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Abstract: Recently, carbon materials have attracted considerable attention with their strong potential for hydrogen storage. In the present study, the possibility for dissociative adsorption of hydrogen on the surface of graphene is investigated by using ab initio molecular dynamics (MDs) based on density functional theory. The orientation of a H2 molecule with respect to a modeled graphene surface (perpendicular or parallel) is taken into account in this investigation, and the differences between results obtained with different values of the incident energy are discussed. The adsorption processes of hydrogen molecules are simulated by focusing on electron transfer between H and C atoms, in which dissociation and adsorption of H2 are found to be promoted above the steric graphene structure due to pronounced electron transfer at the impact point. The local steric structure forms sp3 hybridized molecular orbitals, which results in increased electron density and acts as a catalytic agent inducing cleavage of the H–H bond. In MD simulations, an excess incident energy of 6.00eV (579kJ/mol) is required to promote the reaction, although the activation energy is evaluated as 3.33eV (321kJ/mol) by static electronic structure computation. This result is obtained by taking both the motion of molecules as well as electron transfer into account and assuming that chemical reactions do not always progress along the ideal reaction pathway in actual systems. [Copyright &y& Elsevier]

Abstract: An elevated urinary albumin excretion is associated with an increased risk of cardiovascular disease due to atherosclerosis, but the pathophysiological mechanism underlying this association is poorly understood. We studied 217 diabetic patients, that is, 121 normoalbuminuric patients, 71 microalbuminuric patients, and 25 macroalbuminuric patients. We evaluated flow-mediated dilatation of brachial artery (%FMD, one endothelial function marker associated with endogenous NO production), von Willebrand factor (vWF, endothelial activation marker), high-sensitive CRP (hsCRP, a low-grade inflammation marker), asymmetric dimethyl arginine (ADMA, an endogenous inhibitor of NO synthesis), and insulin sensitivity by steady-state plasma glucose method. %FMD was apparently decreased in microalbuminuric and macroalbuminuric patients compared with normoalbuminuric patients (p <0.001). Moreover, %FMD was significantly correlated with the degree of albuminuria (r =−0.38, p <0.05). On the other hand, vWF and hsCRP did not show significant difference between normoalbuminuric patients and microalbuminuric patients. In diabetic patients with macroalbuminuria, ADMA was significantly elevated compared to those with normoalbuminuria. Insulin sensitivity was significantly associated with urinary albumin excretion rate. These results suggested that endothelial dysfunction which may be due to impaired NO production and insulin resistance underlie the association between diabetic nephropathy and atherosclerosis in diabetic patients. [Copyright &y& Elsevier]

Frozen-solution ESR spectra of 4-hydroxy-1,3-phenylenebis(imino nitroxide) (1) and 2-hydroxy-5-methyl-1,3-phenylenebis(imino nitroxide) (2) in toluene showed fine structures due to the triplet states (imino nitroxide stands for 2-substituted 4,4,5,5-tetramethylimidazolin-3-yloxyl). The temperature dependence of the Δms=±2 signal intensity for 1 followed the Curie law, suggesting that 1 has a ground triplet state. On the other hand, the triplet signal intensity of 2 did not obey the Curie law. The intramolecular magnetic coupling seems to depend on the twist angle between the imino nitroxide group and benzene ring. Complexation with Cu(CH3CO2)2·H2O in ethanol gave a mononuclear complex, Cu(L1)2, where L1 is the anionic form derived from 1. The X-ray diffraction study of Cu(L1)2 revealed that the central copper(II) ion had a twisted square plane; the dihedral angle between two chelating O&z.sbnd;Cu&z.sbnd;N planes was 45°. The magnetic measurements of Cu(L1)2 indicated the presence of intramolecular ferromagnetic interaction, which is ascribed mainly to a ground quartet formation at the directly bonded radical&z.sbnd;copper&z.sbnd;radical moiety with Jradical&z.sbnd;copper/kB=+132±5 K, where the Heisenberg spin Hamiltonian is defined as H=−2JSiSj. [Copyright &y& Elsevier]

