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Search Results: 1 - 10 of 1428 matches for " Hiroyasu Sakai "
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Matrix Metalloproteinases-9 (MMPs-9) and -12 Are Upregulated in the Airways of Mice with Chronic Airway Inflammation and Remodeling
Yingyan Yu,Hiroyasu Sakai,Miwa Misawa,Yoshihiko Chiba
ISRN Pulmonology , 2012, DOI: 10.5402/2012/840489
Abstract: In the present study, we tried to develop a mouse model of chronic airway inflammation and remodeling induced by chronic exposure to antigen. Furthermore, the expressions of MMPs-9 and -12 were also investigated. BALB/c mice were sensitized and then repeatedly challenged with OVA every 3 days for 54 days. At the following day after the last challenge, of days 24, 39, and 54, histological changes of the airways were studied by hematoxylin-eosin and Masson's trichrome stains. The expressions of MMPs-9 and -12 were also measured by western blot. Persistent inflammatory cells infiltration and collagen deposition in the lung tissue were observed in repeatedly challenged mice. Furthermore, the expressions of MMPs-9 and -12 were increased in the airways after repeated antigen challenges. The severest inflammation was observed in the day-54 challenged group. These results suggest that MMPs-9 and -12 might be involved in the pathogenesis of chronic airway inflammation and remodeling induced by antigen exposure in mice. 1. Introduction Airway inflammation and remodeling are important features of chronic allergic airway diseases such as asthma [1]. Severe inflammatory cell infiltration into the lung tissue, airway structure changes including epithelium desquamation and abnormal, extracellular matrix (ECM) degradation are observed in the patients with chronic allergic airway diseases [2, 3]. These structure changes of the airways are thought to be the result from chronic repetitive injury to the airway wall caused by airway inflammation; however, the relationship between airway remodeling and inflammation is poorly understood. Matrix metalloproteinases (MMPs) are a family of proteinases with zinc-dependent proteolysis, which play important roles in matrix turnover [3]. MMPs, most of which are expressed in the airways, cleave a number of ECM constituents and can be broadly divided into collagenases, gelatinases, stromelysins, elastinases, and membrane-bound forms [4–6]. In particular, MMP-9 (gelatinase B) and MMP-12 (macrophage elastase), both of which are reportedly increased in the airways of asthmatic patients [7, 8], are thought to be associated with the pathogenesis of airway inflammatory diseases [9, 10]. The expressions and involvements of MMPs-9 and -12 in the pathogenesis of allergic airway disease were tried to be studied in some animal models with acute allergic airway disease [11–15]. However, the detailed involvements of MMPs-9 and -12 in the process of chronic allergic airway inflammation and airway remodeling are still to be revealed. Therefore, a
Finite size melting of spherical solid-liquid aluminium interfaces
Johan Chang,Erik Johnson,Takamichi Sakai,Hiroyasu Saka
Physics , 2009, DOI: 10.1080/14786430902720952
Abstract: We have investigated the melting of nano-sized cone shaped aluminium needles coated with amorphous carbon using transmission electron microscopy. The interface between solid and liquid aluminium was found to have spherical topology. For needles with fixed apex angle, the depressed melting temperature of this spherical interface, with radius $R$, was found to scale linearly with the inverse radius $1/R$. However, by varying the apex angle of the needles we show that the proportionality constant between the depressed melting temperature and the inverse radius changes significantly. This lead us to the conclusion that the depressed melting temperature is not controlled solely by the inverse radius $1/R$. Instead we found a direct relation between the depressed melting temperature and the ratio between the solid-liquid interface area and the molten volume.
