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Biological Evaluation of Tissue-Engineered Cartilage Using Thermoresponsive Poly(N-isopropylacrylamide)-Grafted Hyaluronan

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Journal of Biomaterials and Nanobiotechnology 2012年第1期3卷 1-9页

作者： kazuaki muramatsu Mika Ide Fujio Miyawaki Division of Life Science and Engineering School of Science and Engineering Tokyo Denki University Saitama Japan

In order to contribute to the development of minimally invasive surgery techniques for autologous chondrocyte implantation, a novel self-assembling biomaterial consisting of thermoresponsive poly(N-isopropylacrylamide)-grafted hyaluronan (PNIPAAm-g-HA) has been synthesized as an injectable scaffold for cartilage tissue engineering. The aim of this study was to investigate the efficacy and cytocompatibility of PNIPAAm-g-HA to normal chondrocytes by using reverse transcription-polymerase chain reaction (RT-PCR) analysis and histochemical staining in preliminary in vitro and in vitro experiments. Hematoxylin and eosin staining showed homogeneous distribution of cells in the PNIPAAm-g-HA hydrogel in 3-dimensional in vitro cultivation. Alcian blue staining also indicated that abundant extracellular matrix formation, including acidic glycosaminoglycans, occurred in tissue-engineered cartilage over time in vitro. Cartilage-related gene expression patterns, which were tested in rabbit normal chondrocytes embedded in the hydrogel, were almost maintained for 4 weeks. Transforming growth factor-β1 (TGF-β1) stimulation enhanced the expression of SRY-related HMG box-containing gene 9 (Sox9) and type X collagen genes suggesting promotion of chondrogenic differentiation. Histochemical evaluation showed neocartilage formation following subcutaneous implantation of the chondrocyte-gel mixture in nude mice. Furthermore, TGF-β1 stimulation promoted production and maturation of the extracellular matrix of the in situ tissue engineered hyaline cartilage. These data suggested that PNIPAAm-g-HA could be a promising biomaterial, i.e., a self-assembling and injectable scaffold for cartilage tissue engineering.

关键词： Cartilage Tissue Engineering Hyaluronan Self-Assembly Thermally Responsive Material

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Poly(N-isopropylacrylamide-co-N-tert-butylacrylamide)- grafted hyaluronan as an injectable and self-assembling scaffold for cartilage tissue engineering

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Journal of Biomedical Science and Engineering 2012年第11期5卷 639-646页

作者： kazuaki muramatsu Yuji Saito Takuya Wada Hiroyuki Hirai Fujio Miyawaki Division of Life Science and Engineering School of Science and Engineering Tokyo Denki University Saitama Japan

Novel poly(N-isopropylacrylamide-co-N-tert-butylacrylamide)-grafted hyaluronan [P(NIPAAm-co-NtBAAm)-g-HA] has been developed as a modified derivative to improve phase-transition characteristics of PNIPAAm-g-HA, which has a lower critical solution temperature (LCST) of approximately 32°C. This promising self-assembling biomaterial has potential as an injectable scaffold for in situ cartilage tissue engineering. LCST of the P(NIPAAm-co-NtBAAm)-g-HA decreased to approximately 3.6°C compared to that of the original PNIPAAm-g-HA. This modification enabled self-assembly at body temperatures lower than the temperature of the parental PNIPAAm-g-HA molecule. Cytotoxicity and acute systemic toxicity assays revealed that P(NIPAAm-co-NtBAAm)-g-HA was not hazardous. The DNA content of chondrogenic differentiated mesenchymal stem/stromal cells (MSCs) embedded in the gels was higher than that of biomaterial-free aggregates during the culture periods. Cartilage-related genes were also expressed in chondrogenic differentiated MSCs embedded in the P (NIPAAm-co-NtBAAm)-g-HA hydrogel. Specifically, an increased expression of SRY-related HMG box-containing gene 9 (Sox9) observed in the hydrogel group compared to controls. These data suggest that P(NIPAAm-co-NtBAAm)-g-HA is a promising injectable scaffold with thermoresponsive properties suitable for in situ cartilage tissue engineering.

