Their study will appear in the May 08 issue of Experimental Biology and Medicine. Multiple tachycardia-associated factors appear to contribute to this response, which all are directly or indirectly linked to oxidative stress. Accordingly, blockade of the angiotensin II type 1 receptor, inhibition of L-type calcium channels, inhibition of NADPH oxidase, applications of antioxidants, and inhibition of NF-ƒÛB activation were all found to abolish or decrease the tachycardia-dependent changes in the atrial tissue.
The interdisciplinary research team, led by Uwe Lendeckel, a professor of Experimental Internal Medicine and Andreas Goette, Deputy Chief of Cardiology, designed the study to determine the influence of tachyarrhythmia on endocardial dysfunction (called endocardial remodelling) and to decipher the molecular mechanism(s) that translate pathologically increased heart rates into myocardial/endocardial dysfunction. Endocardial dysfunction appears as a well recognised risk factor for thromboembolic events in patients with atrial fibrillation (AF). Therefore, the underlying pathophysiology of endocardial remodelling is of clinical importance.
¡§The facts that equal results were observed in ex vivo atrial tissue from patients with AF and in ex vivo rapidly paced tissue samples from patients with sinus rhythm (SR), together with the observation that verapamil most potently prevented oxidative stress and associated signalling pathway activation, led us to conclude that the elevated frequency per se and concomitant Ca2+-overload precede and induce mitochondrial dysfunction and oxidative stress in AF¡¨ said Lendeckel. Goette added ¡§Our results have several clinical implications. Atrial ischemia produces an increase in cellular calcium load and oxidative stress in the atria. Thereby, atrial ischemia provides a specific substrate for AF. Recent experimental and clinical data showed that calcium channel blockers have a specific efficacy to prevent AF in this specific situation. Thus, our data provide more information about the potential pathophysiologic mechanism explaining why calcium channel blockers are effective and useful to attenuate atrial cellular remodelling especially under conditions of increased cellular calcium load and oxidative stress¡¨. The authors say ¡§ the use of ex vivo human atrial tissue from patients with and without AF as well as the rapid pacing of atrial tissue slices to mimic AF ex vivo is a valuable approach to identify molecular and cellular effects that are solely due to the AF excluding the effects of concomitant cardiac diseases.¡§
Dr. Steven R. Goodman, Editor-in-Chief of Experimental Biology and Medicine said ¡§Professor Lendeckel, Professor Goette and colleagues have demonstrated that inward calcium current via L-type calcium channels contributes to oxidative stress and increased expression of oxidative stress markers and adhesion molecules during cardiac tachyarrhythmia.¡§. He further stated ¡§These observations are important to the understanding of the molecular mechanisms by which calcium overload and resulting mitochondrial dysfunction and resulting oxidative stress impact atrial remodelling during atrial fibrillation.¡¨
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07.08.2017 | University of Manchester
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
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