A Comparison of Social Exclusion Towards People with Depression or Chronic Back Pain.

Objectives: Research comparing mental and physical health stigma is scarce. The aim of this study was to compare social exclusion towards hypothetical males and females with depression or chronic back pain. Furthermore, the study investigated whether social exclusion is associated with participant's empathy and personality traits, while controlling for their sex, age and personal exposure to mental/physical chronic health conditions. Design: This study employed a cross-sectional questionnaire design. Methods: Participants (N = 253) completed an online vignette-based questionnaire and were randomly allocated to either a depression or chronic back pain study condition. Measures of social exclusion through respondents' willingness to interact with hypothetical individuals, empathy and the Big Five personality traits were completed. Results: Willingness to interact scores did not significantly differ depending on the diagnosis or sex of the hypothetical person in the vignette. For depression, higher levels of conscientiousness significantly predicted less willingness to interact. Whilst being a female participant and having higher empathy significantly predicted greater willingness to interact. For chronic back pain, higher empathy significantly predicted greater willingness to interact, with no significant predictors found from the Big Five personality traits. Conclusion: Findings indicate that females and males with depression or chronic back pain face similar levels of social exclusion, with empathy being a core variable driving social exclusion behaviours. These findings enhance our understanding of potential variables driving social exclusion, in-turn informing campaign development to reduce public stigma towards depression and chronic back pain.

Simultaneous Quantification of Protein Binding Kinetics in Whole Cells with Surface Plasmon Resonance Imaging and Edge Deformation Tracking.

Most drugs work by binding to receptors on the cell surface. Quantification of binding kinetics between drug and membrane protein is an essential step in drug discovery. Current methods for measuring binding kinetics involve extracting the membrane protein and labeling, and both have issues. Surface plasmon resonance (SPR) imaging has been demonstrated for quantification of protein binding to cells with single-cell resolution, but it only senses the bottom of the cell and the signal diminishes with the molecule size. We have discovered that ligand binding to the cell surface is accompanied by a small cell membrane deformation, which can be used to measure the binding kinetics by tracking the cell edge deformation. Here, we report the first integration of SPR imaging and cell edge tracking methods in a single device, and we use lectin interaction as a model system to demonstrate the capability of the device. The integration enables the simultaneous collection of complementary information provided by both methods. Edge tracking provides the advantage of small molecule binding detection capability, while the SPR signal scales with the ligand mass and can quantify membrane protein density. The kinetic constants from the two methods were cross-validated and found to be in agreement at the single-cell level. The variation of observed rate constant between the two methods is about 0.009 s-1, which is about the same level as the cell-to-cell variations. This result confirms that both methods can be used to measure whole-cell binding kinetics, and the integration improves the reliability and capability of the measurement.

Optical Tracking of Nanometer-Scale Cellular Membrane Deformation Associated with Single Vesicle Release.

Exocytosis involves interactions between secretory vesicles and the plasma membrane. Studying the membrane response is thus critical to understand this important cellular process and to differentiate different mediator release patterns. Here we introduce a label-free optical imaging method to detect the vesicle-membrane-interaction-induced membrane deformation associated with single exocytosis in mast cells. We show that the plasma membrane expands by a few tens of nanometers accompanying each vesicle-release event, but the dynamics of the membrane deformation varies from cell to cell, which reflect different exocytosis processes. Combining the temporal and spatial information allows us to resolve complex vesicle-release processes, such as two vesicle-release events that occur closely in time and location. Simultaneous following a vesicle release with fluorescence and membrane deformation tracking further allows us to determine the propagation speed of the vesicle-release-induced membrane deformation along the cell surface, which has an average value of 5.2 ± 1.8 µm/s.

Label-Free Quantification of Small-Molecule Binding to Membrane Proteins on Single Cells by Tracking Nanometer-Scale Cellular Membrane Deformation.

Measuring molecular binding to membrane proteins is critical for understanding cellular functions, validating biomarkers, and screening drugs. Despite the importance, developing such a capability has been a difficult challenge, especially for small-molecule binding to membrane proteins in their native cellular environment. Here we show that the binding of both large and small molecules to membrane proteins can be quantified on single cells by trapping single cells with a microfluidic device and detecting binding-induced cellular membrane deformation on the nanometer scale with label-free optical imaging. We develop a thermodynamic model to describe the binding-induced membrane deformation, validate the model by examining the dependence of membrane deformation on cell stiffness, membrane protein expression level, and binding affinity, and study four major types of membrane proteins, including glycoproteins, ion channels, G-protein coupled receptors, and tyrosine kinase receptors. The single-cell detection capability reveals the importance of local membrane environment on molecular binding and variability in the binding kinetics of different cell lines and heterogeneity of different cells within the same cell line.

Self-Assembly of Complex DNA Tessellations by Using Low-Symmetry Multi-arm DNA Tiles.

Modular DNA tile-based self-assembly is a versatile way to engineer basic tessellation patterns on the nanometer scale, but it remains challenging to achieve high levels of structural complexity. We introduce a set of general design principles to create intricate DNA tessellations by employing multi-arm DNA motifs with low symmetry. We achieved two novel Archimedean tiling patterns, (4.8.8) and (3.6.3.6), and one pattern with higher-order structures beyond the complexity observed in Archimedean tiling. Our success in assembling complicated DNA tessellations demonstrates the broad design space of DNA structural motifs, enriching the toolbox of DNA tile-based self-assembly and expanding the complexity boundaries of DNA tile-based tessellation.

A new chemical probe for phosphatidylinositol kinase activity.

Phosphatidylinositol kinases (PIKs) are key enzymatic regulators of membrane phospholipids and membrane environments that control many aspects of cellular function, from signal transduction to secretion, through the Golgi apparatus. Here, we have developed a photoreactive "clickable" probe, PIK-BPyne, to report the activity of PIKs. We investigated the selectivity and efficiency of the probe to both inhibit and label PIKs, and we compared PIK-BPyne to a wortmannin activity-based probe also known to target PIKs. We found that PIK-BPyne can act as an effective in situ activity-based probe, and for the first time, report changes in PI4K-IIIß activity induced by the hepatitis C virus. These results establish the utility of PIK-BPyne for activity-based protein profiling studies of PIK function in native biological systems.

Synthesis of azomethine imines using an intramolecular alkyne hydrohydrazination approach.

Azomethine imines can be accessed upon heating appropriate alkynylhydrazide precursors. This simple thermal hydroamination approach allows the formation of five- and six-membered dipoles in modest to excellent yields. The structure of the acyl group is important to minimize side reactions and allow the isolation of the azomethine imines by column chromatography.

Hydrazides as tunable reagents for alkene hydroamination and aminocarbonylation.

Benzoic hydrazides (R = Ph), which are remarkably bench and thermally stable reagents (often up to 230 degrees C), afford intramolecular hydroamination products upon heating at high temperatures (120-235 degrees C). A concerted Cope-type hydroamination event, followed by a hydrazide-mediated proton transfer step of the hydrazinium ylide intermediate, is proposed and supported by DFT calculations. In contrast, a simple modification of the reagent structure (R = Ot-Bu or NH(2)) favors the formation of aminocarbonylation products at 200 degrees C, and the latter reaction is shown to be stereospecific.