Diverse mechanisms underlying the regulation of ion channels by carbon monoxide

Carbon monoxide (CO) is firmly established as an important, physiological signalling molecule as well as a potent toxin. Through its ability to bind metal-containing proteins, it is known to interfere with a number of intracellular signalling pathways, and such actions can account for its physiological and pathological effects. In particular, CO can modulate the intracellular production of reactive oxygen species, NO and cGMP levels, as well as regulate MAPK signalling. In this review, we consider ion channels as more recently discovered effectors of CO signalling. CO is now known to regulate a growing number of different ion channel types, and detailed studies of the underlying mechanisms of action are revealing unexpected findings. For example, there are clear areas of contention surrounding its ability to increase the activity of high conductance, Ca2+ -sensitive K+ channels. More recent studies have revealed the ability of CO to inhibit T-type Ca2+ channels and have unveiled a novel signalling pathway underlying tonic regulation of this channel. It is clear that the investigation of ion channels as effectors of CO signalling is in its infancy, and much more work is required to fully understand both the physiological and the toxic actions of this gas. Only then can its emerging use as a therapeutic tool be fully and safely exploited.

Probing the mucoadhesive interactions between porcine gastric mucin and some water-soluble polymers

This study investigates the structural features of porcine gastric mucin (PGM) in aqueous dispersions and its interactions with water-soluble polymers (poly(acrylic acid) (PAA), poly(methacrylic acid) (PMAA), poly(ethylene oxide), and poly(ethylene glycol)) using isothermal titration calorimetry, turbidimetric titration, dynamic light scattering, and transmission electron microscopy. It is established that PAA (450 kDa) and PMAA (100 kDa) exhibit strong specific interactions with PGM causing further aggregation of its particles, while PAA (2 kDa), poly(ethylene oxide) (1 000 kDa), and poly(ethylene glycol) (10 kDa) do not show any detectable effects on mucin. Sonication of mucin dispersions prior to their mixing with PAA (450 kDa) and PMAA (100 kDa) leads to more pronounced intensity of interactions.

G band atmospheric radars: new frontiers in cloud physics

Clouds and associated precipitation are the largest source of uncertainty in current weather and future climate simulations. Observations of the microphysical, dynamical and radiative processes that act at cloud scales are needed to improve our understanding of clouds. The rapid expansion of ground-based super-sites and the availability of continuous profiling and scanning multi-frequency radar observations at 35 and 94 GHz have significantly improved our ability to probe the internal structure of clouds in high temporal-spatial resolution, and to retrieve quantitative cloud and precipitation properties. However, there are still gaps in our ability to probe clouds due to large uncertainties in the retrievals. The present work discusses the potential of G band (frequency between 110 and 300 GHz) Doppler radars in combination with lower frequencies to further improve the retrievals of microphysical properties. Our results show that, thanks to a larger dynamic range in dual-wavelength reflectivity, dual-wavelength attenuation and dual-wavelength Doppler velocity (with respect to a Rayleigh reference), the inclusion of frequencies in the G band can significantly improve current profiling capabilities in three key areas: boundary layer clouds, cirrus and mid-level ice clouds, and precipitating snow.