論文 - 顧　萍

Palmitate increases musclin gene expression through activation of PERK signaling pathway in C2C12 myotubes

Ning Gu, Qian Guo, Ke Mao, Hailong Hu, Sanli Jin, Ying Zhou, Hongjuan He, Yuri Oh, Chuanpeng Liu, Qiong Wu

Biochemical and Biophysical Research Communications ( Academic Press Inc. )  467 ( 3 ) 521 - 526   2015年11月  [査読有り]

　概要を見る

Musclin is a type of muscle-secreted cytokine and its increased gene expression induces insulin resistance in type 2 diabetes. However, the mechanism underlying increased musclin gene expression is currently unclear. Excessive saturated fatty acids (SFA) can activate the secretion of several muscle-secreted cytokines as well as endoplasmic reticulum (ER) stress pathway, thereby contributing to the development of type 2 diabetes. The purpose of this study was to investigate the mechanisms responsible for the effect of palmitate, the most abundant SFA in the plasma, on the gene expression of musclin in C2C12 myotubes. Treatment of C2C12 myotubes with palmitate or tunicamycin significantly increased the expression of musclin as well as ER stress-related genes, but treatment with oleate did not. Pre-treatment of C2C12 myotubes with 4-phenyl butyrate suppressed the expression of ER stress-related genes, simultaneously, resulting in decreased expression of the musclin gene induced by palmitate or tunicamycin. These results indicate that ER stress is related to palmitate-induced musclin gene expression. Moreover, palmitate-induced musclin gene expression was significantly inhibited in C2C12 myotubes when PERK pathway signaling was suppressed by knockdown of the PERK gene or treatment with GSK2656157, a PERK autophosphorylation inhibitor. However, there was no difference in the palmitate-induced musclin gene expression when IRE1 and ATF6 signaling pathways were suppressed by knockdown of the IRE1 and ATF6 genes. These findings suggest that palmitate increases musclin gene expression via the activation of the PERK signaling pathway in C2C12 myotubes.

DOI

Growth mechanism of zinc sulfide films by mist chemical vapor deposition

Yuichiro Yamasaki, Kazuyuki Uno, Gu Ping, Ichiro Tanaka

Zairyo/Journal of the Society of Materials Science, Japan ( Society of Materials Science Japan )  64 ( 9 ) 707 - 710   2015年09月  [査読有り]

　概要を見る

The mist chemical vapor deposition (mist CVD) method, which uses ultrasonically atomized solutions as sources, is an environmental friendly and cost-effective technology for the growth of compound semiconductors. This growth process is realized under atmospheric pressure and allows us to use many kinds of salts, complexes, and compounds with low toxicity for sources. Using the oxidizability of water including the source, most of the previous reports of the mist-CVD method are on oxide materials. In this study, we fabricated zinc sulfide (ZnS) films by mist-CVD method using thiourea-based water solutions as sources. Investigating the growth of ZnS by mist-CVD under various growth conditions and experimental setups, we proposed zinc-chloride complexes are necessary for the growth of ZnS and vaporized mist sources act as precursors.

DOI

Titanium dioxide nanoparticles increase plasma glucose via reactive oxygen species-induced insulin resistance in mice.

Hu Hailong, Guo Qian, Wang Changlin, Ma Xiao, He Hongjuan, Oh Yuri, Feng Yujie, Wu Qiong, Gu Ning

Journal of Applied Toxicology   35 ( 10 ) 1122 - 1132   2015年  [査読有り]

Effects of oral administration of titanium dioxide fine-sized particles on plasma glucose in mice

Ning Gu, Hailong Hu, Qian Guo, Sanli Jin, Changlin Wang, Yuri Oh, Yujie Feng, Qiong Wu

Food and Chemical Toxicology   86   124 - 131   2015年  [査読有り]

4-Phenylbutyric Acid Increases GLUT4 Gene Expression through Suppression of HDAC5 but not Endoplasmic Reticulum Stress

