Although microRNA analysis is necessary for early detection of cancer, conventional device is large and heavy, and also requires a lot of high cost reagents for analysis. To solve these problems, we previously fabricated the RT-PCR microdevice. But this microdevice has to use the conventional device for RNA quantitative analysis. Here, we have developed a microdevice for qRT-PCR by sub-microliter scale samples. The microdevice can perform multiple analysis all at once. This device is composed by reactor module, spacer module, heater module and photo sensor module. By assembling these parts sterically, we succeeded to reduce the performing energy and observation area. The reactor is fabricated by deforming the polypropylene film. This improve the heat conductivity and transparency. Also the reactor improve the disposability by the easy fabrication. We performed qRT-PCR at the microdevice, and we observed the increasing of the fluorescence intensity of the sample per PCR thermal cycle.
Recently, it is said that call response relates to viscoelasticity. So, the knowledge of cell response to various stimulation of instantaneous frequency is required. Here, we have developed instantaneous stimulation loading system including 1kHz to 1MHz by irradiating laser pulse to the cantilever. However, since the evaluating system of cell response is unequipped, the response to this region of frequency is still unknown. Here, we have developed fluorescence imaging system which can evaluate calcium signaling and be integrated to loading system. By using this imaging system, we analyzed Ca[2+] concentration change. Our system consists two imaging system. One is for an alignment of a cell and a cantilever and the other is for fluorescence imaging. By introducing flipper mirror and setting both system in infinity optical system, shift to both imaging system is allowed. Observing the result of cell response to instantaneous stimulation, we confirmed a change in fluorescent signal.
Membrane proteins are major targets for drug development. Since membrane proteins must be inserted into lipid bilayers for functional evaluation, a number of method for lipid bilayer formation has been developed. However, there is a lack of efficient method for forming hydrogel-supported bilayer. Here, we aimed to develop a method for patterning a lipid bilayer on hydrogel with a large area. We applied self-spreading method for hydrogel-supported bilayer, which was originally developed for solid-supported bilayer. Agarose gel was patterned with a stripe manner, and then lipid bilayer composed of DPhPC and fluorescein-eggPC was formed on the gel. Bilayer formation was examined with fluorescence imaging and FRAP method. As a result, it is suggested that lipid bilayer was formed on the hydrogel pattern.
Tissue-engineered constructs hold three elements: cells, bioactive factors, and scaffolds. Scaffolds function not only as passive culture substrates but also as active partner interacting with the cells. For example, the elasticity of polyacrylamide gel can determine the differentiation of mesenchymal stem cells. However, it is difficult to regulate solely the elasticity of the culture substrates. In this study, we took the advantages of the non-linear mechanical characteristics of porcine amniotic membrane (pAM) to adjust its elasticity by imposing different tensile stresses on the pAM and examined influence to the behavior of the rat embryonic fibroblasts cultured on it. The elasticity of pAM was set at 30 kPa (the slack state), 500 kPa, 1000 kPa, and 2000 kPa, respectively. As a result, cell adhesion ratio, cellular area, and aspect ratio tended to decrease as the elasticity increased; whereas cell growth rate tended to increase.
iPS cell and stem cell can be able to become various tissue cells. But, non differentiated cell may become cancer cell. So, differentiated cells need to be separated to each group. In this study, label free cell separation technique is investigated by cell deformation ability. Micro cylindrical pattern was created by photolithography technique. Cylindrical pattern gaps were 25, 20, 15 and 10 μm. Before experiment, micro flow device was processed by hydrophilic treatment with O2 plasma ashing. After that, micro flow device was filled with a 4 wt.% diluted solution of bovine serum albumin. It was then left for 1 h in incubator. Two kinds of cells were used: C2C12 and Hepa1-6. Cell suspension of 60 μl was introduced in micro flow device. Movie images of cell passing through 10 μm micro cylindrical gap were taken by a digital camera. There was a correlation between cell diameter and passing time.
