A Synthesis of All Stereoisomers of Tenuecyclamide A Employing a Fluorous-Fmoc Strategy

A concise liquid-phase combinatorial synthesis of all stereoisomers of Tenuecyclamide A was achieved using a mixture of d-/l-alanine with each stereoisomer encoded by a different f-Fmoc tag. The synthetic strategy using f-Fmoc reagents as the protecting group for amino acids has been demonstrated to be a useful method for diverse polypeptide analogue synthesis

Direct Observation of Group‑V Dopant Substitutional Defects in CdTe Single Crystals

Point defect chemistry strongly affects the fundamental properties of materials and has a decisive impact on device performance. The Group-V dopant is prominent acceptor species with high hole concentration in CdTe; however, its local atomic structure is still not clear owing to difficulties in definitive measurements and discrepancies between experimental observations and theoretical models. Herein, we report on direct observation of the local structure for the As dopant in CdTe single crystals by the X-ray fluorescence holography (XFH) technique, which is a powerful tool to visualize three-dimensional atomic configurations around a specific element. The XFH result shows the As substituting on both Cd (AsCd) and Te (AsTe) sites. Although AsTe has been well known as a shallow acceptor, AsCd has not attracted much attention and been discussed so far. Our results provide new insights into point defects by expanding the experimental XFH study in combination with theoretical first-principles studies in II–VI semiconductors

Nanophase Separation in K_1–<i>x</i>Ca_<i>x</i>C₈ Revealed by X‑ray Fluorescence Holography and Extended X‑ray Absorption Fine Structure

Even at low Ca concentrations, the binary-element intercalated graphite K1–xCaxC8 exhibits high superconducting transition temperatures Tc, closer to that of CaC6 (11.5 K) than KC8 (0.169 K). To investigate the behaviors of K and Ca within the graphite matrix, their local structures have been investigated by using X-ray fluorescence holography and extended X-ray absorption fine structure (EXAFS) spectroscopy. The atomic images reconstructed from the K–Kα and Ca–Kβ holograms showed that K0.7Ca0.3C8 did not take the solid-solution type random distribution of Ca and K atoms; instead, a nanoscale phase separation of CaC6 and KC8 was observed, which was also supported by the EXAFS results. While the lattice constant of K0.7Ca0.3C8 was close to that of KC8, we found a nanoscale Ca layer dispersed within the sample. The Ca nanolayer was offset from the center between the C sublayers. The superconducting behavior found in K1–xCaxC8 was discussed with two scenarios of percolation of CaC6 and deformation of graphene based on such a specific inhomogeneous binary element monatomic layers. This study represents an important step for understanding the superconducting properties in a nanoscale phase-separated system

Ghrelin Protects against Renal Damages Induced by Angiotensin-II via an Antioxidative Stress Mechanism in Mice

<div><p>We explored the renal protective effects by a gut peptide, Ghrelin. Daily peritoneal injection with Ghrelin ameliorated renal damages in continuously angiotensin II (AngII)-infused C57BL/6 mice as assessed by urinary excretion of protein and renal tubular markers. AngII-induced increase in reactive oxygen species (ROS) levels and senescent changes were attenuated by Ghrelin. Ghrelin also inhibited AngII-induced upregulations of transforming growth factor-β (TGF-β) and plasminogen activator inhibitor-1 (PAI-1), ameliorating renal fibrotic changes. These effects were accompanied by concomitant increase in mitochondria uncoupling protein, UCP2 as well as in a key regulator of mitochondria biosynthesis, PGC1α. In renal proximal cell line, HK-2 cells, Ghrelin reduced mitochondria membrane potential and mitochondria-derived ROS. The transfection of UCP2 siRNA abolished the decrease in mitochondria-derived ROS by Ghrelin. Ghrelin ameliorated AngII-induced renal tubular cell senescent changes and AngII-induced TGF-β and PAI-1 expressions. Finally, Ghrelin receptor, growth hormone secretagogue receptor (GHSR)-null mice exhibited an increase in tubular damages, renal ROS levels, renal senescent changes and fibrosis complicated with renal dysfunction. GHSR-null mice harbored elongated mitochondria in the proximal tubules. In conclusion, Ghrelin suppressed AngII-induced renal damages through its UCP2 dependent anti-oxidative stress effect and mitochondria maintenance. Ghrelin/GHSR pathway played an important role in the maintenance of ROS levels in the kidney.</p></div

Amelioration of renal tubular damages and increased renal oxidative stress by Ghrelin in AngII-infused mice.

