The objective of this study was to examine the validity of estimating cell number using the water-soluble tetrazolium salts-8 (WST-8) assay for normal cells. The changes in mitochondrial activity of human umbilical vein endothelial cells (HUVECs) cultured under various culture conditions were evaluated using this assay. We found that cell counting of HUVECs by the WST-8 assay was not accurate under certain culture conditions, because the mitochondrial activity per cell changed depending on culture duration and medium composition. When charcoal/dextran-treated fetal bovine serum (FBS) -supplemented medium was used in cultures, the mitochondrial activity per cell was similar both in the presence and in the absence of vascular endothelial growth factor (VEGF). Furthermore, the mitochondrial activity did not affect the proliferative activity of cells, because we observed VEGF-dependent proliferation of HUVECs in this medium. For precise evaluation of cell number using the WST-8 assay, it is important to consider the accuracy of the assay results. Thus, a reliable method of cell counting using WST-8 needs to be developed.

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Spatio-temporal reconstruction methods for positron emission tomography estimate the tissue time-activity curves that are required for functional imaging. Since the time-related change of activity at a voxel has a temporal correlation by itself, temporal basis function approaches can be adopted. However, these image reconstruction methods suffer from a high computational cost. We have proposed a novel spatio-temporal reconstruction method using a temporal basis function approach, which is based on a fast block-iterative algorithm named Dynamic Row-Action Maximum-Likelihood Algorithm (DRAMA). Using the proposed method, data quickly converge to an estimate after around two iterations. This study aimed to validate the performance of the proposed algorithm on small animal PET data. We applied the proposed method to ¹⁸F-FDG mouse dynamic PET data. A parametric image of regional glucose metabolism reconstructed from the proposed method was almost identical to those obtained from conventional reconstruction algorithms. The proposed method took 14.3 h for computation, which was twice as fast as conventional algorithms. These results support the usability of the proposed algorithm for voxel-by-voxel estimation.

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Knowing the mechanical characteristics of organs during surgery ensures effective diagnosis and treatment. A surgeon's hand can sense the characteristics of organs in open abdominal or chest surgery. However, this sensing ability is reduced in endoscopic surgery, and it is completely lacking in robot-assisted endoscopic surgery. A surgical manipulator with a sensing function should have an autoclavable mechanism, and should be simple to control. In this paper, we propose a method of measuring elasticity using the step-out phenomenon of a stepper motor. Prototype devices were constructed and tested on silicone rubber test pieces and on organs both in vitro and in vivo.The devices were then calibrated using a material testing machine. Elasticity was defined in terms of the Young's modulus E or the spring constant K, which was calculated based on the force applied by the motor, the length of the arm attached to it, and the angular displacement of the arm when step-out occurred. Three different prototype devices were constructed to evaluate the effectiveness of the proposed method. All devices consisted of a stepper motor, a rotary encoder, and an arm. To measure silicone rubber objects, the arm was a simple bar. To measure organs in vitro, a bevel-geared jaw was used, and to measure organs in vivo, a long linkage-type forceps was employed. Each prototype had a resolution of approximately 1 µm. The elasticity values determined using these devices were compared with those measured using a material testing machine. For silicone rubber objects and organs in vitro, a good correlation was found between the elasticity values determined using the prototype devices and the material testing machine. In the in vivo experiment, the prototype device was capable of distinguishing differences between organs. This paper demonstrates the possibility of replacing a force sensor by using the proposed stepper motor-based method for measuring organ properties.

