The basic research on stem cells have been reported one after another in Japan recently Based on these superb outcomes it seems that generating organs in vitro has been booming. Nevertheless, generating complete organs in vitro is not foreseeable. The author has been pushing forward " Transplantable organ fabrication " with the following three strategies;
(1) To generate human organs in the body of heterozoic animals such as pig, animal factory or In vivo Bioreactor.
(2) The method of fabricating human organ bud in vitro and transplanting it to patients, Organ Bud Transplantation.
(3) The multilayer method to fill cells Ex vivo. Perfusion culture system is essential to develop by use of biomedical technology.
In this lecture, I would like to review recent organ perfusion system for organ transplantation and share our recent knowledge for organ fabrication using biomedical engineering technology.
Ex vivo organ machine perfusion is a promising technology for organ preservation and resuscitation for solid organ transplantation. There are various researches to preserve the organ functions and to access the organ viabilities with the perfusion technology. In the case of the kidney preservation, some clinical machine perfusion systems have been developed as commercial products in EU and USA. Recently, donation after cardiac death hearts were resuscitated with the treatment by the perfusion technology and transplanted it as clinical trial studies. The perfusion technology has many possibilities. However, many consideration points are remained to enhance the perfusion technology and to develop future technologies. Combination of the perfusate and the profusion technology is essential point and temperature, oxygenation, pressure and flow rate are particularly important conditions to consider the perfusion technology. In this presentation, the current perfusion technologies are introduced and discussed important conditions to preserve and resuscitate organs. Furthermore, the future perfusion technology as the organ engineering is suggested for not only the solid organ transplantation but also the regenerative medicine and the cell medicine.
Current drastic shortage of donor organs has led to acceptance of extended-criteria donor (ECD) livers for transplantation, despite higher risk of primary graft dysfunction.
Here we report the impact of normo- (30-37℃) and/or subnormothermic (20-25℃) machine perfusion (MP) preservation on the integrity of non-parenchymal cells of liver grafts in the model of isolated perfused rat liver (IPRL). Moreover, we investigated whether MP could resuscitate marginal fatty livers those should be discarded when preserved by the gold standard method, cold storage (CS).
Compared with CS, normothermic MP could maintain functional and morphological viability of not only parenchymal but also non-parenchymal cells, such as sinusoidal endothelial cells and stellate cells. Furthermore, subnormothermic MP resulted in significantly better preservation of sinusoidal microvasculature and hepatocellular mitochondria, both of which are characteristic disadvantages of steatotic liver grafts. Thus subnormothermic MP could prevent primary non function of 50-60% macro-steatotic livers, thereby providing a new possibility to expand the donor pools available.
To overcome the donor shortage in lung transplantation, it is crucial to use the marginal donor lungs and lungs from cardiac-death donors, which are supposed to be actually or potentially damaged. To utilize these damaged donor lungs safely, it is important to evaluate such donor lungs objectively before transplantation. Recently, ex vivo lung perfusion (EVLP) has been introduced internationally and several clinical trials are also ongoing in western countries. On the other hand, we have investigated the quality of donor lungs using EVLP and tried to treat the donor lungs during EVLP before lung transplantation. Herein, we would like to demonstrate our findings and discussed the future of EVLP. In fact, we established small animal EVLP in 2003 and large animal EVLP in 2006. We also established several injured lung models and performed various experiments using EVLP, proving that damaged donor lungs could be treated with several drugs using EVLP.
Ovary is an organ which produces eggs as gonads. However, its ability declines with age due to decreases in ovarian follicles. The number of ovarian follicles is fixed at birth and do not increase during postnatal stages. In addition to aging, follicular numbers decline by some pathophysiological reasons. When the number of residual follicles reaches to 1,000, follicular development and subsequent ovulation is arrested, thus resulting in menopause. Although the most effective infertility treatment for these women is egg donation followed by in vitro fertilization and embryo transfer, majority of women desire to conceive using their own eggs. We developed a new infertility treatment (IVA, in vitro activation) to allow these women become pregnant by regenerate reproductive functions through in vitro ovarian cultures. We succeeded the first live birth in a patient with primary ovarian insufficiency after IVA in 2013 and IVA was successfully repeated in other countries under our guidances. In this lecture, I introduce the IVA and then suggest an ovarian prefusion culture to improve the IVA approach.
