Faculty Profiles - KUMAGAI, Jun

Papers - KUMAGAI, Jun

Division display 21 - 40 of about 80 ／ All the affair displays >>

Solar-UV-signature mutation prefers TCG to CCG: extrapolative consideration from UVA1-induced mutation spectra in mouse skin Reviewed

H. Ikehata, J. Kumagai, T. Ono, A. Morita

Photochem. Photobiol. Sci. Vol. 12 ( 8 ) page： 1319-27 2013.7

Language：English Publishing type：Research paper (scientific journal)

UVA1 exerts its genotoxicity on mammalian skin by producing cyclobutane pyrimidine dimers (CPDs) in DNA and preferentially inducing solar-UV-signature mutations, C T base substitution mutations at methylated CpG-associated dipyrimidine (Py-mCpG) sites, as demonstrated previously using a 364 nm laser as a UVA1 source and lacZ-transgenic mice that utilize the transgene as a mutational reporter. In the present study, we confirmed that a broadband UVA1 source induced the same mutation profiles in mouse epidermis as the UVA1 laser, generalizing the previous result from a single 364 nm to a wider wavelength range of UVA1 (340-400 nm). Combined with our previous data on the mutation spectra induced in mouse epidermis by UVB, UVA2 and solar UVR, we proved that the solar-UV-signature mutation is commonly observed in the wavelength range from UVB to UVA, and found that UVA1 induces this mutation more preferentially than the other shorter wavelength ranges. This finding indicates that the solar-UV-signature mutation-causing CPDs, which are known to prefer Py-mCpG sites, could be produced with the energy provided by the longer wavelength region of UVR, suggesting a photochemical reaction through the excitation of pyrimidine bases to energy states that can be accomplished by absorption of even low-energy UVR. On the other hand, the lower proportions of solar-UV-signature mutations observed in the mutation spectra for UVB and solar UVR indicate that the direct photochemical reaction through excited singlet state of pyrimidine bases, which can be accomplished only by high-energy UVR, is also involved in the mutation induction at those shorter wavelengths of UVR. We also found that the solar-UV signature prefers 5'-TCG-3' to 5'-CCG-3' as mutational target sites, consistent with the fact that UVA induces CPDs selectively at thymine-containing dipyrimidine sites and that solar UVR induces them preferably at Py-mCpG sites. However, the mutation spectrum in human p53 gene from non-melanoma skin cancers shows the opposite preference for 5'-CCG-3' sites. This apparent discrepancy in the site preference seems to result from the lack of 5'-TCG-3' sites mutable to missense mutations on the nontranscribed strand of human p53 gene, which should be evolutionally acquired under selective pressure from the sun.

DOI： 10.1039/c3pp25444e

Suppressive effect of ascorbic acid on the mutagenesis induced by the bystander effect through mitochondrial function Reviewed

G. Kashino, Y. Tamari, J. Kumagai, K. Tano, M. Watanabe

Free Radic. Res. Vol. 47 ( 6-7 ) page： 474-479 2013.7

Language：English Publishing type：Research paper (scientific journal)

We focused on suppressive effect of ascorbic acid (AsA) on changes in mitochondrial function and mutagenesis by the radiation-induced bystander eff ect (RIBE). In mammalian cell lines, medium transfer assay was performed and conditioned medium including secreted factors after X-irradiation were examined to detect the RIBE. We found that the membrane potential and increased levels of superoxide radical (O-2(-)) in mitochondria were modulated in cells treated with conditioned medium from irradiated cells. The result of the present study also demonstrated that increases in reactive oxygen species (ROS) levels led to the induction of gene mutations. Interestingly, the modulations in mitochondria, in addition to mutation inductions by RIBE, were completely suppressed by treatment with AsA in cells treated with conditioned medium. These results suggest that mutagenesis, which may have resulted from secreted factors involving the RIBE, may be induced by ROS that are localized in mitochondria and may be relieved by AsA.

