S Nakamura

Nagoya University, Nagoya-shi, Aichi-ken, Japan

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Publications (33)35.89 Total impact

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    ABSTRACT: Geodesic acoustic modes (GAM) driven by energetic particles are observed in the Large Helical Device (LHD) by a heavy ion beam probe. The GAM localizes near the magnetic axis. It is confirmed that the energetic-particle-induced GAM is accompanied by an electrostatic potential fluctuation and radial electric field fluctuation. The amplitude of the potential fluctuation is several hundred volts, and it is much larger than the potential fluctuation associated with turbulence-induced GAMs observed in the edge region in tokamak plasmas. The energetic-particle-induced GAM modulates the amplitude of the density fluctuation in a high-frequency range. The observed GAM frequency is constant at the predicted GAM frequency in plasmas with reversed magnetic shear. On the other hand, it shifts upwards from the predicted GAM frequency in plasmas with monotonic magnetic shear.
    Preview · Article · Jun 2011 · Nuclear Fusion
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    ABSTRACT: A heavy ion beam probe was installed on the Large Helical Device (LHD) to investigate the roles of radial electric fields (Er) in magnetically confined high-temperature plasmas. Two new observations are presented. One is the observation of electrostatic potential profiles during the formation of extremely hollow density profiles of impurities, called the impurity hole (Ida K et al 2009 Phys. Plasmas 16 056111), in the LHD plasmas. The measured Er is negative, and the Er determined by the ambipolarity condition of neoclassical particle fluxes is consistent with this observation. However, the transport analysis indicates that the formation of the extremely hollow profile is not attributable to the impurity fluxes driven by Er and the density and temperature gradients of the impurity. The other new observation is on the geodesic acoustic mode (GAM). The electrostatic potential fluctuation associated with the GAM, which is probably induced by energetic particles, in plasmas with the reversed or weak magnetic shear is identified. The GAM is localized in the core region of the plasma.
    No preview · Article · Nov 2010 · Plasma Physics and Controlled Fusion
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    A Shimizu · T Ido · S Nakamura · K Toi · M Nishiura · S Kato
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    ABSTRACT: The heavy ion beam probe system in the Large Helical Device (LHD) was improved as follows. At first, the additional new sweeper was installed into the diagnostic port to extend the observable region. By using this sweeper, the potential profile was measured in a wider minor radius range than in previous experiments, in the case of outward shifted magnetic configuration of LHD. Next, the real time control system was installed to control the probe beam orbit for measuring the potential in plasma with large plasma current. In this system, a digital signal processor was used to control the probe beam in real time. The system worked well in the fixed position observation mode. In the sweeping mode for profile measurement, this control system became unstable. The details of this system and the experimental results are reported in this article.
    Preview · Article · Oct 2010 · The Review of scientific instruments
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    ABSTRACT: A heavy-ion beam probe (HIBP) using a 3-MV tandem accelerator was installed in Large Helical Device (LHD). It is designed to measure the electrostatic potential in the core region directly. The electrostatic potential profiles can be measured successfully using the HIBP, and the radial electric field predicted by the neoclassical theory is consistent with that measured using the HIBP as long as the ambipolarity condition of the neoclassical particle flux has a single solution. Although the turbulent fluctuation is not detected because of low signal-to-noise ratio, several coherent fluctuations, which are inferred to be reversed-shear-induced Alfvén eigenmode and the geodesic acoustic mode, are observed directly in core plasmas, and the spatial distribution is revealed.
    No preview · Article · Jul 2010 · Fusion Science and Technology
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    K Noguchi · M Nakase · M Inui · S Nakamura · K Okumura · T Tagawa
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    ABSTRACT: Graft-versus-host disease (GVHD) can occur at various sites, including the oral mucosa, where it is associated with a high risk of head and neck cancer. We report the case of a 46-year-old woman with tongue cancer that developed following Hodgkin's lymphoma and chronic GVHD, and we discuss the possible causes of cancer development.
    Full-text · Article · Jun 2010 · Australian Dental Journal
  • K. Okumura · M. Nakase · S. Nakamura · M. Inui · T. Tagawa

