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A new dipeptide with an acridone chromophore, namely 2-acridonylalanine-phenylalanine (AAP) was synthesized, and a fluorescent hydrogel was produced under physiological pH conditions by the AAP self-assembly process. The hydrogel exhibited a blue emission and reasonable thermoresponsiveness. Therefore, dipeptides containing an acridone side chain of the first residue were found to be effective hydrogelators. [ABSTRACT FROM AUTHOR]

Cytochrome c oxidase (CcO), a membrane enzyme in the respiratory chain, catalyzes oxygen reduction by coupling electron and proton transfer through the enzyme with a proton pump across the membrane. In all crystals reported to date, bovine CcO exists as a dimer with the same intermonomer contacts, whereas CcOs and related enzymes from prokaryotes exist as monomers. Recent structural analyses of the mitochondrial respiratory supercomplex revealed that CcO monomer associates with complex I and complex III, indicating that the monomeric state is functionally important. In this study, we prepared monomeric and dimeric bovine CcO, stabilized using amphipol, and showed that the monomer had high activity. In addition, using a newly synthesized detergent, we determined the oxidized and reduced structures of monomer with resolutions of 1.85 and 1.95 Å, respectively. Structural comparison of the monomer and dimer revealed that a hydrogen bond network of water molecules is formed at the entry surface of the proton transfer pathway, termed the K-pathway, in monomeric CcO, whereas this network is altered in dimeric CcO. Based on these results, we propose that the monomer is the activated form, whereas the dimer can be regarded as a physiological standby form in the mitochondrial membrane. We also determined phospholipid structures based on electron density together with the anomalous scattering effect of phosphorus atoms. Two cardiolipins are found at the interface region of the supercomplex. We discuss formation of the monomeric CcO, dimeric CcO, and supercomplex, as well as their role in regulation of CcO activity. [ABSTRACT FROM AUTHOR]

Troglitazone and pioglitazone were developed as thiazolidinedione-type antidiabetes drugs, but only troglitazone was withdrawn from the markets due to severe liver injury. As both troglitazone and its sulfate metabolite are strong inhibitors of the bile salt export pump (BSEP), troglitazone-induced bile acid (BA) retention is thought to be one of the underlying mechanisms of liver injury. However, pioglitazone is also a strong BSEP inhibitor, indicating other mechanisms may also be involved in troglitazone-induced BA retention. Although retention of hydrophobic BAs (eg, chenodeoxycholic acid [CDCA]: a nonamidated BA) is known to cause hepatocyte injury, little is known about the hepatic conversion of nonamidated, hydrophobic BA species into less toxic hydrophilic BAs (eg, glycochenodeoxycholic acid: amidated BA) as a mechanism of drug-induced liver injury. In this study, we, therefore, investigated the effects of troglitazone and pioglitazone on BA amidation and the role of amidated BAs in troglitazone-associated BA-mediated hepatotoxicity. We also evaluated the intracellular BA composition of human hepatocytes treated with nonamidated BA species (CDCA or deoxycholic acid [DCA]) in the presence of troglitazone or pioglitazone. Amidation of CDCA and DCA was significantly inhibited by troglitazone (IC50: 5 and 3 mmol/l, respectively), but not pioglitazone. Moreover, treatment with troglitazone led to the retention of CDCA and DCA and decrease of glycine-amidation in hepatocytes. From these results, we suggest that troglitazone-induced liver injury might be caused by the accumulation of nonamidated BAs in hepatocytes due to inhibition of BA amidation. [ABSTRACT FROM AUTHOR]

Thermoelectrics is a challenging issue for modern and future energy conversion and recovery technology. Carbon nanotubes are promising active thermoelectic materials owing to their narrow bandgap energy and high charge carrier mobility, and they can be integrated into flexible thermoelectrics that can recover any waste heat. We here report air-stable n-type single walled carbon nanotubes with a variety of weak electron donors in the range of HOMO level between ca. -4.4 eV and ca. -5.6 eV, in which partial uphill electron injection from the dopant to the conduction band of single walled carbon nanotubes is dominant. We display flexible films of the doped single walled carbon nanotubes possessing significantly large thermoelectric effect, which is applicable to flexible ambient thermoelectric modules. [ABSTRACT FROM AUTHOR]