We adopt first-principle approach to calculate potential energy surfaces for α-quartz and -cristobalite silicon dioxide (SiO2) with hydrogenated impurities in the neutral, positive, and negative charged states. It is expected that H atoms in SiO2 have an important role to generate leakage current paths. In this paper, we calculate stable and unstable positions of a migrating H atom and discuss electrons or holes trapping mechanism. These results clarify that the dynamics of the H atom in the neutral, negative, and positive charged states should be different from one another, and therefore, the mechanism of the dielectric break down of SiO2 also depends on the charged environment. Based on the regional density functional theory, we have calculated the effective charge tensor density of the migrating H atom in the neutral state. [Copyright &y& Elsevier]

Abstract: We have carried out first-principle calculations of simple models for Al nanowire wrapped in carbon nanotube and have investigated the electronic properties of them based on the regional density functional theory. For both the (8,0) zigzag nanotube-wrapped and the (4,4) armchair nanotube-wrapped Al nanowire models, the nanowire with a monoatomic thickness is stabilized just on the center axis of the carbon nanotube due to a shortage of the tube radius. The microscopic image that electrons in the Al nanowire interact with the electrons in the nanotube on every side is obtained clearly in terms of the quantum energy densities. Band structures of the nanotube-wrapped Al nanowire models represent the conductivity along the wire, where bands originated from the Al atom raise and cross the Fermi level for each model. We have confirmed that reversible hydrogen storage processes are realized in our model. Under the external electric field and current, the effective charge tensor density of the Al atom has been computed using the non-relativistic limit of quantum electrodynamics. [Copyright &y& Elsevier]

Abstract: Ghrelin, a novel 28-amino acid peptide with an n-octanoyl modification at Ser3, has been isolated from rat and human stomach as an endogenous ligand for the growth hormone secretagogue receptor. Here, we purified feline ghrelin and examined its possible physiological role in cats. The major active form of feline ghrelin is a 28-amino acid peptide octanoylated (C8:0) at Ser3; except for one amino acid residue replacement, this structure is identical to those of rat and human ghrelins. However, much structural divergence in peptide length and fatty acid modification was observed in feline ghrelin: peptides consisting of 27 or 26 amino acids lacking Gln14 and/or Arg28 were found, and the third serine residue was modified by octanoic acid (C8:0), decanoic acid (10:0), or unsaturated fatty acids (C8:1, C10:1 and C10:2). In agreement with the structural divergence, two kinds of cDNA with different lengths were isolated. Administration of synthetic rat ghrelin increased plasma growth hormone levels in cats, with a potency similar to that in rat or human. Plasma levels of ghrelin in cats increased approximately 2.5-fold after fasting. The present study indicates the existence of structural divergence in feline ghrelin and suggests that, as in other animals, ghrelin may play important roles in GH release and feeding in cats. [Copyright &y& Elsevier]

Abstract: Oxidative stress is known to be involved in growth control of vascular smooth muscle cells (VSMCs). We and others have demonstrated that angiotensin II (Ang II) has an important role in vascular remodeling. Several reports suggested that VSMC growth induced by Ang II was elicited by oxidative stress. Gax, growth arrest-specific homeobox is a homeobox gene expressed in the cardiovascular system. Over expression of Gax is demonstrated to inhibit VSMC growth. We previously reported that Ang II down-regulated Gax expression. To address the regulatory mechanism of Gax, we investigated the significance of oxidative stress in Ang II-induced suppression of Gax expression. We further examined the involvement of mitogen-activated protein kinases (MAPKs), which is crucial for cell growth and has shown to be activated by oxidative stress, on the regulation of Gax expression by Ang II. Ang II markedly augmented intracellular H2O2 production which was decreased by pretreatment with N-acetylcystein (NAC), an anti-oxidant. Ang II and H2O2 decreased Gax expression dose-dependently and these effects were blocked by administration of both NAC and pyrrolidine dithiocarbamate (PDTC), another anti-oxidant. Ang II and H2O2 induced marked activation of extracellular signal-responsive kinase1/2 (ERK1/2), which was blocked by NAC. Ang II and H2O2 also activated p38MAPK, and they were blocked by pre-treatment with NAC. However, the level of activated p38MAPK was quite low in comparison with ERK1/2. Ang II- or H2O2-induced Gax down-regulation was significantly inhibited by PD98059, an ERK1/2 inhibitor but not SB203580, a p38MAPK inhibitor. The present results demonstrated the significance of regulation of Gax expression by redox-sensitive ERK1/2 activation. [Copyright &y& Elsevier]

