Takashi Kumazawa

Saitama Institute of Technology, Saitama, Saitama, Japan

Are you Takashi Kumazawa?

Claim your profile

Publications (16)20.73 Total impact

  • Gang An · Dong Ying Ju · Takashi Kumazawa

    No preview · Article · Nov 2015 · Materials Science Forum
  • [Show abstract] [Hide abstract]
    ABSTRACT: We previously showed that the hypertonicity of taste stimulating solutions modified tonic responses, the quasi-steady state component following the transient (phasic) component of each integrated taste nerve response. Here we show that the hypertonicity opens tight junctions surrounding taste receptor cells in a time-dependent manner and modifies whole taste nerve responses in bullfrogs. We increased the tonicity of stimulating solutions with non-taste substances such as urea or ethylene glycol. The hypertonicity enhanced phasic responses to NaCl>0.2 M, and suppressed those to NaCl<0.1 M, 1 mM CaCl2, and 1 mM bitter substances (quinine, denatonium and strychnine). The hypertonicity also enhanced the phasic responses to a variety of 0.5 M salts such as LiCl and KCl. The enhancing effect was increased by increasing the difference between the ionic mobilities of the cations and anions in the salt. A preincubation time>20 s in the presence of 1 M non-taste substances was needed to elicit both the enhancing and suppressing effects. Lucifer Yellow CH, a paracellular marker dye, diffused into bullfrog taste receptor organs in 30 s in the presence of hypertonicity. These results agreed with our proposed mechanism of hypertonic effects that considered the diffusion potential across open tight junctions.
    No preview · Article · Mar 2014 · Brain research
  • Kiyonori YOSHII · Takashi KUMAZAWA · Yoshitaka OHTUBO
    [Show abstract] [Hide abstract]
    ABSTRACT: Many scientists have investigated taste nerve responses without regarding the tonicity of taste stimulating solutions that varies in a wide range. We increased the tonicity by adding nonelectrolytes that elicited no taste nerve responses in bullfrogs, and investigated hypertonicity effects on the taste nerve responses to inorganic salts and bitter substances. Here, we show that the hypertonicity opens tight junctions surrounding taste receptor cells and changes the magnitude and firing pattern of taste nerve responses. We quantitatively suggest that the changes result from the magnitude and direction of local circuit currents generated by diffusion potentials across the tight junctions.
    No preview · Article · Jan 2014 · Seibutsu Butsuri
  • [Show abstract] [Hide abstract]
    ABSTRACT: Taste receptor cells fire action potentials in response to taste substances to trigger non-exocytotic neurotransmitter release in type II cells and exocytotic release in type III cells. We investigated possible differences between these action potentials fired by mouse taste receptor cells using in situ whole-cell recordings, and subsequently we identified their cell types immunologically with cell-type markers, an IP3 receptor (IP3 R3) for type II cells and a SNARE protein (SNAP-25) for type III cells. Cells not immunoreactive to these antibodies were examined as non-IRCs. Here, we show that type II cells and type III cells fire action potentials using different ionic mechanisms, and that non-IRCs also fire action potentials with either of the ionic mechanisms. The width of action potentials was significantly narrower and their afterhyperpolarization was deeper in type III cells than in type II cells. Na(+) current density was similar in type II cells and type III cells, but it was significantly smaller in non-IRCs than in the others. Although outwardly rectifying current density was similar between type II cells and type III cells, tetraethylammonium (TEA) preferentially suppressed the density in type III cells and the majority of non-IRCs. Our mathematical model revealed that the shape of action potentials depended on the ratio of TEA-sensitive current density and TEA-insensitive current one. The action potentials of type II cells and type III cells under physiological conditions are discussed.
    No preview · Article · Oct 2013 · European Journal of Neuroscience
  • Gang An · Ping Ma · Dong Ying Ju · Takashi Kumazawa
    [Show abstract] [Hide abstract]
    ABSTRACT: It is well known that the advances in the biomedicinal applications of magnetite nanoparticles were studied recently. As a drug delivery tools, it only affects on the target region of illness. We investigated the application of magnetic nanoparticles as drug delivery tools by the mice model of atopic dermatitis. The results involve that after magnetic nanoparticles are applied to the skin, the condition of atopic dermatitis becomes much better than the former one of atopic mice model. It only affects on the illness region and healthy regions almost have no influence. It is suitable for the medical treatment technique usage on the atopic dermatitis.
    No preview · Article · Mar 2013 · Materials Science Forum
  • [Show abstract] [Hide abstract]
    ABSTRACT: The tonicity of taste stimulating solutions has been usually ignored, though taste substances themselves yielded the tonicity. We investigated the effect of hypertonicity on bullfrog taste nerve responses to inorganic salts by adding nonelectrolytes such as urea and sucrose that elicited no taste nerve responses. Here, we show that hypertonicity alters bullfrog taste nerve-response magnitude and firing pattern. The addition of urea or sucrose enhances the taste nerve-response magnitude to NaCl and shifts the concentration-response curve to the left. The effect of hypertonicity on responses to CaCl(2) is bimodal; hypertonicity suppresses CaCl(2) responses at concentrations less than ~30 mM and enhances them at concentrations greater than ~30 mM. The hypertonicity also enhances response magnitude to other monovalent salts. The extent of the enhancing effects depends on the difference between the mobility of the cation and anion in the salt. We quantitatively suggest that both the enhancing and suppressing effects result from the magnitude and direction of local circuit currents generated by diffusion potentials across tight junctions surrounding taste receptor cells.
    No preview · Article · Mar 2012 · Pflügers Archiv - European Journal of Physiology
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this study, the composite magnetic nanoparticles of coated SiO nano film with about 8 nm size and high saturation magnetization value, were synthesized by liquid phase precipitation method. The magnetic nanoparticles can be dispersed in various liquid media, widely known as magnetic fluids or ferrofluids with both magnetic and liquid properties. The materials been collected great interests and more and more attentions to focus into Drug Delivery System (DDS) as a new technology in this paper. We use the composite nanoparticles to disperse H2O and inject the solutions into rat's in-vivo organs. And, in the experiments by using a strong photon beam of SPring-8 Synchrotron Radiation facility, the distribution stat and the effects of magnetic field as well as drug delivery behaviour of nanoparticles in the rat' kidney are verified by the in-vivo observations.
    No preview · Article · Oct 2011 · Journal of Nanoscience and Nanotechnology
  • G An · D. Y Ju · T Kumazawa · M Okasabe
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper is mainly to describe coating method of MgO nano film with about 2nm and Bio-medicine materials on surface the magnetic nanoparticle. The coated composite magnetic nanoparticles of coated were dispersed into ion exchange water, widely known as magnetic fluids for applying to Drug Delivery System(DDS). Through observation of micro-structure of MgO film and the bio-nanopaticles on coating surface, and evaluation of magnetic property, we known that the effectiveness of this coating method of MgO and the bio-medicine coated on surface of magnetic nanoparticles was confirmed.
    No preview · Article · Aug 2011
  • G. An · Dong Ying Ju · Pei Bian · T. Kumazawa · M. Okasabe
    [Show abstract] [Hide abstract]
    ABSTRACT: The composite magnetic nanoparticles of coated SiO nano film with about 8 nm size can be dispersed in various liquid media, widely known as magnetic fluids or ferrofluids with both magnetic and liquid properties. In this paper, a bio-medicine coating technology on surface of magnetic nanoparticles and the optimum fabrication condition and the magnetism of composed bio-nanoparticles are investigated. Through observation of micro-structure of the bio-nanopaticles on coating surface, and evaluation of magnetic property and safety to apply to biomaterials, we know the bio-medicine coated on surface of magnetic nanoparticles is suitable of bio-solutions into surface of biomaterials.
    No preview · Article · Feb 2011 · Materials Science Forum