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Bubble liposomes (BLs), which are gas-encapsulated liposomes several hundred nanometers in diameter, are expected to be developed as a novel tool for gene and drug delivery using ultrasound acoustic radiation force. However, since BLs are several hundred nanometers in diameter, difficulties exist in controlling their behaviors in blood flow under ultrasound exposure, since acoustic radiation forces have less effect on these small bubbles. In this study, we investigated the feasibility of active control of BLs in an artificial blood vessel under ultrasound exposure and attempted to evaluate the controllability. Then, we investigated the appropriate ultrasound conditions for active path selection of BLs in a bifurcated flow by applying acoustic radiation force. We prepared a single transducer to orient BLs toward one desired path. Two other transducers were targeted at the two paths after the bifurcation. We evaluated the areas of trapped BLs in the two paths after the bifurcation, to determine which path had increased BLs. The result showed a significant increase in area of trapped BLs in the desired path compared to the other path. Then, we defined the induction index of BLs by evaluating the area of trapped BLs, and changed the ultrasound conditions for active path selection of BLs by varying the sound pressure and frequency. We found that more BLs could be oriented to a desired path at higher sound pressure. For further study, we are aiming at active control of BLs in vivo.

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This paper provides a 3D ultrasound navigation system with a blood vessel network (BVN) reconstruction algorithm for microbubble delivery therapy, which manipulates microbubbles in blood vessel by acoustic radiation force of ultrasound, aiming to increase the efficiency of high-intensity focused ultrasound (HIFU) and realize acoustic drug/gene delivery. To apply the technique in vivo, reconstruction of the BVN from 3D volume, such as bifurcation positions and flow direction, and visualization of the relative positions of the BVN and ultrasound field for microbubble manipulation are required. To address these issues, we have developed a 3D ultrasound navigation system to guide microbubbles in blood vessel. The novel navigation system consists of an ultrasound imaging device with a 2D array probe, an optical tracking device, a focused ultrasound transducer, and a Windows workstation with in-house navigation software. The system visualizes three-dimensionally both the BVN and the focal position of the transducer. When a 3D volume is acquired by an imaging device, the volume is automatically sent to the navigation system. Then, the system visualizes the volume and its bifurcations, which are estimated by 3D thinning processing. In this study, we examined the feasibility of the system by evaluating the guidance accuracy and microbubble induction rate. From the results, we confirm that microbubbles can be navigated by the system.

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When magnetic nanoparticles (MNPs) are used as a contrast agent for magnetic particle imaging (MPI), they are rapidly excreted during systemic circulation by the reticuloendothelial system such as Kupffer cells in the liver. Therefore, when considering clinical applications of MPI such as long-term monitoring of cardiovascular diseases, increasing the blood circulation time of MNPs by encapsulating the MNPs into actual cells such as red blood cells (RBCs) as a carrier may be practical. The purpose of this study was to create a biocompatible tracer for MPI by encapsulating MNPs (Resovist^®) into RBCs, and to investigate the effect of the encapsulating procedure on the properties of the RBCs loaded with MNPs (L-RBCs). MNPs were encapsulated into RBCs by the hypotonic dialysis method using a hypotonic buffer solution at three different osmotic pressures. Transmission (TEM) and scanning electron microscopic (SEM) images of the L-RBCs were obtained, and the saturation magnetic moment (Ms) was measured using vibrating sample magnetometry (VSM). From the response to a permanent magnet, the findings on TEM images, and the Ms values measured by VSM, we confirmed that RBCs were successfully loaded with MNPs using the hypotonic dialysis method. When the osmotic pressure was 80 mOsm, MNPs were not retained sufficiently inside the RBCs but were adhered to the membrane surface (TEM images), and RBCs lost their biconcave disc shape and shrunk after resealing (SEM images). At 160 mOsm, the Ms value was much lower than those at 80 and 120 mOsm. At 120 mOsm, the shape of RBCs was preserved (SEM images) and the Ms value was the highest when 0.2 ml (5.6mg of Fe) of Resovist^® was added to the dialysis tube for loading. In conclusion, we successfully encapsulated MNPs into RBCs using the hypotonic dialysis method. Our results suggest that an osmotic pressure of 120 mOsm is optimal for encapsulating MNPs into RBCs using the hypotonic dialysis method.