    No preview · Article · Nov 2007 · International Journal of Oral and Maxillofacial Surgery
  • T Sugiyama · T Nakagawa · M Narita · S Nakamura · M Inui · T Tagawa
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    ABSTRACT: In this study we evaluated pedunculated oncocytic carcinoma (OC) in the buccal mucosa via immunohistochemical and ultrastructural studies. An 84-year-old man was referred to our clinic with a pedunculated mass about 4 cm in diameter in the right buccal mucosa. An incision biopsy revealed the diagnosis of oncocytic tumor, and enucleation was performed. The tumor was stained for immunohistochemical analysis using the ABC method and antibodies against cytokeratin (CK), epithelial membrane antigen (EMA), desmin, S-100 protein and muscle-specific actin, respectively. The tumor was stained with uranyl acetate and lead citrate for visualization by electron microscopy. Histopathology results revealed that the tumor consisted of oncocytic cells, characterized by eosinophilic and granular cytoplasm, and atypical nuclei. These cells had infiltrated local blood vessels, salivary glands and muscles. Immunohistochemical staining indicated that these cells were positive for CK and EMA, and negative for desmin, muscle-specific actin and S-100 protein. Electron microscopy revealed numerous dilated cytoplasmic mitochondria, and the cell contours and nucleic shapes of tumor cells were often irregular. Because the histopathologic features of OC are similar to those of benign oncocytoma, the diagnosis of OC must be confirmed by a combination of clinical and ultrastructural characteristics.
    No preview · Article · Jun 2006 · Oral Diseases
  • T Tamura · M Inui · M Nakase · S Nakamura · K Okumura · T Tagawa
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    ABSTRACT: The purpose was to evaluate carotid calcifications on panoramic radiographs, and relate to risk factors for vascular diseases. Between 1997 and 2001, 2568 radiographs were retrospectively collected from new patients at Mie University Hospital whose ages ranged from 50 to 70 years. The mean age of the subjects was 62.2 years (men 61.9 years, women 62.3 years). Medical and social data were collected from case notes, and body weight, height, and age of menopause confirmed by telephone interviews. About 106 carotid calcifications were found on the panoramic radiographs of 26 males and 80 females. The ratio of males to females was 1:3.07. The subjects with carotid calcifications had medical histories that included hypertension (27.6%), obesity (21.1%), hyperlipidemia (14.5%), and cardiovascular diseases (13.2%), all with recognized risk factors for atheromas. Of 76 patients who responded to follow up interviews, two (2.63%) died from cardiovascular stroke during an average follow up of 2.43 years. The results show carotid calcifications detected on panoramic radiographs can be used to help predict vascular strokes in patients. In cases where calcified carotid artery atheromas are detected, the dentist or oral and maxillofacial surgeon should refer the patient to a specialized physician.
    No preview · Article · Oct 2005 · Oral Diseases
  • M Nakase · K Okumura · T Tamura · T Kamei · K Kada · S Nakamura · M Inui · T Tagawa
