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Dive into the research topics where Masashi Koka is active.

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Featured researches published by Masashi Koka.


Respiratory Research | 2011

Elemental analysis of lung tissue particles and intracellular iron content of alveolar macrophages in pulmonary alveolar proteinosis

Yasuo Shimizu; Shinichi Matsuzaki; Kunio Dobashi; Noriko Yanagitani; Takahiro Satoh; Masashi Koka; Akihito Yokoyama; Takeru Ohkubo; Yasuyuki Ishii; Tomihiro Kamiya; Masatomo Mori

BackgroundPulmonary alveolar proteinosis (PAP) is a rare disease occurred by idiopathic (autoimmune) or secondary to particle inhalation. The in-air microparticle induced X-ray emission (in-air micro-PIXE) system performs elemental analysis of materials by irradiation with a proton microbeam, and allows visualization of the spatial distribution and quantitation of various elements with very low background noise. The aim of this study was to assess the secondary PAP due to inhalation of harmful particles by employing in-air micro-PIXE analysis for particles and intracellular iron in parafin-embedded lung tissue specimens obtained from a PAP patient comparing with normal lung tissue from a non-PAP patient. The iron inside alveolar macrophages was stained with Berlin blue, and its distribution was compared with that on micro-PIXE images.ResultsThe elements composing particles and their locations in the PAP specimens could be identified by in-air micro-PIXE analysis, with magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), scandium (Sc), potassium (K), calcium (Ca), titanium (Ti), chromium (Cr), copper (Cu), manganase (Mn), iron (Fe), and zinc (Zn) being detected. Si was the major component of the particles. Serial sections stained by Berlin blue revealed accumulation of sideromacrophages that had phagocytosed the particles. The intracellular iron content of alveolar macrophage from the surfactant-rich area in PAP was higher than normal lung tissue in control lung by both in-air micro-PIXE analysis and Berlin blue staining.ConclusionThe present study demonstrated the efficacy of in-air micro-PIXE for analyzing the distribution and composition of lung particles. The intracellular iron content of single cells was determined by simultaneous two-dimensional and elemental analysis of paraffin-embedded lung tissue sections. The results suggest that secondary PAP is associated with exposure to inhaled particles and accumulation of iron in alveolar macrophages.


International Journal of PIXE | 2011

DEVELOPMENT OF ANALYSIS SYSTEM OF MICRO-IBIL COMBINED WITH MICRO-PIXE

Wataru Kada; Akihito Yokoyama; Masashi Koka; Takahiro Satoh; T. Kamiya

An ion beam induced luminescence analysis system using ion micro-beam (micro-IBIL) was newly developed on the microbeam system of the 3 MeV single-ended accelerator at ion-irradiation research facility TIARA, JAEA. The developed IBIL system consisted of an aspheric microlens, optical fibers, a monochromator and a photon-counting system to observe IBIL photons of specific wavelength with the resolution of 2 nm. A photomultiplier in the photon-counting system was cooled to around 0°C by a peltier device to reduce the background noises down to 10 cps and able to observe weak photon signals from specific chemical composites of the target. Experiments of micro-IBIL were performed using 3 MeV proton microbeam for several scintillators and particulate targets i.e. aerosol particles. The system had achieved chemical-imaging of aerosols by obtaining wavelength-dispersive micro-IBIL image at luminescence center of silicon dioxide.


International Journal of PIXE | 2012

EFFECTIVENESS OF A COMBINATION OF ML-EM AND STIM-CT IN PIXE-CT FOR BIOLOGICAL SPECIMEN

Takahiro Satoh; Masashi Koka; Wataru Kada; Akihito Yokoyama; T. Ohkubo; A. Yamazaki; Y. Ishii; T. Kamiya; N. Kozai

In this study, we applied ML-EM (maximum likelihood expectation maximization) iterative algorithm and STIM-CT to a three dimension imaging technique of PIXE -CT for cellular analysis using 3 MeV proton microbeam with a diameter of 1 μm at TIARA (Takasaki Ion Accelerators for Advanced Radiation Application). The algorithm had been applied to tomography such as SPECT (Single Photon Emission Computed Tomography). It is also possible and suitable to apply the algorithm to PIXE-CT because the algorithm can be used to project images taking into account errors due to rare events. Energy loss of incident particles and absorption of X-rays, however, affect quantitative values dramatically in the case of PIXE -CT. We estimated those effects from density distribution of major elements measured by STIM-CT in this work. In order to show the appropriateness of this method, X-ray yield and absorption were calculated using density distribution of two-dimensional Shepp phantom. The PIXE-CT experiments were carried out using a dried unicellulate as a test sample placed on an automatic rotation stage, which made a full turn by rotating 360° at each step of 18° in vacuum. The results of those simulation and experiments have proved that this method is effective.