Involvement of RhoA-mediated Ca2+ sensitization in antigen-induced bronchial smooth muscle hyperresponsiveness in mice
Yoshihiko Chiba, Ayako Ueno, Koji Shinozaki, Hisao Takeyama, Shuji Nakazawa, Hiroyasu Sakai, Miwa Misawa
Respiratory Research , 2005, DOI: 10.1186/1465-9921-6-4
Abstract: Ovalbumin (OA)-sensitized BALB/c mice were repeatedly challenged with aerosolized OA and sacrificed 24 hours after the last antigen challenge. The contractility and RhoA protein expression of BSMs were measured by organ-bath technique and immunoblotting, respectively.Repeated OA challenge to sensitized mice caused a BSM hyperresponsiveness to acetylcholine (ACh), but not to high K+-depolarization. In α-toxin-permeabilized BSMs, ACh induced a Ca2+ sensitization of contraction, which is sensitive to Clostridium botulinum C3 exoenzyme, indicating that RhoA is implicated in this Ca2+ sensitization. Interestingly, the ACh-induced, RhoA-mediated Ca2+ sensitization was significantly augmented in permeabilized BSMs of OA-challenged mice. Moreover, protein expression of RhoA was significantly increased in the hyperresponsive BSMs.These findings suggest that the augmentation of Ca2+ sensitizing effect, probably via an up-regulation of RhoA protein, might be involved in the enhanced BSM contraction in antigen-induced airway hyperresponsiveness.Increased airway narrowing in response to nonspecific stimuli is a characteristic feature of human obstructive diseases, including bronchial asthma. This abnormality is an important symptom of the disease, although the pathophysiological variations leading to the hyperresponsiveness are unclear now. Several mechanisms have been suggested to explain the airway hyperresponsiveness (AHR), such as alterations in the neural control of airway smooth muscle [1], increased mucosal secretions [2], and mechanical factors related to remodeling of the airways [3]. In addition, it has also been suggested that one of the factors that contribute to the exaggerated airway narrowing in asthmatics is an abnormality of the nature of airway smooth muscle [4,5]. Rapid relief from airway limitation in asthmatic patients by β-stimulant inhalation may also suggest an involvement of augmented airway smooth muscle contraction in the airway obstruction. Thus, it m
Pharmacological Modulation by Shakuyakukanzoto (Shao-Yao-Gan-Cao-Tang) and the Ingredients in Rat Intestinal Smooth Muscle  [PDF]
Hiroyasu Satoh, Kiminori Tsuro
Chinese Medicine (CM) , 2011, DOI: 10.4236/cm.2011.22012
Abstract: Shakuyakukanzoto (Shao-Yao-Gan-Cao-Tang), a formulation of Japanese herbal (Kampo) medicines, is composed of Paeoniae Radix and Glycyrrhizae Radix. Effects of Shakuyakukanzoto and the ingredients on rat intestinal tract were examined. Shakuyakukanzoto (0.01 - 0.3 mg/ml) relaxed a carbachol (CCh, 0.3 μM) - induced contraction in a concentration-dependent manner. Both components (Paeoniae radix and Glycyrrhizae radix) also relaxed the CCh-induced contraction. At 0.1 to 1 mM, their constituents (paeoniflorin and glycyrrhetic acid) and the metabolic products (18-α- and 18-β-glycyrrhetinic acids) exerted almost the same actions. The relaxations induced by Shakuyakukanzoto were not modified by 1 μM nicardipine, 10 μM suramin (ATP receptor inhibitor) and several K+ channel inhibitors, but was attenuated by 20 μM IBMX (a phosphodiesterase inhibitor). Also, IBMX inhibited the relaxations induced by paeoniflorin and glycyrrhetic acid, but not by other ingredients. Nicardipine decreased the relaxation of just 18-α-glycyrrhetinic acid. Even in non-treatment with CCh, Shakuyakukanzoto relaxed the intestinal tract. CCh (0.3 μM) elicited spontaneous contractions in 23% specimens, depressed by application of Shakuyakukanzoto. These results indicate that Shakuyakukanzoto causes a remarkable relaxation by the anti-cholinergic and the PDE inhibitory actions, but by minor contribution of Ca2+ channel inhibition. Thus, Shakuyakukanzoto exerts an anti-spasmodic action due to the interaction with pharmacological effects of its ingredients.
