Discerning γ‑Alumina Surface Sites with Nitrogen-15 Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy of Adsorbed Pyridine

Low-temperature ¹⁵N dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP SENS) of adsorbed pyridine in combination with FTIR measurements and DFT calculations was applied to investigate the surface sites of γ-alumina, which can be divided into four groups: (1) groups 1 and 2, associated with less shielded ¹⁵N chemical shifts and the lowest ν­(8a) frequencies of adsorbed pyridine, corresponding to weakly adsorbed H-bonding pyridine to hydroxyl group or chemisorbed water on alumina; (2) group 3, with intermediate ¹⁵N chemical shifts and ν­(8a) frequencies, corresponding to pyridine coordinated to specific Lewis acid sites, namely five-coordinated (Al_V) aluminum atoms of the (100) facet, as well as some H-bonded pyridine; (3) group 4, associated with the most shielded ¹⁵N chemical shift and the highest ν­(8a) frequency, selectively assigned to Lewis acid Al sites located on the (110) facet and corresponding to both four- and five-coordinated aluminum atoms (Al_IV and Al_V). Noteworthy, a correlation between the ¹⁵N chemical shift and the adsorption energy of pyridine, that is H-bonded or coordinated to Al Lewis acid sites, was identified: the stronger the adsorption, the more shielded the ¹⁵N chemical shift. According to Natural Chemical Shielding (NCS) analysis, this behavior is traced back to the bonding interaction of the lone pair of pyridine and the Lewis acid or OH sites, which controls a specific principal component of the chemical shift tensor of pyridine on one hand, and the adsorption energy on the other hand. This correlation between ¹⁵N chemical shift and adsorption energy is likely general since it has a well-defined molecular origin and can thus be extended to other oxides

Electronic Structure–Reactivity Relationship on Ruthenium Step-Edge Sites from Carbonyl ¹³C Chemical Shift Analysis

Ru nanoparticles are highly active catalysts for the Fischer–Tropsch and the Haber–Bosch processes. They show various types of surface sites upon CO adsorption according to NMR spectroscopy. Compared to terminal and bridging η¹ adsorption modes on terraces or edges, little is known about side-on η² CO species coordinated to B₅ or B₆ step-edges, the proposed active sites for CO and N₂ cleavage. By using solid-state NMR and DFT calculations, we analyze ¹³C chemical shift tensors (CSTs) of carbonyl ligands on the molecular cluster model for Ru nanoparticles, Ru₆(η²-μ₄-CO)₂(CO)₁₃(η⁶-C₆Me₆), and show that, contrary to η¹ carbonyls, the CST principal components parallel to the C–O bond are extremely deshielded in the η² species due to the population of the C–O π* antibonding orbital, which weakens the bond prior to dissociation. The carbonyl CST is thus an indicator of the reactivity of both Ru clusters and Ru nanoparticles step-edge sites toward C–O bond cleavage

Photoinduced Electron Transfer as a Probe for the Folding Behavior of Dimethylsilylene-Spaced Alternating Donor–Acceptor Oligomers and Polymers

A series of oligomers and polymers having dimethylsilylene-spaced alternating 4-aminostyrene donor and stilbene acceptor chromophores (two to one) are regioselectively synthesized, and the two donor chromophores are separated by different bridges between two donors. Photophysical tools have been used to examine the folding behavior of these copolymers. Both steady-state and time-resolved fluorescence spectroscopic measurements were examined. The relative intensities (<i>I</i>_CT/<i>I</i>_LE) between emission from charge-separated state (CT emission) and local excited emission of acceptor chromophore (LE emission) increase with increasing number of repeating units, and reach a plateau, when the linkers between the two aminostyrene chromophores are trimethylene bridges. Replacements of these by dimethylene or tetramethylene linker reduce the relative intensities of CT emission of the polymers, owing to the different folding behavior of these polymers. The CT emission intensity of the polymer with rigid piperazine linkers is much lower than that with trimethylene-bridged copolymer of the same degree of polymerization. Slight conformational change of these polymers would lead to slight variation of the distance between donor and acceptor chromophores so that the nonadiabatic interactions in the excited state between donor–acceptor pairs in these oligomers and polymers would be perturbed by such change of conformations

SOX4 Transcriptionally Regulates Multiple SEMA3/Plexin Family Members and Promotes Tumor Growth in Pancreatic Cancer

<div><p>Semaphorin signaling through Plexin frequently participates in tumorigenesis and malignant progression in various types of cancer. In particular, the role of semaphorin signaling in pancreatic ductal adenocarcinoma (PDAC) remains unexplored, despite a high likelihood of metastasis and mortality. Unlike other epithelial malignancies that often express a small number of specific genes in the Semaphorin/Plexin family, five or more are often expressed in human PDAC. Such concomitant expression of these SEMA3/Plexin family members is not a result of gene amplification, but (at least partially) from increased gene transcription activated by SOX4 de novo expressed in PDAC. Via chromatin-immunoprecipitation, luciferase promoter activity assay and electrophoresis mobility shift assay, SOX4 is demonstrated to bind to the consensus site at the promoter of each <em>SEMA3</em> and <em>Plexin</em> gene to enhance transcription activity. Conversely, RNAi-knockdown of SOX4 in PDAC cell lines results in decreased expression of SEMA3/Plexin family members and is associated with restricted tumor growth both <em>in vitro</em> and in SCID mice. We further demonstrate that SOX4 levels parallel with the summed expression of SEMA3/Plexin family members (<em>P</em> = 0.033, <em>NPar</em> Kruskal-Wallis <em>one</em>-<em>way</em> analysis), which also correlates with poor survival in human PDAC (<em>P</em> = 0.0409, <em>Kaplan-Meier</em> analysis). Intriguingly, miR-129-2 and miR-335, both of which target SOX4 for degradation, are co-repressed in human PDAC cases associated with up-regulated SOX4 in a statistically significant way. In conclusion, we disclose a miR-129-2(miR-335)/SOX4/Semaphorin-Plexin regulatory axis in the tumorigenesis of pancreatic cancer.</p> </div

The incidence (%) of iatrogenic pneumothorax after bronchoscopy.