DNA damage induced by the radiation including ultraviolet (UV) light exerts adverse effects on genome stability, and causes many kinds of diseases. In this study, we investigated the effects of the nuclear deformation on UV radiation resistance of DNA in epithelial-like cells using a microfabricated cell culture substrate. The cells spread normally in the space between the microfabricated array of pillars and their nuclei appeared to be trapped mechanically on the array of pillars. The fluorescent intensity of DNA around the trapped reason of the nucleus was significantly higher, and UV radiation-induced DNA damage was significantly inhibited in the cells cultured on the pillar substrates. These results indicate that the inhibition of UV radiation-induced DNA damages might be resulted from DNA aggregation caused by the mechanical stress of the nucleus of the cells on the pillars. Our study first demonstrated the nuclear stress-induced inhibition of DNA damages in living cells.
p53 is one of the most essential tumor suppressor and its abundance is tightly regulated in cells: in normal state, the amount of p53 is kept low through ubiquitylation by MDM2 and subsequent degradation by proteasome. In response to DNA damage, p53 undergoes phosphorylation by ATM, which interferes with its association with MDM2, and, as the result, its abundance is greatly increased. We sought to develop a live cell imaging system to monitor the cellular status of DNA damage response based on this life cycle of p53. We first introduced a plasmid vector (pEGFP-C1) expressing GFP-p53 fusion protein into human cancer cells with normal p53, mutant p53 and p53 deletion and analyzed p53 abundance and its change after irradiation by Western blotting and flowcytometry. Furthermore, we are in progress to engineer cells to express p53-GFP fusion gene from chromosome by CRISPR/Cas9 genome editing technology.
Current approach of cancer theraphy, such as chemotheraphy, radiotheraphy and surgery, has been treated for many years, but it is still hard to cure completely. Immune system which is one of the important system for cancer patient is designed to produce antibody and protect the body from external threats like viruses and foreign bacteria. However, some cancer cells escape from the attack of the immune system. In presents, there are conventional anticancer drug to fight against the cancer cells that's can work to help the immune system in the fight against cancer and it is a completely new idea that acts on immunity of humans. The mechanism of the antibody producing cells and cancer cells reaction is still unclear. Using the scaffold coated with a-C:H:N, we produce an evaluation system to evaluate the movement properties of individual cells and to understand the morphology of the cells.
Accurate positions and angles of optical fibers attached on the body surface are crucial information on the image reconstruction of the diffuse optical tomography. In this study, we developed a tailor-made fiber holder that fits to the subject's anterior neck because we assumed that such a holder would provide attachment positions and angles from the design if it possesses the sufficient wearing reproducibility. The holder is formed of thin curved board. The curvature of the holder was modeled from the subject's neck shape of the anatomical MRI by the 3D CAD software. The holder has 35 holes to hold optical fibers. A 3D printer created the holder with polylactic acid resin. The subject wore the holder that equipped cylindrical MRI markers in the hole. The position and angle of each MRI marker was similar between twice MRI scan, which indicate that the tailor-made holder has sufficient wearing reproducibility.
This paper reports on a capacitor divided microcoil as high sensitive MRI (Magnetic Resonance Imaging). A capacitor divided microcoil was fabricated by assembling 3D printed structures and planar coil wirings fabricated by MEMS (Micro Electro Mechanical Systems) technology. Since a capacitor was inserted into the coil wirings, this microcoil has high self-resonant frequency. The number of turns, diameter and length of the coil were 12, 12 mm and 16 mm, respectively. We also fabricated a non-divided microcoil without a capacitor for comparison. This non-divided microcoil is the same design value as the divided microcoil. The self-resonant frequency of the divided microcoil and the non-divided microcoil were 179 MHz and 156 MHz, respectively. We took MRI image of the cooking oil by the divided microcoil. SNR of the MRI image was 64. Since the capacitor divided microcoil has high self-resonant frequency, we acquired high sensitive MRI image.
