Comparison of active and passive electrodes in their optimized electroencephalography amplifier system

Electroencephalography (EEG) is a common method of obtaining temporally distinguishable event-related potentials (ERP). The quality of the signal is dependent on several factors, including the selection of the amplifier system and electrode type. The aim of this study is to compare the performance of two electrode types, active and passive, with their respectively optimized amplifier system, in distinguishing an ERP signal. The QuickAmp system was used with passive electrodes, while the ActiCHamp was used with active electrodes. EEG data were recorded by the two amplifier systems in different experimental sessions. In each experimental session, the same participant listened to the same set of acoustically controlled English sentences. Data were obtained from the participant via a 32-channel Easycap (10-20 configuration), through the amplifier, to the BrainVision signal recording software. Based on the analysis using EEGlab, it appears that ActiCHamp reduced noise power, but also yielded lower signal power. The results are preliminary, being from a single participant, but suggest both electrode types can yield comparable signal-to-noise ratios

Mechanical properties of soft biological membranes for organ-on-a-chip assessed by bulge test and AFM

Advanced in vitro models called "organ-on-a-chip" can mimic the specific cellular environment found in various tissues. Many of these models include a thin, sometimes flexible, membrane aimed at mimicking the extracellular matrix (ECM) scaffold of in vivo barriers. These membranes are often made of polydimethylsiloxane (PDMS), a silicone rubber that poorly mimics the chemical and physical properties of the basal membrane. However, the ECM and its mechanical properties play a key role in the homeostasis of a tissue. Here, we report about biological membranes with a composition and mechanical properties similar to those found in vivo. Two types of collagen-elastin (CE) membranes were produced: vitrified and nonvitrified (called "hydrogel membrane"). Their mechanical properties were characterized using the bulge test method. The results were compared using atomic force microscopy (AFM), a standard technique used to evaluate the Young's modulus of soft materials at the nanoscale. Our results show that CE membranes with stiffnesses ranging from several hundred of kPa down to 1 kPa can be produced by tuning the CE ratio, the production mode (vitrified or not), and/or certain parameters such as temperature. The Young's modulus can easily be determined using the bulge test. This method is a robust and reproducible to determine membrane stiffness, even for soft membranes, which are more difficult to assess by AFM. Assessment of the impact of substrate stiffness on the spread of human fibroblasts on these surfaces showed that cell spread is lower on softer surfaces than on stiffer surfaces

Cancer-cell stiffening via cholesterol depletion enhances adoptive T-cell immunotherapy

Malignant transformation and tumour progression are associated with cancer-cell softening. Yet how the biomechanics of cancer cells affects T-cell-mediated cytotoxicity and thus the outcomes of adoptive T-cell immunotherapies is unknown. Here we show that T-cell-mediated cancer-cell killing is hampered for cortically soft cancer cells, which have plasma membranes enriched in cholesterol, and that cancer-cell stiffening via cholesterol depletion augments T-cell cytotoxicity and enhances the efficacy of adoptive T-cell therapy against solid tumours in mice. We also show that the enhanced cytotoxicity against stiffened cancer cells is mediated by augmented T-cell forces arising from an increased accumulation of filamentous actin at the immunological synapse, and that cancer-cell stiffening has negligible influence on: T-cell-receptor signalling, production of cytolytic proteins such as granzyme B, secretion of interferon gamma and tumour necrosis factor alpha, and Fas-receptor-Fas-ligand interactions. Our findings reveal a mechanical immune checkpoint that could be targeted therapeutically to improve the effectiveness of cancer immunotherapies

Support Data to "Interface flexibility controls the nucleation and growth of supramolecular networks"

Overview This repository contains the inputs and support data for the publication "Interface Flexibility Controls the Nucleation and Growth of Supramolecular Networks," which is currently under review in Nature Chemistry. Folder Structure Each subfolder is named after the primary method used to obtain the data. The internal structure may vary depending on whether it was more convenient to organize the data by the figure they were used for or by the structures analyzed. Each folder includes a detailed README.md file providing further information

Support Data to "Interface flexibility controls the nucleation and growth of supramolecular networks"

Overview This repository contains the inputs and support data for the publication "Interface Flexibility Controls the Nucleation and Growth of Supramolecular Networks," which is currently under review in Nature Chemistry. Folder Structure Each subfolder is named after the primary method used to obtain the data. The internal structure may vary depending on whether it was more convenient to organize the data by the figure they were used for or by the structures analyzed. Each folder includes a detailed README.md file providing further information