In order to optimize bone regeneration, it is necessary to improve the performance of bio-absorbable materials, which act as substitution of bone function and scaffold of bone formation. We had tried to improve mechanical properties of HAp/PLA composite materials by the hybrid interface control using both chitosan and pectin and the control of interface control ratio. However, since the degradation speed of PLA is low, it is concerned that HAp crystals under the degradation state might remain without being absorbed. Therefore, we aimed to verify the applicability of the hybrid interface control and the control of interface control ratio to HAp/PCL composite materials, which can enable the acceleration of absorption utilizing osteoclastic metabolic behavior. As results of FT-IR measurement and tensile test, the fracture strain of HAp/PCL was significantly improved in the case of 100% of interface control ratio
Calcined bovine trabecular bone is an attractive material for bone tissue engineering, due to low-cost, natural porous structure, and absent of any immunogens, i.e., type I collagen and the other osteoproteins, which are removed out by calcination process. To determine an optimal calcination temperature, in our previous studies, the chemical and mechanical characteristics of calcined bovine trabecular bone were investigated. However, the bio-absorbability of calcined bovine trabecular bone is not understood enough. Bioabsorption is crucial for complete tissue replacement, and realized by osteoclastic matrix resorption and chemical dissolution to body fluid. In this study, to evaluate the biosolubility of calcined bovine bone, change in calcium amount released from calcined bovine bone in simulated body fluid was investigated, additionally the microscopic structure of the bone surface was observed after immersing in the fluid. The results were compared with those of HA and b-TCP.
The holmium: YAG (Ho:YAG) laser is effectively used for transurethral ureterolithotripsy. The laser is applied through an optical fiber in a ureter. A calculus is crushed by the energy of laser including the impact due to collapse of bubble that formed by a laser irradiated from the fiber tip. In this study, we observed the characteristic behavior of a bubble induced by a fiber type laser near a wall surface, using a high-speed video camera. Furthermore, we measured the forces of a bubble collapse using an impulsive force sensor. As a result, we showed characteristic bubble collapse behavior and impulsive force distribution for various fiber placement conditions.
Polyvinyl alcohol hydrogel (PVA-H) is expected as an artificial articular cartilage. In this study, a pendulum type tribometer was manufactured to imitate the joint movement of human body. A sus304 stainless steel ball with the diameter 35mm was slid to concave PVA-H with the same radius of curvature to the mating ball. The PVA-H specimen was formed by 5 repeated thaw-freeze cycles. The normal load and period of pendulum was 200N and 0.5 Hz, respectively. The PVA-H and ball was slid under saline lubricant at room temperature. Since the principle of this tribometer is pendulum, the oscillation amplitude decreased as the experiment duration progress. On the other hand, the oscillation period was the same even if the test duration. As a result, the coefficient of friction at the end of the test reached around 0.01, though initial coefficient of friction represented around 0.08.
In situ gelling materials are promising materials for tissue-engineering applications. Gelling properties of such materials are divided into two types: rapid and hard gelation without temperature-responsiveness or temperature-responsive slow and fragile gelation. These properties are not suitable for through-a-catheter uses and gel deposition on the surfaces of living tissues. To address these limitations, we developed in situ rapid-gelling collagen (Col)-genipin sols. Col fibril formation responding to body temperature was accelerated by concentrated sodium phosphate buffer at NaCl concentrations >140 mM, probably due to modification of protein-protein interaction similar to salting out. The Col-Col crosslinking activity of genipin was low at room temperature, but enhanced by warming at 37°C in neutral phosphate buffer due to polymerization of genipin monomer. This characteristic allowed for sequence of rapid gelation by Col fibril formation and subsequent genipin-induced gel fixation. The Col-genipin sols enable us to create hard gels in body through a catheter.
The thrombus existence is an important criterion in the Judgment of circulatory system diseases and the development of circulator organ device. In this study, the possibility of thrombus detection using electrical measurements was explore.Electrical measurement of thrombus formation process was carried out in a circulation. Swine blood was coagulated by the addition of 0.02M calcium chloride solution. Impedance between two stainless rings attached to the circulation was measured 120 minutes to determine the relaxation frequency by Cole-Cole analysis. The ACT was measured every 20 minutes.Relaxation frequency increases initially and reaches a peak at 85 minutes. The ACT were less than 100 near 85 minutes. It is presumed that influence of the thrombus formation is strong after the peak.Since the peak of the relaxation frequency appeared in thrombus formation process, the possibility of thrombus detection using the peak of the relaxation frequency is shown.