We have proposed a noninvasive technique to observe an arteriovenous fistula using an optical transillumination image of a blood vessel. To improve the accuracy of inner-diameter measurement of the vessel, we examined the effectiveness of the image-subtraction technique using multi-wavelength light sources. In the experiment, we fabricated a model-phantom to simulate a human forearm. It contained the tube filled with replaceable absorber liquid which simulated the blood in different wavelengths of illuminating light. The transillumination images of the blood column were recorded with the liquid of different absorption coefficients. The image-subtraction technique was applied and the images were analyzed. With the subtraction, the sharpness of the column image was improved by 55%, and the error in the diameter measurement was reduced from 28% to 4%. This result verified the effectiveness of the image-subtraction to promote the clinical application of the proposed technique for the controlled care of the arteriovenous fistula.
In the world, more than two million patients require hemodialysis with renal failure. However, hemodialysis requires hospital treatment three times a week. To overcome the problem, we are planning to develop an implantable centrifugal artificial kidney. We adopted two-stage centrifugal separation for this novel system. In the first stage, blood cells are separated from whole blood. In the second stage, protein is separated from plasma. In this study, we developed the first stage centrifuge experimentally having rotating disk of 70 mm in diameter and performed centrifugal separation of blood cells using porcine blood. We succeeded to separate 50 ml/h of plasma continuously at 1000 rpm. However, hemolysis occurred. The hemolysis was considered to occur with frictional heat generation at the mechanical seal of the shaft. Although further study is necessary, possibility of implantable centrifugal artificial kidney was demonstrated.
We have been developing an optical system for monitoring urinary substances and reported the results of the preliminary experiments using an FT-IR spectrometer for estimating concentration of four urine substances, i.e., glucose, urea, sodium chloride, and creatinine. In this study, we selected four wavelengths sensitive to concentration change in each four component and carried out the multiple regression analysis. As a result, it was confirmed that concentration of the four substances could be predicted with high accuracy (correlation coefficient:γ>0.8) . Also evaluated was the effect of broad emission characteristics of LED on the accuracy of concentration estimation when it was used as a light source. From the results obtained, it was suggested that the multi-wavelength near-infrared LED could be used as a light source for optically monitoring concentration of the four components.
Three major diseases (cancer, heart failure, and apoplexy) account for about half of the cause of death in Japan. Therefore, the monitor by a daily inspection and the diagnosis to do earlier detection and treatment smoothly is necessary and indispensable. Especially, it is a technology that is paid attention that visualizes the inside of the blood vessel of the heart and brain that cannot be obtained from the outside immediately.From the above-mentioned background, we are accomplishing the experiment concerning the development of the blood vessel imaging system using reflection / absorption / fluorescence of near-infrared radiation that has the living body permeability (700-1400 nm). Concretely, the experiment to understand the optimum conditions of the vascular imaging was conducted with super-high luminance LED and cooling CMOS camera. As a result of experiment, it turned out the vascular imaging that the blood flow volume and quantities of light greatly influenced.
An optical fiber probe for measurement of water content of oral mucosa is proposed. The probe is composed of silica optical fibers to radiate white light and fibers for detection of diffusely reflected light from the sample. Firstly, by experiment using gelatin film, it is confirmed that the intensity of absorption peak of water at 1450-nm wavelength linearly increases with water content. As a result of in-vivo experiment using human tongue as a sample, it is shown that water content can be measured by the diffuse reflectance detected by the proposed method.
Home medical care is promoted widely as the population ages. In this environment, remote monitoring system, which can measure vital data in real time, is important to care patients safely. Nail tip sensor, which can be attached to fingernail, is developed as remote monitoring device in home medical care. This nail tip sensor can measure vital data in real time without any cable. In addition, the sensor can be used without uncomfortable feeling, because sensory nerves and sweat gland is not distributed in fingernails. Nail tip sensor can realize rigid fixation over a long period, due to hardness of the nail. The sensor also realizes Multi point simultaneous measuring, because human body has twenty nails. In this research, miniature photoplethysmographic sensor is developed and measure in daily life.