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    ABSTRACT: This study was designed to assess the effect of stellate ganglion near-infrared irradiation (SGR) on glossodynia and the mechanism of action. Thirty-seven patients with glossodynia received SGR once weekly for 4 weeks. The response to treatment was evaluated on the basis of the change in pain intensity, assessed with a visual analogue scale (VAS) before and after 4 weeks of treatment. The temperature and blood flow of the tongue were also measured before and after first SGR. As control, eight healthy subjects were studied. Tongue pain as assessed by the VAS decreased in 28 of the 37 patients (75.7%). Mean pain intensity decreased significantly from 5.1 +/- 2.2 to 1.9 +/- 2.1 (P < 0.05). Tongue blood flow at rest in the patients with glossodynia [7.2 +/- 1.6 ml min(-1) (100 g)(-1)] was significantly lower than that in the healthy subjects [7.8 +/- 0.23 ml min(-1) (100 g)(-1)]. Five minutes after SGR, the temperature of the tongue rose 1.5 +/- 0.21 degrees C, and blood flow increased to 8.5 +/- 1.2 ml min(-1) (100 g)(-1). Tongue blood flow (at rest) after 4 weeks of SGR had increased to 7.7 +/- 1.1 ml min(-1) (100 g)(-1). SGR is an effective treatment for glossodynia. The mechanism by which SGR improves symptoms associated with glossodynia is thought to be as follows: SGR inhibits abnormally increased sympathetic activity associated with glossodynia. This is followed by normalization of decreased tongue blood flow, thereby alleviating pain.
    No preview · Article · Jul 2004 · Oral Diseases
  • T Nakagawa · T Sugiyama · K Shimizu · T Murata · M Narita · S Nakamura · T Tagawa
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    ABSTRACT: To investigate the characteristics of ectopic chondroid/bone matrix and chondrogenic/osteogenic cells induced by recombinant human bone morphogenetic protein-2 (rhBMP-2). rhBMP-2 (5 microg) combined with atelocollagen was implanted into calf muscles of rats and removed on days 7, 10, 14, 21, or 28. Tissue sections were examined using: (i) hematoxylin/Alcian blue/Sirius red stain, (ii) enzyme histochemistry for alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase activity, (iii) immunohistochemistry for types I, II, and X collagen, and (iv) electron microscopy. On day 7, numerous fibroblast-like cells with ALP activity were present on the pellet rim. On day 10, chondroid matrix (CM) had formed, contained both type I collagen and proteoglycans, and often continued into the BMP pellet. On day 14, bone-like matrix formed around hypertrophic chondrocytes simultaneously with endochondral ossification. Coexpression of types I and II collagen within chondrocytes and osteocytes was observed throughout the time course of the experiment. These results suggest that fibroblast-like cells invading the pellet differentiate into chondrocytes and form CM under the scaffold of the carrier component. It appears that some chondrocytes change their phenotype to produce the bone-like matrix and remain within the endochondral bone. This process enables rapid osteogenesis to occur.
    No preview · Article · Oct 2003 · Oral Diseases