Pediatric portable ventricular assist device is still lacking in Japan. We have developed three small axial-flow blood pumps, KPAP1, KPAP2, and KPAP3, which feature in blood contacting surfaces made of polymer and can be disassembled with a screw. Though the impeller diameters are all 12.4 mm, necessary pressure of 100mmHg can be attained at 13000, 12500, 12000 rpm for three pumps, respectively. When the impeller outflow angles were changed from 90 deg to 50 deg, the overall efficiencies have improved from 14% to 16% and the hemolysis rates have improved from 9.3 times to 3.6 times, compared with an extracorporeal centrifugal pump. It is thought to be caused by reduction of fluid dynamic stall.
A navigation system with high accuracy is required for performing precise surgery. To obtain high accuracy, three factors should be considered: acquiring precise image data of patient, measuring an accurate intraoperative patient position and reducing registration error. Although it spends a lot of efforts to set up the system during surgery, its performance does not always satisfy surgeons.
During this decade, we have developed a surgical navigation system for aortic aneurysm repair and utilized it in one hundred clinical cases. It has been found that this system has needed to improve the usability and the reliability in registration process to show valuable information for surgery. Our recent system adopts a two-phased approach with different goals. Before thoracotomy, it exhibits the location of a target intercostal artery in the thorax and supports a surgeon to determine an appropriate approach to repair aortic aneurysm in each patient setup and anatomy. After adhesiolysis, it narrows the range of existing area of the artery within five millimeters and assists him to identify the artery.
In 2016, its improved system is ready to use for clinical pre-trial with approval from Hospital Ethics Committee of Tokyo Women's Medical University. In the next two years, it is hoped that the improved system provides the clinical benefit.
This talk introduces spatio-temporal modeling targeting lung tumors and inflamed lymph with showing several examples including micro-to-macro image analysis for micro-CT images and automated detection and temporal analysis of inflamed lymph nodes. Spatio-temporal analysis of tumors plays an important role in the multi-disciplinary computational anatomy models defined by the space, time, function and pathology axes. We show new techniques for seamless temporal registration of different resolution images and its application to tumor modeling. Also we introduce latest techniques for lymph node detection and their applications for measuring cancer treatment effect.
We report on a study for constructing a multi-scale statistical model of pancreatic cancer with its mechanical characteristics. The model is constructed from images captured from KPC mice: Temporal series of MR images captured during the progress of their pancreatic cancers, micro CT images of the extracted pancreases, and their microscopic images. In addition, we measure the mechanical characteristics when we extract the pancreases from the mice. We need to register these images of different modalities together in order for the construction of the model. For registering the microscopic images and the MR ones, of which the spatial resolutions are seriously different, we firstly register the 2D microscopic images together to construct a 3D microscopic image from them, then register the 3D microscopic image with the micro CT image that has the intermediate level of the spatial resolution, and finally register the micro CT image with the MR images.
Medical imaging is one of the major tools that have enriched medical sciences in both function and pathology modeling. Computed tomography (CT) is the most widely used imaging modality in clinical practice. Our research of multiscale (macro and micro) structures of lung and thoracic diseases using synchrotron radiation- micro-computed tomography (SR-CT) and commercial high resolution CT images, allows elucidation of microstructures and development of detection and diagnosis systems. To analyze microstructure of acinus region with isotropic spatial resolution, we developed a method that segments acinar and subacinar airspaces by SR-CT. Results demonstrate that the proposed method can extract several acinar airspaces. We develop cancer computer-aided detection/diagnosis (CADe/CADx) systems using CT images based on multidisciplinary computational anatomy models that support clinicians to detect early-stage cancers, to determine risk-adaptive treatments, and to diagnose various thoracic diseases. We describe overview of our project and potential benefits of implementing our CAD systems clinically.
Due to increasing interest to healthy life expectancy, the significance of the musculoskeletal system is recognized more than before. In addition to medicine, musculoskeletal anatomy is related to sports science, art, computer graphics and so on. In this talk, anatomy-based multiscale function and pathology modeling of the musculoskeletal system is presented, which is under development in the "Multidisciplinary Computational Anatomy" project. This model consists of mathematical and statistical models on bone-muscle relations, muscle fibers, bone orientations at the standing position, articular motions, and bone micro-structure from the aspect of function, as well as deformations due to osteoarthritis from the aspect of pathology. This model is constructed from clinical CT database and other modality data, including micro-CT, histology, X-ray, ultrasound images, and so on. Fundamental technologies for representation and construction of the model are presented and its applications to segmentation, muscle fiber modeling, and computer-aided diagnosis and therapy are overviewed.