Hailong Hu, Li Li, Changlin Wang, Hongjuan He, Ke Mao, Xiao Ma, Ruoyu Shi, Yuri Oh, FengWei Zhang, Ying Lu, Qiong Wu, Ning Gu

CELLULAR PHYSIOLOGY AND BIOCHEMISTRY ( KARGER )  33 ( 6 ) 1899 - 1910   2014年  [査読有り]

　概要を見る

Background:The chemical chaperone 4-phenylbutyric acid (4-PBA) has been shown to relieve endoplasmic reticulum (ER) stress. Therefore, it improves insulin sensitivity and promotes glucose metabolism in skeletal muscle. Glucose transporter type 4 (GLUT4), as a major glucose transporter protein, plays a central role in glucose metabolism. Until now, it has been unclear whether 4-PBA affects GLUT4 gene expression and thus, contributes to glucose metabolism. Methods: C2C12 myotubes were treated with 4-PBA, tunicamycin or butyrate and subjected to Western blot and RT-PCR. Results: 4-PBA-treated C2C12 myotubes increased GLUT4 expression and promoted glucose metabolism. Most interestingly, GLUT4 gene expression induced by 4-PBA was not associated with ER stress even in the presence of tunicamycin, an ER stress inducer. Moreover, we also found that 4-PBA inhibited histonedeacetylase 5 (HDAC5) expression in C2C12 myotubes, resulting in hyperacetylation of the histone H3 at the myocyte enhancer factor 2 (MEF2) binding site. This increased the binding of MEF2A to the site on the GLUT4 promoter, resulting in increased GLUT4 expression. Conclusions: Our data indicate that 4-PBA increases GLUT4 expression by acetylating the MEF2 site to increase the MEF2A binding through a mechanism that involves suppression of the HDAC5 pathway, but without involving ER stress. Copyright (C) 2014 S Karger AG, Basel

DOI

Size dependent optical properties of quinacridonequinone nanoparticles prepared by liquid laser ablation in water

Ikuko Akimoto, Masahiro Ohata, Nobuhiko Ozaki, Ping Gu

CHEMICAL PHYSICS LETTERS   552   102 - 107   2012年11月  [査読有り]

DOI

Formation of nanoparticles of organic molecules by liquid laser ablation

Ikuko Akimoto, Masahiro Ohata, Nobuhiko Ozaki, Gu Ping

Materials Research Society Symposium Proceedings   1455   55 - 60   2012年  [査読有り]

　概要を見る

We carried out laser ablation of three organic molecules, rubrene (Rb), Oralith Brilliant Pink R (BP) and quinacridonequinone (QQ) in a poor solvent, water. As a result, nanoparticles of BP and QQ were formed, but those of Rb were not formed because of photodissociation. For a rigid molecule, QQ, optical properties of colloidal solutions were investigated in relation to the size of the included nanoparticles. A linear correlation between the blue shift of the absorption peak energy and the decrease in the diameter of the nanoparticles was found, indicating that the nanoparticle diameter can be easily estimated from the absorption spectrum of a colloidal solution. From the solution, a nanoparticle film was fabricated on an electrode by the electrophoretic deposition method. © 2012 Materials Research Society.

DOI

Terahertz-photomixing efficiency of a photoconductive antenna embedded in a three-dimensional photonic crystal

M Iida, M Tani, P Gu, K Sakai, M Watanabe, H Kitahara, S Kato, M Suenaga, H Kondo, MW Takeda

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS ( INST PURE APPLIED PHYSICS )  42 ( 12A ) L1442 - L1445   2003年12月  [査読有り]

　概要を見る

We report on generation of coherent terahertz radiation by photomixing with a photoconductive antenna placed in a three-dimensional photonic crystal cavity. We observed efficiency peaks around the frequencies near the photonic bandedges and at the planar defect modes. The efficiency peaks observed near the photonic bandedges are associated with the increase of the optical mode density at the bandedge. The relatively low efficiency at the planar defect mode frequencies are explained by the mode diffusion in the lateral direction of the defect layer.