DOI： 10.3109/10715762.2013.791025

Reaction Mechanism of Aromatic Ring Amination of Benzene and Substituted Benzenes by Aqueous Ammonia over Platinum-Loaded Titanium Oxide Photocatalyst Reviewed

H. Yuzawa, J. Kumagai, H. Yoshida

J. Phys. Chem. C Vol. 117 ( 21 ) page： 11047-11058 2013.5

A heterogeneous palladium catalyst hybridised with a titanium dioxide photocatalyst for direct C-C bond formation between an aromatic ring and acetonitrile Reviewed

H. Yoshida, Y. Fujimura, H. Yuzawa, J. Kumagai, T. Yoshida

Chem. Commun. Vol. 49 ( 36 ) page： 3793-3795 2013.3

Electrical properties of lead-free ferroelectric Mn-Doped K0.5Na0.5NbO3-CaZrO3 thin films prepared by chemical solution deposition Reviewed

T. Matsuda, W. Sakamoto, B.Y. Lee, T. Iijima, J. Kumagai, M. Moriya, T. Yogo

Vol. 51 ( 9 ) page： 09LA03 2012.9

Language：English Publishing type：Research paper (scientific journal)

Lead-free ferroelectric K0.5Na0.5NbO3-CaZrO3 thin films were prepared by chemical solution deposition. Chemically optimized K0.5Na0.5NbO3-CaZrO3 precursor thin films crystallized in the perovskite single phase on Pt/TiOx/SiO2/Si substrates at 650 degrees C. The K0.5Na0.5NbO3-CaZrO3 thin films showed poor ferroelectric polarizations due to the insufficient insulating resistance. The leakage current of the K0.5Na0.5NbO3-CaZrO3 films, especially in the high-applied-field region, was markedly reduced by 1 mol % Mn doping for the Nb site. Also, the ferroelectric properties of the K0.5Na0.5NbO3-CaZrO3 thin films depended on CaZrO3 concentration. 1 mol % Mn-doped K0.5Na0.5NbO3-CaZrO3 thin films exhibited slim and small ferroelectric polarization-electric field (P-E) hysteresis loops at room temperature with an increase in CaZrO3 amount. Furthermore, these films showed a typical field-induced displacement curve with a small hysteresis, and the estimated effective d(33) values were 32 pm/V for the 1 mol % Mn-doped 0.95K(0.5)Na(0.5)NbO(3)-0.05CaZrO(3) thin films and 21 pm/V for the 1 mol % Mn-doped 0.9K(0.5)Na(0.5)NbO(3)-0.1CaZrO(3) thin films.

DOI： 10.1143/JJAP.51.09LA03

The Bystander Effect is a Novel Mechanisms of UVA-Induced Melanogenesis Reviewed

H. Nishiura, J. Kumagai, G. Kashino, T. Okada, K. Tano, M. Watanabe

Vol. 88 ( 2 ) page： 389-397 2012.3

Language：English Publishing type：Research paper (scientific journal)

We successfully identified the bystander effect in B16 murine melanoma cells exposed to UVA irradiation. The effect was identified based on melanogenesis following the medium transfer of the B16 cells, which had been cultured for 24 h after being exposed to UVA irradiation, to nonirradiated cells (bystander cells). Our confirmation study of the functional mechanism of bystander cells confirmed the reduced levels of mitochondrial membrane potential 14 h after the medium transfer. In addition, we observed increased levels of intracellular oxidation after 912 h, and the generation of melanin radicals, including long-lived radicals, 24 h after medium transfer. Further analysis of bystander factors revealed that the administration of EGTA treatment at the time of medium transfer led to an inhibition of melanogenesis and to neutralization of the mitochondrial membrane potential level, as well as to the restoration of intracellular oxidation levels to those of controls. The results demonstrated that the UVA irradiation bystander effect in B16 cells, as indicated by melanogenesis, was induced by the increase in intracellular oxidation due to the mitochondrial activity of calcium ions, which were among the bystander factors involved in the increase.