Japanese Journal of Applied Physics | 2010

Micrometer-Sized Magnetic Patterning of FeRh Films Using an Energetic Ion Microbeam

Naoki Fujita; T. Matsui; Shinya Kosugi; Takahiro Satoh; Yuichi Saitoh; Katsuyoshi Takano; Masashi Koka; Tomihiro Kamiya; Shuhei Seki; Akihiro Iwase

FeRh thin films were irradiated with a focused 10 MeV I 2 ×2 µm2 ion microbeam at intervals of several µm. Following irradiation, the magnetic state at the surface was observed via magnetic force microscopy. The micrometer-sized regions irradiated with the microbeam show a ferromagnetic state while unirradiated regions remain in an anti-ferromagnetic state. Results indicate that an energetic ion microbeam can be used as a tool to produce micrometer-sized modulations of lateral magnetic states of FeRh films.


Journal of Clinical Biochemistry and Nutrition | 2015

Co-localization of iron binding on silica with p62/sequestosome1 (SQSTM1) in lung granulomas of mice with acute silicosis.

Yasuo Shimizu; Kunio Dobashi; Hiroyuki Nagase; Ken Ohta; Takaaki Sano; Shinichi Matsuzaki; Yoshiki Ishii; Takahiro Satoh; Masashi Koka; Akihito Yokoyama; Takeru Ohkubo; Yasuyuki Ishii; Tomihiro Kamiya

The cellular mechanisms involved in the development of silicosis have not been fully elucidated. This study aimed to examine influence of silica-induced lung injury on autophagy. Suspensions of crystalline silica particles were administered transnasally to C57BL/6j mice. Immunohistochemical examination for Fas and p62 protein expression was performed using lung tissue specimens. Two-dimensional and quantitative analysis of silica deposits in the lungs were performed in situ using lung tissue sections by an in-air microparticle induced X-ray emission (in-air micro-PIXE) analysis system, which was based on irrradiation of specimens with a proton ion microbeam. Quantitative analysis showed a significant increase of iron levels on silica particles (assessed as the ratio of Fe relative to Si) on day 56 compared with day 7 (p<0.05). Fas and p62 were expressed by histiocytes in granulomas on day 7, and the expressions persisted for day 56. Fas- and p62-expressing histiocytes were co-localized in granulomas with silica particles that showed an increase of iron levels on silica particles in mouse lungs. Iron complexed with silica induces apoptosis, and may lead to dysregulations of autophagy in histiocytes of granulomas, and these mechanisms may contribute to granuloma development and progression in silicosis.


Biomedicine & Pharmacotherapy | 2015

Targeted concurrent chemoradiotherapy, by using improved microcapsules that release carboplatin in response to radiation, improves detectability by computed tomography as well as antitumor activity while reducing adverse effect in vivo

S. Harada; Shigeru Ehara; K. Ishii; Takahiro Sato; Masashi Koka; Tomihiro Kamiya; K. Sera; S. Goto

PURPOSE The effect of alginate-hyaluronate microcapsules that release carboplatin in response to radiation was improved by adding ascorbic acid (AA). MATERIALS AND METHODS Four measures of the effectiveness of the microcapsules were evaluated: 1) release of carboplatin in response to radiation in vitro and in vivo; 2) detectability of their accumulation by computed tomography (CT) in vivo; 3) enhancement of antitumor effects in vivo; and 4) reduction of adverse effects in vivo. RESULTS There were significant increases in the rupture of microcapsules by adding AA in vitro. Subcutaneously injected microcapsules around the tumor could be detected by using CT and the alteration of CT-values correlated with the accumulation of the microcapsules. Those microcapsules released carboplatin and resulted in synergistic antitumor effect with concomitant radiation. With the encapsulation of carboplatin, chemotherapeutic effects were still observed two weeks after treatment. However, addition of AA did not result in increased antitumor effect in vivo. A reduction in adverse effects was observed with the encapsulation of carboplatin, through localization of carboplatin around the tumor. CONCLUSION Addition of AA to the materials of microcapsules did not result in increasing antitumor effect. However encapsulation of carboplatin will be useful as a clinical cancer-therapy option.