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To date, no method is available to quantify jerk at a local point of the human joint along a direction that depends on the 3D curvature of the articular surface. This paper proposes a new measurement technique of normalized jerk-cost(NJC)of a target point movement along a direction that is normal to the 3D curvature of the condyle of human temporomadibular joint (TMJ). This study aimed to investigate the reliability and effectiveness of NJC measurements at 9 condylar points. Five control subjects and 3 subjects with condylar asymmetry participated in this study. Each participant performed unilateral gum-chewing. In all control subjects, an artificial occlusal interference(OI)was inserted to the lower molar. The NJCs and intra-articular space of the TMJ on the working side were calculated with and without OI. In 3 control subjects and 3 test subjects, the experiment was repeated after an average interval of 2 months to evaluate reproducibility of the measurements. By means of dynamic stereometry, the NJCs of the 9 condylar point movements towards a direction normal to the condylar surface and intra-articular space were calculated and compared between control group with and without OI, between control group without OI and test group, and between group data measured in two separate sessions. Significantly greater NJC and joint space were observed after insertion of OI(P< 0.05). The NJC in test subjects was greater than that in the control group without OI(P< 0.05). In addition, these parameters measured at different sessions did not differ significantly. These findings suggest that measurement of the NJC and intraarticular space are effective and reliable to evaluate the instability of condylar movements due to OI or joint deformation.

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Specialized languages used for describing computational models in the field of systems biology and physiology, such as Systems Biology Markup Language (SBML), CellML, and Physiological Hierarchy Markup Language (PHML), have been devised to enhance effective model reuse and sharing among researchers for developing large, multilevel models. Each language has its own specialty. By combining two of these languages, i. e. SBML for illustrating subcellular phenomena and PHML for expressing supracellular dynamics, a novel technology has been developed to describe models of multilevel biophysiological systems. For practical use of the aforementioned languages, consolidated software applications providing intuitive graphical user interfaces are necessary. Starting from 2011, a versatile platform called PhysioDesigner has been developed for multilevel modeling of physiological systems based on PHML. In this article, we focus on the newly developed distinguishing features of PhysioDesigner and PHML for the development of multilevel biophysiological models using SBML-PHML hybridization.

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The implantable cardioverter-defibrillator is an effective therapeutic device for preventing death from life-threatening arrhythmias such as ventricular tachycardia and ventricular fibrillation in patients with cardiac diseases. It is important to prevent their recurrence and treat these arrhythmias as early as possible. It is also essential to accurately distinguish among normal sinus rhythm, ventricular tachycardia, ventricular fibrillation, and supraventricular tachycardia. Therefore, in this study, we proposed a classification method that uses multiple regression model based on information extracted from simultaneous intracardiac electrocardiograms, to identify episodes of sinus rhythm, supraventricular tachycardia, and ventricular tachycardia from human intracardiac electrocardiograms. From the results of validation, we confirmed that the proposed method is able to distinguish shockable cardiac rhythms from nonshockable cardiac rhythms based on indices obtained from simultaneous intracardiac electrocardiograms.

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Immature neovessels in tumors lead to the formation of heterogeneous hypoxic areas within tumors. Such hypoxic conditions not only reduce the effectiveness of radiation treatment but are also related to tumor invasion and metastasis. To better understand tumor-related mechanisms, it is important to quantitate the temporal and spatial changes of tumor hypoxia. However, no useful technique capable of measuring oxygen concentration in vivo has been proposed to date. We aimed to develop a microscope system to measure oxygen metabolism in tumor tissues using a laser-assisted oxygen quenching method. A scanning laser with galvano mirrors was capable of imaging tissue hypoxia and allowed configuration of time and spatial resolution by altering the laser spot size, scan rate, or scan distance. We examined the feasibility of the system by in vitro oxygen measurement, and applied this method to in vivo imaging of tumor oxygenation during oxygen inhalation in tumor-implanted mice. Oxygen tension inside tumors increased soon after oxygen inhalation, but decreased gradually after 20 min in spite of continuous oxygen inhalation, indicating that this model replicates the clinical experience that long-term tumor oxygenation cannot be achieved by oxygen inhalation. Quantitative analysis of tumor oxygenation may help reveal the mechanisms of oxygen metabolism in tumor tissues, leading to the development of more effective radiation therapy.

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In this study we investigated the cerebral correlation of computer-and paper-based neuropsychological tests commonly used as measures of frontal lobe function. Functional magnetic resonance imaging (fMRI) was used to record the brain activity of 12 right-handed, healthy, young adults (five males, seven females, mean age 26.4 years) during performance of the Trail Making Test (TMT) using a special writing device. In the paper-based TMT, subjects were presented with a random distribution of numbers and asked to rank them in ascending order. In computer-based neuropsychological testing (CBT), subjects were asked to rank numbers in ascending order by touching the numbers on the screen. Despite the atypical use of a virtual stylus, fMRI results in the present study illustrated a distinct left-sided dorsolateral and medial frontal activation during both paper- and computer-based versions of the TMT. These findings are in agreement with previous results indicating the sensitivity of frontal regions in the left hemisphere to the TMT task. In addition, the present study indicates that both versions of the TMT result in similar activation of frontal brain regions during cognitive tasks. Finally, these results suggest that CBT may be effectively employed as a neuropsychological testing tool.

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The number of elderly individuals in need of care is increasing with the growing elderly population in Japan, resulting in the increased production of disposable diapers. Several warning detectors for urinary incontinence have been developed to provide high-quality care, several of which have been marketed. Most of these detectors use disposable sensors. These sensors must be attached to a new diaper at the time of diaper changing. To reduce both the effort and the cost required to replace the sensor, we developed a warning system to detect urinary incontinence using a reusable sensor on the outside of a diaper. The newly developed system is essentially divided into a sensor unit and an alarm unit. The sensor unit consists of a pair of electrodes; a timer; a signal generator; bridge, rectifier, and smoother circuits; and a transmitter. The alarm unit consists of a receiver and LEDs. The alarm unit delivers a warning about incontinence to care staff via LED lighting. When 500 mL of tap water was absorbed into a diaper, on the outside of which the system was attached by its electrodes, the capacitance and conductance increased 2.5 times and 50 times, respectively, compared with those of a dry diaper. When 50 mL of saline was poured into a diaper that was attached to the crotch region of a torso mannequin to model incontinence, the incontinence warning functioned as intended. The impedance of the pad-type diaper, which was measured by an impedance analyzer, decreased from 270 kΩ to 86 kΩ. The electrodes remained dry after the saline was poured into the diaper. The novel warning system was evaluated in a special nursing home for the aged. Twelve elderly people participated in this trial. The system operated correctly in 49 of 65 trials.

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A heart model that can be expressed mathematically in a computer is desirable. Heart modeling applications can be classified into four areas : clinical, research, educational, and communications. A heart model for clinical application can be used as prior knowledge for segmentation and registration in medical image processing. A heart model for research application could be constructed each time using a combination of selected elements to reproduce the behavior of interest. However, a heart model for educational use does not necessarily have to follow actual data faithfully. A combination of visualization techniques, rich text information, and interaction is most important for effective teaching. Also, graphical information is used frequently by medical staff to explain the disease condition to patients and their families. It is important to understand what is to be communicated in such cases. For example, it is not necessarily important to represent precise shape information. In this review, we present several applications of heart models. We also introduce a novel application of a congenital heart disease model for communications uses. Finally, we discuss future perspectives in this field.

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Event-related potentials (ERPs)—in particular, the P300 component—have come under increasing scrutiny as a means of clarifying brain functions, as they are considered to reflect higher brain activity. Although much research has been devoted to the P300 signal, its source within the human brain remains unclear. Electroencephalogram (EEG) is often used in ERP studies because it directly reflects neurological responses to external stimulus. However, owing to the low spatial resolution of EEG, many surface or intracranial electrodes are required to estimate the signal source. We have attempted to develop a new signal source estimation method using only one signal electrode, which utilizes the switching voltage divider technology for simultaneous measurement of the potential and location of the signal source;i. e., whether the signal source is far from or near the signal electrode. This signal source estimation method may improve the low spatial resolution of EEG. Using our proposed method, we measured the ERPs of subjects participating in an oddball paradigm using auditory stimuli. The results suggest that the P300 component of an ERP is generated in a region deep within the brain.