DOI： 10.1111/j.1751-1097.2011.01046.x

放射線誘導長寿命ラジカルが DNA 損傷を起源としない発がん経路の引き金 Invited Reviewed

渡邉正己, 菓子野元郎, 熊谷　純

放射線化学 Vol. 93 page： 15-22 2012.3

Negative and positive ion trapping by isotopic molecules in cryocrystals in case of solid parahydrogen containing electrons and H6+ radical cations Reviewed

Y. Shimizu, M. Inagaki, T. Kumada, J. Kumagai

Vol. 132 ( 24 ) page： 244503 2010.6

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We performed electron spin resonance studies of trapped electrons and H-6(+) radical cations produced by radiolysis of solid parahydrogen (p-H-2), p-H-2-ortho-D-2 (o-D-2), and p-H-2-HD mixtures. Yields of trapped electrons, H-6(+) radical cations, and its isotopic analogs H6-nD(n)(+) (4 >= n >= 1) increased with increasing o-D-2 and HD concentrations in solid p-H-2. Electrons were found trapped near an o-D-2 or an HD in solid p-H-2 due to the long-range charge-induced dipole and quadrupole interactions between electrons and isotopic hydrogen molecules. H-6(+) radical cations diffuse in solid p-H-2 by repetition of H-6(+)+H-2 -> H-2+H-6(+) and are trapped by ortho-D-2 or HD to form H6-nDn+ (4 >= n >= 1) as isotope condensation reactions. Decay behaviors of these cations by the repetition, isotope condensation, and geminate recombination between electrons and H6-nDn+ (4 >= n >= 0) were reproduced by determining the corresponding reaction rate constants k(1), k(2), and k(3). Values of 0.045 and 0.0015 L mol(-1) min(-1) were obtained for k1 (H-6(+)+D-2 -> H-2+H4D2+) and k(2) (H4D2++D-2 -> H-2+H(2)D4+), respectively, and the value was quasinull for k(3) (H(2)D4++D-2 -> H-2+D6+). These rate constants suggest that hole mobility drastically decreased in the repetition reaction when H-6(+) radical cations acting as hole carriers formed H4D2+ or H(2)D4+. HD and D-2 molecules, therefore, act as electron and hole acceptors in irradiated solid p-H-2-o-D-2 and p-H-2-HD mixtures.

DOI： 10.1063/1.3432780

照射培地移動による放射線バイスタンダー効果を遅発性長寿命ラジカルから探る Reviewed

熊谷　純、菓子野元郎

放射線化学 Vol. 89 page： 20-24 2010.3

Improvement in Ferroelectric Properties of Chemically Synthesized Lead-Free Piezoelectric (K,Na)(Nb,Ta)O3 Thin Films by Mn Doping Reviewed

N. Kondo,W . Sakamoto, B.Y. Lee, T. Iijima, J. Kumagai, M. Moriya T. Yogo

Jpn. J. Appl. Phys. Vol. 49 page： 09MA04 2010

*固体パラ水素中の H6+同位体イオンと捕捉電子の放射線化学 Invited Reviewed

清水裕太、熊谷　純

放射線化学 Vol. 87 page： 23-33 2009.3

Electron spin resonance spectroscopy of molecules in large precessional motion: A case of H6+ and H4D2+ in solid parahydrogen Reviewed

Yuta Shimizu, Takayuki Kumada, Jun Kumagai

J. Mag. Reson. Vol. 194 ( 1 ) page： 76–80 2008.9

Language：English Publishing type：Research paper (scientific journal)

We have measured electron spin resonance (ESR) spectra of H-6(+) and H4D2+ tons produced in gamma-ray irradiated solid parahydrogen. Anisotropic hyperfine-coupling constants for H-6(+) and H4D2+ determined by the analysis of ESR lines at 4.2 K were -0.06 and -0.12 mT, respectively, which were opposite in sign to and much smaller than theoretical results of 1.17-1.25 mT. Although no change was observed in H-6(+), the constant for H4D2- increased to be 1.17 mT at 1.7 K, which is very close to the theoretical value. We concluded that H-6(-) both at 4.2 and 1.7 K and H4D2+ at 4.2 K should be in a large precessional motion with the angle of 57-59 degrees, but the precession of H4D2+ is stopped at 1.7 K.