Journal of Clinical Biochemistry and Nutrition | 2011

In-air microparticle induced X-ray emission analysis of particles in interstitial pneumonia lung tissue obtained by transbronchial biopsy

Yasuo Shimizu; Shinichi Matsuzaki; Takahiro Satoh; Masashi Koka; Akihito Yokoyama; Takeru Ohkubo; Yasuyuki Ishii; Tomihiro Kamiya; Makoto Fueki; Masatomo Mori; Kunio Dobashi

Interstitial pneumonia develops in association with inhaled particles. In-air microparticle induced X-ray emission (in-air micro) analysis was previously employed to assess the spatial distribution and content of particles in surgical lung biopsy specimens. The aim of this study was to assess the efficacy of in-air micro-analysis for transbronchial lung biopsy specimens in patients with or without occupational exposure. The elements composing lung particles and their locations could be identified by in-air micro-analysis. Silicon was the major component of particles. Quantitative analysis revealed that the elements composing lung particles varied between patients. In a patient with suspected nickel exposure, aluminium, vanadium, and calcium were detected, but was not detected. In a patient without a work history (housewife), various elements were detected. In-air micro-analysis was useful for assessing the spatial distribution and content of particles in specimens from patients. Occupational exposure was not necessarily associated with deposition of particles in the lungs. Therefore, in the diagnosis of, elemental analysis of specimens by in-air micro-analysis could be useful for assessing exposure to particles objectively.


Applied Radiation and Isotopes | 2014

Intra-tumor distribution of metallofullerene using micro-particle induced X-ray emission (PIXE).

Yohei Yamamoto; Tetsuya Yamamoto; Yukichi Horiguchi; Makoto Shirakawa; Takahiro Satoh; Masashi Koka; Yukio Nagasaki; Kei Nakai; Akira Matsumura

To clarify the intra tumor distribution of gadlinium containing fullerene (Gd@C82), micro particle induced X-ray emission (Micro-PIXE) analysis were performed. The tumor bearing BALB/c mice were injected Gd@C82 and subcutaneous tumors were taken from 48h after the intravenous injection. Using the Micro-PIXE method, we could visualize Gd intra tumor distribution. Therefore our results indicate the possibility that Micro-PIXE is useful technique for imaging the bioditribution of Gd, and Gd@C82 is potentially useful Gd carrier for NCT.


International Journal of PIXE | 2015

Continuous observation of ion beam induced luminescence spectra from organic standard targets

Wataru Kada; Akihito Yokoyama; Masashi Koka; Kenta Miura; Takahiro Satoh; Osamu Hanaizumi; Tomihiro Kamiya

Ion beam induced luminescence (IBIL) analysis was performed on organic targets are typical organic contaminants in aerosols. An external proton microbeam with an energy of 3 MeV was selected as the probe for the continuous IBIL measurement. Commercially available organic standards, including common amino acids (nicotinamide adenine dinucleotide, riboflavin and tryptophan) and a polycyclic aromatic hydrocarbon (benzo[a]pyrene), were used to test the analysis. Differences in chemical composition were distinguished by the shape of the IBIL spectrum in the UV/visible/near-IR region (200–900 nm). The IBIL spectrum changed as the proton irradiation damage increased. These results suggest that qualitative characterization of organic materials might be possible through the continuous measurement of IBIL spectra.


Japanese Journal of Applied Physics | 2012

Ion-Beam-Induced Luminescence Analysis as Diagnostic Tool for Microstructure Patterning on Diamond by Proton Beam Writing

Wataru Kada; Akihito Yokoyama; Masashi Koka; Katsuyoshi Takano; Takahiro Satoh; Tomihiro Kamiya

An in situ diagnostics technique for proton beam writing (PBW) on chemical vapor deposition (CVD) diamond was newly established by developing a method of monochromatic ion-beam-induced luminescence (IBIL) analysis. As a compact optic system of IBIL analysis, a couple of optics including a monochromator and a photon counting photomultiplier were installed on the microbeam line of a 3 MV single-ended accelerator. Changes in the crystal structure of single-crystal CVD diamond were continuously monitored by observing the decay of IBIL at a wavelength related to them. Two-dimensional microscopy images of IBIL were also clearly visualized as patterns on diamond in the postprocess of PBW with the same experimental setup. The total fluence of the proton microbeam was well linked to the photon count of IBIL for the fabrication of micrometer-sized carbonized layers in the CVD diamond crystal.

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Takahiro Satoh

Japan Atomic Energy Agency

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Yasuyuki Ishii

Japan Atomic Energy Agency

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Takeru Ohkubo

Japan Atomic Energy Agency

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Masaki Sugimoto

Japan Atomic Energy Agency

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Hiroyuki Nishikawa

Shibaura Institute of Technology

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