Central effects of ghrelin, a unique peptide, on appetite and fluid/water drinking behavior

Ghrelin is a stomach-derived peptide discovered as a ligand of the orphan G-protein coupled receptor. Ghrelin is now recognized as a major orexigenic neuropeptide. Immunohistochemical studies demonstrated that centrally administered ghrelin induced c-fos protein expression in many areas in the brain. Indeed, centrally administered ghrelin has various effects such as stimulating feeding, arousal, increasing gastric acid secretion, release of hormones from the pituitary, and inhibition of water intake. In particular, we recently showed that ghrelin was an antidipsogenic peptide with a simultaneous orexigenic effect. This may be of important, because most spontaneous daily water intake is temporally associated with feeding. Here, we summarise recent findings on the integration of central effects of ghrelin that regulate feeding, release hormones from the pituitary and inhibit fluid/water intake.     

Auger recombination dynamics in hybrid silica-coated CdTe nanocrystals

CdTe quantum dots coated with a silica layer containing CdS-like clusters exhibit intense photoluminescence and a spectral red-shift. Biexciton Auger recombination of these particles is examined by transient absorption spectroscopy. A lengthening of the Auger recombination lifetime by a factor of ～3.5 in the presence of the CdS-like clusters is observed and may contribute to the good PL properties of these nanostructures.     

Sequential mechanism of assembly of multidrug efflux pump AcrAB-TolC

Multidrug efflux pumps adversely affect both the clinical effectiveness of existing antibiotics and the discovery process to find new ones. In this study, we reconstituted and characterized by surface plasmon resonance the assembly of AcrAB-TolC, the archetypal multidrug efflux pump from Escherichia coli. We report that the periplasmic AcrA and the outer membrane channel TolC assemble high-affinity complexes with AcrB transporter independently from each other. Antibiotic novobiocin and MC-207,110 inhibitor bind to the immobilized AcrB but do not affect interactions between components of the complex. In contrast, DARPin inhibits interactions between AcrA and AcrB. Mutational opening of TolC channel decreases stability of interactions and promotes disassembly of the complex. The conformation of the membrane proximal domain of AcrA is critical for the formation of AcrAB-TolC and could be targeted for the development of new inhibitors.     

An iminocoumarin-Cu(II) ensemble-based chemodosimeter toward thiols

An 'ensemble'-based fluoregenic chemodosimeter 1-Cu(II) for detection of thiols is reported. Complex 1-Cu(II) sensitively senses thiols followed by hydrolysis to give a marked fluorescence enhancement over other amino acids at pH 7.4 under aqueous media. Confocal microscopic imaging of complex 1-Cu(II) is also herewith demonstrated for cellular thiol detection in HepG2 cells.     

Smectogenic properties of N,N′‐bis[(2‐hydroxy‐4‐alkoxyphenyl)methylene]benzene‐1,4‐diamine liquid crystals with double lateral H‐bonds

A series of eight liquid crystalline compounds, N,N′‐bis[(2‐hydroxy‐4‐alkoxyphenyl)methylene]benzene‐1,4‐diamines, has been synthesized and characterized. These homologous compounds differ in the length of terminal alkyl group C _n H_2n+1 wherein n is an even number ranging from 4 to 18. The spectroscopic techniques, FTIR, ¹H NMR and ¹³C NMR, were employed to characterize the molecular structure. The transition temperatures of all the title compounds and their mesophases were studied by differential scanning calorimetry and polarizing microscopy. All the compounds were smectogenic, exhibiting both tilted and non‐tilted molecular orientation in their smectic phases. Further investigation to ascertain the anisotropic nature of subphases within the smectogenic region was carried out using X‐ray diffraction.     

Photoinduced change in the charge order pattern in the quarter-filled organic conductor (EDO-TTF)2PF6 with a strong electron-phonon interaction

The quasistable state in the photoinduced phase transition for the quasi-one-dimensional quarter-filled organic conductor (EDO-TTF)2PF6 has been examined by ultrafast reflective measurements and time-dependent model calculations incorporating both electron-electron and electron-phonon interactions. The transient optical conductivity spectrum over a wide probe photon-energy range revealed that photoexcitation induced a new type of charge-disproportionate state. Additionally, coherent and incoherent oscillations dependent on probe photon energies were found, as predicted by the calculation.