Thermoelectric properties and electronic structure of the Zintl phase Sr_5Al_2Sb_6

The Zintl phase Sr_5Al_2Sb_6 has a large, complex unit cell and is composed of relatively earth-abundant and non-toxic elements, making it an attractive candidate for thermoelectric applications. The structure of Sr_5Al_2Sb_6 is characterized by infinite oscillating chains of AlSb_4 tetrahedra. It is distinct from the structure type of the previously studied Ca_5M_2Sb_6 compounds (M = Al, Ga or In), all of which have been shown to have promising thermoelectric performance. The lattice thermal conductivity of Sr_5Al_2Sb_6 (∼0.55 W mK^(-1) at 1000 K) was found to be lower than that of the related Ca_5M_2Sb_6 compounds due to its larger unit cell (54 atoms per primitive cell). Density functional theory predicts a relatively large band gap in Sr_5Al_2Sb_6, in agreement with the experimentally determined band gap of E_g ∼ 0.5 eV. High temperature electronic transport measurements reveal high resistivity and high Seebeck coefficients in Sr_5Al_2Sb_6, consistent with the large band gap and valence-precise structure. Doping with Zn^(2+) on the Al^(3+) site was attempted, but did not lead to the expected increase in carrier concentration. The low lattice thermal conductivity and large band gap in Sr_5Al_2Sb_6 suggest that, if the carrier concentration can be increased, thermoelectric performance comparable to that of Ca_5Al_2Sb_6 could be achieved in this system

Activation of Mitogen-Activated Protein Kinase in Descending Pain Modulatory System

The descending pain modulatory system is thought to undergo plastic changes following peripheral tissue injury and exerts bidirectional (facilitatory and inhibitory) influence on spinal nociceptive transmission. The mitogen-activated protein kinases (MAPKs) superfamily consists of four main members: the extracellular signal-regulated protein kinase1/2 (ERK1/2), the c-Jun N-terminal kinases (JNKs), the p38 MAPKs, and the ERK5. MAPKs not only regulate cell proliferation and survival but also play important roles in synaptic plasticity and memory formation. Recently, many studies have demonstrated that noxious stimuli activate MAPKs in several brain regions that are components of descending pain modulatory system. They are involved in pain perception and pain-related emotional responses. In addition, psychophysical stress also activates MAPKs in these brain structures. Greater appreciation of the convergence of mechanisms between noxious stimuli- and psychological stress-induced neuroplasticity is likely to lead to the identification of novel targets for a variety of pain syndromes

Neuroprotective effects of 5-S-GAD against oxidative stress-induced apoptosis in RGC-5 cell.

金沢大学医薬保健研究域　医学系N-β-Alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD), an antibacterial substance isolated from the flesh fly, has been described as having multipotential biological activities toward various tissues. In a previous paper, we reported a novel neuroprotective action of 5-S-GAD on rat retinal ganglion cell apoptosis induced by optic nerve injury and intraocular N-methyl-d-aspartate treatment in vivo. In the present study, we further investigated the protective mechanism of this small peptide against other types of apoptosis in cultured cells of the established rat retinal ganglion cell line RGC-5. Hydrogen peroxide and serum deprivation treatments induced intracellular reactive oxygen species levels and lipid peroxidation, revealed by 4-hydroxy-2-nonenal production, in RGC-5 cells within 9-12 h. The treatments also induced cell death accompanied by nuclear condensation, DNA laddering and increases in apoptotic Bax and caspase-3 proteins in RGC-5 cells within 12-24 h. 5-S-GAD at 25-50 μM clearly suppressed the cell death and apoptotic features induced by these treatments. 5-S-GAD restored the nuclear condensation, DNA laddering and increases in apoptotic proteins. Furthermore, 5-S-GAD directly activated anti-apoptotic phospho-Akt and Bcl-2 proteins in RGC-5 cells. 5-S-GAD also quenched the reactive oxygen species production and inhibited the lipid peroxidation induced by oxidative stress. Therefore, 5-S-GAD may complementarily protect RGC-5 cells against apoptosis through dual actions as a radical scavenger and an inducer of anti-apoptotic phospho-Akt and Bcl-2. Taken together, 5-S-GAD is a high-potential tool for rescuing the retinal ganglion cell apoptosis induced by a variety of glaucomatous conditions. Crown Copyright © 2009

