Stretchable Device for Simultaneous Measurements of Contractility and Electrophysiology of Neuromuscular Tissue in the Gastrointestinal Tract.

Devices interfacing with biological tissues can provide valuable insights into function, disease, and metabolism through electrical and mechanical signals. However, certain neuromuscular tissues, like those in the gastrointestinal tract, undergo significant strains of up to 40%. Conventional inextensible devices cannot capture the dynamic responses in these tissues. This study introduces electrodes made from poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and polydimethylsiloxane (PDMS) that enable simultaneous monitoring of electrical and mechanical responses of gut tissue. The soft PDMS layers conform to tissue surfaces during gastrointestinal movement. Dopants, including Capstone FS-30 and polyethylene glycol, are explored to enhance the conductivity, electrical sensitivity to strain, and stability of the PEDOT:PSS. The devices are fabricated using shadow masks and solution-processing techniques, providing a faster and simpler process than traditional clean-room-based lithography. Tested on ex vivo mouse colon and human stomach, the device recorded voltage changes of up to 300 µV during contraction and distension consistent with muscle activity, while simultaneously recording resistance changes of up to 150% due to mechanical strain. These devices detect and respond to chemical stimulants and blockers, and can induce contractions through electrical stimulation. They hold great potential for studying and treating complex disorders like irritable bowel syndrome and gastroparesis

Heterogeneity of Microglial Activation in the Innate Immune Response in the Brain

The immune response in the brain has been widely investigated and while many studies have focused on the proinflammatory cytotoxic response, the brain’s innate immune system demonstrates significant heterogeneity. Microglia, like other tissue macrophages, participate in repair and resolution processes after infection or injury to restore normal tissue homeostasis. This review examines the mechanisms that lead to reduction of self-toxicity and to repair and restructuring of the damaged extracellular matrix in the brain. Part of the resolution process involves switching macrophage functional activation to include reduction of proinflammatory mediators, increased production and release of anti-inflammatory cytokines, and production of cytoactive factors involved in repair and reconstruction of the damaged brain. Two partially overlapping and complimentary functional macrophage states have been identified and are called alternative activation and acquired deactivation. The immunosuppressive and repair processes of each of these states and how alternative activation and acquired deactivation participate in chronic neuroinflammation in the brain are discussed

Strain modulation spectroscopy

The technique of resonant strain modulation has been applied for the first time to the modulation of optical transitions occurring between levels of the 4f shell of lanthanide ions. This allows changes in signal strength of typically 0.01% of the maximum spectral line height, which results from spectral line shifts smaller than 10-²/(kg/mm²), to be easily detected. After a full description the method is used to obtain the orbit lattice parameters dB₀²/dδ of Pr³⁺ in CaF₂ and SrF₂ hosts. On the assumption of a local cubic lattice these are found to be (-4.5 ± 1.5) x 10 cm and (-5.4 ± 1.0) x 10 cm respectively. The shifts of some optical transitions of CaF₂:Er³⁺are also presented. Application of the method to shifts of the vibronic sided bans of MeF₂:sm²⁺, polarisation studies of the no phonon f-d transitions of Sm²⁺, and to Er³⁺ and Sm²⁺ in different site symmetries, is also discussed