Pulse-rate (PR) has become one of the most important indexes for health monitoring. It is well known that photoplethysmography (PPG) is widely used for PR monitoring and uses relationships between light reflection/absorption in blood vessel and blood volume [1,2]. In this work, we integrated a LED driver circuit, a 600×600μm2 Photodiode (PD), and signal processing front-end circuits including a I/V converter, LNA(20-40dB), LPF, 12bit SAR-ADC into one chip to realize a wearable and comfortable PPG sensor system placed on fingernails. We designed and fabricated the above circuits using a 180-nm-CMOS technology. We confirmed that all circuits worked correctly, and we will present the detailed results in a conference.  Kohei Ishii et. al., 3T6-2-9, 55th Annual Conf. JSMBE, 2016.  Yu Sun et. al., IEEE Trans. on Biomed. Eng., Vol. 63, No. 3, 2016.
Slicing sample preparation in tissue optical characteristics measurement mat makes huge error over individual optical differences. We proposed the combination of light intensity measurement through an optical fiber puncturing into a bulk tissue varying NA and ray tracing calculation to avoid slicing degradation of living tissue. To reveal the characteristics of this measurement, optical coefficients of pig myocardium obtained by the IAD method with slicing living tissue sample preparation and proposed measurement method were compared. In the proposed method, a silica fiber installed in an 18G needle was punctured up to the bottom of the myocardial bulk tissue to measure light intensity in the bulk tissue changing depth and NA. The author found that measured apparent attenuation coefficients tended to strongly depend on NA. The ray trace calculation explained the same NA dependence in above mentioned experimental result. Optical characteristics of sliced myocardial samples revealed temporal change due to dehydration.
A Monte Carlo simulation for photon propagation through a scattering medium using a multilayered model was performed to estimate the Doppler signal signals, with the aim of measuring noninvasive blood perfusion in deeper region from the body surface. The results show that when the dimensions of the layer structure are known and their optical parameters are constant, the target flow in the deep layer can be estimated.
We compared the heart rate (HR) derived from electrocardiogram (ECG) as a reference with the pulse rate (PR) derived from the ear photoplethysmogram (PPG) using green light. In 20 participants (21.7 ± 2.7 S.D. years), simultaneous measurements of ECG (lead II), near-infrared light (810 nm) PPG, and green light (525 nm) PPG from the front of tragus and helix were made at the following treadmill speeds: 0, 2, 4, 6 km/h. The results showed that the PR derived from the green light PPG from the ear significantly related to HR derived from ECG (tragus: r = 0.98, helix: r = 0.97, respectively). In addition, the limit of agreement in Bland-Altman plots between these indices were ± 7.95 (2 SD) bpm and ± 5.96 (2SD) bpm, respectively. In conclusion, these findings suggest that the green light ear PPG might be practical measurement for monitoring HR in a daily life.
We investigated the influence of photoplethysmogram (PPG) to the finger contact pressure, on indices derived from the acceleration PPG (APPG) believed to reflect arterial aging using a smartphone photoplethysmograthy. The first and second peak amplitudes in the APPG, 'a' and 'b' respectively, were measured using an iPhone 7 in 12 participants and the 'b/a' ratios for 4 conditions (i.e., relaxed, normal, little strengthened, and strengthen take hold the iPhone 7) were derived. Results indicate that the b/a ratio of 3 condition (i.e., relaxed, normal, little strengthened) were not significantly different except for 'strengthen'. In conclusion, these findings suggest that use of b/a iPhone photoplethysmography, if the range of normal contact pressure, might be practical measurement when assessing arterial aging.
[Purpose] Total peripheral resistance (TPR) and reflected wave from the lower body affect blood pressure. However, the relationship between them is obscure. Wave intensity (WI) is a hemodynamic index, which is defined as WI=(dP/dt)(dU/dt) (P:pressure, U:velocity), and indicates ventriculo-arterial coupling. The negative values of WI indicate that reflected wave is predominant. We investigated the relationship between the negative value (NA) and TPR using a circulation model. [Methods] A circulation system was fabricated incorporating artificial elastic vessels and a syringe pump. WI was measured by ultrasonography. TPR was manipulated by clamping a peripheral tube, and the reflection points were adjusted by moving the clamp positions. [Result] The increase in TPR increased the NA, and moving the clamp position further from the pump delayed the time of NA emersion. [Conclusion] NA is an indicator of the strength of TPR and the distance from the point where the reflection wave is produced.
