Designing a Useful Lipid Raft Model Membrane for Electrochemical and Surface Analytical Studies

A model biomimetic system for the study of protein reconstitution or drug interactions should include lipid rafts in the mixed lipid monolayer, since they are usually the domains embedding membrane proteins and peptides. Four model lipid films composed of three components: 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), cholesterol (Chol) and sphingomyelin (SM) mixed in different molar ratios were proposed and investigated using surface pressure measurements and thermodynamic analysis of the monolayers at the air–water interface and imaged by Brewster angle microscopy. The ternary monolayers were transferred from the air–water onto the gold electrodes to form bilayer films and were studied for the first time by electrochemical methods: alternative current voltammetry and electrochemical impedance spectroscopy and imaged by atomic force microscopy. In excess of DOPC, the ternary systems remained too liquid for the raft region to be stable, while in the excess of cholesterol the layers were too solid. The layers with SM in excess lead to the formation of Chol:SM complexes but the amount of the fluid matrix was very low. The equimolar content of the three components lead to the formation of a stable and well-organized assembly with well-developed raft microdomains of larger thickness, surrounded by the more fluid part of the bilayer. The latter is proposed as a convenient raft model membrane for further physicochemical studies of interactions with drugs or pollutants or incorporation of membrane proteins.

Chiral Synthesis of 3-Amino-1-phenylbutane by a Multi-Enzymatic Cascade System

Asymmetric synthesis of chiral amines from prochiral ketones using transaminases is an attractive biocatalytic strategy. Nevertheless, it is hampered by its unfavorable thermodynamic equilibrium. In the present work, an insitu by-product removal strategy was applied for the synthesis of 3-amino-1-phenylbutane (3-APB) by coupling a transaminase with a pyruvate decarboxylase (PDC), which does not require the use of any expensive additional cofactor. Using this strategy, the pyruvate obtained in the transamination reaction is transformed by PDC into acetaldehyde and CO2 which are of high volatility. Two different transaminases from Chromobacterium violaceum (CviTA) and Vibrio fluvialis (VflTA) were characterized to find out the appropriate pH conditions. In both cases, the addition of PDC dramatically enhanced 3-APB synthesis. Afterwards, different reaction conditions were tested to improve reaction conversion and yield. It was concluded that 30 °C and a 20-fold alanine excess lead to the best process metrics. Under the mentioned conditions, yields higher than 60% were reached with nearly 90% selectivity using both CviTA and VflTA. Moreover, high stereoselectivity for (S)-3-APB was obtained and ee of around 90% was achieved in both cases. For the first time, the asymmetric synthesis of 3-APB using PDC as by-product removal system using CviTA is reported.

The role of echocardiography in predicting technical problems and complications of transvenous leads extractions procedures

Introduction Transesophageal echocardiography (TEE) is a useful tool in preoperative observation of patients undergoing transvenous leads extraction (TLE) due to complications associated with implanted devices. Echocardiographic phenomena may determine the safety of the procedure. Methods and results Data from 936 transesophageal examinations (TEE) performed at a high volume center in patients awaiting TLE from 2015 to 2019 were assessed. TEE revealed a total of 1156 phenomena associated with the implanted leads in 697 (64.85%) patients, including: asymptomatic masses on endocardial leads (AMEL) (58.65%), vegetations (12,73%), fibrous tissue binding the lead to the vein or heart wall (33.76%), lead-to-lead binding sites (18.38%), excess lead loops (19.34%), intramural penetration of the lead tip (16.13%), lead-dependent tricuspid dysfunction (LDTD) (6.41%). Risk factors for technical difficulties during TLE in multivatiate analysis were: fibrous tissue binding the lead to atrial wall (OR=1.738; p<0.05), to right ventricular wall (OR=2.167; p<0.001), lead-to-lead binding sites (OR=1.628; p<0.01) and excess lead loops (OR=1.488; p<0.05). Lead-to-lead binding sites increased probability of major complications (OR=3.034; p<0.05). Presence of fibrous tissue binding the lead to the superior vena cava (OR=0.296; p<0.05), right atrial wall (OR=323; p<0.05) and right ventricular wall (OR=0.297; p<0.05) reduced the probability of complete procedural success, whereas fibrous tissue binding the lead to the tricuspid apparatus decreased the probability of clinical success (OR=0.307; p<0.05), Conclusions: Careful preoperative TEE evaluation of the consequences of extended lead implant duration (enhanced fibrotic response) increases the probability of predicting the level of difficulty of TLE procedures, their efficacy and risk of major complications.

Queer Musical Excess

Queer reading strategies based on the approach of Alexander Doty reveal transgressive moments in Cukor’s three musical comedies: Les Girls (1957), Let’s Make Love (1960), and My Fair Lady (1964). Queer conceptualizations of the Hollywood musical, particularly the concept of “excess,” lead to readings of specific scenes that disrupt the heteronormative flow of the narratives. Gene Kelly performs a spoof of Marlon Brando in The Wild One, within a tale of a womanizer and the three women who love him; Milton Berle camps up a lesson on dating opposite Yves Montand; and Rex Harrison ponders why a woman can’t be more like a man, within a narrative that resists romantic closure.

Easy Ligand Activation in the Coordination Sphere of Ru inside the [PW11O39]7– Backbone

Irradiation of the Keggin-type [PW11O39{Ru(NO)}]4− (Ru-NO) polyoxometalate in CH3CN results in rapid NO ligand elimination with the formation of [PW11O39{RuIII(CH3CN)}]4− (Ru-CH3CN). This complex offers an easy entry into the Ru-based chemistry of the {PW11Ru} complex. Attempts to substitute N3− for CH3CN in the presence of an NaN3 excess lead a variety of products: (i) [PW11O39{RuIII(N3)}]4− (Ru-N3); (ii) [PW11O39{RuIII(N4HC-CH3)}]4− (Ru-Tz) as a click-reaction product; and (iii) [PW11O39{RuII(N2)}]5− (Ru-N2). UV-VIS, CV, and HR-ESI-MS techniques were used for the reaction monitoring and characterization of the products.