  • No preview · Conference Paper · Jan 2011
  • [Show abstract] [Hide abstract]
    ABSTRACT: Nano drug delivery system (nano-DDS) is a new medical technology. We studied medical use used by about 7 [nm] ferromagnetic fluids. We searched good energy condition of ferrofluid contrast medium radiograph image used by SPring-8 synchrotron radiation X-ray. As results, in case of low photon energy 15.0 [KeV] ( lambda = 0.8 Aring). We showed ferrofluid in Acryl amid gel and taro leaf and mugwort. #1. We found Low photon energy could show vascular tissue and ferrofluid distribution respectively. In case of medium photon energy 20.0 [KeV] ( lambda = 0.6 Aring). We observed ferrofluid in rat ear lobe and rat stomach and rat foot. #2. We found medium photon energy could see several organizations by changing exposure. In case of high photon energy 25.0 [KeV] ( lambda = 0.5 Aring). We showed ferrofluid in chicken egg and pork. #3. We found high proton energy was suitable for observing ferrofluid distribution in plain organization, but was not suitable for observing ferrofluid distribution in complicate organization.
    No preview · Conference Paper · Jul 2008
  • [Show abstract] [Hide abstract]
    ABSTRACT: Nano-size magnetic magnetide is considered important for various medical applications. Dynamic motion of the magnetic particle is investigated in two essential models from a theoretical point of view. One is a drag model of the magnetic particle in an artery. The second is a pull model towards the surface of artery. Threshold conditions of external variables are obtained by dimensional analysis. On the basis of all these results, it is concluded that the movement of magnetic fluids can be controlled by external magnetic fields in blood vessels.
    No preview · Conference Paper · Jul 2008
  • Kennji Kimura · Yoshitaka Ohtubo · Takashi Kumazawa · Kiyonori Yoshii
    [Show abstract] [Hide abstract]
    ABSTRACT: Taste buds, biological chemical sensors, consist of four types of taste bud cells (Types I to IV TBCs) classified morphologically or immunohistochemically. Since both morphological and immunohistochemical classification essentially require the fixation of TBCs, the physiological properties of classified cells are completely destroyed. We have developed a physiological classification, typically for Type II cells, taste receptor cells, as well as for Type III cells, the only one cell type that has synaptic contacts with taste nerve fibers, based on voltage-gated currents of TBCs. Here we show that the magnitude of outward rectifier currents was much larger in Type II and III cells than in Type I cells, and that the main component of the outward rectifier currents was TEA-insensitive Cl− channel currents in Type II cells but TEA-sensitive K+ channel currents in Type III cells. These results enable us to apply protocols appropriate to elucidate the physiological role of each cell type in taste reception.
    No preview · Article · Jul 2007 · International Congress Series
  • Kiyonori YOSHII · Yoshitaka OHTUBO · Takashi KUMAZAWA