Recently, the need for cuffless blood pressure (BP) monitoring devices is growing as an alternative to conventional BP measurement based on cuff occlusion. Pulse arrival time (PAT) is a potential parameter for cuffless BP prediction. We investigated whether incorporating pulsatile systolic area (PSA) into the formula is effective for accurate estimation of systolic BP (SBP). Beat-by-beat SBP, PAT and PSA were determined in eight healthy subjects at rest for 3-min. Sit-stand-sit maneuver was included in the first half recording. The model parameters were estimated by partial least squares using the first half of the recording. Validation was performed using the latter half recorded at rest. There was a significant negative correlation between SBP and PAT, and a positive correlation between SBP and PSA. Tracking SBP via PAT and PSA was better than via PAT only, indicating the benefit of utilizing PSA as an input parameter for the estimation of SBP.
For early detection of disorder in the vascular endothelial function, a technique to evaluate the viscoelastic characteristic of the vascular wall was developed by measuring the blood pressure of the radial artery and measuring the change of the vessel diameter at a different close position. By it measurement, however, an accurate evaluation of the viscoelastic characteristic is difficult due to the small time lag between the waveforms. Therefore, for measuring both the blood pressure and the change of the vessel diameter at the same position, the present study presents a new method to acquire the blood pressure by the same ultrasonic probe as that for the ultrasonic measurement of the change of the vessel diameter. From the resultant waveforms, the hysteresis characteristic of the vessel diameter was obtained in in vivo experiments.
A novel photoplethysmograph (PPG) embedded in a head-mounted virtual reality (VR) headset was developed. This measurement has been attempted for spontaneous physiological measurement while VR headset using such as gaming, 3D movie viewing, working in 3D circumstances and so on. PPG was derived from subject's forehead using reflectance-type measurement of green and infrared light. PPG probes were embedded with a VR headset then, PPG were measured from subject waring it. As results, green PPG were more stable than the infrared one. Stable measurements were obtained by green PPG under several conditions such as VR monitor switching, voluntary breath holding, 3D movie viewing and so on. PPG from forehead was compared with finger/ear PPG, then found those are synchronized. It is considered that heart rate change during VR viewing is able to be measured autonomously.This work was partially supported by JSPS KAKENHI Grant Number 15H02798.
Motivation: Over the past few years, activity trackers which can measure everyday steps, energy expenditures, and sleeping time are getting popular. Especially these days, some activity trackers use not only accelerometers but also optical heart rate monitors based on photopletysmography. In this study, we evaluated reliability of an optical heart rate activity tracker(Polar A360) during running. Method and Results: Several subjects(n=11, all male) ran 1km on a flat road and we analyzed heart rate errors to check if there was a difference between subjects. We found that some subjects had significantly higher MAE than others(highest MAE,20.54±13.64; average MAE, 8.41±6.47), and there was a strong correlation between each subject's MAE and the standard deviation of running speed(Pearson's r=0.87, p<0.001). Conclusion: Our results suggests that it is important to use users' differences of running speed for revising heart rate errors.
Novel color lighting system and its evaluation method are required. As a fundamental study on quantifying subjective evaluation by RRI (R-R interval) information, ECG measurement and opinion test were done in a room with color lightings. Color lightings with Organic-LED panels were prepared. The lighting was located at front of a subject, with the distance of approximately 2.7 m and the height of 1 m. In the cases of eight colors, the ECG was measured when the color light turned on and off. The opinion test about "Comfortableness" was done with seven-grade scale. Twelve male subjects (20-55 years old) provided written informed consent.LF/HF and RMSSD were calculated from RRI sequence. In the cases of five colors, LF/HF decreased and RMSSD increased in half or more of subjects who evaluated as "Comfortable". These results indicate the feasibility of use of RRI information to evaluate the interior with the lighting system.
The extension of healthy life expectancy is of high concern these days. Keeping some functions above a certain level is necessary for body activities, like muscular skeleton system, respirator circulation system and nervous system. Although function aging may be unavoidable, through analyzing their quantity, body age can be inferred, furthermore getting body age younger through specific functional exercise may become possible.One kind of total body scoring technology is used to calculate the body age of 42 managers and executives of one corporate, and 16 body items are measured. It is based on research about relationships of 430 body items collected from three-dimensional body.