  • No preview · Article · Nov 2000 · Developmental Dynamics
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    ABSTRACT: A number of developmental regulatory genes, including homeobox genes, are dynamically expressed in the mammalian cephalic ectomesenchyme during craniofacial morphogenesis. Owing to the vast amount of gene knock out experiments, functions of such genes are now being revealed in the mammalian skeletal patterning process. The murine goosecoid (Gsc) and Msx1 genes are expressed during craniofacial development and each mutant mouse displays intriguing facial abnormalities including those of middle ear ossicles, suggesting that both genes play roles in spatial programming of craniofacial regions. In order to examine whether these genes could function in concert to direct particular craniofacial morphogenesis, double knock out mice were analyzed. The phenotype of the double mutant mice was restricted to the first arch derivatives and was apparently additive of the single gene mutant mice, implying region specific genetic interactions of these homeobox genes expressed in overlapping regions of middle ear forming ectomesenchyme. Our results also suggested that the patterning of distal portions of the malleus depends on the tympanic membrane, for which normal expressions of both the genes are prerequisite.
    Full-text · Article · Aug 1999 · Cellular and molecular biology
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    ABSTRACT: One of the challenging issues in modern biomedical science is the increasing number of osteoporosis patients due to the expansion of elderly populations. Among aging-related pathogenic changes, alterations in bone function and skeletal pathogenesis is a particularly important issue of concern. Osteoporosis is one of the most serious bone-related pathogenic states, as it causes serious loss of quality of life. Alterations in estrogen levels in accordance with aging are one of the key risk factors for osteoporosis. Complexed estrogen actions on bones can be traced by analyzing bone mineral components, as those elements accumulate as mineral complexes, reflecting the context of multiple cellular reactions such as bone resorption/osteogenesis. We have analyzed bone trace element composition in ovariectomized (OVX-treated) Cynomolgus monkey models in this study. In order to gain insights into the effects of such defects on bone trace element composition, inductively coupled plasma atomic emissions spectrometry (ICP-AES) analysis was performed. Marked changes in bone trace element levels were found in vertebral bones of OVX-treated Cynomolgus monkeys. An assessment of these trace element spectra in OVX model animals is discussed. These results could provide useful markers for understanding the physiological states of bones in postmenopausal women.
    No preview · Article · Jan 1999 · Cellular and molecular biology
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    ABSTRACT: Increasing numbers of genetic diseases involving bone development and models for these diseases have been identified recently. Analysis of these bone diseases have revealed that regulated action of multiple growth factors and subsequent signal transduction are essential for normal bone formation. In this paper, two murine mutant mice viable motheaten and osteopetrosis are analyzed. Mice with the recessive 'viable motheaten' mutation express a severe immunodeficiency syndrome and bone defects. Mutations at the motheaten locus were shown to be the result of aberrant splicing of the gene encoding hematopoietic cell phosphatase (Hcph). Mice homozygous for the osteopetrosis mutation develop congenital osteopetrosis due to a severe deficiency of osteoclasts. It has been recognized that bone trace element composition analysis helps to define bone-related physiological conditions. We have analyzed bone trace element composition in viable motheaten and osteopetrosis mutant animal models in this study. In order to gain insights into the effects of particular genetic defects on bone trace element composition, inductively coupled plasma atomic emissions spectrometry (ICP-AES) analysis was performed. Marked changes in bone trace element levels were found in limb bones of viable motheaten and osteopetrosis mutant mice. An assessment of these trace element spectrum in the two mutant models with respect to each genetic defects are discussed in this paper.
    No preview · Article · Apr 1998 · Cellular and molecular biology
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    ABSTRACT: It has been recognized that bone trace element composition analysis provides clues when analyzing bone-related physiological conditions. Increasing numbers of bone-related genetic diseases have been identified recently. In this study, we have analyzed bone trace element composition in a genetic mutant animal model. Mutations in the mouse microphthalmia (mi) gene affect the development of a number of cell types, including melanocytes, mast cells, and osteoclasts. Previous studies have shown that different alleles of the mi locus show osteopetrosis. In order to gain insights into the effects of a particular genetic defect on bone trace element composition and bone structure, we performed bone trace element composition analysis using inductively coupled plasma atomic emissions spectrometry (ICP-AES). Marked changes in bone trace element levels were found in vertebrate bones of mi mutant mice. The implications and possible applications of bone trace element analysis will be discussed in this article.
    No preview · Article · Apr 1998 · Biological Trace Element Research
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    ABSTRACT: Hemagglutinating virus of Japan (HVJ)-liposome mediated gene-transfer permitted to clarify the mechanisms of embryonic organogenesis of the branchial arches, neural tubes and heart by micro-injecting reporter-plasmid DNA, containing the Escherichia coli LacZ gene, in embryos at several stages.
    No preview · Article · Jan 1998 · Cellular and molecular biology