    No preview · Article · Jan 2004 · Seibutsu Butsuri
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We identified a Cl^- channel, two K^+ channels and a cAMP-gated channel which were isolated from bullfrog fungiform papilla cell membranes and incorporated into phospholipid bilayers using the tip-dip method. The 156 pS channels were inhibited by 100μM 4, 4'-diisothiocyanostilbene-2, 2'-disulfonic acid (DIDS) and displayed the reversal potential identical to the equilibrium potential of Cl^-, it was identified as a Cl^- channel. Two types of K^+ channel had unitary conductances of 79 and 43 pS, which may correspond to those of Ca^<2+>-activated and cAMP-blockable K^+ channels observed in isolated intact frog taste cell membranes, respectively. These results suggest that the tip-dip method is useful for stable investigation of the properties of ion channels already identified in the taste cell. Furthermore, the 23 pS channels were newly found and were activated directly by internal cAMP as cyclic nucleotide-gated (CNG) nonselective cation channels established in olfactory receptor cells. Thus, our results suggest the possibility that besides Cl^- and K^+ channels, the cAMP-gated channels contribute to taste transduction
    Preview · Article · Apr 2001 · ZOOLOGICAL SCIENCE
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Single taste buds in mouse fungiform papillae consist of approximately 50 elongated cells (TBCs), where fewer than three TBCs have synaptic contacts with taste nerves. We investigated whether the non-innervated TBCs were chemosensitive using a voltage-sensitive dye, tetramethylrhodamine methyl ester (TMRM), under in situ optical recording conditions. Prior to the optical recordings, we investigated the magnitude and polarity of receptor potentials under in situ whole-cell clamp conditions. In response to 10 mM HCl, several TBCs were depolarized by approximately 25 mV and elicited action potentials, while other TBCs were hyperpolarized by approximately 12 mV. The TBCs eliciting hyperpolarizing receptor potentials also generated action potentials on electrical stimulation. A mixture of 100 mM NaCl, 10 mM HCl and 500 mM sucrose depolarized six TBCs and hyperpolarized another three TBCs out of 13 identified TBCs in a taste bud viewed by optical section. In an optical section of another taste bud, 1 M NaCl depolarized five TBCs and hyperpolarized another two TBCs out of 11 identified TBCs. The number of chemosensitive TBCs was much larger than the number of innervated TBCs in a taste bud, indicating the existence of chemosensitivity in non-innervated TBCs. There was a tendency for TBCs eliciting the same polarity of receptor potential to occur together in taste buds. We discuss the role of non-innervated TBCs in taste information processing.
    Preview · Article · Feb 2001 · The Journal of Physiology