Novel EuIIIcomplexes with bidentate phosphine oxide ligands containing a bipyridine framework, i.e., 3,3′bisdiphenylphosphoryl2,2′bipyridinetrishexafluoroacetylacetonatoeuropiumIII Euhfa3BIPYPO and 3,3′bisdiphenylphosphoryl6,6′dimethyl2,2′bipyridinetrishexafluoroacetylacetonatoeuropiumIII Euhfa3MeBIPYPO, were synthesized for lanthanidebased sensor materials having high emission quantum yields and effective chemosensing properties. The emission quantum yields of Euhfa3BIPYPO and Euhfa3MeBIPYPO were 71 and 73, respectively. Metalion sensing properties of the EuIIIcomplexes were also studied by measuring the emission spectra of EuIIIcomplexes in the presence of ZnIIor CuIIions. The metalion sensing and the photophysical properties of luminescent EuIIIcomplexes with a bidentate phosphine oxide containing 2,2′bipyridine framework are demonstrated for the first time. [ABSTRACT FROM AUTHOR]

Luminescence properties and their photoinduced control of the electric dipole transitions of a Eu(III) complex that has photochromic triangle terarylenes ligands, tris(hexafluoroacetylacetonato)bis[4,5- bis(5-methyl-2-phenylthiazol-4-yl)-2-phenylthiazole]europium(III) (Eu(hfa) 3(THIA) 2), were studied. Fairly high photochromic reactivity of the ligand between the open-ring and closed-ring forms were found to be maintained even in the complex, and reversible color change could be observed many times. The photocyclization and the cycloreversion quantum yields of the Eu(hfa) 3(THIA) 2were found to be 37% and 3.4%, respectively. The thermal stability of the closed-ring form of THIA ligand is significantly improved in the Eu(III) complex. The 5D 0- 7F 2transition intensity of the Eu(III) complex with open-ring form ligands (Eu(hfa) 3(THIA) 2−O) is larger than that of the Eu(III) complex with closed-ring form ligands (Eu(hfa) 3(THIA) 2−C). The radiative rate constants of Eu(hfa) 3(THIA) 2−O and Eu(hfa) 3(THIA) 2−C are estimated to be 1.7 × 10 2and 1.5 × 10 2s −1, respectively. The reversible control of the emission properties of the Eu(III) complex by the photochromic reactions is demonstrated for the first time. [ABSTRACT FROM AUTHOR]

The hypothalamic-pituitary-thyroidal axis was studied in 17 normal-weight patients with bulimia. Basal levels of serum thyroxine (T4), triiodothyronine (T3), reverse triiodothyronine (rT3), and thyrotropin (TSH) were determined in all patients; responses of TSH and T3 to thyrotropin-releasing hormone (TRH) were investigated in nine patients. Mean basal serum T4, T3, and TSH concentrations were significantly lower in the patients than in the normal control subjects but serum rT3 levels were essentially the same. In nine patients TSH responses to TRH were normal in five, delayed in three, and low in one. The maximum increase in serum TSH and TSH net secretory response were not significantly different from those of control subjects. With respect to the T3 response to TRH, various indices in patients appeared significantly lower than in the control subjects. These results suggest that normal-weight patients with bulimia have abnormalities in the hypothalamic-pituitary-thyroidal axis. [ABSTRACT FROM AUTHOR]

A spiro compound DPAA-AF combining an electronaccepting diazafluorene unit and an electron-donating bis(diphenylamino) acridane unit has been synthesized and used as an emitter in organic light-emitting diodes. DPAA-AF exhibits efficient thermally activated delayed fluorescence, and a device based on this compound emits blue-greenish electroluminescence with a maximum external quantum efficiency of 9.6%. [ABSTRACT FROM AUTHOR]