肺高血圧症に対するトロンボキサン合成阻害作用をもった新規長期作用型プロスタサイクリンアゴニストの経口投与

BACKGROUND: Continuous administration of prostacyclin has improved the survival of patients with pulmonary arterial hypertension (PAH). However, this treatment has some problems, including its short duration of activity and difficult delivery. Therefore, we developed ONO-1301, an orally active, long-acting prostacyclin agonist with thromboxane synthase inhibitory activity. METHODS AND RESULTS: We investigated whether oral administration of ONO-1301 can both prevent and reverse monocrotaline (MCT)-induced PAH in rats. Rats were randomly assigned to receive repeated oral administration of ONO-1301 twice daily beginning either 1 or 8 days after subcutaneous injection of MCT. A control group received oral saline, and a sham group received a subcutaneous injection of saline instead of MCT. MCT-treated controls developed significant pulmonary hypertension. Treatment with ONO-1301 from day 1 or 8 significantly attenuated the increases in right ventricular systolic pressure and the increase in medial wall thickness of pulmonary arterioles. Kaplan-Meier survival curves demonstrated that the effect of ONO-1301 was equivalent to that of an endothelin receptor antagonist and a phosphodiesterase-5 inhibitor. A single oral dose of ONO-1301 increased plasma cAMP levels for up to 6h. Treatment with ONO-1301 significantly decreased urinary 11-dehydro-thromboxane B2 and increased the plasma hepatocyte growth factor concentration. CONCLUSIONS: Oral administration of ONO-1301 ameliorated PAH in rats, an effect that may occur through cAMP and hepatocyte growth factor.博士（医学）・乙1326号・平成26年3月17日日本循環器学会の許諾を得て登録（2014年6月6日付）ジャーナル公式サイト（日本循環器学会HP内）：https://www.j-circ.or.jp/journal/公開サイト（J-STAGE）：https://www.jstage.jst.go.jp/browse/circj

A novel neuroprotective role of a small peptide from flesh fly, 5-S-GAD in the rat retina in vivo.

金沢大学医薬保健研究域　医学系N-β-Alanyl-5-S-glutathionyl-3,4-dihydroxyphenylalanine (5-S-GAD), an antibacterial substance isolated from flesh fly, has been described as having multipotential biological activities toward various tissues. However, there has been no report testing its action on neural cells. In the present study, we investigate whether 5-S-GAD is neurotoxic or neuroprotective to the rat retina. 5-S-GAD at high doses (more than 200 pmol) induced apoptosis of retinal neurons 7 days after intraocular injection. 5-S-GAD at low doses (2-20 pmol) significantly attenuated the loss of retinal ganglion cells (RGCs) and the thinning of inner retina induced by NMDA in a dose-dependent manner. To understand the protective mechanism of 5-S-GAD, we investigated the influence of 5-S-GAD on the cell survival molecules, phospho-Akt and Bcl-2. 5-S-GAD (2-20 pmol) rapidly increased phospho-Akt expression 1-7 days and Bcl-2 expression 3-7 days after injection. The cellular localization of this increase was both in bipolar cells and RGCs. This neurosurvival effect of 5-S-GAD was further tested using another model of optic nerve injury. 5-S-GAD significantly blocked the apoptosis of RGCs 7 days after optic nerve crush. These results show that 5-S-GAD (2-20 pmol) protects against the NMDA- and optic nerve crush-induced apoptosis of RGCs. The neuroprotective action of 5-S-GAD in the retina might be mediated by the cell survival phospho-Akt/Bcl-2 system and offers a therapeutic option to rescue RGCs from various types of excitotoxic disease, such as glaucoma. © 2008 Elsevier B.V. All rights reserved