126 research outputs found
In vivo measurements of atrial repolarization alternans based on standard pacemaker technology
It has been shown that repolarization alternans, a beat-to-beat alternation in action potential duration, enhances dispersion of repolarization above a critical heart rate and promotes susceptibility to ventricular arrhythmias. It is unknown whether repolarization alternans is measurable in the atria using standard pacemakers and whether it plays a role in promoting atrial fibrillation. In this work, atrial repolarization alternans amplitude and periodicity are studied in a sheep model of pacing-induced atrial fibrillation. Two pacemakers, each with one right atrial and ventricular lead, were implanted in 4 male sheep after ablation of the atrioventricular junction. The first one was used to deliver rapid pacing for measurements of right atrial repolarization alternans and the second one to record a unipolar electrogram. Atrial repolarization alternans appeared rate-dependent and its amplitude increased as a function of pacing rate. Repolarization alternans was intermittent but no periodicity was detected. An increase of repolarization alternans preceding episodes of non-sustained atrial fibrillation suggests that repolarization alternans is a promising parameter for assessment of atrial fibrillation susceptibility
Dominant-Negative Tumor Necrosis Factor Protects from Mycobacterium bovis Bacillus Calmette-Guérin (BCG) and Endotoxin-Induced Liver Injury without Compromising Host Immunity to BCG and Mycobacterium tuberculosis
BackgroundTumor necrosis factor (TNF) is associated with the development of inflammatory pathologies. Antibodies and soluble TNF (solTNF) receptors that neutralize excessive TNF are effective therapies for inflammatory and autoimmune diseases. However, clinical use of TNF inhibitors is associated with an increased risk of infections MethodsA novel dominant-negative (DN) strategy of selective TNF neutralization, consisting of blocking solTNF while sparing transmembrane TNF (tmTNF), was tested in mouse models of mycobacterial infection and acute liver inflammation. XENP1595, a DN-TNF biologic, was compared with etanercept, a TNF receptor 2 (TNFR2)-IgG1 Fc fusion protein that inhibits murine solTNF and tmTNF ResultsXENP1595 protected mice from acute liver inflammation induced by endotoxin challenge in Mycobacterium bovis bacillus Calmette-Guérin (BCG)-infected mice, but, in contrast to etanercept, it did not compromise host immunity to acute M. bovis BCG and Mycobacterium tuberculosis infections in terms of bacterial burden, granuloma formation, and innate immune responses ConclusionsA selective inhibitor of solTNF efficiently protected mice from acute liver inflammation yet maintained immunity to mycobacterial infections. In contrast, nonselective inhibition of solTNF and tmTNF suppressed immunity to M. bovis BCG and M. tuberculosis. Therefore, selective inhibition of solTNF by DN-TNF biologics may represent a new therapeutic strategy for the treatment of inflammatory diseases without compromising host immunit
Measurement of the Omega_c Lifetime
We present the measurement of the lifetime of the Omega_c we have performed
using three independent data samples from two different decay modes. Using a
Sigma- beam of 340 GeV/c we have obtained clean signals for the Omega_c
decaying into Xi- K- pi+ pi+ and Omega- pi+ pi- pi+, avoiding topological cuts
normally used in charm analysis. The short but measurable lifetime of the
Omega_c is demonstrated by a clear enhancement of the signals at short but
finite decay lengths. Using a continuous maximum likelihood method we
determined the lifetime to be tau(Omega_c) = 55 +13-11(stat) +18-23(syst) fs.
This makes the Omega_c the shortest living weakly decaying particle observed so
far. The short value of the lifetime confirms the predicted pattern of the
charmed baryon lifetimes and demonstrates that the strong interaction plays a
vital role in the lifetimes of charmed hadrons.Comment: 15 pages, including 7 figures; gzipped, uuencoded postscrip
Search for the exotic Resonance in 340GeV/c -Nucleus Interactions
We report on a high statistics search for the resonance in
-nucleus collisions at 340GeV/c. No evidence for this resonance is
found in our data sample which contains 676000 candidates above
background. For the decay channel and the
kinematic range 0.150.9 we find a 3 upper limit for the
production cross section of 3.1 and 3.5 b per nucleon for reactions with
carbon and copper, respectively.Comment: 5 pages, 4 figures, modification of ref. 43 and 4
Search for the pentaquark candidate (1540) in the hyperon beam experiment WA89
We report on a high-statistics search for the \t1540 resonance in
-nucleus collisions at 340 \gevc1 . No evidence for this resonance
was found in our data sample which contains 13 millions
decays above background. For the decay channel and the
kinematic range 0.05 we find the production cross section to be
1.8 b per nucleon at 99% CL.Comment: 5 pages, 4 figure
Enhancing e-learning systems with personalized recommendation based on collaborative tagging techniques
Tracking of Stepwise Ablation of Persistent Atrial Fibrillation using Synchronization of nearby Electrogams
Intracardiac organization indices such as atrial fibril-
lation (AF) cycle length (AFCL) have been used to track
the efficiency of stepwise catheter ablation (step-CA) of
long-standing persistent AF (pers-AF), however, with lim-
ited success. The timing between nearby bipolar intracar-
diac electrograms (EGMs) reflects the spatial dynamics of
wavelets during AF. The extent of synchronization between
EGMs is an indirect measure of AF spatial organization.
The synchronization between nearby EGMs during step-
CA of pers-AF was evaluated using new indices based on
the cross-correlation. The first one (spar(W)) quantifies
the sparseness of the cross-correlation of local activation
times. The second one (OI(W)) reflects the local concen-
tration around the largest peak of the cross-correlation. By
computing their relative evolution during step-CA until AF
termination (AF-term), we found that OI(W) appeared su-
perior to AFCL and spar(W) to track the effect of step-CA
"en route" to AF-term
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