DOI： 10.1016/j.jmr.2008.05.024

*放射線照射後に細胞中で生じてくる遅発性長寿命ラジカルと遅延放射線生物影響 Invited

熊谷　純

電子スピンサイエンス Vol. 6 ( 11 ) page： 109-115 2008.9

H atom, e(-), and H(6)(+) ions produced in irradiated solid hydrogens: An electron spin resonance study Reviewed

T. Kumada, Y. Shimizu, T. Ushida, J. Kumagai

Radiat. Phys. Chem. Vol. 77 ( 10-12 ) page： 1318-1322 2008

Language：English Publishing type：Research paper (scientific journal)

We carried out electron spin resonance (ESR) study of irradiated solid H(2) and para-H(2). H-atom, e(-), and H(6)(+) lines were observed. The H-atom radicals diffuse in solid H2 by the tunneling chemical reaction H+H(2) -> H(2)+H below 4 K, and by the thermally activated process above 5 K. These decay via H-H recombination. Yield of trapped electrons e- produced by the radiolysis of solid para-H2 increases with increase in the concentration of added isotopic hydrogen, HD or D(2). These decay via geminate recombination with positive ions with a half-life of 8 h at 4 K. H(6)(+) ion is an ionic hydrogen radical whose spectrum has firstly been observed in irradiated solid para-H(2). H(6)(+) ions diffuse in solid H2 by sequence of H(6)(+)+H(2) -> H(2)+H(6)(+) reactions, and terminate by the isotope-exchange reaction H(6)(+)+HD -> H(5)D(+)+H(2) or H(6)(+)D(2) -> H(4)D(2)(+)+H(2). Unlike H(6)(+), isotopically substituted H(5)D(+) and H(4)D(2)(+) cannot diffuse in solid para-H(2). Rate-determining step of their decay is charge recombination with e(-).

DOI： 10.1016/j.radphyschem.2008.05.026

放射線照射後に細胞中で生じてくる遅発性長寿命ラジカルと遅延放射線生物影響 Invited

熊谷　純

電子スピンサイエンス Vol. 6 page： 109-115 2008

Electron spin resonance study on H6+, H5D+, H4D2+, and H2D4+ in solid parahydrogen Reviewed

Jun Kumagai, Hiroki Inagaki, Susumu Kariya, Takahiro Ushida, Yuta Shimizu, Takayuki Kumada

J. Chem. Phys. Vol. 127 ( 2 ) page： 024505 2007.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We carried out an electron spin resonance (ESR) study on hydrogen ion radicals produced by radiolysis of solid para-H-2. In addition to quartet ESR lines proposed to be H-2(+)-core H-6(+) (D-2d) ions in solid para-H-2 [T. Kumada , Phys. Chem. Chem. Phys. 7, 776 (2005)], we newly observed totally more than 50 resolved lines in gamma-ray irradiated solid para-H-2-ortho-D-2 (1 mol %) and para-H-2-HD (1 mol %) mixtures. We assigned these lines to be isotope substituents of H-2(+)-core H-6(+) ions such as H5D+, H4D2+, and H2D4+ throughout the comparison of their ESR parameters with theoretical results. These results provide a conclusive evidence that H-2(+)-core H-6(+) ions are generated in irradiated solid hydrogens. Analysis of the EPR spectrum and ab initio calculations predicts D-2d symmetry of the H-6(+) ions, whereas a lowering symmetry (D-2d -> C-2v) induced by asymmetric nuclear wave function is observed in H5D+ and H4D2+. We also observed isotope-substitution reactions such as H-6(+)+D-2 -> H4D2++H-2 and H-6(+)+HD -> H5D++H-2, which are analogous to the well-known isotope-condensation reactions of H-3(+) in dark nebula, H-3(+)+HD -> HD2++H-2 and HD2++HD -> D-3(+)+H-2.

