A Safety Comparison of Single-Agent Methohexital, Ketamine, or Propofol for Musculoskeletal Procedural Sedation in the Emergency Department.

BACKGROUND: The use of sedative and analgesic agents is required for procedural sedation in the emergency department (ED). Agents such as ketamine and propofol are commonly used for procedural sedation. This is likely due to clinical experience with these agents, as well as optimal pharmacologic properties when used in combination with one another. Methohexital, a barbiturate, is less frequently used due to concerns for adverse events associated with this drug class. OBJECTIVE: The objective of this study is to evaluate the safety of methohexital in comparison with ketamine and propofol when used for procedural sedation in musculoskeletal procedures. METHODS: A retrospective chart review was conducted to evaluate adult ED patients who received ketamine, propofol, or methohexital for procedural sedation from January 1, 2014 to June 30, 2020. RESULTS: Overall, a total of 43 procedures were included in the study. Procedures included shoulder relocation, elbow relocation, hip relocation, ankle reduction, radius/ulnar reduction, mandibular relocation, patellar relocation, and wrist reduction. There was a 90.6% overall procedural success rate, which was similar between groups. Overall adverse events occurred in 34.8% of patients. Respiratory depression occurred in 9.3% of patients. No incidence of respiratory depression was observed in the methohexital group, compared with 2 patients receiving ketamine and 4 receiving propofol (p = 0.44). CONCLUSION: Methohexital is a safe and effective option for procedural sedation for musculoskeletal procedures in the ED when compared with ketamine and propofol.

Variation in Spot and Stripe Patterns in Original and Regenerated Zebrafish Caudal Fins.

Tissue regeneration requires not only the replacement of lost cells and tissues, but also the recreation of morphologies and patterns. Skin pigment pattern is a relatively simple system that can allow researchers to uncover the underlying mechanisms of pattern formation. To gain insight into how pigment patterns form, undergraduate students in the senior level course Developmental Biology designed an experiment that assayed pigment patterns in original and regenerated caudal fins of wild-type, striped, and mutant, spotted zebrafish. A majority of the WT fins regenerated with a similar striped pattern. In contrast, the pattern of spots even in the original fins of the mutants varied among individual fish. Similarly, the majority of the spots in the mutants did not regenerate with the same morphology, size, or spacing as the original fins. This was true even when only a small amount of fin was removed, leaving most of the fin to potentially reseed the pattern in the regenerating tissue. This suggests that the mechanism that creates the wild-type, striped pattern persists to recreate the pattern during regeneration. The mechanism that creates the spots in the mutants, however, must include an unknown element that introduces variability.

Randomly organized lipids and marginally stable proteins: a coupling of weak interactions to optimize membrane signaling.

Eukaryotic lipids in a bilayer are dominated by weak cooperative interactions. These interactions impart highly dynamic and pliable properties to the membrane. C2 domain-containing proteins in the membrane also interact weakly and cooperatively giving rise to a high degree of conformational plasticity. We propose that this feature of weak energetics and plasticity shared by lipids and C2 domain-containing proteins enhance a cell's ability to transduce information across the membrane. We explored this hypothesis using information theory to assess the information storage capacity of model and mast cell membranes, as well as differential scanning calorimetry, carboxyfluorescein release assays, and tryptophan fluorescence to assess protein and membrane stability. The distribution of lipids in mast cell membranes encoded 5.6-5.8bits of information. More information resided in the acyl chains than the head groups and in the inner leaflet of the plasma membrane than the outer leaflet. When the lipid composition and information content of model membranes were varied, the associated C2 domains underwent large changes in stability and denaturation profile. The C2 domain-containing proteins are therefore acutely sensitive to the composition and information content of their associated lipids. Together, these findings suggest that the maximum flow of signaling information through the membrane and into the cell is optimized by the cooperation of near-random distributions of membrane lipids and proteins. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova.