Gifu University of Medical Science

About: Gifu University of Medical Science is a education organization based out in Gifu City, Japan. It is known for research contribution in the topics: Imaging phantom & Motion sickness. The organization has 89 authors who have published 202 publications receiving 1350 citations.

A Study of Stochastic Resonance as a Mathematical Model of Electrogastrography during Sitting Position

Abstract: Electrogastrography (EGG) is an abdominal surface measurement of the electrical activity of the stomach. It is very important clinically to record and analyze multichannel EGGs, which provide more information on the propagation and co-ordination of gastric contractions. This study measured the gastrointestinal motility with an aim to obtain a mathematical model of EGG and to speculate factors to describe the diseases resulting from constipation and erosive gastritis. The waveform of the electric potential in the Cajal cells is similar to the graphs of numerical solutions to the van der Pol equation. Hence, we added the van der Pol equation to a periodic function and random white noises, which represented the intestinal motility and other biosignals, respectively. We rewrote the stochastic differential equations (SDEs) into difference equa-tions, and the numerical solutions to the SDEs were obtained by the Runge—Kutta—Gill formula as the numerical calculus, where we set the time step and initial values to be 0.05 and (0, 0.5), respectively. Pseudorandom numbers were substituted in the white noise terms. In this study, the pseudorandom num-bers were generated by the Mersenne Twister method. These numerical calculations were divided into 12000 time steps. The numerical solutions and EGG were extracted after every 20 steps. The EGG and numerical solutions were compared and evaluated by the Lyapunov exponent and translation error. The EGG was well described by the stochastic resonance in the SDEs.

Image-quality assessment method for digital phase-contrast imaging based on two-dimensional power spectral analysis

Abstract: With use of the phase shift of X-rays that occurs when they pass through an object, phase-contrast imaging (herein referred to as “phase imaging”) can produce images different from those of conventional contact imaging (herein referred to as “conventional imaging”). For this reason, assessment of the image quality based on noise-equivalent quanta (NEQ) and detective quantum efficiency (DQE) which does not include object-based information may not be appropriate for comparison of image quality between phase and conventional images. As an alternative method, we conceived a new image-quality assessment method with images that contain information about an object. First, we constructed images with an object and without an object under the same imaging parameters; then, we obtained two-dimensional power spectra by Fourier transform of those images. Second, we calculated the radial direction distribution function with the power spectra, and the distribution of signal intensity, which we defined as a signal intensity distribution function (SIDF). In this way, differences in image quality were evaluated relatively based on the SIDF of the imaged object. In our study, we first confirmed that phase-imaging evaluation was not appropriate by comparing NEQ and DQE of conventional, magnification, and phase imaging. Further, comparing the image quality of projected plant seeds by employing conventional, magnification, and phase imaging, we found that the phase-imaging method provided a higher image quality regarding edge sharpness than did conventional and magnification imaging. Therefore, based on these results, our image assessment method is considered useful for evaluation of images which include object-based information.

Intimate Adhesion Is Essential for the Pathogen-Specific Inflammatory and Immune Responses in the Gut of Mice Infected with Citrobacter rodentium.

Abstract: Citrobacter rodentium is a murine pathogenic bacterium that adheres to intestinal epithelial cells, resulting in loss of microvilli and pedestal formation, and alters multiple cellular processes, including actin dynamics. Translocated intimin receptor (Tir), one of its virulence factors, functions as receptor for intimin, a bacterial adhesin, thereby mediating bacterial adhesion to epithelial cells. Although robust immune responses are induced to eliminate pathogenic bacteria in the host, they are suppressed against harmless commensal bacteria. The mechanism(s) underlying such a differentiation remains unclear. This study sought to determine the roles of intimate adhesion in the induction of specific immune responses upon C. rodentium infection. To this end, microbiota-depleted mice were infected with the Tir-F strain expressing full-length Tir or mutant strains expressing the C-terminal truncated Tir that is defective in intimin binding and host cell actin polymerization. There were no differences in the colonization kinetics and Abs responses against C. rodentium LPS among the strains, whereas Abs against the virulence factors were only produced on Tir-F infection. Although there were no differences in the virulence factors mRNA expression levels, colonic hyperplasia, and bacterial translocation to the systemic organs irrespective of the strain, adhesion to colonic epithelial cells was reduced in the mutant strain-infected mice. Furthermore, transcriptomic analysis indicated that robust inflammatory and immune responses were only induced in the Tir-F-infected group and were suppressed in the mutant-infected groups. Taken together, these findings suggest that Tir-mediated intimate adhesion induces inflammatory and immune responses, resulting in the induction of virulence factor-specific Abs.