DOI： 10.1063/1.2748046

固体パラ水素中に生成したH6+のESR分光研究 Reviewed

熊田高之、牛田考洋、清水裕太、熊谷　純

電子スピンサイエンス Vol. 5 page： 134-139 2007

ESR study of H₆⁺ and H₄D₂⁺ produced in irradiated solid hydrogens Reviewed

T. Kumada, T. Takayanagi, J. Kumagai

J. Mol. Struc. Vol. 786 ( 2-3 ) page： 130-133 2006.4

Language：English Publishing type：Research paper (scientific journal)

We reinvestigated the quartet ESR lines with g-valueg=2.002 and hyperfine coupling constant A approximate to 20 mT produced in gamma-ray irradiated solid pH, in order to determine to which the lines should be assigned, H-2(-) or H-6(+). We newly found further splitting of each of the quartet lines into quintet ones in irradiated solid p-H-2 containing o-D-2 at 1 mol%. ESR parameters of these new lines were found to be consistent with those of H4D2+ calculated. This result supports the assignment to H-6(+) rather than H-2(-).

DOI： 10.1016/j.molstruc.2005.08.036

Is the ESR spectrum attributable to H2- or H2+(H2)2? Precise measurement of the g-value and anisotropic hyperfine structure in gamma-irradiated solid parahydrogen Reviewed

Jun Kumagai, Masatsugu Hanabusa, Hiroki Inagaki and Susumu Kariya

Phys. Chem. Chem. Phys. Vol. 6 ( 17 ) page： 4363-4368 2004.6

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Four ESR lines, found by Miyazaki et al. in 1995 in irradiated solid parahydrogen (ca. 92% para-purity) at 4.2 K, assigned as "H-2(-),'' were precisely re-measured with highly pure solid parahydrogen (>99.9%) and compared with calculated g-value and hyperfine coupling constants of H-2(+)(H-2)(2). The g-value of I,M-I=0,0 feature, reported previously as 2.0033 or 2.0023, was found to be incorrect and has now been corrected to 2.002120+/-0.000012. This corrected value is clearly smaller than that of free electron. We also found that the remaining three lines corresponding to I, M-I=1,0; 1, +1; and 1, -1 features have axially symmetric hyperfine anisotropic structure i.e., A(parallel to)=20.318 and A(perpendicular to)=20.502 mT. This anisotropy corresponds to the rotation of the species in solid parahydrogen. Although the experimental g-value and isotropic hyperfine coupling constants are in good agreement with those of H-2(+)(H-2)(2) estimated by ab initio calculation, it is still difficult to explain why H-2(+)(H-2)(2) clusters turned into ESR inactive species by addition of 0.1similar to1% D-2 in the present system. In this regard, we still maintain that the species in solid parahydrogen are H-2(-).

DOI： 10.1039/b402756f

Long-lived mutagenic radicals induced in mammalian cells by ionizing radiation are mainly localized to proteins Reviewed

J. Kumagai, K. Masui, Y. Itagaki, M. Shiotani, S. Kodama, M. Watanabe, T. Miyazaki

Radiat. Res. Vol. 160 ( 1 ) page： 95-102 2003.7

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

We have provided evidence that long-lived radicals, produced by ionizing radiation, are highly mutagenic and transforming in mammalian cells. Long-lived radicals are scavenged effectively by vitamin C or by epigallocatechin-3-O-gallate (EGCG). Long-lived radicals are not involved in lethality or in the induction of chromosome aberrations. We now report the results of experiments that define the relative amounts of long-lived radicals in DNA and proteins and identify the major protein radicals as sulfinyl radicals (R-CH2-S-O-.). To make these assignments, yields of long-lived radicals in gamma-irradiated salmon sperm DNA and albumin were compared by ESR. ESR spectra of long-lived radicals produced in irradiated Syrian hamster embryo (SHE) cells were analyzed precisely and compared with ESR parameters obtained by density functional theory calculations. Long-lived radicals yields of 99.8% were produced in proteins. We also identified a new type of long-lived radical as H-added phenylalanine radicals. While our evidence does not rule out the possibility of important biological consequences of the low-level long-lived radicals created by radiation, it implicates radicals in proteins as playing a key role in genetic effects of ionizing radiation. We suggest that these novel radicals, wherever they reside, need to be considered in explanations of biological sequela of radiation.

DOI： 10.1667/RR3015

　 PREV - NEXT 　

<KUMAGAI, Jun>

Papers - KUMAGAI, Jun