Principal factors that determine the extension of detection range in molecular beacon aptamer/conjugated polyelectrolyte bioassays.

A strategy to extend the detection range of weakly-binding targets is reported that takes advantage of fluorescence resonance energy transfer (FRET)-based bioassays based on molecular beacon aptamers (MBAs) and cationic conjugated polyelectrolytes (CPEs). In comparison to other aptamer-target pairs, the aptamer-based adenosine triphosphate (ATP) detection assays are limited by the relatively weak binding between the two partners. In response, a series of MBAs were designed that have different stem stabilities while keeping the constant ATP-specific aptamer sequence in the loop part. The MBAs are labeled with a fluorophore and a quencher at both termini. In the absence of ATP, the hairpin MBAs can be opened by CPEs via a combination of electrostatic and hydrophobic interactions, showing a FRET-sensitized fluorophore signal. In the presence of ATP, the aptamer forms a G-quadruplex and the FRET signal decreases due to tighter contact between the fluorophore and quencher in the ATP/MBA/CPE triplex structure. The FRET-sensitized signal is inversely proportional to [ATP]. The extension of the detection range is determined by the competition between opening of the ATP/MBA G-quadruplex by CPEs and the composite influence by ATP/aptamer binding and the stem interactions. With increasing stem stability, the weak binding of ATP and its aptamer is successfully compensated to show the resistance to disruption by CPEs, resulting in a substantially broadened detection range (from millimolar up to nanomolar concentrations) and a remarkably improved limit of detection. From a general perspective, this strategy has the potential to be extended to other chemical- and biological-assays with low target binding affinity

Anti-inflammatory effect of neo-lignan isoamericanin A via suppression of NF-κB in liposaccharide-stimulated RAW 264.7 cells

Purpose: To investigate the potential anti-inflammatory effects of the seeds of Opuntina humifusa and its active constituents.Methods: The extract of O. humifusa seeds was tested for the inhibition of nitric oxide (NO) production in liposaccharide (LPS)-stimulated RAW 264.7 cells using Griess reagent. The active constituents were isolated using bioassay-guided isolation methods. The effects of the active constituent on NO, proinflammatory cytokines, nuclear factor-kappa B (NF-κB) and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor (IκB) were evaluated by enzyme-linked immunosorbent assay (ELISA) and western blot analysis.Results: The seed extract of O. humifusa significantly attenuated LPS-induced NO production in RAW 264.7 cells (p < 0.05). Bioassay-guided fractionation resulted in the isolation of isoamericanin A as an active constituent. Isoamericanin A reduced LPS-induced production of NO, iNOS, and proinflammatory cytokines (TNF-α and IL-6) in a concentration-dependent manner (p < 0.05). Furthermore, the effect was accompanied by decreased translocation of NF-κB from the cytosol to the nucleus and the decreased phosphorylation of IκB in the cytosol induced by LPS (p < 0.05).Conclusion: The seed extract of O. humifusa and its active constituent, isoamericanin A, have antiinflammatory effects in LPS-stimulated RAW 264.7 cells, suggesting that they have potentials as antiinflammatory agents. Keywords: Opuntia humifusa seeds, Isoamericanin A, Nitric oxide, RAW 264.7 cells, NF-kappa

Brain-based medical education model for expert’s clinical decision making

Purpose The expertise of medicians in clinical decision-making is very important since it improves the quality of medical services provided to patients. This study analyzed the characteristics of the decision-making process and confirmed clinicians’ electroencephalography (EEG) characteristics by measuring their cerebral activity during clinical decision-making. This study aims to present learning directions for brain-based clinical decision-making to develop medical experts. Methods This study was performed in the following two projects: (1) a qualitative study of clinical decision-making in a clinical scenario and (2) an analysis of differences in cortical activity of experts and novices through EEG. Results In the 1st study, this study found that “confirmation of the patient’s chief complaints,” “physical examination,” and “radiography reading” steps, which showed the most prominent differences in the experts’ and novices’ decision making, were set as the significant steps of dentists’ clinical decision making. In the 2nd study, the experts’ and novices’ cortical activities were measured through a 32-channel EEG. In task 6, which had the lowest accuracy of diagnoses made by the experts, the brain activities in both groups were higher than in other tasks. Conclusion This study developed and suggested a model of the decision-making process for experts and novices and suggested the basic directions for brain-based learning needed to raise experts based on brain activity

Inhomogeneous Defect Distribution in Mixed-Polytype Metal Halide Perovskites

The competition between corner, edge and face-sharing octahedral networks is a cause of phase inhomogeneity in metal halide perovskite thin-films. Here we probe the charged iodine vacancy distribution and transport at the junction between cubic and hexagonal polytypes of CsPbI$_3$ from first-principles materials modelling. We predict a lower defect formation energy in the face-sharing regions, which correlates with a longer Pb$-$I bond length and causes a million-fold increase in local defect concentration. These defects are predicted to be more mobile in the face-sharing regions with a reduced activation energy for vacancy-mediated diffusion. We conclude that hexagonal phase inclusions or interfaces will act as defect sinks that could trap charges and enhance current-voltage hysteresis in perovskite-based solar cells and electrical devices

PD-1 deficiency protects experimental colitis via alteration of gut microbiota

Programmed cell death-1 (PD-1) is a coinhibitory molecule and plays a pivotal role in immune regulation. Here, we demonstrate a role for PD-1 in pathogenesis of inflammatory bowel disease (IBD). Wild-type (WT) mice had severe wasting disease during experimentally induced colitis, while mice deficient for PD-1 (PD-1(-/-)) did not develop colon inflammation. Interestingly, PD-1(-/-) mice cohoused with WT mice became susceptible to colitis, suggesting that resistance of PD-1(-/-) mice to colitis is dependent on their gut microbiota. 16S rRNA gene-pyrosequencing analysis showed that PD-1(-/-) mice had altered composition of gut microbiota with significant reduction in Rikenellaceae family. These altered colon bacteria of PD-1(-/-) mice induced less amount of inflammatory mediators from colon epithelial cells, including interleukin (IL)-6, and inflammatory chemokines. Taken together, our study indicates that PD-1 expression is involved in the resistance to experimental colitis through altered bacterial communities of colon.112Ysciescopuskc

Methano­ldinitrato[N-(2-pyridylmethyl­ene)aniline]copper(II)

The Cu atom in the title compound, [Cu(NO3)2(C12H10N2)(CH3OH)], adopts a square-pyramidal geometry, being ligated by two N atoms of the bidentate N-(2-pyridylmethyl­ene)­aniline (ppma) ligand, two O atoms of NO3 ligands and one O atom of a methanol molecule, which occupies the apical position. The phenyl ring on the ppma ligand is twisted out of the pyridine plane, forming a dihedral angle of 42.9 (1)°. In the crystal, inter­molecular O—H⋯O hydrogen bonds between methanol and NO3 ligands form an extensive one-dimensional network extending parallel to [100]