DOI

Highly efficient terahertz radiation from YBa2Cu3O7-delta thin film log-periodic antennas

M Tonouchi, H Saijo, M Hangyo, O Morikawa, P Gu, M Tani, K Sakai

PHYSICA C ( ELSEVIER SCIENCE BV )  357   1600 - 1602   2001年08月  [査読有り]

　概要を見る

We report on the radiation power of the terahertz (THz) beam from YBa2Cu3O7-delta (YBCO) thin film antennas. InSb hot-electron bolometer is used to estimate the radiation power after being calibrated in the THz beam generation and detection system. The 100-nm-thick and 30-mum-wide YBCO thin film bridges are connected to a self-complimentary log-periodic toothed planar antenna or a bow-tie antenna. Femtosecond optical pulses are focused onto the center bridge of the antennas being biased with a current up to 1 A. The detected power increases in proportion with increasing bias current, and reaches over 22 muW in the average at an excitation power of 98 mW. (C) 2001 Elsevier Science BY. All rights reserved.

Generation of THz radiation by excitation of InAs with a femtosecond free-electron laser

M Tani, S Kono, P Gu, K Sakai, M Usami, M Shinn, JF Gubeli, G Neil, JZ Xu, R Kersting, XC Zhang

ULTRAFAST ELECTRONICS AND OPTOELECTRONICS, PROCEEDINGS ( OPTICAL SOC AMERICA )  49   166 - 170   2001年  [査読有り]

　概要を見る

Terahertz (THz) radiation is generated by exciting an un-doped InAs wafer with a femtosecond free-electron laser (FEL) at the Thomas Jefferson National Accelerator Facility. A microwatt level of THz radiation is detected from the unbiased InAs emitter when it is excited with the femtosecond FEL pulses operated at a wavelength of 1.06 mum and 10 W average power.

Ultrabroadband detection of THz radiation by LT-GaAs photoconductive antenna gated with 15-fs laser pulses

S Kono, M Tani, P Gu, K Sakai

ULTRAFAST PHENOMENA XII ( SPRINGER-VERLAG BERLIN )  66   218 - 220   2001年  [査読有り]

　概要を見る

Ultrabroadband detection of terahertz radiation is demonstrated with a low-temperature-grown GaAs photoconductive antenna gated with 15-fs laser pulses. The observed spectra extends up to 20 THz and shows an absorption band between 7 similar to 10 THz due to the phonon resonance in GaAs substrate of the detector.

Coherent THz wave generation by photomixing in photonic crystal cavity

M Tani, P Gu, K Sakai, M Suenaga, H Kondo, H Kitahara, MW Takeda

CLEO(R)/PACIFIC RIM 2001, VOL I, TECHNICAL DIGEST ( IEEE )    196 - 197   2001年  [査読有り]

　概要を見る

We demonstrate generation of coherent. terahertz radiation by photomixing with a photoconductive antenna placed in a 3-D photonic crystal cavity. We observe a sharp gain peak at a frequency in the photonic bandgap, suggesting a cavity effect for it localized defect mode.

Coherent phonons in InSb and their properties from femtosecond pump-probe experiments

OV Misochko, P Gu, K Sakai

PHYSICA B-CONDENSED MATTER ( ELSEVIER SCIENCE BV )  293 ( 1-2 ) 33 - 37   2000年12月  [査読有り]

　概要を見る

We report the ultrafast impulsive excitation of coherent LO phonons with the frequency of 5.57 THz in InSb. These phonons, when generated by femtosecond laser pulses. exhibit phase-dependent fluctuation properties. that is, the variance of coherent amplitude is a function of time delay. The variance oscillations occur, for short time delays, at twice the frequency of the coherent amplitude. (C) 2000 Elsevier Science B.V. All rights reserved.

Detection of up to 20 THz with a low-temperature-grown GaAs photoconductive antenna gated with 15 fs light pulses

S Kono, M Tani, P Gu, K Sakai

APPLIED PHYSICS LETTERS ( AMER INST PHYSICS )  77 ( 25 ) 4104 - 4106   2000年12月  [査読有り]

　概要を見る

We report on the ultrabroadband coherent detection of radiation in wavelengths spanning from far to midinfrared with a low-temperature-grown GaAs photoconductive dipole antenna gated with 15 fs light pulses. The detected spectral frequency exceeds 20 THz. (C) 2000 American Institute of Physics. [S0003-6951(00)05451-6].

