Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists solve chaotic heartbeat mystery

06.02.2003


Fatal, electrical chaos can develop in the hearts of otherwise healthy people who produce a defective accessory protein called ankyrin-B, reports W. Jonathan Lederer of the University of Maryland Biotechnology Institute (UMBI) and collaborators, in the February 6 issue of the scientific journal Nature.



By discovering the molecular and cellular causes of the electrical chaos-known as Long QT Syndrome Type 4, or LQT4-Lederer and collaborators open the door to possible therapies and diagnostics for this and related heart diseases. The work also provides a clue to how important, specific proteins are organized within heart cells.

Several years ago, clinical researchers in France, headed by Denis Escande, discovered an inheritance pattern in members of a family who had been dying suddenly and unexpectedly in the prime of life. Lederer’s team at UMBI and the University of Maryland at Baltimore and researchers at Duke University, headed by Vann Bennett, collaborated with the French by applying state-of-the-art heart physiology tools to mouse heart cells in order to find the cause of the sudden deaths.


Cardiovascular disease, including cardiac arrhythmia and sudden cardiac death and stroke are the leading causes of death worldwide. The term QT in LQT4 and other long QT syndromes refers to a time period, normally about 300 milliseconds (read between points Q and T on an electrocardiogram) when each electrical pulse, or action potential, starts a heart beat. Longer QT periods can signal heart problems.

The researchers discovered that the LQT4 is linked to a genetic defect in humans and in a mutant mouse developed by the Bennett laboratory. The defect is expressed as an inadequate amount of an important adaptor protein called ankyrin-B that is involved in enriching cells with key proteins at specific locations within the cell. Lederer’s group studied the dynamic physiology of single cells in the Bennett mouse.

The reduction or absence of functional ankyrin-B in the cells causes proteins involved in cellular calcium regulation to be inadequate or absent from critical locations within the cell. Cells load up with too much calcium. The change in calcium causes the heart to beat improperly and, in the case of LQT4, chaotically. The electrical chaos that can cause death appears to be triggered by unexpected stress and possibly an increase in adrenaline - as would happen when individuals are startled, says Lederer. Even then, the death-causing electrical chaos is rare.

Humans and animals are afflicted with LQT4 when only one of the two genes for ankyrin-B is defective or absent. When both are absent, the condition is lethal.

However, says Lederer, many individuals survive for a long time with the defect. The rare occurrence of the development of calcium-dependent electrical chaos in the heart means that most individuals have normal heart behavior even when they are afflicted with LQT4.

Finding the defective protein to be ankyrin-B was somewhat of a surprise, says Lederer, a world leader in studies ion channels and calcium sparks in heart cells. "We thought it would make sense if the defective protein were a channel protein. The other long QT syndromes are caused by defects in channel proteins. This is the first example of a cytoskeletal or structural protein causing such an arrhythmia."

Lederer and his team collaborated with other primary investigators from Duke University and the Howard Hughes Institute headed by Vann Bennett and Peter Mohler and with investigators at the French Institute of Health and Medical Research (INSERM) in Nantes, France, headed by Denis Escande. Key local investigators on the Lederer team included S. Guatimosim, L-S. Song and K. Dilly from MBC and T. B. Rogers and W. duBell from the School of Medicine at University of Maryland, Baltimore.


The University of Maryland Biotechnology Institute was mandated by the state of Maryland legislature in 1985 as "a new paradigm of state economic development in biotech-related sciences." With five major research and education centers across Maryland, UMBI is dedicated to advancing the frontiers of biotechnology. The centers are the Center for Advanced Research in Biotechnology in Rockville; Center for Biosystems Research in College Park; and Center of Marine Biotechnology, Medical Biotechnology Center, and the Institute of Human Virology, all in Baltimore.


Steve Berberich | EurekAlert!
Further information:
http://www.umbi.umd.edu/

More articles from Health and Medicine:

nachricht Hot cars can hit deadly temperatures in as little as one hour
24.05.2018 | Arizona State University

nachricht 3D images of cancer cells in the body: Medical physicists from Halle present new method
16.05.2018 | Martin-Luther-Universität Halle-Wittenberg

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>