In recent years, the scene of the use of touch panel devices such as smartphones has been increasing. About 50% of user are operating devices with their one-hand. Also, about 70% of the one-handed users operate devices with a thumb finger. The one-handed users may have high risks of becoming tenosynovitis. Because tenosynovitis increased with the spread of computers in the past, increase of the tenosynovitis is expected due to the recent spread of smartphone. Tenosynovitis disturb healthy living and work, so it is necessary to investigate the burden of thumb finger in smartphone operation of daily life. In order to investigate the burden, it is necessary to examine the characteristics of smartphone operation, but there are still few studies yet. In this study, we aimed to clarify the characteristics of the thumb-operation of one-handed user from measurements of the joint angle, speed, EMG and thumb movement.
Non-contact vital sensing is gathering attention associated with the development of Doppler sensors. It radiates an electromagnetic wave and receives the reflected waves yielded by a human body. Then it detects the frequency deviation by comparing the transmitted wave with the received wave. Since this frequency deviation is caused by the Doppler effect along with the movement of the body surface, we can detect vital signs such as heartbeat, breathing and body movement, through signal processing. We have proposed a new and unique signal processing scheme for the non-contact vital sensing using Doppler sensors. The uniqueness of the proposed method is summarized as follows: (1) It enables a Doppler sensor to cope with multiple human bodies, (2) It detects the direction of the multiple human bodies as well as the other vital signs. This paper provides in-depth performance verification through computer simulations.
Japan is ranked first in average life expectancy in 2015.However, the proportion of elderly people in the total population is increasing year by year.Therefore, the importance of self-care is increased to the same extent as treatment, and it is expected that the system will be created in which individuals can grasp health status on a daily basis in the near future.In paying attention to realizing the system, it is necessary to have a data format for integrally and efficiently recording biosignals.The data standardization will be a key element to realize the ubiquitous health care systems.
The purpose of this study is to visualize how the obstruction occurs and clarify the interaction between human and bolus physiology to prevent the accident suffocation.The human model was created using medical images of CT and Video-fluorography of swallowing. The toy and food bolus model was created using experimental measurements. Those two models were integrated in a software,which was based on one of the meshless methods, moving particle simulation (MPS) method.As a result, two types of suffocation were revealed. One is obstruction of the pharyngeal space. A elastic jerry with high rigidity can occupy the pharyngeal space to obstruct air flow. The other is obstructing the glottis. A peanut or small toy can pass through the pharynx to the larynx, then it remains on the glottis obstructing air flow.The future study will create more models to clarify the biomechanics and suggest public proposal to prevent suffocation.
Evaluation of swallowing motion is necessary for preventing aspiration pneumonia. MRI and sound analyses are recent deglutition diagnoses, however, these are inherently susceptible to noise. We focused on the detection of skin motion around pharyngeal portion, and examined the feasibility of information measured by a depth camera. Firstly, we measured the pharyngeal portion in healthy subjects during the process of drinking water or saline. Secondly, we measured the pharyngeal skin during eating process of a piece of bread pasted with oil or with high viscosity gelatin. Results were as follows: a) we obtained the prospective self-gating of swallowing using depth information, b) the measurement is available for frequency analysis of the gating, and c) the deglutition was associated with the taste with respect to the sensory inspection. Consequently, periodical measurements by the 3-D depth camera might be useful for the selection of profiles corresponding to food intake including individual preferences.
In this study, a combination treatment system of cryosurgery and hyperthermia treatment was fabricated and evaluated. This system consists of a surgical probe and a coolant circulation system. In the system fabrication, Peltier device with a surgical probe tip was adhered to a metal circular disk attached to a plastic pipe. A coolant chamber was bonded to Stirling cooler. And the flexible tubes for the coolant circulation were attached to the chamber. The probe and the chamber was connected with the tube, thus the treatment system was fabricated. In the evaluation test of the system performances, the temperature of the probe reached to -46.6 degrees C. Temperature cycles of the freezing and the warming automatically was repeated at three times in the temperature cyclic test. In the animal test, the necrosis was observed in the tissue after the combination treatment. These results suggest the effectiveness of the combination treatment.
