
A central pattern generator (CPG) is a half-center rhythm generator, which is constructed from neural networks of the spinal cord. The remarkable CPG's phenomena, observed in the experiments on the fictive locomotor activity of decerebrate cats, are that the rhythmic activity that re-emerges following a spontaneous omission of activity (deletion) is often not phase shifted. Rybak et al. (2006) propose a neural network model composed of multiple Hodgkin-Huxley type equations replicating such physiological phenomena. Maeda (2008) proposed a hardware design of the Rybak's mathematical model, using the SPICE simulation. Main purpose of this study is to reproduce dynamics of both the CPG and motoneuron networks using electronic circuits. As a result, the hardware CPG-motoneuron complex network showed the same response phenomena to the perturbation, which causes the deletion, as the mathematical model. Furthermore, the phase shift, observed after the perturbation to the rhythm generator of CPG, was nearly constant against increasing the amplitude of perturbation. The phase advanced about 0.2 seconds on average.
The present investigation aimed to clarify the effect of muscle length on the mechanomyogram (MMG) during isometric twitch contraction of quadriceps femoris muscle. Single twitch contraction of quadriceps femoris muscle was elicited electrically. The muscle length was identically represented using different combinations of hip and knee joint angle. The MMGs were recorded by small accelerometers over each muscle belly of rectus femoris, vastus medialis and vastus lateralis muscle. The electromyograms (EMGs) of same muscles were recorded simultaneously with bipolar surface electrodes placed at both sides of the accelerometer. The twitch force of quadriceps femoris muscle was measured as knee extension force. There was no significant change in the EMG amplitude with muscle length. The MMG demonstrated the greatest amplitude at intermediate length and decreased with muscle shortening as well as lengthening. The behavior in the MMG associated with muscle length was similar to that in force production. The present results suggest that the MMG reflects interaction between actin and myosin filaments of skeletal muscle fibers.
The purpose of this study is to simulate the deformation of a plastic shoehorn-type ankle-foot orthosis (AFO), because the contact of the AFO with the lower leg and deformation of the AFO affect gait. In this study, bone, muscle, and fat models of a virtual human lower leg consisting of 6,650 elements were constructed. Further, a bone model composed of the tibia, fibula, tarsals, metatarsals, and phalanges was constructed, with the ankle joint and 5 metacarpophalangeal (MP) joints as rotatable joints. An AFO composed of 1,536 elements including belts was also developed. Using the dynamic finite element analysis program LS-DYNA (LSTC Corp.), we simulated the motion and deformation from the moment of heel contact to that of the heel-off position, where the lower leg, AFO, and its belt were in contact with each other. By loading the same weight as a subject onto the model at the center of gravity of the human body and by defining the moment of the ankle joint resistance, we were able to simulate similar time variations in the ankle joint angle as observed in the subject's gait. In addition, by mounting a shortened belt after applying an inward-directed enforced displacement at the belt-mounting points of the orthosis, close contact was maintained between the lower leg and the AFO during movement. The results were compared with the measured data obtained from gait experiments performed on the normal subject wearing the AFO. The trend of strain distribution around the ankle portion of the AFO as determined by the simulation method coincided with the measured data, except in the outside region ofthe ankle. The results indicate the validity and effectiveness of the dynamic finite element method for analyzing an AFO by using a human lower leg model.
An effective microbial contamination control is certainly requested for the high quality sanitary condition of hemodailysate preparation. To gratify this request, several disinfectants and the other bactericidal processes are employed to make clean condition for the inner tubes or some water reservoir of hemodialysate preparing instrument. Particularly, the hot water disinfection is widely employed many hospitals and hemodialysis therapy section because this procedure do not uses any drugs or chemical substances. Whereas hot water disinfection killed most of bacteria in hemodialysate preparation instrument, it was also confirmed that the bacteria was recovered immediately after heat treatment. From these backgrounds, the authors attempted to keep clean condition after hot water disinfection treatment using Hinokitiol which has been known as an essence of the forest bath. This paper demonstrated that the antibacterial activity of Hinokitiol against clinically isolated bacteria and its heat stability. These findings indicated that Hinokitiol could employ for useful supplement of hot water disinfection and we also propose a newly hot water disinfection system using Hinokitiol treatment.
Mechanical stretching was applied to normal human pulmonary artery endothelial cells (HPAEC) and human lung adenocarcinoma epithelial cells (A549) using an Flexcell® FX-4000T™ Tension Plus™ System. The cells, cultured on a flexible silicoelastic membrane, were stretched by the FX-4000T and cell images were recorded using a Stage Flexer Jr., a microscope and a CCD camera. Strain was calculated from the cell images before and after stretching. The strain on HPAEC was nearly equal to that on the membrane at any location when the cells were both sparse and confluent. On the other hand, the strain on A549 was nearly equal at any location on the membrane under both sparse and confluent conditions, but less than the strain on the membrane. The lower strain on A549 might be attributable to differences in cell shape from HPAEC.