We investigated the possible roles of the prelimbic (PL) and infralimbic (IL) prefrontal cortex in the regulation of anxiety-like behaviors by pharmacologically activation with a sodium channel activator veratrine. The extracellular glutamate levels were measured by in vivo microdialysis and the behaviors were assessed in the open field test in mice, simultaneously. The extracellular glutamate levels rose significantly after perfusion of veratrine in the IL and PL. Interestingly, the PL, but not IL, activation produced anxiety-like behaviors in mice. The local co-perfusion of a NMDA receptor antagonist MK-801 in the PL completely diminished the behavioral changes, without any effects on the veratrine-induced elevated extracellular glutamate levels. These results suggested that although the IL is adjacent to the PL, these two regions have differential functions in the expression of anxiety-like behaviors, and also the activation of the PL induces the anxiety-like behaviors via glutamatergic neurotransmission in mice.
Microdialysis technique has been first developed for monitoring neurotransmitter release in the brain. We have applied this technique to the heart and monitored myocardial interstitial levels of endogenous substances including norepinephrine, serotonin, and their metabolites during myocardial ischemia-reperfusion. Cardiac microdialysis technique is a powerful tool for investigating the pathological changes within the ischemic region during myocardial ischemia-reperfusion. Advantages of using microdialysis technique during myocardial ischemia-reperfusion are following: 1) simultaneous monitoring myocardial interstitial levels of endogenous substances in both ischemic and non-ischemic regions of the heart; 2) continuous monitoring in the ischemic region during ischemia as well as after reperfusion; 3) local administration of pharmacological agents into the ischemic region without systemic effects. Although microdialysis technique has several disadvantages, cardiac microdialysis technique has been widely used at present. In this session, we would like to explore advantages of using microdialysis technique during myocardial ischemia-reperfusion by showing practical data.
We used in vivo microdialysis methods to clarify the mechanism of a drug dependence-related novel molecule Shati/Nat8L, and the therapeutic tools for drug dependence Leu-Ile and Pseudoginsenoside-F11 (PF11). Overexpression of Shati/Nat8L in the mice nuclear accubems was rescued the methamphetamine induced place preference and sensitization. In vivo microdialysis experiments showed that Shati/Nat8L reduced the DA release from nuclear accubems in mice. Further, Leu-Ile has therapeutic actions in the methamphetamine-treated-mice. Interestingly, repeated administration of Leu-Ile suppressed dopamine release induced by methamphetamine in mice, although one shot administration of Leu-Ile has no effect on the dopamine release. PF11 is an ocotillol-type saponin that is isolated from American ginseng and shown protective effects against methamphetamine preference and dopamine release. In vivo microdialysis methods also showed that GABA regulates the DA release in mice. Taken together with these results, In vivo microdialysis methods are essential for investigation of the mechanism of drug dependence.
We have proposed a method for estimating the flow volume and flow rates from the streakline images based on the multi-cylindrical model. This approach provides the flow volume by integrating the flow rates calculated from liquid trajectories in images taken liquid immediately after urination in the air. Thus, the subject can measure the urine volume with high accuracy under a normal urination behavior. Our method can be applied to both the male urinal and the western-style toilet stool. The measurement accuracy of our method compared to other sensors has been raised to a feasible level depending on the ingenuity. In this manner, life log data to be recorded in the toilet have potential for one of the important indicators in healthcare. Here, we show remaining problems to be solved by introducing advantages and disadvantages of our method when it was applied to urine volume estimation.
This study proposes a method to measure urine volume estimate by non-contact matrix temperature sensors in a toilet. Four matrix temperature sensors were installed under a toilet seat. Radiant heat from a dropping water of 37 °C was measured to estimate the water volume using these sensors. In the previous study, we reported that water volume estimate was affected by various flow volumes and flow rates using a real toilet bowl. The toilet bowl is warmed by the urination, and radiates heat from it is surface. The radiated heat makes an estimated volume over. In this study, we developed an analysis method to deal with this problem.
Conventional uroflowmetry (UFM) performs an observation of time-serial urinary flow pattern, together with measurements for voided volume, flow rate, etc. Although it's a relatively simple and non-invasive examination, it is based on a urine receiving container like a toilet device equipped with various sensors in hospital. It also causes an unnatural urination due to such unnatural environment, and hence improper understanding of patient status. Our new UFM device aims to abolish the concept of equipping the toilet bowl with various sensors while satisfying the need of measuring urination anytime, anywhere in an easy, natural and repeated manner. We developed two new wearable finger-tip mounted continuous-wave Doppler UFM devices, one with 40KHz airborne ultrasound and the other with K-band (24GHz) millimeter wave. They provide time-series pattern of frequency spectrogram of the Doppler shifted echo of a urination. The Doppler spectrogram gives qualitatively and diagnostically equivalent impression to the urinary flow curve derived from conventional UFM devices. Furthermore, the system can estimate same parameters as conventional UFM devices by integrating locally weighted frequency spectra. It was confirmed that there is a potential for the clinical application of the new UFM devices.
Background and Objectives A Simple screening tool for voiding dysfunction affecting daily life is expected in the era of aging society. The frequency volume chart (FVC) is a gold standard to check voiding patterns, but is difficult for the elderly to record for 3 consecutive days. Although uroflowmetry is useful for checking the voiding status, it can be performed only in medical facilities. The primary objective was to develop a handheld device which integrates FVC and uroflowmetry as a screening tool for lower urinary tract symptoms (LUTS) at home. Our project had two major tasks: firstly, the handheld device can precisely measure the urine flow at home, and, secondly, the software can analyze the large data and provide simple data sheet to help physicians during their daily practices.
Materials and methods We developed a handheld device, P-Flowdiary®, which records time, voiding parameters including voided volume and flow rate using the gravimetric method, and voiding satisfaction (Fig. 1). The device consists of a disposable urine cup, a load cell and the circuit board on which microcomputer, clock, angle/ acceleration sensor, audio guidance, Bluetooth and SD card are mounted. Voiding satisfaction is recorded by pushing the buttons which represent "good", "fairly good", "fairly bad" and "bad". The data stored in a SD card are analyzed using the dedicated software.
Results The first semester feasibility study focused on user-friendliness in 230 healthy volunteers. The usability was acceptable to male volunteers, but not to female volunteers, especially elderly people. This problem was resolved by a dedicated portable chair. The noise caused by shaking and angle position was canceled using the sensors. The smoothing were achieved using software which calculated moving average and so on. We also revealed the accuracy equal with other uroflowmeters using gravimetric methods. P-Flowdiary® achieved electrical safety test and Electro-Magnetic Compatibility test, and was approved for use as medical device of class 1. The dedicated software displayed the spread sheet of micturitions, the scatter plot of voided volume and maximum flow rate, and the time series of micturitions in different windows. Flow curves linking to the raw data were drawn when we clicked the data in other windows (Fig. 2). The color of dots in a scatter plot meant voiding satisfaction. A single record in a medical facility was also available like a conventional uroflowmeter. Flow curves and voiding parameters could be displayed on the tablet via Bluetooth.
Conclusion The primary objective to develop a handheld device which integrates FVC and uroflowmetry was achieved. Also, the dedicated software could provide useful information of voiding status in every subjects. The significance of consecutive recordings of urinary flow is still obscure. Clinical trials are in operation to establish the novel concepts of urinary flow nomogram, diagnostic tool to clarify several types of voiding dysfunction and the assessment tool for therapeutic performance.
P-Flowdiary® is convenient and easy-to-use at home even in the elderly. We have proved the practical usefulness as a screening tool for voiding dysfunction, which provides better informed consent as well as assessment of therapeutic performance for every patient. However, the clinical usefulness of uroflowmetry and self-assessment of every urination is not clarified yet.
The blood pressure is the best index to check cardiovascular diseases. Generally, we use cuff-based blood pressure monitor, but the handling is sometimes not easy. Thus we have attempted a cuffless blood pressure monitor. Recently IEEE approved a standard of cuffless blood pressure. However, cuffless blood pressure has not been interested both in clinical point of view and approve of certification agency. The cuffless blood pressure has several advantages such as easy to handle, relatively inexpensive and reliable for long term monitoring. In this session, the current activity of approving and distributing cuffless blood pressure is discussed.
To date, the definition and diagnosis of hypertension has been made by auscultation, so called Korotkoff procedure. Therefore, most devices for the measurement of blood pressure have been invented with purpose and direction to measure the cuff-induced changes in Korotkoff sounds. However, at least in part, several clinical difficulties have arisen regarding this classical blood pressure measurement by use of classical cuff procedure. The cuffless devices for the blood pressure measurement is expected as a paradigm shift that presumably introduces solutions for the current concerns by clinicians and patients regarding blood pressure measurement at any situation. In this session, we would like to count the concrete issues to be solved regarding the blood pressure monitoring by use of current apparatuses and propose the expected possibilities regarding the “cuffless” devices.
In healthy longevity society, prevention of lifestyle-related diseases and enhancement of home healthcare are required for improvement of QOL (quality of life). It is well known that blood pressure estimation is useful for prevention of hypertension and patient monitoring. It is the key technology for improvement of QOL, but the measurement by using a cuff all the time is a heavy burden. Therefore, we co-developed “the continuous health monitoring system with the cuffless sphygmomanometer using the pulse wave” to facilitate health care and home care patient monitoring. In particular, we constructed a cloud system to collect and manage blood pressure data using the internet and a wristwatch type photoplethysmograph sensor. Thus we applied the cuffless blood pressure estimation by a single photoplethysmograph sensor to the continuous health monitoring system.
PAT and PTT are considered one of the effective methods for cuffless blood pressure estimation. On the other hand, the arterial properties are extremely sensitive to measurement position. For this reason, PAT and PTT may also be affected by the arm position. The aim of this study was to verify the effect of the arm position changes on monitoring PAT and PTT. Eleven healthy volunteers participated in this experiment. Subjects were asked to put their right arm down and up. The results showed that the changes of PTT during the arm position change revealed the effect of blood pressure change. From a standpoint of estimating blood pressure, PPT was more useful than PAT.
In recent years,the music market has changed from CD to digital distribution. MP3 is the representative compressed sound source of online music services. However, MP3 formatted quality is inferior to uncompressed sound sources such as CD-DA formatted. Because MP3 formatted quality has less information as compared to CD-DA formatted. The object this study is used by analyzing EEG to determine if people can recognize such difference sound.This time we divide into two subject patterns which worry about less information quality data such as MP3 formatted whereas others don't worry about less information data. As a result we cloud find difference. So we report the progress of this study.
The purpose of our study is to obtain knowledge of decision-making related to movements.
We especially focus on the EEG signals when the Direction-Cue is presented to a subject. The Direction-Cue indicates the direction to press a button. In this paper, we investigate the variation of power spectrum in alpha frequency band (8-12Hz) by the time-frequency analysis.
We perform an experiment on pressing a button over 11 subjects. In this experiment, two cues are shown to subjects. First cue is called the Direction-Cue, and the other cue is called the Go-Cue. The Go-Cue indicates a starting time to press a button by beep sound.
As the results from the short-term Fourier transformation, we obtained two features of power spectrum change. 1) The sharp change of the ERS occurred after 200～500[ms] in presenting the Direction-Cue. 2) The sharp change of ERD occurred after 800～1000[ms]in presenting the Direction-Cue.
Our purpose of this study is to quantify the extent of mental fatigue by EEG signals. In this paper, we aim to observe relationship between the change of alpha band power and the extent of mental fatigue during a task inducing fatigue. We perform the experiments against 5 subjects. Subjects are instructed to read 50-sentences aloud and to take a 60-seconds rest in one trial. In this experiment, subjects take a 60-seconds rest in the first time and then repeat this trial ten times. We calculate the total power between 8 and 70 [Hz] and relative band powers of alpha. As results, two features are observed. The first feature is that the relative band power of alpha in Fp1, Fp2 electrode decreases as the experiment progresses. The second feature is that the relative band power of alpha in T7, P7 electrode increases as the experiment progresses.
Our research's purpose is clarifying P300 characteristics related to spatial attention. In this paper, we examine laterality differences for the P300 by three tasks (Task1: directional discrimination task (20%:80%), Task2: directional discrimination task (50%:50%), Task3: simple oddball task). In task1, stimuli (1kHz pure tone) are presented on a left or a right speaker of a subject. The target stimuli are generated on one of the left or the right speaker. The stimuli are presented 100 times (target: 20 times, non-target: 80 times). In task2, the stimuli are presented 100 times (target: 50 times, non-target: 50 times). In task3, two stimuli (target: 1kHz, non-target: 500Hz pure tone) are presented on one of the left or the right speaker. The stimuli are presented 100 times (target: 20, non-target: 80). As a result, the difference of target sound direction influences the difference of a peak time in P300.
