Tuesday, October 28, 2008

French doctor unveils artificial heart

By Henry Samuel in Paris

French heart transplant specialist Alain Carpentier presents a prototype of the world's first fully implantable artificial heart.
French heart transplant specialist Alain Carpentier presents a prototype of the world's first fully implantable artificial heart. Photo: AP

Three decades after the world's first human heart transplant, this revolutionary life-size mixture of animal tissue, titanium and missile technology that its inventor says perfectly replicates the human organ could save the lives of thousands of heart patients, many of whom die while waiting for a heart donation.

Pumping and rippling in an eerily lifelike way, the new heart is covered in specially treated tissue to avoid rejection by the body's immune system and in particular the formation of blood clots.

Thanks to the latest electronic sensor technology used in guided missiles, the heart can also respond instantly to changes in blood pressure and flow and adapt the heart beat rate accordingly.

"If you showed the electrocardiogram to a cardiologist he would say 'that's a human heart.' Well no, it isn't: it's a prosthesis," said its creator, Prof Alain Carpentier, head of research on cardiac grafts and prostheses at Georges Pompidou hospital in Paris.

Prof Carpentier has been working in the utmost secrecy on the project for 15 years in conjunction with engineers from the Franco-German defence and aerospace company EADS.

While there are other rival laboratories working on artificial hearts in America, Japan and South Korea, the French say their design is superior.

In particular, Prof Carpentier used his expertise as a world authority in artificial heart valves to overcome the problem of blood clots - the main stumbling block in other attempts to build an artificial heart. He did this by using specially sterilised "bioprosthetic" pig cartilage and by replicating the exact same blood flow - or hemodynamics - of the human heart that reduce blood clot risks.

"The aim of this heart is to allow patients to go from an impossible life where they can do just a few steps from their bed to an armchair to a normal social life. They will even be able to run - although naturally not a marathon," he said.

Weighing around a kilo, the only external part of the man-made organ is its battery which has a five-hour charge life.

Prof Carpentier said the new heart was necessary given the chronic shortage of heart donors and growing heart patient waiting lists. "I couldn't stand seeing young, active people dying aged 40 from massive heart attacks," he said.

Heart disease is among the world's biggest killers, claiming 17 million lives per year.

About 55 million euros (£44 million) has been spent creating the prototype. The groundbreaking organ has already been successfully implanted in calves although most tests have been done via computer simulation.

"The artificial heart is ready and now needs to be industrially made," said Prof Carpentier, who added that none of its parts had shown any sign of "wearing out".

Assuming French medical authorities give the go-ahead, it will be tested on around 20 volunteer heart patients within the next two and a half years.

The heart will be built by Carmat, a biomedical subsidiary of EADS, with funding from Oseo, the French state bank that supports innovative companies, as well as from venture capitalists.

Given the materials and technology involved, it is estimated that each heart will cost around £120,000.

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Suicide linked to brain changes

The researchers looked at brain tissue

The brains of people who commit suicide are chemically different to those who die from other causes, a Canadian study has suggested.

Researchers analysed brain tissue from 20 dead people and, in those who killed themselves, they found a higher rate of a process that affects behaviour.

Writing in Biological Psychiatry, they said it appeared environmental factors played a part in the changes.

And they said the discovery opened up a new avenue of research.

This is exciting new evidence that genetic and environmental factors may interact to produce specific and long-lasting modifications in brain circuits
John Krystal, Biological Psychiatry editor

The researchers, from the University of Western Ontario, Carleton University and University of Ottawa, analysed tissue from 10 people who had a serious depressive disorder and had committed suicide and 10 who had died suddenly from other causes, such as a heart attack.

They found that the DNA in the suicide group was being chemically modified by a process normally involved in regulating cell development, called methylation.

It is methylation which shuts down the unwanted genes in a cell - so the necessary genes are expressed to make a cell a skin cell rather than, for example, a heart cell.

The rate of methylation in the suicide brains was almost 10 times that of the other group, and the gene that was being shut down was a chemical message receptor that plays a major role in regulating behaviour.

In the paper, the researchers suggest this reprogramming could contribute to the "protracted and recurrent nature of major depressive disorder".

Previous research has suggested that changes to the methylation process can be caused by a combination of genetic and environmental factors called epigenetics.

Modifications 'shape life'

Dr Michael Poulter, who led the research, said: "The whole idea that the genome is so malleable in the brain is surprising, because brain cells don't divide.

"You get dealt your neurons at the start of life, so the idea that there are still epigenetic mechanisms going on is pretty unusual."

He said the findings of the study opened up a new avenue of research and potential therapies for depression and suicidal tendencies.

John Krystal, the editor of Biological Psychiatry, said: "This is exciting new evidence that genetic and environmental factors may interact to produce specific and long-lasting modifications in brain circuits.

"Further, these modifications may shape the course of one's life in extremely important ways, including increasing the risk for major depressive disorder and perhaps suicide."

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Cancer cure in a sponge? Institute tests synthetic version of substance

By Robyn Shelton, Medicine & Health / Cancer

As one of their first projects in Florida, scientists at the Burnham Institute for Medical Research in Orlando have created a man-made version of the substance.

Previous research showed the compound could zap the cancer cells in lab tests. Now the goal is to improve on nature to make it more potent, yet less toxic, so it someday can be tested as a drug for patients.

"The sponge itself only has very tiny quantities of the material," said Gregory Roth, Burnham's director of medicinal chemistry and exploratory pharmacology. "By making it synthetically, we can get larger quantities to do the kind of testing we need."

Roth's laboratory is working on the project with Harbor Branch Oceanographic Institution at Florida Atlantic University, which discovered the substance's cancer-fighting abilities in routine testing of deep-sea creatures.

Many sponges produce a variety of compounds themselves or harbor microorganisms that churn them out. Scientists don't always know what the substances do in nature, though they likely repel predators or serve as chemical signals, said Amy E. Wright, who directs Harbor Branch's biomedical-marine-research program.

The sponge - called Aphrocallistes Beatrix - lives on the cold-water reef that lies deep under the ocean off Florida's coast.

Wright's team uses a submersible vehicle that can dive 3,000 feet to collect a variety of sponges, soft corals and other organisms. The sponge was ground up and made into a solution tested with various cancer cells. It showed the most promise with colon and pancreatic cells, which together are expected to kill about 83,000 Americans this year.

Scientists rate a substance's cancer-fighting ability by the amount needed to wipe out 50 percent of the tumor cells in a lab test.

"This compound is about as potent as the best drug that's currently used for pancreatic cancer," Wright said.

Her team collects sea life on regular expeditions. A chemist in Roth's laboratory, Jennifer Hoffman, went with Harbor Branch on a recent dive. Sitting in the four-person submersible vehicle, Hoffman could see shrimp, squid and other creatures swimming in the lights as they traversed the dark, cool waters. The sub is equipped with a robotic arm that can pluck sponges off the coral and place them in containers.

Hoffman, who previously worked for the Pfizer drug company, said more work is needed before the compound even can be considered for human testing.

"It takes a lot of time and a lot of effort by many different people to develop a drug," said Hoffman, a senior research associate with Burnham. "But we know the compound is active, so we'll be making little changes to it and see if we can improve upon it."

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