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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University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
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