KCNE1 (minK), found in the human heart and, cochlea is a transmembrane protein that modulates the voltage-gated potassium KCNQ1 channel. While KCNE1 has previously been the subject of extensive structural studies in lyso-phospholipid detergent micelles, key observations have yet to be confirmed and refined in lipid bilayers. In this study a reliable method for reconstituting KCNE1 into lipid bilayer vesicles composed of POPC and POPG was developed. Microinjection of the proteoliposomes into Xenopus oocytes expressing the human KCNQ1 (KV7.1) voltage-gated potassium channel led to native-like modulation of the channel. CD spectroscopy demonstrated that the %-helicity of KCNE1 is significantly higher for the protein reconstituted in lipid vesicles relative to the previously described structure in 1.0% LMPG micelles. SDSL EPR spectroscopic techniques were used to probe the local structure and environment of Ser28, Phe54, Phe57, Leu 59, and Ser64 KCNE1 in both POPC/POPG vesicles and in LMPG micelles. Spin-labeled KCNE1 cysteine mutants at Phe54, Phe57, Leu 59, and Ser64 were found to be located inside POPC/POPG vesicles, whereas Ser28 was found to be located outside the membrane. Ser64 was shown to be water-inaccessible in vesicles, but found to be water-accessible in LMPG micelle solutions. These results suggest that key components of the micelle-derived structure of KCNE1 extend to the structure of this protein in lipid bilayers, but also demonstrates the need to refine this structure using data derived from bilayer-reconstituted protein in order to more accurately define its native structure. This work establishes the basis for such future studies.

A new approach has been developed to probe the structural properties of membrane peptides and proteins using the pulsed electron paramagnetic resonance technique of electron spin echo envelope modulation (ESEEM) spectroscopy and the a-helical M2d subunit of the acetylcholine receptor incorporated into phospholipid bicelles. To demonstrate the practicality of this method, a cysteine-mutated nitroxide spin label (SL) is positioned 1, 2, 3, and 4 residues away from a fully deuterated Val side chain (denoted i 1 1 to i 1 4). The characteristic periodicity of the a-helical structure gives rise to a unique pattern in the ESEEM spectra. In the i 1 1 and i 1 2 samples, the 2

Inhaled Veletri was demonstrated to be non-inferior to inhaled Flolan when comparing change in PaO/FiO ratio 1 hour post -therapy initiation,and inhaled Veletri was an acceptable alternative to inhaled Flolan in a cardiothoracic surgery patient population.

Background: No previous studies exist examining 2 inhaled epoprostenol formulations in an acute respiratory distress syndrome (ARDS) patient population. Objective: The study aim was to evaluate a formulary conversion from inhaled Flolan to Veletri to determine the impact on effectiveness, safety, and cost in patients with ARDS. Methods: This was a single-center, retrospective, matched cohort observational study at a tertiary care academic medical center. Patients included were mechanically ventilated, adult patients with ARDS receiving inhaled Flolan or Veletri for ≥1 hour in the intensive care unit. Results: A total of 132 patients were included in the matched cohort. There was no difference detected in change in partial pressure of arterial O2/fraction of inspired O2 (PaO2/FiO2) ratio after 1 hour of therapy between the inhaled Flolan and Veletri groups (27.2 ± 46.2 vs 30 ± 68 mm Hg, P = 0.78). Significant differences in secondary outcomes included incidence of hypotension (83% vs 95.5%, P = 0.04) and thrombocytopenia (9.1% vs 29.5%, P < 0.01) in the inhaled Flolan and Veletri groups, respectively, with no difference in cost per duration of therapy ( P = 0.29). Conclusions and Relevance: There was no difference in the change in PaO2/FiO2 ratio after 1 hour of therapy between inhaled Flolan and Veletri in an ARDS patient population. The formulary conversion from inhaled Flolan to Veletri was likely justified.

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