Using fNIRS and Macaro's model of strategy use among language learners we try to observe changes in brain activity on people learning a new language. Research subjects are taught the Japanese language skill of reading, this means that they become able to understand the meaning and reading behind a group of words written with Chinese characters. A matrix of different words is shown to the subject measuring their brain activity to see their behavior while they lack the proper knowledge, after gaining the proper skills, activity is again measured and compared to the previous acquisition. A combined method of spaced repetition technique and mnemonics is used to make the learning process faster for the subjects. Although the words were studied for only a few minutes subjects were capable of retaining information in a fast manner remembering them even days after the learning session.
We have tried to obtain knowledge of decision-making by analyzing EEG in the Cued-movements Task. The aim of using the Cued-Movements Task is to observe two factors separately. One factor is decision-making of movement-direction. The other factor is execution of movements.
In this paper, we performed the Direction-Cue Task with auditory stimuli and the Direction-Cue Task with visual stimuli. First, the Direction-Cue is presented. The Direction-Cue indicate direction for movements. Next the Go-Cue is presented. After presenting the Go-Cue, a subject starts a movement. In the Direction-Cue Task with auditory stimuli, the Direction-Cue is presented by right- or left-arrow on display. In the Direction-Cue Task with visual stimuli, the Direction-Cue is presented by beep tone.
As results, we found that the stimulus of modality of the Cue has the influence on EEG potentials in Cued-movements.
Functional near-infrared spectroscopy (fNIRS) is a useful approach for monitoring changes in the oxygenated and the deoxygenated hemoglobin (Hb) concentration of cerebral blood flow. When the brain is activated, oxygen is supplied to capillaries and the increase of oxygenated Hb and the decrease of deoxygenated Hb are observed. During the measurements, physiological fluctuations sometimes cause parallel changes in the oxygenated and deoxygenated Hb concentrations and falsely recognized as brain activity. Thus, we propose an analysis method using the time variation of the correlation coefficient for extracting the characteristics of Hb concentration of brain activity. We use two kinds of indicators. One is a correlation coefficient of the oxygenated Hb concentration between measured channels and the other one is a correlation coefficient of oxygenated and deoxygenated Hb concentration within the channel. We applied this method to the measurement with short-term memory tasks in the forehead using a 16 channel system.
A measurement technique of brain activity using fNIRS is drawing attention. The contamination of skin blood flow (SBF) is often interpreted as brain activities in fNIRS measurements, which makes the reliability of fNIRS studies uncertain. The independent component analysis (ICA) is frequently applied to decrease the SBF artifacts. However, there is not an appropriate criterion to determine which independent components contain meaningful features. Here, we proposed a criterion based on a cross-correlation coefficient (CCC) and a coefficient of spatial uniformity (CSU). fNIRS signals were measured while subjects utter vowels rhythmically while measuring SBF simultaneously. The result indicates that many channels contain SBF artifacts and show strong correlation with uttering. We applied an ICA to pseudo fNIRS signals, which generated by using SBF signals measured in an uttering task. The results suggest that brain activity is properly extracted by using CCC and CSU, unless SBF has a correlation with brain activities.
Microsaccades are rapid and involuntary fixation eye movements. Previous studies have shown that shapes of fixation targets affect microsaccades rate. However, other characteristics of microsaccades have not been analyzed. Here, we investigated the relationship between target shapes and characteristics of microsaccades. Subjects gazed at one of the seven targets, which was composed from a point, a circle, and a cross, for 10 sec. The results indicate that the relationship between amplitude and peak-velocity of microsaccade had no correlation with target shapes, while there were some pairings that have significant differences in the relation between amplitude and frequency. The differences between point-only or point-and-cross target and circle target were salient. When point-only or point-and-cross target was presented, amplitude became small and frequency increased. They were reversed when circle target was presented. These results suggest that microsaccades are controlled to maintain the integration value of amplitude and frequency.
