Publications (8)10.77 Total impact
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Article: Matrix metalloproteinase-2 regulates the expression of tissue inhibitor of matrix metalloproteinase-2.
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ABSTRACT: 1. Matrix metalloproteinases (MMP) are associated with the vascular remodelling seen in atherosclerosis and aneurysm. The activation and activity of MMP-2 are regulated by the intrinsic tissue inhibitor of MMP-2 (TIMP-2). The aim of the present study was to examine whether, conversely, MMP-2 can affect the gene and protein expression of TIMP-2. 2. In the present study, we examined the mRNA and protein expression of MMP-2 and TIMP-2 in cultured smooth muscle cells (SMC) from the aortas of MMP-2(+/+) and MMP-2(-/-) mice. We also examined the roles of MMP-2 in SMC cellular events. 3. Western blotting showed that less TIMP-2 protein was present in the conditioned medium of MMP-2(-/-) SMC than in that of MMP-2(+/+) SMC. Real-time reverse transcription polymerase chain reaction analysis showed that MMP-2 deficiency reduced TIMP-2 mRNA expression in SMC. Recombinant MMP-2 enhanced the expression of TIMP-2 protein in cultured SMC from MMP-2(-/-) mice. Furthermore, a siRNA targeting MMP-2 impaired the gene and protein expression of MMP-2 in cultured SMC from MMP-2(+/+) mice. MMP-2 deficiency impaired SMC invasion, but not their proliferation, adhesion or migration. 4. Our findings suggest that MMP-2 is likely to be responsible, at least in part, for regulating TIMP-2 expression and is thus a potential target, in addition to TIMP-2, for therapeutics aimed at preventing cardiovascular remodelling in response to injury.Clinical and Experimental Pharmacology and Physiology 11/2010; 37(11):1096-101. · 1.85 Impact Factor -
Article: Synthesis and formation mechanism of hydrogenated boron clusters B(12)H(n) with controlled hydrogen content.
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ABSTRACT: We present the formation of hydrogen-content-controlled B(12)H(n) (+) clusters through the decomposition and ion-molecule reactions of the decaborane (B(10)H(14)) and diborane (B(2)H(6)) molecules in an external quadrupole static attraction ion trap. The hydrogen- and boron-contents of the B(10-y)H(x) (+) cluster are controlled by charge transfer from ambient gas ions. In the process of ionization, a certain number of hydrogen and boron atoms are detached from decaborane ions by the energy caused by charge transfer. The energy caused by the ion-molecule reactions also induces H atom detachment. Ambient gas of Ar leads to the selective generation of B(10)H(6) (+). The B(10)H(6) (+) clusters react with B(2)H(6) molecules, resulting in the selective formation of B(12)H(8) (+) clusters. Ambient gas of Ne (He) leads to the generation of B(10-y)H(x) (+) clusters with x=4-10 and y=0-1 (with x=2-10 and y=0-2), resulting in the formation of B(12)H(n) (+) clusters with n=4-8 (n=2,4-8). The introduction of ambient gas also increases the production of clusters. PBE0/6-311+G(d)//B3LYP/6-31G(d)-level density functional theory calculations are conducted to investigate the structure and the mechanism of formation of B(10-y)H(x) (+) and B(12)H(n) (+) clusters.The Journal of chemical physics 08/2010; 133(7):074305. · 3.09 Impact Factor -
Article: Metallic-covalent bonding conversion in boron icosahedral cluster solids studied using electron localizability indicator
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ABSTRACT: The metallic-covalent bonding conversion of clusters in boron icosahedral cluster solids was studied using the electron density and electron localizability indicator (ELI). The comparison of B12 and B13 clusters revealed that the bonding conversion from covalent to metallic one involved a decrease in both the electron density and ELI between two boron atoms in the clusters. On the other hand, in the case of vanadium doping into the B48 cluster surrounding the vanadium doping site in β-rhombohedral boron, the electron density increased in some parts of the cluster and decreased in other parts. This uncertainty regarding the bonding conversion was clarified by the use of the ELI. The ELI analysis clearly revealed that bonding conversion occurs in the cluster surrounding the vanadium doping site.Journal of Physics Conference Series 07/2009; 176(1):012027. -
Article: Energy barrier of structure transition from icosahedral B12H6+ to planar B12H5+ and B12H4+ clusters
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ABSTRACT: Ab initio calculations indicated that icosahedral structure is more stable for B12Hn+ clusters with n = 6–12, but planar configuration is more stable for B12Hn+ with n = 0–5. Here, we report the energy barriers of structure transition by detaching H atoms from icosahedral B12H6+ to planar B12H5+, planar B12H4+, icosahedral B12H5+ or icosahedral B12H4+ cluster. We performed density functional theory calculations to explore the energy barriers and the reaction path of the structure transition. The resultant energy barriers are almost the same, enabling the transition to proceed and suggesting that the structure of B12Hn+ clusters is controlled by the number of hydrogen atoms n.Journal of Physics Conference Series 07/2009; 176(1):012030. -
Article: Formation of hydrogenated boron clusters in an external quadrupole static attraction ion trap.
