Proton transfer and regulation across chemical interfaces by small-molecule assemblies.

We report on measurements and control of proton gradient across interfaces of water and dichloroethane. Such interfaces are interesting as mimics of biological membranes. We use impedance spectroscopy to quantify interfacial proton gradient and identify proton transfer modes. We quantify proton movement using reciprocal of time constant (τ-1 ) acquired from electrochemical impedance modeling. We show that proton gradient across interfaces of water/dichloroethane and τ-1 correlate with the aqueous phase pH, changing from ca. 1 s-1 at pH 1 to 0.2 s-1 at pH 7. τ-1 changes in the presence of proton shuttling fat-soluble molecules. Dinitrophenol acts as a pH activated proton coupler which is active at around neutral pH and inert at pH <4. However, quinone type cofactors change the interfacial proton transport when activated by redox reactions with ferrocene type molecules, such as decamethyl ferrocence (DMFc). Quinone type cofactors show distinct features in their impedance response assigned to a proton coupled electron transfer (PCET) process, different from the uncoupled proton transfer activity of dinitrophenol. The observed PCET reaction significantly changes τ-1 . We use τ-1 as a proton transport descriptor. In particular, CoQ10 -DMFc shows a τ-1 of 3.5 s-1 at pH 7, indicating how small-molecule assemblies change proton availability.

Update on pressure ulcer management and deep tissue injury.

OBJECTIVE: To review recent literature regarding therapeutic management of pressure ulcers and to discuss the potential implications of the newly recognized entity, deep tissue injury (DTI). DATA SOURCES: A MEDLINE search was conducted of pressure ulcer therapy published between January 2001 and October 2009. Key search terms included pressure ulcers, deep tissue injury, nutrition, antibiotics, and therapy. STUDY SELECTION AND DATA EXTRACTION: Comparative clinical trials involving pharmacologic agents in the treatment of pressure ulcers and DTI were evaluated. Included trials were those with defined interventions and outcome parameters for wound healing. DATA SYNTHESIS: Pressure ulcers remain an important issue in the care of elderly and immobilized patients. DTI has been recently added by the National Pressure Ulcer Advisory Panel as a separate category in the staging of pressure ulcers. There is currently a lack of consensus on how to identify and treat DTI, but preventive measures typically employed in the management of all pressure ulcers have been recommended. Recent studies on topical phenytoin, silver preparations, and growth factors report benefit in the management of pressure ulcers. However, studies evaluating these treatment approaches often lack the sample size necessary to adequately support recommendations. CONCLUSIONS: Determining the extent of tissue damage in DTI is currently not possible. Therefore, management recommendations focus on limiting extension of the ulcer stage through preventive strategies. Routine use of topical phenytoin, silver preparations, or growth factors in therapy of pressure ulcers cannot be recommended until more data from rigorously designed studies are available.