Abstract: Thiazolidinediones, a new class of antidiabetic drugs that increase insulin sensitivity, have been shown to be ligands for peroxisome proliferator-activated receptor γ (PPARγ). Recent studies demonstrating that PPARγ occurs in macrophages have focused attention on its role in macrophage functions. In this study, we investigated the effect of thiazolidinediones on monocyte proliferation and migration in vitro and the mechanisms involved. In addition, we examined the therapeutic potentials of thiazolidinediones for injured atherosclerotic lesions. Troglitazone and pioglitazone, the two thiazolidinediones, as well as 15-deoxy-Δ12,14-prostaglandin J2 inhibited in a dose-dependent manner the serum-induced proliferation of THP-1 (human monocytic leukemia cells) and of U937 (human monoblastic leukemia cells), which permanently express PPARγ. These ligands for PPARγ also significantly inhibited migration of THP-1 induced by monocyte chemoattractant protein-1 (MCP-1). Troglitazone and 15-deoxy-Δ12,14-prostaglandin J2 significantly suppressed the mRNA expression of the MCP family-specific receptor CCR2 (chemokine CCR2 receptor) in THP-1 at the transcriptional level. Furthermore, troglitazone significantly inhibited MCP-1 binding to THP-1. Oral administration of troglitazone to Watanabe heritable hyperlipidemic (WHHL) rabbits after balloon injury suppressed acute recruitment of monocytes/macrophages and accelerated re-endothelialization. These results suggest that thiazolidinediones have therapeutic potential for the treatment of diabetic vascular complications. [Copyright &y& Elsevier]

Shear stress is known to dilate blood vessels and exert an antiproliferative effect on vascular walls. These effects have partly been ascribed to shear stress-induced regulation of the secretion of endothelium-derived vasoactive substances. In this study, to elucidate the role of shear stress in endothelin production by endothelial cells, we examined the effect of physiological shear stress on the mRNA expression of endothelin-converting enzyme-1 (ECE-1) as well as endothelin-1 (ET-1) in cultured bovine carotid artery endothelial cells (BAECs) and human umbilical vein endothelial cells (HUVECs), using a parallel plate-type flow chamber.ECE-1 mRNA expression was significantly down-regulated by shear stress in an intensity- and time-dependent manner within the physiological range (1.5 to 15 dyn/cm2). ET-1 mRNA expression decreased together with ECE-1 mRNA expression. Shear stress at 15 dyn/cm2 for 30 min induced a significant increase in the intracellular peroxide concentration, and the down-regulation of ECE-1 and ET-1 mRNA expression by shear stress was attenuated almost completely on treatment with N-acetyl cysteine (NAC), an antioxidant (20 mM). Furthermore, when H2O2 (0.5 to 2 mM) was added to BAECs in static culture, the ECE-1 as well as ET-1 mRNA expression was attenuated in proportion to the concentration of H2O2. It is suggested that endothelial cells sense shear stress as oxidative stress and transduce signal for the regulation of the gene expression of ECE as well as ET to attenuate vascular tone and inhibit the proliferation of vascular smooth muscle cells. [Copyright &y& Elsevier]