Breast reconstruction would be operated immediate after mastectomy from the point of view on cosmetic figuration and QOL in patients. However, there is an issue that cosmetic outcome in surgery because quantitative evaluation index for three-dimensional shape of the breasts has not been established. We developed image processing system that is able to evaluate quantitatively the shape of patient's breasts with pre and postoperative 2D and 3D information. Firstly, 3D surface data of patient's breast were scanned on pre and post mastectomy timing using Kinect V2. After that, 3D breast shape data were divided into small grid data and were used to calculating breast volume difference. The total difference information between pre and post mastectomy were plotted on a two-dimensional map image. At the same time, the volume difference histogram was derived and shown to the surgeon. Then, we developed such a system, evaluated this system with trial subjects.
The purpose of the present study is to determine the tensile properties of the collagen fibrils composing tendons and ligaments of knee joint. The fibrils were directly isolated from patellar tendons, anterior cruciate ligaments, posterior cruciate ligaments, and medial collateral ligaments of rats by stirring in distilled water. Both the ends of each fibril were wound onto the tips of two microneedles several times using micromanipulators. The fibril and tips were immersed in physiological saline solution. Then, the fibril was stretched to failure by moving the one microneedle. During tensile testing, the fibril was firmly attached to the tips of the microneedles, and broken between the tips with no slippage observed. The stress-strain relations of these fibrils were almost linear. There were no significant differences in the tensile strength, strain at failure, and tangent modulus among these tendons and ligaments.
Recently, many new Ti alloys with low elastic moduli were designed for biomedical applications. However, all of these alloys can't meet the requirements both of surgeon and patient with spinal disease; surgeon hopes the material with high elastic modulus, but requirement from patient is on the contrary. In this study, in order to develop a new Ti alloy with changeable elastic modulus, the chemical composition of Ti-Cr alloys were optimized. The elastic modulus increases by the formation of deformation-induced omega phase transformation. Further, the increase in elastic modulus of Ti-12mass%Cr alloy is largest among the Ti-(10-14mass%)Cr alloys. Therefore, Ti-12mass%Cr alloy is the most suitable chemical compositions among these alloys for spinal fixation applications.
Bone is often regarded as a composite material consisting of mineral particles and organic matrix (mostly Type I collagen) on a microscopic scale. The mechanical properties of bone tissues at a macroscopic scale depend on the structural organization and properties of constituents in the microscopic scale. It is the interaction between the mineral and organic material that determines the mechanical properties. However, both mechanical behaviors of mineral and collagen phases are not clear yet. In this study, to clear both mechanical behaviors of collagen matrix and apatite crystals in bone, the cortical bone samples were collect from bovine femoral diaphysis. The microscopic mechanical behaviors of both mineral particles of apatite and collagen matrix in bone tissues were observed by wide angle X-ray diffraction (WAXD) and small angle X-ray scattering (SAXS), respectively. In combination with micro-tensile device, both strains of mineral and collagen phases were measured.
Bone fractures caused by osteoporosis have been big problems in the field of orthopedics. Especially, vertebral compression fracture is one of the main problems in spinal orthopedics. Recently, BKP has been applied to reconstruct the fractured vertebra by inserting bone cement into the vertebra, however, secondary vertebral fracture is still main concern due to degradation of the other osteoporotic vertebrae. In this study, CT image based finite element analysis of two osteoporotic patients having vertebral fracture was performed to analyze the effects of BKP on the secondary fracture. Spinal models consisting five vertebrae were constructed with a compressive boundary condition. Single vertebra models were also developed to analyze the strength of each vertebra. Then, the FE results obtained from five and single models were combined to analyze the secondary fracture. It was found that BKP can effectively increase the onset load of fracture.
