RNV is helpful in optimising pacing parameters for resynchronisation therapy. Varying AVD did not have a major impact on intra- or inter-ventricular resynchronisation. Thus, the benefit of AVD-based LVEF optimisation seems to result from atrioventricular resynchronisation.
Background: Biventricular pacing (bivPM) in patients with heart failure results in improved left ventricular performance through resynchronization of systolic myocardial contraction. A prolonged AV-delay improves diastolic left ventricular filling but is associated with increased probability of AV fusion beats that may interfere with resynchronization. The relative influence of these two potentially opposing effects is unknown so far. Aim: To assess the influence of different AV-delays on left ventricular synchrony and left ventricular ejection fraction (EF) using multigated acquisition radionuclide ventriculography (MUGA). Methods: In 12 patients with severe congestive heart failure EF and synchrony was assessed without (noPM) and during bivPM at different AV-delays (80ms, 100ms, 120ms, 140ms, 160ms) with MUGA. Synchrony was defined by the standard deviation in the phase-delay within the left ventricle (LV-SD). This was calculated by use of a phasehistogram and expressed as fraction of a 360°heart cycle. EF was compared to LV-SD at the different AV-delays using Pearson Correlation.
Rat brain proteins presenting high-affinity binding of S-adenosyl-L-homocysteine were solubilized and purified. Extraction of binding protein was carried out in the presence of Triton X-100 and 1 M NaCl; this solubilized fraction exhibits similar kinetic properties than the membrane proteins. Purification was performed using affinity chromatography on S-adenosyl-L-homocysteine carboxyhexyl Sepharose 48 conjugate. The analysis of the affinity gel eluate by SDS-PAGE showed high purification ratios for two proteins exhibiting 54 and 68 kDa. Three activity peaks were separated when solubilized membrane proteins were submitted to isoelectric focusing; the activity peaks corresponded to proteins of pH1 6.0, 6.5, and 7.2. SDS-PAGE separation of proteins contained in each peak showed protein aggregation; a 54-kDa subunit was present in each aggregate. Solubilized membrane proteins were labeled by photoaffinity labeling with tritiated S-adenosyl-L-homocysteine; the 54- and 68-kDa proteins were found among the specifically labeled proteins. Finally, according to the previous data from the literature, the purified S-adenosyl-L-homocysteine binding proteins do not seem to be the same as adenosine receptors or phosphatidylethanolamine-N-methyltransferase.
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