Differential effect with septal and apical RV pacing on ventricular activation in patients with left bundle branch block assessed by non-invasive electrical imaging and in silico modelling.

PURPOSE: It is uncertain whether right ventricular (RV) lead position in cardiac resynchronization therapy impacts response. There has been little detailed analysis of the activation patterns in RV septal pacing (RVSP), especially in the CRT population. We compare left bundle branch block (LBBB) activation patterns with RV pacing (RVP) within the same patients with further comparison between RV apical pacing (RVAP) and RVSP. METHODS: Body surface mapping was undertaken in 14 LBBB patients after CRT implantation. Nine patients had RVAP, 5 patients had RVSP. Activation parameters included left ventricular total activation time (LVtat), biventricular total activation time (VVtat), interventricular electrical synchronicity (VVsync), and dispersion of left ventricular activation times (LVdisp). The direction of activation wave front was also compared in each patient (wave front angle (WFA)). In silico computer modelling was applied to assess the effect of RVAP and RVSP in order to validate the clinical results. RESULTS: Patients were aged 64.6 ± 12.2 years, 12 were male, 8 were ischemic. Baseline QRS durations were 157 ± 18 ms. There was no difference in VVtat between RVP and LBBB but a longer LVtat in RVP (102.8 ± 19.6 vs. 87.4 ± 21.1 ms, p = 0.046). VVsync was significantly greater in LBBB (45.1 ± 20.2 vs. 35.9 ± 17.1 ms, p = 0.01) but LVdisp was greater in RVP (33.4 ± 5.9 vs. 27.6 ± 6.9 ms, p = 0.025). WFA did rotate clockwise with RVP vs. LBBB (82.5 ± 25.2 vs. 62.1 ± 31.7 op = 0.026). None of the measurements were different to LBBB with RVSP; however, the differences were preserved with RVAP for VVsync, LVdisp, and WFA. In silico modelling corroborated these results. CONCLUSIONS: RVAP activation differs from LBBB where RVSP appears similar. TRIAL REGISTRATION: (ClinicalTrials.gov identifier: NCT01831518).

Edge-on adsorption of multi-chain functional alkanes stabilizes noncovalent monolayers on MoS2.

Modified long-chain alkanes are often used to functionalize graphene and MoS2 noncovalently, with the goal of controlling the substrate electronic structure or interactions with the environment. Alkyl chain adsorption enthalpy is lower on MoS2 than on graphite; the decreased molecule-substrate interaction strength suggests utility for monolayer structures that increase stability through other means. Previously, we have found that diyne phospholipid monolayers on HOPG are more stable toward solution processing than monolayers of single-chain amphiphiles. Here, we show that this is also true for assembly on MoS2, but that the additional stability appears to arise from edge-on adsorption, producing monolayers in which alkyl chains form two stacked layers on the substrate.

Standing, lying, and sitting: translating building principles of the cell membrane to synthetic 2D material interfaces.

A striking number of problems in modern materials chemistry relate to controlling structure at scales 5-10 nm, important in applications ranging from nanoscale electronics to organic materials for energy conversion. Interfacial patterning is potentially valuable in establishing and stabilizing high-resolution structural features. While chemical patterning at such short length scales is unusually difficult using many traditional top-down approaches, it has been achieved with remarkable efficiency and chemical diversity in two seemingly unrelated areas: in the lipid bilayers that make up cell membranes, and in the noncovalent functionalization of 2D materials such as graphene. At the intersection of these two areas are lessons of significant utility for controlling synthetic material interface chemistry across a range of length scales.

Prolonged intermittent high intensity exercise impairs neuromuscular performance of the knee flexors.

This study investigated the effect of prolonged intermittent high intensity exercise upon the isokinetic leg strength and electromechanical delay of the knee flexors. Seven male collegiate soccer players were exposed to: (i) a prolonged intermittent high intensity exercise task (PIHIET) which required subjects to complete a single-leg pedalling task, with the preferred limb, (75 rpm for all constant-load portions of the task) consisting of 48 x 1.8 minute cycles of exercise, and (ii) a control task consisting of no exercise. Pre-, mid- and post-PIHIET gravity corrected indices of knee flexion angle-specific torque (0.44 rad knee flexion (AST); 0 rad=full knee extension; [1.05 rad x s(-1)]) were made for both intervention and control limbs. Electromechanical delay (EMD) of the m. biceps femoris during supine knee flexion movements was evaluated in the preferred leg on both intervention and control days. Repeated measures ANOVAs revealed significant condition (intervention; control) by time (pre; mid; post) interactions for both knee flexor AST (F[2,12]=4.8; p < 0.03) and EMD (F[2,12]=4.1; p < 0.05). AST was observed to decrease by 16% and EMD increase by 30% pre to post intervention. These observations suggest an impairment of neuromuscular control and the ability to maintain force generation in the knee flexors, near the extremes of the range of motion during prolonged intermittent high-intensity exercise activities. Changes of this magnitude may pose a threat to the integrity of the knee joint.

Probing the importance of spacial and conformational domains in captopril analogs for angiotensin converting enzyme activity.

A new synthesis of 4,5-methano-L-prolines and the enzymatic activity of the corresponding N-(3-mercapto-2-R-methyl-propionyl) analogs as inhibitors of angiotensin converting enzyme are described.