Plastron Respiration Using Commercial Fabrics

A variety of insect and arachnid species are able to remain submerged in water indefinitely using plastron respiration. A plastron is a surface-retained film of air produced by surface morphology that acts as an oxygen-carbon dioxide exchange surface. Many highly water repellent and hydrophobic surfaces when placed in water exhibit a silvery sheen which is characteristic of a plastron. In this article, the hydrophobicity of a range of commercially available water repellent fabrics and polymer membranes is investigated, and how the surface of the materials mimics this mechanism of underwater respiration is demonstrated allowing direct extraction of oxygen from oxygenated water. The coverage of the surface with the plastron air layer was measured using confocal microscopy. A zinc/oxygen cell is used to consume oxygen within containers constructed from the different membranes, and the oxygen consumed by the cell is compared to the change in oxygen concentration as measured by an oxygen probe. By comparing the membranes to an air-tight reference sample, it was found that the membranes facilitated oxygen transfer from the water into the container, with the most successful membrane showing a 1.90:1 ratio between the cell oxygen consumption and the change in concentration within the container.     

The Diagnosis of Diverticulitis in Outpatients: On What Evidence?

Purpose  

Diverticular disease is common in the outpatient setting; yet, rigorous study of diagnosis and management strategies is currently limited to hospitalized patients. Here, we characterize the clinical assessment generating the diagnostic label of diverticulitis in outpatients.     

Incubation of nicotine seeking is associated with enhanced protein kinase A‐regulated signaling of dopamine‐ and cAMP‐regulated phosphoprotein of 32 kDa in the insular cortex

A recent clinical study demonstrated that damage to the insular cortex can disrupt tobacco addiction. The neurobiological mechanisms for this effect are not yet understood. In this study we used an animal model of nicotine addiction to examine the possibility that changes in insular cortex levels of dopamine (DA)‐ and cAMP‐regulated phosphoprotein of 32 kDa (DARPP‐32), a phosphoprotein enriched in DA neurons containing DA D1 receptors, may be associated with changes in vulnerability to nicotine addiction. Once rats acquired self‐administration, they were given unlimited access to nicotine (0.01 mg/kg/infusion) for 23 h/day for a total of 10 days. Each infusion was paired with a visual cue (stimulus light) and auditory cue (sound of pump). Nicotine seeking, as assessed under a cue‐induced reinstatement paradigm, and markers of DARPP‐32 signaling, as assessed using western blot analysis, were examined in separate groups of rats at two different abstinent intervals: 1 and 7 days. Consistent with findings with other drugs of abuse, rats in the 7‐day abstinence group took longer to extinguish and responded at higher levels during reinstatement testing as compared with rats in the 1‐day reinstatement group. Relative to saline controls, rats in the 7‐day but not the 1‐day abstinence group had higher levels of DARPP‐32 phosphorylated at the protein kinase A site in the insular cortex. These results demonstrate incubation of drug seeking following extended access to nicotine self‐administration and suggest that enhanced protein kinase A signaling in the insular cortex via phosphorylation of DARPP‐32 at Thr34 is associated with this effect.