Temperature dependence of terahertz radiation from n-type InSb and n-type InAs surfaces

S Kono, P Gu, M Tani, K Sakai

APPLIED PHYSICS B-LASERS AND OPTICS ( SPRINGER-VERLAG )  71 ( 6 ) 901 - 904   2000年12月  [査読有り]

　概要を見る

The azimuthal angle dependence and the temperature dependence of terahertz (THz) radiation generated from n-type (111) InSb and n-type (111) InAs surfaces irradiated with similar to 80 fs near-infrared laser pulses are investigated. The azimuthal angle dependence shows that the contribution of the difference-frequency mixing (DFM) is not dominant for both materials at the excitation density of similar to 1 GW/cm(2). At an appropriate azimuthal angle, the radiation due to DFM is excluded from the total THz radiation and the temperature dependence of THz radiation due to the surge current is observed. The increase of THz radiation with decrease of the temperature is found to be much more pronounced for InSb than for InAs. The different temperature dependence can be attributed to the different radiation mechanisms dominant for both materials. Especially, the temperature dependence of the THz radiation from InSb is well explained by the photoDember effect.

Generation of coherent terahertz radiation by photomixing of dual-mode lasers

M Tani, P Gu, M Hyodo, K Sakai, T Hidaka

OPTICAL AND QUANTUM ELECTRONICS ( KLUWER ACADEMIC PUBL )  32 ( 4-5 ) 503 - 520   2000年05月  [査読有り]

　概要を見る

We have reviewed and discussed the generation of continuous-wave terahertz radiation by the photomixing of dual-mode lasers, which includes a multi-mode laser diode (LD), a dual-mode microchip laser, a monolithic dual-mode DBR LD, and a widely tunable dual-mode external cavity LD. It is demonstrated by several experiments that the beat frequency of a dual-mode laser is more stable than the original laser modes because of the common-mode rejection effect. We also suggest a novel scheme by which the optical beat is stabilized to less than 1 kHz and its frequency can be precisely determined as well.

Terahertz radiation from LO phonon-plasmon coupling modes in InSb film

P Gu, M Tani, K Sakai, TR Yang

2000 25TH INTERNATIONAL CONFERENCE ON INFRARED AND MILLIMETER WAVES CONFERENCE DIGEST ( IEEE )    67 - 68   2000年  [査読有り]

Magnetic field dependence of THz radiation from InSb surface

Ping Gu, Masahiko Tani, Kiyomi Sakai

IQEC, International Quantum Electronics Conference Proceedings ( IEEE )    171 - 172   1999年

Generation of cw-terahertz radiation using a two-longitudinal-mode laser diode

P Gu, M Tani, M Hyodo, K Sakai, T Hidaka

JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS ( JAPAN J APPLIED PHYSICS )  37 ( 8B ) L976 - L978   1998年08月  [査読有り]

　概要を見る

Coherent cw-terahertz (THz) radiation has been generated by photomixing with a photoconductive antenna fabricated on a low-temperature-grown (LTG) GaAs film using a two-longitudinal-mode distributed Bragg reflector (DBR) laser diode (LD). The frequency of the emitted radiation corresponds to the difference frequency between the two modes of the LD. The linewidth of the radiation is much narrower than that of each laser mode oscillating in the same cavity due to the common-mode rejection effect between the two modes oscillating in the same cavity. This property of the two-mode LD, as well as its compactness and ease of optical alignment, make the device promising as an excitation laser source for photomixing.

Generation of sub-THz radiation using a two-longitudinal-mode laser diode

Ping Gu, Masahiko Tani, Kiyomi Sakai, Takehiro Hidaka

Conference on Lasers and Electro-Optics Europe - Technical Digest ( IEEE )    261 - 262   1998年