关键词： Thermally Responsive Material Cartilage Tissue Engineering Biocompatibility Mesenchymal Cells

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Effect of the Suppression of Cariesitic Bacterial Growth and Biofilm Formation Using Hydrogen/Free Chlorine Mixed Water Produced by an Electrolysis-Type Hydrogen Generator

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Health 2019年第2期11卷 142-151页

作者： Ryusuke Suzuki Rin Kaneko Masaru Nakano Masato Kanda Yuji Sebata Shota Motegi Tomoko Abe kazuaki muramatsu Division of Life Science and Engineering School of Science and Engineering Tokyo Denki University Saitama Japan SHEM Corporation Tokyo Japan

OBJECTS: Hydrogen has been shown to possess antibacterial effects at high concentrations. In addition, chlorine has a strong bactericidal effect even at low concentrations. Electrolysis is a way to simultaneously generate these two components. However, the concentration of hydrogen/free chlorine mixed water generated through electrolysis decreases quickly. It is predicted that the concentration of hydrogen/free chlorine mixed water will vary depending on the quality of water used. After investigating the optimum generation conditions, the effects of the most stable concentration of hydrogen/free chlorine mixed water on carious tooth fungus were evaluated in vitro. Thus, in this experiment, our goal was to evaluate the effects of hydrogen/free chlorine mixed water on oral bacteria. MATERIALS AND METHODS: Using a device that generates hydrogen/free chlorine through electrolysis, the differences in the concentrations of hydrogen and free chlorine based on electrolysis time were evaluated using tap water. Additionally, various concentration changes due to electrolysis time on the hydrogen/free chlorine mixed water were evaluated. Distilled tap water as a control group, hydrogen/free chlorine mixed water, and commercially available mouthwash were added for 1 minute to cultured Streptococcus mutans and then rinsed out with the culture medium. Bacterial growth (600 nm) and biofilm formation (590 nm) were measured at 3 and 6 hours after the addition of the medium. RESULTS: The concentration of hydrogen/chlorine mixed water produced by electrolysis varied depending on electrolysis time and the water used. The inhibitory effect of bacterial growth was enhanced depending on the chlorine concentration. Regarding the inhibitory effect on biofilm formation, only the mixed water of hydrogen/free chlorine concentration (500 ppb - 1.0 mg/L) had a suppressing effect after 6 hours. CONCLUSION: It was suggested that hydrogen/chlorine mixed water can be easily produced by electrolysis a

关键词： Hydrogen Chlorine Bactericidal Capacity Bacteria Effect

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On the Existence of Feller Semigroups with Discontinuous Coefficients

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Acta Mathematica Sinica,English Series 2006年第2期22卷 595-606页

作者： kazuaki TAIRA Institute of Mathematics University of Tsukuba

This paper is devoted to the functional analytic approach to the problem of the existence of Markov processes in probability theory. More precisely, we construct Feller semigroups with Dirichlet conditions for second-order, uniformly elliptic integro-differential operators with discontinuous coefficients. In other words, we prove that there exists a Feller semigroup corresponding to such a diffusion phenomenon that a Markovian particle moves both by jumps and continuously in the state space until it dies at the time when it reaches the boundary.

关键词： Feller semigroup Dirichlet condition VMO function

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On the Existence of Feller Semigroups with Discontinuous Coefficients Ⅱ

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Acta Mathematica Sinica,English Series 2009年第5期25卷 715-740页

作者： kazuaki TAIRA Institute of Mathematics University of Tsukuba

This paper is devoted to the functional analytic approach to the problem of existence of Markov processes with Dirichlet boundary condition, oblique derivative boundary condition and first-order Wentzell boundary condition for second-order, uniformly elliptic differential operators with discontinuous coefficients. More precisely, we construct Feller semigroups associated with absorption, reflection, drift and sticking phenomena at the boundary. The approach here is distinguished by the extensive use of the ideas and techniques characteristic of the recent developments in the Calderon- Zygmund theory of singular integral operators with non-smooth kernels.