<p>The incidence (%) of iatrogenic pneumothorax after bronchoscopy.</p

Diagnostic modalities for tissue sampling and histological diagnosis for lung malignancy between the conventional bronchoscopy and endobronchial ultrasound periods.

<p>Diagnostic modalities for tissue sampling and histological diagnosis for lung malignancy between the conventional bronchoscopy and endobronchial ultrasound periods.</p

The proportion of patients who needed a CT-guided biopsy for diagnosis after failure of bronchoscopy.

<p>The proportion of patients who needed a CT-guided biopsy for diagnosis after failure of bronchoscopy.</p

Co-repressed miR-129-2 and miR-335 are associated with expression of SOX4, which correlates with shorter survival in patients with pancreatic cancer.

<p>(A) time-course change of ERK1/2 phosphorylation and the cytoplasm-nucleus distribution of SOX4 after PD98059 treatment. The whole cell lysates at the indicated time after treatment with 20 µM PD98059 were subjected fractionation, resolved by SDS-PAGE, and immunoblotted with the indicated antibodies. At 40 min after PD98059 treatment when ERK1/2 phosphorylation was inhibited, no difference was observed in the total amount of SOX4 protein, or the cytoplasm-nuclear distribution of SOX4. (B) <i>Left</i> and <i>Central</i> plots: Strong inverse correlation between miR-129-2 expression/miR-335 expression and SOX4 expression in PDAC cases as analyzed by Pearson correlation with log transformation for normality in scatter plots. n, the number of cases analyzed; Negative value in R indicates inverse correlation between X- and Y-variables. <i>Right</i> plot: the expression level of miR-335 in pancreatic carcinoma samples is positively correlated with the level of miR-129-2 in a linear regression way. (C) Marginal effect on suppressing SOX4 expression by transient transfection of miR-129-2 in PANC-1 cells as assessed by quantitative real-time PCR analysis in triplicate using a paired <i>t</i>-test. (D) Kaplan-Meier curves were shown as a function of SOX4 or E2F1 immunohistochemistry. <i>Left</i>: SOX4 expression in human PDAC correlates with shorter patient survival. <i>Right</i>: E2F1 expression did not correlate with patient survival. The <i>P</i>-value corresponds to the log-rank test by comparing the survival curves.</p

Reduced <i>in vitro</i> and <i>in vivo</i> tumor growth by SOX4 suppression.

<p>(A) Cell proliferation is affected in PANC-1 cells with RNAi-suppression of SOX4. 30000 cells were seeded into each well in a 12-well plate. At 24, 48 or 72 hours after seeding, cells were harvested and counted by trypan blue exclusion assay. <i>Error bars</i>, SD from six independent experiments, Student's <i>t</i>-test. (B) Representative flow cytometry of siSOX4 cells stained with propidium iodide shows no significant variation from scrambled-siRNA cells in apoptosis (depicted by sub-G1) or in cell cycle progression. The percentage of cells in sub-G1, G0/G1, S and G2/M phase was shown at the right downward corner of each plot. (C) representative TUNEL-labeling of cells challenged by the genotoxic agent cisplatin (10 µg/ml, 12-h). Differences in apoptosis was not observed between SOX4-knockdown (siSOX4#1 and siSOX4#2) and control (scrambled-siRNA) cells. (D) lower cell proliferation rate and decreased number of cells staying at M phase in siSOX4 cells. siSOX4 and scrambled-siRNA cells were plated on coverslips and incubated for 48 hours. Before harvest and fixation with paraformaldehyde, cells were incubated with 10 µM of BrdU for 3 hours and were then subjected to anti-Ki-67 or anti-BrdU immunofluorescent staining. Twenty randomly selected high power fields (x400) were counted for statistical analysis (Student's <i>t</i>-test). (E) Tumor xenograft of siSOX4/PANC-1 cells grows smaller than that of control cells (scrambled-siRNA) in a SCID mouse. The mice were sacrificed 30 days after subcutaneous inoculation of the control cells on the left and the siSOX4 cells on the right side of the flank. (F) Smaller and lighter tumor xenografts of siSOX4 cells compared to those of control (n = 9, Student's <i>t</i>-test). (G) representative H&E, Ki-67, PHH3 immunostain, and TUNEL labeling in tissue sections from tumor xenografts. Scale bars = 50 µm. (H, I, and J) quantification of proliferation (Ki-67 labeling), apoptosis (TUNEL stain) and mitosis (PHH3-immunostain). Eighteen randomly selected fields (x200) in each Ki-67-stained section and cells in twenty-seven randomly selected fields (x400) for TUNEL labeling or PHH3 immunostain were counted in each xenograft tumor. The proliferating index and the mitotic counts of siSOX4 tumor cells are significantly lower than that of control cells, while the percentage of apoptotic cells did not differ (Student's <i>t</i>-test). n, the total number of cells counted.</p

The comparative complication rates of bronchoscopy and CT-guided biopsy during the endobronchial bronchoscopy period.

<p>The comparative complication rates of bronchoscopy and CT-guided biopsy during the endobronchial bronchoscopy period.</p