<p>The effects of Ghrelin treatment on the phenotypes of AngII-infused mice. Blood pressures (A), daily chow intake (B) and body weight (C) were compared among saline-infused mice (NS), AngII-infused mice (AngII), and AngII-infused mice treated with Ghrelin (AngII+Ghrelin) or Hydralazine (AngII+Hydralazine). Serum levels of blood urea nitrogen (BUN, D) and creatinine (E), urinary excretion of protein (F), neutrophil gelatinase-associated lipocalin (NGAL, G), n-acetyl-galactasaminase (NAG, H) were compared among the experimental groups. (I) Representative immunostaining for the Ghrelin receptor (Growth hormone secretagogue receptor, GHSR) is shown in the middle panel. Negative control without using anti-GHSR antibody is shown in the left panel. The staining of GHSR in the kidney of GHSR null mice is also shown in the right panel. Scale bar, 50 µm. G represents glomerulus. (J) Representative immunostaining for 4-Hydroxynonenal-2-nonenal (4HNE) of four experimental groups. Bar graphs represent the quantification of immunostained areas. Scale bar; 50 µm. **p<0.01 vs. NS, *p<0.05 vs. NS, ##p<0.01 vs. AngII, #p<0.05 vs. AngII, N.S. represents no significant difference. n = 8.</p

Amelioration of renal tissue senescent and fibrotic changes by Ghrelin in AngII-infused mice.

<p>(A) Representative staining of senescence-associated β-Galactosidase (SA β-Gal). Scale bar, 100 µm. NS represents normal saline. (B) The protein expressions of p53 (left) and p21 (right) in saline-infused mice (NS), AngII-infused mice (AngII), and AngII-infused mice treated with Ghrelin. The representative immunoblotting (upper panel) and the results of densitometry analysis (lower panel) are shown. (C) The expression of TGF-β (left) and PAI-1 (right) mRNA in mice of each group. (D) The representative results of Masson-Trichrome staining of each experimental group. Bar graphs represent the quantification of fibrotic areas. Scale bar; 100 µm. (E) The mRNA expression levels of type I collagen in the kidney of each group. **p<0.01 vs. NS, *p<0.05 vs. NS, ##p<0.01 vs. AngII, #p<0.05 vs. AngII, n = 8.</p

The amelioration of cellular senescent changes in AngII-treated HK-2 by Ghrelin.

<p>(A) Representative staining of senescence-associated β-Galactosidase (SA β-Gal) in untreated HK-2 cells (control), AngII-treated HK-2 cells (AngII, 1 µM), and AngII-treated with the pretreatment of 10 nM Ghrelin (AngII+Ghrelin), 10 nM Des-acyl-Ghrelin (AngII+Des-acy-Ghrelin), or 1 µM AngII type 1 receptor antagonist, irbesartan (left panel). Bar graphs represent the quantification of stained cells (right panel). (B) The protein expressions of p53 (left) and p21 (right) in HK-2 cells. The representative immunoblotting (upper panel) and the results of densitometry analysis (lower panel) were shown. (C) The expression of TGF-β mRNA in HK-2 cells (upper panel) and the concentration of TGF-β in the medium of HK-2 cells (lower panel). (D) The expression of PAI-1 mRNA in HK-2 cells (upper panel) and the concentration of PAI-1 in the medium of HK-2 cells (lower panel). C; control cells, AngII; HK-2 cells treated with 1 µM of AngII, G1, G10, G100; HK-2 cells treated with 1 nM, 10 nM, and 100 nM of Ghrelin, respectively, Des-G; HK-2 cells treated with 10 nM of Des-acyl-Ghrelin, Irb; HK-2 cells treated with 1 µM of irbesartan **p<0.01 vs. control HK-2 cells, *p<0.05 vs. control HK-2 cells, ##p<0.01 vs. AngII-treated HK-2 cells, #p<0.05 vs. AngII-treated HK-2 cells, n = 8.</p

Mitochondria-derived ROS was reduced by Ghrelin through the induction of UCP2.