关键词： singular integral Feller semigroup elliptic operator with VMO coefficients Wentzellboundary condition

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3D Computation of Hydrogen-Fueled Combustion around Turbine Blade-Effect of Arrangement of Injector Holes

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Journal of Thermal Science 2006年第3期15卷 233-239页

作者： Makoto YAMAMOTO Junichi IKEDA kazuaki INABA Department of Mechanical Engineering Tokyo University of Science 1-3 KagurazakaShinjuku-kuTokyo162-8601Japan Graduate School of Mechanical Engineering Tokyo University of Science 1-3 KagurazakaShinjuku-kuTokyo162-8601Japan

Recently, a number of environmental problems caused from fossil fuel combustion have been focused on. In addition, with the eventual depletion of fossil energy resources, hydrogen gas is expected to be an alternative energy resource in the near future. It is characterized by high energy per unit weight, high reaction rate, wide range of flammability and the low emission property. On the other hand, many researches have been underway in several countries to improve a propulsion system for an advanced aircraft. The system is required to have higher power, lighter weight and lower emissions than existing ones. In such a future propulsion system, hydrogen gas would be one of the promising fuels for realizing the requirements. Considering these backgrounds, our group has proposed a new cycle concept for hydrogen-fueled aircraft propulsion system. In the present study, we perform 3 dimensional computations of turbulent flow fields with hydrogen-fueled combustion around a turbine blade. The main objective is to clarify the influence of arrangement of hydrogen injector holes. Changing the chordwise and spanwise spacings of the holes, the 3 dimensional nature of the flow and thermal fields is numerically studied.

关键词： computational fluid dynamics turbine blade hydrogen combustion injector hole arrangement

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Numerical Simulation of Tip Leakage Vortex Effect on Hydrogen-Combustion Flow around 3D Turbine Blade

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Journal of Thermal Science 2008年第2期17卷 186-192页

作者： Naoto Miyama kazuaki Inaba Makoto Yamamoto Department of Mechanical Engineering Tokyo University of Science Graduate Aeronautical Laboratories California Institute of Technology

In these years, a lot of environmental problems such as air pollution and exhaustion of fossil fuels have been discussed intensively. In our laboratory, a hydrogen-fueled propulsion system has been researched as an alternative to conventional systems. A hydrogen-fueled propulsion system is expected to have higher power, lighter weight and lower emissions. However, for the practical use, there exist many problems that must be overcome. Considering these backgrounds, jet engines with hydrogen-fueled combustion within a turbine blade passage have been studied. Although some studies have been made on injecting and burning hydrogen fuel from a stator surface, little is known about the interaction between a tip leakage vortex near the suction side of a rotor tip and hydrogen-fueled combustion. The purpose of this study is to clarify the influence of the tip leakage vortex on the characteristics of the 3-dimensional flow field with hydrogen-fueled combustion within a turbine blade passage. Reynolds-averaged compressible Navier-Stokes equations are solved with incorporating a k-ε turbulence and a reduced chemical mechanism models. Using the computational results, the 3-dimensional turbulent flow field with chemical reactions is numerically visualized, and the three-dimensional turbulent flow fields with hydrogen combustion and the structure of the tip leakage vortex are investigated.

关键词： numerical simulation CFD gas turbine hydrogen combustion tip leakage vortex

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Numerical Simulation of Sand Erosion Phenomena in Rotor/Stator Interaction of Compressor

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Journal of Thermal Science 2008年第2期17卷 125-133页

作者： Masaya Suzuki kazuaki Inaba Makoto Yamamoto Department of Mechanical Engineering Tokyo University of Science

Sand erosion is a phenomenon where solid particles impinging to a wall cause serious mechanical damages to the wall surface. This phenomenon is a typical gas-particle two-phase turbulent flow and a multi-physics problem where the flow field, particle trajectory and wall deformation interact with each other. On the other hand, aircraft engines operating in a particulate environment are subjected to the performance and lifetime deterioration due to sand erosion. Especially, the compressor of the aircraft engines is severely damaged. The flow fields of the compressor have strongly three dimensional and unsteady natures. In order to estimate the deterioration due to sand erosion, the sand erosion simulation for a compressor is required under the consideration of the rotor-stator interaction. In the present study, we apply our three dimensional sand erosion prediction code to a single stage axial flow compressor. We numerically investigate the change of the flow field, the particle trajectories, and the eroded wall shape in the compressor, to clarify the effects of sand erosion in the compressor.

关键词： sand erosion axial compressor rotor/stator interaction computational fluid dynamics

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Evidence of spin density wave of CeOs4Sb12

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Rare Metals 2006年第S1期25卷 550-552页

作者： IWASA kazuaki SUGAWARA Hitoshi SATO Hideyuki Department of Physics Tohoku University Sendai 980-8578 Japan Department of Physics Tokyo Metropolitan University Tokyo 192-0397 Japan

Elastic neutron diffraction measurements were performed on single crystals to study the ground state below the mysterious exotic transition temperature 0.86 K. An antiferromagnetic order with a tiny moment of 0.027 μB per formula is formed as the ground state for CeOs4Sb12 below the transition point. Our neutron data gives the evidence of spin density wave state for CeOs4Sb12 in this work.

关键词： elastic neutron scattering skutterudite structure antiferromagnetic ordering spin density wave

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Influence of comorbidity on outcomes of older patients with acute pancreatitis based on a national administrative database

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Hepatobiliary & Pancreatic Diseases International 2015年第4期14卷 422-428页

作者： Atsuhiko Murata Makoto Ohtani Keiji muramatsu Shinya Matsuda Department of Preventive Medicine and Community Health School of Medicine University of Occupational and Environmental Health

Little information is available on the influ- ence of comorbidities on outcomes of older patients with acute pancreatitis. This study aimed to investigate the influence of co- morbidities on outcomes of older patients with acute pancreati- tis using data from a national Iapanese administrative database. METHODS： A total of 14 322 older patients （〉70 years） with acute pancreatitis were referred to 1090 hospitals between 2010 and 2012 in Japan. We collected patients＇ data from the administrative database to compare the in-hospital mortal- ity and length of stay of older patients with acute pancreatitis. The patients were categorized into four groups according to comorbidity level using the Charlson Comorbidity Index （CCI）： none （CCI score=0; n=6890）; mild （1; n=3874）; moder- ate （2; n=2192） and severe （〉3; n=1366）. RESULTS： Multiple logistic and linear regression analyses revealed that severe comorbidity was significantly associated with higher in-hospital mortality and longer length of stay [odds ratio （OR）=2.26; 95% confidence interval （CI）： 1.75-2.92, P〈0.001 and coefficient 4.37 days; 95% CI： 2.89-5.85, P〈0.001, respectively]. In addition, cardiovascular and renal diseases were the most significant comorbidities affecting outcomes of the older patients. ORs of cardiovascular and renal diseases for mortality were 1.44 （95% CI： 1.13-1.85, P=0.003） and 2.69 （95% CI： 1.88-3.85, P〈0.001）, respectively, and coefficients forlength of stay were 3.01 days （95% CI： 1.34-4.67, P〈0.001） and 3.72 days （95% CI： 1.01-6.42, P=0.007）, respectively. CONCLUSION： This study demonstrated that comorbidities significantly influenced outcomes of older patients with acute pancreatitis and cardiovascular and renal comorbidities were significant factors affecting outcomes.

关键词： acute pancreatitis comorbidity length of stay databases

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