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We have established a technique for quantification of collagen and bone minerals using synchrotron radiation (SR) CT and second harmonic generation (SHG) microscopy. This technique was used to evaluate the anabolic effect of whole body micro-vibration (WBMV) on bone defect healing. Male C57BL/6JJcl mice aged 13 weeks were operated to drill a 0.5-mm hole in the right tibial diaphysis. Two days after the drill-hole injury, the animals were randomly assigned to a WBMV (n=6) or a control (n=6) group. The WBMV group was exposed to a sine wave vibration (0.03g, 30Hz) and the control group to sham treatment for 20 min/day over 10 days. Bone specimens were then harvested and images of the bone mineral density and collagen density (SHG signal intensity) in the defect were acquired by SRCT and SHG microscopy, respectively. After image registration by maximizing mutual information from SRCT and SHG data, we quantified the bone mineral and collagen densities in the regions where bone and collagen overlapped in the defect. Mineralization was promoted in WBMV but collagen density did not differ between two groups. No correlation was found between the SHG signal intensity and the mineral density in both groups. These results suggest that WBMV probably promotes repair of bone defect by enhancing mineral deposition while having no influence on collagen density.

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Recently, the number of elderly people who take medicines daily has been increasing due to the aging population. Because elderly persons tend to experience cognitive deterioration, some may have difficulties in complying with their medication regimens. Therefore, we propose a new fuzzy-based inference algorithm to assist caregivers by providing them with remote monitoring capabilities. In this study, we developed an intelligent living environment with radio frequency identification (RFID) readers to detect when a person inappropriately self-administer medications with meals or drinks, for which coadministration is contraindicated and would decrease beneficial effects of the medicines or produce serious adverse effects. In the laboratory, RFID readers were strategically placed in a novel intelligent medicine case and around the kitchen. The readers recognized RFID tags affixed on objects such as medicines, foods, beverages, and drinking vessels. A wireless device with flow sensors was also placed in the kitchen unit to measure tap water consumption. Our experiments confirmed that based on the proposed algorithm, the system was able to recognize the presence of objects and usage of tap water, and to detect a typical contraindicated coadministration of a medication with a particular food product. The results indicate the potential of the system to directly alert caregivers by using the intelligent medicine case, in order to prevent inappropriate medication administration.

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We evaluated the performance of our automated computerized scheme for determining the likelihood of malignancy of pulmonary nodules on high-resolution computed tomography (HRCT) and positron emission tomography (PET) scans. Our database contained 36 primary lung cancers and 9 benign nodules. After the nodule location was identified by a radiologist, the boundary surface of the nodule was segmented automatically using a spiral-scanning technique. Objective nodular features were assessed by quantitative analysis of the nodular shape and on gray-level histograms of the interior and exterior regions. The likelihood of malignancy was determined by a support vector machine. The performance of our technique in distinguishing between benign and malignant nodules was evaluated by receiver operating characteristic (ROC) analysis. The area under the ROC curve (AUC) value obtained by using HRCT features alone was 0.87. The integration of PET features into the AUC value resulted in a significant improvement from 0.87 to 0.94 (P< 0.01). The AUC value obtained from simultaneous selection of HRCT and PET features was 0.97. A statistically significant difference (P< 0.01) was observed between the result obtained by simultaneous HRCT and PET feature selection (AUC=0.97) and that by integration of PET features (AUC=0.94). Our automated computerized scheme for determining the likelihood of malignancy may help radiologists to differentiate between benign and malignant pulmonary nodules on HRCT and PET scans.