Comfort in observing stereoscopic images reduced by vibration stimuli  [PDF]
Hiroshi Watanabe, Hiroyasu Ujike
Health (Health) , 2012, DOI: 10.4236/health.2012.411157
Abstract: Numerous studies have been conducted to illuminate the effect of image factors to reduce unexpected influence of stereoscopic images on healthy visual experience. In this paper, we introduce changes in the psychological and physiological indexes of observers of a stereo- scopic image disturbed by vibration stimuli. Forty-four healthy university students participated in the experiment. A programmable vibration table generated two types of vibrations (5 Hz and 20 Hz) and provided intermittent vibration stimuli to a stereoscopic projector installed on a vibration table. Our results showed that the frequency of vibration stimuli has a strong impact in evaluating the local comfort of subjects. Our results also showed that the indexes of visual fatigue increased after observation independent of the frequency. The activity status of the autonomic nervous system as a physiological index significantly increased after observing 3D images with vibration stimuli although the vibrational frequency did not have a significant effect on the activity status.
Psychological and physiological effects of stereoscopic movies of real-world scenes containing improper three-dimensional settings  [PDF]
Hiroshi Watanabe, Hiroyasu Ujike
Health (Health) , 2013, DOI: 10.4236/health.2013.57148
Abstract:

By using psychological and physiological indicators, the effects on the body of three-dimensional (3D) movies containing improper settings were evaluated with 139 university students. The experiment consisted of two sessions: 1) a 3D movie containing improper 3D settings was compared with a 2D movie containing only the rightside images presented to both eyes, and 2) the original 3D movie was compared with the same 3D movie altered to contain improper 3D settings. The results of this experiment demonstrated clear deterioration of the subjective psychological indicators (degree of motion sickness after watching the movies and comfort level at 1-min intervals during the movie) with respect to the 3D movie containing improper settings. On the other hand, the physiological indicators (LF/HF ratio indicating the status of the autonomic nervous system) changed as a result of watching a 3D movie, but were unaffected by the presence or absence of improper 3D settings.

Asymmetric Electrostatic Force  [PDF]
Katsuo Sakai
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2014, DOI: 10.4236/jemaa.2014.610026
Abstract: Asymmetric electrostatic forces are a very interesting and new phenomenon. The magnitude of an electrostatic force that acts on a point charge does not change when the direction of the electric field is reversed. On the contrary, the magnitude of the electrostatic force that acts on a charged asymmetric shaped conductor does change when the direction of the electric field is reversed. 5 years ago, this phenomenon was reported by a simple experiment and a simulation and named as an Asymmetric electrostatic force unofficially by the author. After that, several simulations confirmed this phenomenon. However, several experiments did not yet confirm it clearly. The difference between the simulations and the experiments depends upon differences of their conditions. The simulations had been done under ideal (perfect) conditions; the experiments, on the contrary, had been done under actual (not perfect) conditions. In the new experiment, its conditions were improved to near ideal (perfect) conditions. As a result the existence of the Asymmetric electrostatic force was more clearly confirmed.
Surface Properties of Cement Paste Evaluated by Scanning Probe Microscopy  [PDF]
Yuya Sakai
Open Journal of Civil Engineering (OJCE) , 2016, DOI: 10.4236/ojce.2016.64052
Abstract: The microscopic physical properties of Hardened Cement Paste (HCP) surfaces were evaluated by using Scanning Probe Microscopy (SPM). The cement pastes were cured under a hydrostatic pressure of 400 MPa and the contacting surfaces with a slide glass during the curing were studied. Scanning Electron Microscope (SEM) observation at a magnification of 7000 revealed smooth surfaces with no holes. The surface roughness calculated from the SPM measurement was 4 nm. The surface potential and the frictional force measured by SPM were uniform throughout the measured area 24 h after the curing. However, spots of low surface potential and stains of low frictional force and low viscoelasticity were observed one month after curing. This change was attributed to the carbonation of hydrates.
A Study of Weighted Polynomial Approximations with Several Variables (II)  [PDF]
Ryozi Sakai
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.89093
Abstract: In this paper we investigate weighted polynomial approximations with several variables. Our study relates to the approximation for \"\" by weighted polynomial. Then we will give some results relating to the Lagrange interpolation, the best approximation, the Markov-Bernstein inequality and the Nikolskii- type inequality.
A Study of Weighted Polynomial Approximations with Several Variables (I)  [PDF]
Ryozi Sakai
Applied Mathematics (AM) , 2017, DOI: 10.4236/am.2017.89095
Abstract: In this paper, we investigate the weighted polynomial approximations with several variables. Our study relates to the approximation for \"\" by weighted polynomials. Then we will estimate the degree of approximation.
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