Reduction of Dorsolateral Prefrontal Cortex (DLPFC) blood flow measured by near- infrared spectroscopy (NIRS) is reported to be seen during the wakefulness to the early stage of sleep. DLPFC blood flow can be an index of arousal level, while, NIRS needs to wear an annoying and costly headgear and not suitable for daily use. Using cost-effective and compact Doppler radars attached behind chair back, we conducted multivariate study for 5 healthy subjects (23±1years) to estimate DLPFC blood flow using heart rate and heart rate variability index measured by radars. Estimated DLPFC blood flow correlates with that measured by NIRS (R>0.9) only when DLPFC blood flow decreased with time.
A deposit of amyloid β (Aβ) to the central nervous system causes Alzheimer's disease (AD). A periodical evaluation on Aβ, a year, can therefor detect the beginning of AD, and it realizes an effective medical treatment for AD. For quantitative measurement of Aβ deposit is available using PET, and it requires to delineate the cerebellum gray matter as a reference region, when no Aβ deposit occurs physiologically and it has complicated shape. This study aim at proposing automated delineation algorithm based on a kinetics of administered PET tracer for Aβ imaging. The validation using a clinical data presented no significant difference (p < 0.05) between the amount of Aβ deposit using an ordinary manual delineation and the automated method. We can conclude that the algorithm is clinically useful.
Magnetic resonance imaging (MRI) applies radiofrequency (RF) electromagnetic field to scan human bodies. Quantitative evaluations of MRI images are difficult due to the interference between the RF field and conductive implants. In this study, we designed RF pulses for mitigating the inhomogeneity of signal intensities in MRI image induced by interference between RF field and conductive implants. The adaptive RF pulse was calculated by analyzing the Bloch equation inversely. We carried out MRI simulation with a numerical model of inhomogeneous signal intensities. The homogeneity of signal intensities was improved by applying the adaptive RF pulse in the simulation results. We could determine the spatial resolution and excitation field of view (FOV) by changing the amplitude and the number of oscillating gradient field, respectively. The effectiveness of the designed RF pulse waveform was evaluated by performing numerical simulation and experiments with metallic implants.
Atmospheric-pressure plasmas can sterilizing, disinfecting, and disintegrating hazardous materials and modifying material surfaces. Plasma and pulsed electric field technologies have diverse applications, such as skin regeneration by multiple low-energy plasma therapy. Cord blood has hematopoietic stem cells, it has been put to practical use in hematopoietic stem cell transplantation. In addition, the presence of mesenchymal stem cells found in the umbilical cord blood, application to regenerative medicine has been expected. On the other hand, HIE is a condition in which the brain does not receive enough oxygen. Atmospheric-pressure plasmas acts to HIE, angiogenesis is promoted. We expected angiogenesis improving the ischemic condition can be recovery of brain function. And, umbilical cord blood can be expected to play the effect of precursor cells to the HIE. We investigate the method of plasma and cord blood administration and the effect of each method to the HIE model rats.
Photodynamic therapy (PDT), which is already applied in clinical case, selectively destroys tumor cells by the combination of photosensitizer and corresponding-wavelength laser. Our previous flexible laser endoscope properly achieved a main challenge caused by present endoscope and laser fiber technologies, which could not control the laser irradiation target during therapy, and this would hurt surrounding healthy tissue or blood vessel, causing bad complications. However this system exists its own shortcomings: its view angle less than 30 degree, not high image resolution, large laser focusing spot, and unstable XY stage placement rendering a litter large positioning errors. In this paper, we improve the system respecting aforementioned drawbacks. Experimental results prove the effectivity of this improved flexible laser endoscope system: the view angle larger than 70 degree, image resolution 5 times of standard laparoscopy, laser focusing spot almost half of previous, and horizontal stage placement giving out better positioning accuracy.
A maglev ventricular assist device implanted under the thorax muscle layer has been developed for mild heart disease patients. A radial gap maglev motor and a cascade pump are adopted to make the device thinner. The design of the device was modified to improve pump performance and anatomical fitting using a computational fluid dynamic analysis. A motor diameter is enlarged from 30 mm to 35 mm to improve motor performance. An inlet port was bent toward a ventricular side with an angle of 30 degrees for better fitting. An angle between the inlet and outlet ports was adjusted to 60 degrees. The CFD simulation indicates higher pressure production performance by 30 % of a previous device without any negative effect with the bending port. The pump can produce a sufficient flow rate of 2 L/min against a head pressure with a rotating speed of 1800.