<p>(A) The effects of Ghrelin on mitochondria-derived UCP2 mRNA levels. (B) Mitochondrial membrane potential was measured by the specific dye as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0094373#s4" target="_blank">Materials and Methods</a>. **p<0.01 vs. control cells, n = 8. (C, D) The effects of Ghrelin on mitochondria-derived ROS levels (C) and mitochondria number (D) in HK-2 cells. **p<0.01 vs. control HK-2 cells, *p<0.05 vs. control, n = 8. (E) The effects of AMP-kinase inhibitor on Ghrelin-induced UCP2 upregulation. Compound C, AMP-kinase inhibitor at the concentrations of 2 and 20 µM was pretreated 30 minutes before the Ghrelin administration to HK-2 cells. **p<0.01 vs. control HK-2 cells, ##p<0.01 vs. HK-2 cells treated with 100 nM of Ghrelin, ¶p<0.05 vs. Ghrelin-treated cell with 2 µM of Compound C administration, n = 8. (F) Knock-down of UCP2 protein and mRNA were shown in the representative immunoblotting (left panel) and real-time PCR (right panel), respectively. **p<0.01 vs. control siRNA-transfected cells, n = 6. (G–I) Mitochondria-derived ROS (G), total cellular ROS (H), and total cellular superoxide (I) were measured after the transfection of UCP2 siRNA or control siRNA. HK-2 cells were transfected with siRNA and treated with or without 100 nM of Ghrelin **p<0.01 vs. control siRNA-transfected cells without Ghrelin. N.S. represents no significant difference. n = 8. (J) The effects of Ghrelin on AngII-induced Mitochondrial ROS production. HK-2 cells were treated with 1 nM, 10 nM, and 100 nM of Ghrelin 30 minutes before the treatment with 1 mM of AngII. respectively. **p<0.01 vs. control cells, *p<0.05 vs. control cells, ##p<0.01 vs. AngII-treated HK-2 cells, #p<0.05 vs. AngII-treated HK-2 cells, n = 8.</p

Schema depicting the renal protective effects by Ghrelin.

<p>Ghrelin upregulated UCP2 and decreased mitochondria-derived oxidative stress levels. These effects mitigated mitochondria damages and retained the mitochondria number, contributory to its anti-senescent effects. Anti-senescent effects by ghrelin was related to the downregulation of TGF-β and PAI-1, pro-fibrotic genes and inhibited the tissue fibrotic changes.</p

Phenotype of GHSR-null mice.

<p>(A) The primers used for the genotyping in the PCR (left) and representative results of genotyping (right). The primers used are indicated as arrows. TBC, transcription blocking cassette. (B–J) The phenotype differences among the four experimental groups: WT or GHSR^−/− mice infused with normal saline (NS) or AngII. Blood pressure (B), daily chow intake (C), body weight (D) were compared among the four groups. Serum levels of blood urea nitrogen (BUN, E) and creatinine (F) and urinary excretion of protein (G), neutrophil gelatinase-associated lipocalin (NGAL, H), and n-acetyl-galactasaminase (NAG, I) were compared among the four experimental groups. Urinary excretion of each marker was normalized by that of creatinine. (J) Representative immunostaining for 4-Hydroxynonenal-2-nonenal (4HNE) of four experimental groups. Bar graph represents the quantification of immunostained areas. Scale bar; 50 µm. **p<0.01 vs. WT+NS, *p<0.05 vs. WT+NS, ##p<0.01 vs. GHSR^−/−+NS, #p<0.05 vs. GHSR^−/−+NS, n = 8.</p