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    ABSTRACT: The Goosecoid (gsc) gene is a homeobox-containing gene expressed first in the gastrula, and later during organogenesis in development. The gsc gene transcript is found in the first and second branchial arches, frontonasal mass in its late phase of expression. We have previously shown that targeted mutation of the mouse gsc gene leads to neonatal death and craniofacial defects. In this study, we performed histological studies on craniofacial phenotypes in order to elucidate the processes underlying the neonatal death of gsc mutant mice. We found that gsc mutant mice have aplastic nasal cavities and lack the Sinus Paranasalis. We also showed that secretory olfactory glands in the basal layers are aplastic. This is suggested to be essential defects for olfaction. gsc mutant mice also show several pharyngeal phenotypes, including defects in the pharyngeal muscles and the pharyngeal mucosa. It is therefore suggested that mutant mice develop lethal gastro-intestinal phenotypes caused by defects in breathing and sucking of milk as a consequence of these craniofacial disorders. These results should help elucidating the molecular genetic programs essential to the neonatal development of mammals.
    Full-text · Article · May 1997 · Biochemical and Biophysical Research Communications
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    ABSTRACT: The physiological and pharmacobiological changes associated with space flight are of greater concern. Exposure to a weightless environment has been shown to have numerous effects on body composition and organ functions. Alterations include decreases in muscle and liver mass, changes in bone structure and integrity, and changes in cardiovascular functions. Zero-gravity in particular has been reported to inhibit several physiological processes of bone formation, retard bone growth and impair the mechanical properties of bones. This report examines the effect of 14 days of spaceflight on the bone trace element compositions of rapidly growing rats. Marked changes of bone trace element contents were found in either weight-bearing bones or non-weight-bearing bones, depending on the metal species. Histological examination revealed an irregular thickening of the endosteal surface of the cortical bone (thoracic vertebrae) of the in-flight rat, whereas it was uniform in the ground control. We suggest that the microgravity environment causes several bone alternations, such as abnormal trace element compositions and defects in vertebral maturation.
    No preview · Article · Feb 1997 · Life Sciences
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    H Sano · S Nakamura · S Kobayashi · H Takahashi · Y Terashima
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    ABSTRACT: The effect of cold exposure (0 degrees C) on profiles of total heat production (HP), energy metabolism, and blood metabolite and hormone concentrations were measured in nine shorn Suffolk rams. Blood metabolite and hormone responses to feeding and to i.v. arginine injection (.625 mmol/kg BW) and postprandial changes in HP were also measured. Heat production was greater (P < .05) during cold exposure than in the thermoneutral environment due to enhanced (P < .05) nonprotein oxidation. Protein oxidation and nitrogen balance remained unchanged during cold exposure. Plasma glucagon concentrations increased (P < .05) during the initial period of cold exposure. Heat production increased (P < .01) after the initiation of feeding in both environments. Heat production returned gradually to prefeeding values in the thermoneutral environment, but it remained close to the higher levels during cold exposure. Plasma insulin and glucagon concentrations increased (P < .05), and plasma growth hormone concentrations decreased (P < .10) after the initiation of feeding in both environments. Plasma glucagon responses to feeding (P < .05) and plasma insulin responses to arginine injection (P < .01) were reduced by cold exposure. We suggest that 1) enhanced HP in sheep exposed to cold is maintained by enhanced nonprotein oxidation and 2) endocrine responses to stimulants are influenced by cold exposure, even though profiles after cold exposure change little.
    Preview · Article · Aug 1995 · Journal of Animal Science
  • T Nokubi · S Nakamura · T Ono · K Ikebe · S Kita · Y Okuno · Y Taga
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    ABSTRACT: The joining procedure for uniting metal structures is very important in the construction of removable partial dentures. However, it has several restricted problems in joining wrought wire clasps to rests or major connectors. For example, the base metal wires made of chromium-cobalt alloy are subject to changes in their mechanical properties caused by heating, and damage to acrylic resin materials (denture base and artificial teeth) occurs in the repair of removable partial dentures by using the torch soldering method. In this paper, in order to resolve these problems, an electric resistance welding machine was applied to attach wrought wire components to a removable partial denture framework. This welding machine was used to attach metal structures temporarily to each other, and to solder the welded joint with hard solder. Consequently, some problems of the conventional torch soldering method were improved by using the electric resistance welding and soldering methods. It was suggested that the clinical application of the electric welding and soldering methods was very useful in the construction of removable partial dentures.
    No preview · Article · Jan 1991 · The Journal of Osaka University Dental School

Publication Stats

154 Citations
35.89 Total Impact Points

Institutions

  • 2010-2011
    • Nagoya University
      • • Department of Energy Engineering and Science
      • • Graduate School of Engineering
      Nagoya-shi, Aichi-ken, Japan
  • 2003-2010
    • Mie University
      • Department of Oral and Maxillofacial Surgery
      Tu, Mie, Japan
  • 2006
    • Center For Oral & Maxillofacial Surgery
      Georgia, United States
  • 1991
    • Osaka University
      • Department of Prosthetic Dentistry
      Suika, Ōsaka, Japan