It has been advocated that bone apatite crystals are formed via precursor phases, such as octacalcium phosphate (OCP). We have developed OCP-based bone substitute materials which enhance bone formation through a mechanism that simulates bone mineralization (Jpn Dent Sci Rev 49: 58, 2013). We have designed in vitro analytical methods to estimate the bioactivity of OCP to bone tissue-related cells, such as osteoblasts. They include: 1) cell cultures on OCP-coated plate that the cells can directly attach (Biomaterials 27:267, 2006; Tissue Eng Part A 14:965, 2008); 2) cell cultures in media simulating inorganic ion composition that OCP induces at physiological pH (Dent Mater J 33:242, 2014); 3) cell culture in a 3D environment that OCP is included within the cellular construct (spheroid) (Regen Therapy 3: 58, 2016). These studies suggest that OCP stimulates the activity of bone tissue-related cells through its intrinsic physicochemical property (RSC Adv 6: 57475, 2016).
In this study, we have proposed D-OCSA which is a tomographically micro-visualizing method of mechanical properties estimated from continuous OCT images. This can provide temporal and spatial distribution of strain rate during a stress relaxation test and a dynamic viscoelasticity test. This was experimentally applied to comparatively both normal cartilages and cartilages degenerated by the collagenase enzyme treatment. The temporal attenuation and the sinusoidal variation of strain rate were locally observed to have characteristic viscoelastic behaviors around surface zone. In the former, the attenuation of strain rate was visualized to be lager in the superficial tangential zone than that in the middle zone. In the latter, the phase difference of sinusoidal time-varying strain rate corresponded to the degradation of viscoelasticity. Consequently, it is possible to diagnose the degeneration of the early-grade OA, taking the temporal attenuation of relaxation modulus and spatial gradient of phase delay into consideration.
This is a preliminary study of abnormal heart beat detection using non-contact electrocardiograph (NcECG). The NcECG has 3 strips of electrodes placed on bed, with its positive electrode at the buttocks, negative electrode at the shoulder blades and earth at the waist. Two subjects were recruited for a 40 minutes measurement. Raw signal was filtered with a band pass filter [1-40 Hz] and R peaks were located by thresholding. Limb lead ECG detected the arrhythmia of one subject and we were able to detect 1146 heartbeats out of 1162 heartbeats for 14 minutes stable measurement. For the other subject, the signal could be measured stably for 20 minutes. For the whole 1396 heartbeats, 1393 heartbeats could be detected. Although signal was influenced by body movement, P, T waves may also be picked up. By neural network etc., abnormal heart beats might be detected instantly with NcECG.
We report on improvement in detection accuracy (DA) of pulse beet (PB) measured unobtrusively with unitized in-bed sheet electrode sensor (SES). The SES placed under the bed sheet includes two strip electrodes for electrocardiogram (ECG) measurement. The SES also comprises driven shield and ground (GND) plane surrounding the ECG electrodes, and has two primary strip sensors for PB detection on the upper and lower edges of the SES. GND for ECG measurement also functions secondary strip sensor for PB detection. Since initial prototype of the SES revealed low DA of PB due to poor coupling area to the body surface, we introduced additional secondary strip sensor between the two ECG electrodes. The DA after the introduction of additional strip sensor were 17.7, 30.7 or 77.5 % for 10, 30 or 50 mm wide additional strip at the upper back, whereas 13.2, 35.6 or 53.2 % at the lower back.
In this study, we conducted a fundamental study on non-contact simultaneous measurement of electrocardiogram (ECG) and pulse beat (PB) using capacitive in-bed electrode sensors. In the studied system, ECG were measured via clothing by conductive fabric electrodes placed under the upper back and the lower back, respectively. Also, by laying conductive strips under the calf and the heel, two capacitive coupling composed of strip-clothing-body surface were formed, and change in coupling capacitance caused by PB was detected. In this system, however, the signal-to-noise ratio (SNR) of the PB was poor and obtained output was unstable. In the new system, SNR was improved by changing sensor's dimension (strip width). Simultaneous measurement of ECG and PB was conducted for three males in supine position and wearing a commercial cotton sleepwear. As the result, the SNR of PB improved by about 15% on average in the new system.