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ABSTRACT: We report the formation of icosahedral B(12)H(8) (+) through ion-molecule reactions of the decaborane ion [B(10)H(x)(+) (x=6-14)] with diborane (B(2)H(6)) molecules in an external quadrupole static attraction ion trap. The hydrogen content n of B(12)H(n)(+) is determined by the analysis of the mass spectrum. The result reveals that B(12)H(8)(+) is the main product. Ab initio calculations indicate that B(12)H(8)(+) preferentially forms an icosahedral structure rather than a quasiplanar structure. The energies of the formation reactions of B(12)H(14)(+) and B(12)H(12)(+) between B(10)H(x)(+) (x=6,8) ions, which are considered to be involved in the formation of B(12)H(n)(+), and a B(2)H(6) molecule are calculated. The calculations of the detachment pathway of H(2) molecules and H atoms from the product ions, B(12)H(14)(+) and B(12)H(12) (+), indicate that the intermediate state has a relatively low energy, enabling the detachment reaction to proceed owing to the sufficient reaction energy. This autodetachment of H(2) accounts for the experimental result that B(12)H(8)(+) is the most abundant product, even though it does not have the lowest energy among B(12)H(n)(+).The Journal of Chemical Physics 04/2008; 128(12):124304. · 3.33 Impact Factor -
Article: Effects of pesticides on the peripheral and central nervous system in tobacco farmers in Malaysia: studies on peripheral nerve conduction, brain-evoked potentials and computerized posturography.
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ABSTRACT: We examined the effects of pesticides on the central and peripheral nervous system in the setting of a tobacco farm at a developing country. Maximal motor and sensory nerve conduction velocities (MCV and SCV, respectively) in the median, sural and tibial nerves, postural sway, and brain-evoked potentials (auditory event-related and visual-evoked potentials) were measured in 80 male tobacco farmers and age- and sex-matched 40 controls in Kelantan, Malaysia. Median SCV (finger-wrist) in farmers using Delsen (mancozeb, dithiocarbamate fungicide), who showed significant decrease of serum cholinesterase activities, were significantly lower compared with the controls. Sural SCV in farmers using Fastac (alpha-cypermethrin, pyrethroid insecticide) and median MCV (elbow-wrist) in farmers using Tamex (butralin, dinitroaniline herbicide) were significantly slowed compared with their respective controls. In Delsen (mancozeb, dithiocarbamate) users, the power of postural sway of 0-1 Hz was significantly larger than that in the controls both in the anterior-posterior direction with eyes open and in the right-left direction with eyes closed. The former type of sway was also significantly increased in Tamaron (methamidophos, organophosphorus insecticide) users. In conclusion, nerve conduction velocities and postural sway seem to be sensitive indicators of the effects of pesticides on the central and peripheral nervous system.Industrial Health 05/2005; 43(2):285-94. · 0.94 Impact Factor -
Article: Assessment of urinary cotinine as a marker of nicotine absorption from tobacco leaves: a study on tobacco farmers in Malaysia.
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ABSTRACT: To assess dermal absorption of nicotine from tobacco leaves in relation to Green Tobacco Sickness (GTS), urinary cotinine concentrations were measured in 80 male tobacco-growing farmers and in 40 healthy males (controls) who did not handle wet tobacco leaves in Kelantan, Malaysia. Among non-smokers, urinary cotinine levels in farmers were significantly higher than those of controls; farmers with urinary cotinine of 50 ng/ml/m2 or above showed eye symptoms more frequently than those below this level (p<0.05). Farmers who did not wear protective equipment had subjective symptoms more frequently than those who used the equipment (p<0.05); some of these symptoms were seen more frequently in organophosphate (Tamaron) users than in non-users. As tobacco farmers evidence a risk of nicotine poisoning from tobacco leaves, assessment including GTS together with effects of pesticides will be necessary.Journal of Occupational Health 05/2003; 45(3):140-5. · 1.55 Impact Factor -
Article: A novel fluidized bed process to produce fine-grade artificial lightweight aggregates
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ABSTRACT: Fine-grade artificial lightweight aggregates (ALAs) with particle diameters within 300–600 μm were manufactured by using a fluidized bed of spherical mullite particles. The product aggregates contained uniformly dispersed closed bubbles and showed excellent characteristics of light weight, high strength, and low water absorption, all of which are of ideal properties for lightweight concrete production. By applying mercury intrusion test, tensile strength was estimated from isostatic compressive strength with excellent reliability. High strength during pumping and casting concrete mix is expected for the fine ALAs from fluidized bed process.Powder Technology.
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Institutions
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2005–2010
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The University of Tokyo
- • Department of Advanced Materials Science
- • Faculty & Graduate School of Medicine
Tokyo, Tokyo-to, Japan
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