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Traditional Chinese medicine considers the nutritive Qi—which is transported and regulated by the meridian system—to be the major source of energy for the human body. Modern medicine indicates that glucose provides the energy requirements of the body via blood circulation. The hypothesis examined in this study was that there is a correlation between glucose in modern medicine and nutritive Qi in traditional Chinese medicine, which was tested by measuring the changes in the Ryodoraku electrical conductances of acupoints during an oral glucose tolerance test. Twenty subjects drank a glucose solution after 10 hours of overnight fasting. Both acupoint conductance and blood glucose concentration were measured continuously at 30-minute intervals for a total of 2 hours. Since this study had a time-series design, data were analyzed using generalized estimating equations. The results demonstrated that the acupoint conductances varied following glucose digestion. Certain meridian vessels indeed appear to exhibit regular fluctuations:the conductances first decreased, indicative of energy consumption from glucose digestion, and then increased, indicating energy acquisition from glucose and its distribution. Glucose metabolism induces significant physiological responses in the meridian system, implying that the meridian vessels are the measurable indicators of energy distribution and transformation. These observations are very meaningful for clarifying energy regulation in traditional Chinese medicine.

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In this paper, we describe a robotic ultrasound (US) probe scanning system for reducing the manual tasks of US technicians and assisting in interventional procedures. The system consists of a probe scanning robot that uses McKibben artificial muscles, an optical tracking device, and in-house software for volume reconstruction and automatic guidance of surgical tools. The proposed system is lightweight and safe due to the use of artificial muscles, and allows positional control of the B-scan plane through transformation of US calibration. We applied the robotic system to robotic three-dimensional (3D) ultrasound and automatic ultrasound guidance. To clarify the system's feasibility, we performed phantom and human liver volume reconstructions, as well as needle guidance. The volume qualities of the reconstruction were validated by cross-correlation with reference echograms and reslicing of the reconstructed volumes. The correlation values were 0.80 ± 0.06 for the phantom and 0.53 ± 0.06 for the human liver. Regarding needle guidance, we confirmed that the B-scan plane automatically followed the needle. The translation error was −0.10 ± 1.26 mm and rotation error was −0.22 ± 1.81 degrees. Analysis of frequency response confirmed that the system was able to stably follow a motion at frequencies less than 0.3 Hz. The experimental results demonstrate that the robotic probe scanning system has great potential for yielding acceptable 3D volumes using two-dimensional (2D) ultrasound and assisting interventional procedures under US guidance.

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MRI-guided surgical ablation has been used as a novel technique to achieve minimally invasive glioma resection. In this surgery, low-power thermal energy is supplied via a laser probe, which is inserted into the patient's brain to coagulate the tumor region. To position the laser probe precisely, intraoperative MRI is performed. However, MRI images cannot provide sufficient details regarding the fiber tracts. In order for surgeons to know the spatial distribution of subcortical nerve tracts and improve safety during surgery, we propose the use of subcortical mapping to support MRI-guided surgical ablation. Conventional electrical stimulation using biphasic rectangular pulses has poor selectivity in nerve recruitment, and precise spatial distribution of nerve fibers in the subcortical region is difficult to obtain. In this study, we conducted computer simulations to determine which waveform of stimulation results in better spatial selectivity. We used a multi-layer volume conductor model of the human skull and neocortex, in which a mathematical model of a human myelinated nerve fiber was embedded. We numerically calculated the nerve responses to extracellular stimulation provided by an electrode attached to the laser probe inserted into the white matter. We evaluated the distance and diameter selectivity of a solitary test pulse alone and that of conditioning stimuli consisting of a triangular waveform and burst pulses followed by the test pulse. The results showed that the distance and diameter selectivity are markedly improved when using conditioning stimuli prior to the test pulse. A mechanism for improvement of selectivity can be explained based on the nonlinear dynamic properties at the axonal node. These results suggest that the novel conditioning waveform has the potential to provide detailed information of nerve fiber tracts to surgeons during MRI-guided surgical ablation.

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