HEART DISEASE: AN ALTERNATIVE TO TRANSPLANT
WASHINGTON - For the many people who wait futilely each year for heart transplants, researchers are looking at a new option: an experimental operation that wraps the failing heart with a back muscle that contracts to help boost the heart's ability to pump blood.
Known as cardiomyoplasty, the procedure is undergoing evaluation at five medical centers.
"It is a very interesting new technique that may have some use," said Sidney Levitsky, chief of cardiothoracic surgery at the New England Deaconess Hospital in Boston and a member of the American Heart Association's Council of Cardiovascular Surgery. In certain patients with heart failure, "it may be the solution for the transplant problem," he said.
Now, doctors report that death rates range from 0 to 20 percent within one month of surgery at the different hospitals involved.
Many of the deaths are attributed to a range of problems that reflect other underlying heart conditions not corrected by the surgery, including irregular heartbeats and ventricular problems. Some patients have also died from other illnesses, including pneumonia.
George McGovern, the surgeon who first performed the operation at Allegheny General, said about 50 percent of the patients there have survived for five years after surgery.
In comparison, approximately 80 to 85 percent of hearttransplant patients survive one year after surgery.
The concept of cardiomyoplasty has been discussed by physicians for more than 50 years. But there were two major hurdles to overcome.
The first was how to condition a skeletal muscle not to tire during 24 hours of daily contraction. Wayne State University thoracic surgeon Larry Stephenson developed the technique using electrical current to overcome this obstacle.
The second was how to get a large enough contraction to boost the heart's production. Standard pacemakers produced small contractions, not enough to help the failing heart. But a researcher, Ray C.-J. Chiu, at McGill University in Montreal developed what is called a burst pacemaker to stimulate the back muscle.
One of the patients to benefit from the surgery was 74-year-old Reaugh Bonn, a retired business executive who developed congestive heart failure suddenly in 1988.
Despite extensive treatment, Mr. Bonn continued to deteriorate. His age disqualified him for a heart transplant.
"It was terribly discouraging," he said from his home in Vancouver, Washington. "The only story that I really got out of any doctor was that there was no cure and that I would progressively go downhill until it was all over.
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Then Mr. Bonn read an item about cardiomyoplasty in a tabloid newspaper and sought out the operation.
On July II, 1991, Mr. Bonn became the first patient to undergo cardiomyoplasty at St. Vincent Hospital and Medical Center in Portland, Oregon. He spent 11 days recovering in the hospital, two and a half of them in the intensive-care unit, before being discharged. "The day I got out of the hospital I went home, took a nap and then went out to dinner with my wife," he said.
Sally Squires, International Herald Tribune
ТЕКСТ 5
GENETICALLY ENGINEERED PRIZE FISH CAUSE CONCERN
SCIENTISTS are genetically engineering "trophy" fish to make them bigger than ever for competition anglers. But the experiments have become caught in a wrangle over the ethics of such manipulation.
Angling authorities are concerned over the ultimate size of artificially produced catches and environmentalists fear the effect on natural ecosystems of the ones that get away.
Scientists say the most serious risk is that genetically engineered fish might be more competitive than natural fish, upsetting balances between predator and prey populations.
So far, results of only a couple of field trials have been published. Research has concentrated on adding genes to enhance growth by lifting controls on growth hormones. Similar work on pigs and cows produced unexpected side effects, including rheumatism.
Genetic manipulation in fish is even less predictable, since little is known about their molecular make-up, according to Dr David Penman, a research fellow at Stirling University's Institute of Aquaculture.
"All this work is very much at the basic research, or speculation stage," he said, "but the technology is there, or almost there."
Exploration by the fishing industry includes the possibility of giving Atlantic salmon "anti-freeze" genes from cold-tolerant fish to extend their range into colder waters.
Other scientists are working on fish with delayed breeding seasons that allow them to get farter earlier.
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Dr Penman has been commissioned by the Department of the Environment to produce a report on transgenic fish, due for publication next spring. He said the main brake on commercial interest was consumer acceptability and ethical concerns. "People are not so worried about eating engineered plants, but when it comes to animals that is a bit different."
The Independent
ТЕКСТ 6
THE AGE OF GENES
The winsome, sable-haired 4-year-old didn't even know she was making history, or care. By the time of the injection last year, she had been poked and prodded so often that she could not be bothered to take her eyes off the cartoon she was watching on TV.
The injection marked the first human trial of gene therapy, a revolutionary means of treating a disease by giving a patient new genes. The girl suffers from an extremely rare, inherited disorder in which faulty genes have crippled her immune system, leaving her vulnerable to the slightest infection or illness. To treat it, her doctors removed immune cells from her blood, fitted them with a new gene, and reinjected them into her body. Today, four months after her last dose of the groundbreaking therapy, the girl's immune system appears to be fending off infections normally.
In the nearly 40 years since James Watson and Francis Crick elucidated the twisting structure of DNA, scientists have probed deeply the workings of the molecule that governs all living cells. Just in the last month, researchers have announced the discovery of at least four new human genes responsible for ailments ranging from deafness to sterility. And while finding a new gene is only a step toward vanquishing a disease, says Nobel laureate David Baltimore, president of Rockefeller University, "every disease we know about is either being attacked with genetics or is being illuminated through genetics."
Experiments with gene therapy represent a giant step into the medicine of the future.
Yet for all the good molecular medicine will do, the ethical dilemmas are grave. The advances bring closer the day when parents can endow children not only with health but also with genes for height, good balance or lofty intelligence. Of more immediate concern is the possibility that health insurers, employers and the government will gain access to genetic information and unfairly discriminate against people on the basis of their genes.
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Charlene Grable, U.S. News & World Report
ТЕКСТ 7
BUGS SHED LIGHT ON THE OZONE
Meriel Jones examines the use of bacteria to measure UV rays hitting the planet's surface
ONE vital aspect of depletion of the ozone layer is its effect on the planet's surface. Concern is now focusing on the increased levels of ultraviolet light, but there are difficulties in measuring it. The key thing is to be able to assess its biological activity, not just the amount in cold physical terms.
Ultraviolet is the technical term for light in quite a wide band at the blue end of the spectrum, and it is not all the same when it comes to living creatures. Some regions produce suntans, while other parts cause serious damage to tissues.
In hospitals, operating theatres can be bathed with lethal wavelengths of this light to kill germs floating around before an operation.
Researchers know they need a system based on some living organism to measure what type of UV is reaching the ground and have experimented with several systems. A group of Germans, working at the Institute for Aerospace Medicine in Cologne, has come up with a system that worked well in the laboratory and which the scientists are now testing in Antarctica.
Lothar Quintem and his colleagues are exploiting a group of bacteria which have the unique ability to change into a dormant form called a spore if the cell starts to run out of food. It is a protective mechanism and the resting spores can withstand more extreme conditions than the growing cells while waiting for the cue to switch back to normal growth. UV light of the right wavelengths will still kill them.
The scientists stuck a thin layer of millions of these tiny spores on to a polyester film to use as a living UV monitor. To find out the effects of light all they had to do was see how well the spores responded to their usual growth triggers. This involved soaking the film in a solution of nutrients for a few hours to give the spores the opportunity to resume growth.
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After this, the film could be developed with a blue dye where its intensity was related to the number of growing cells. If the spores no longer grew, researchers assumed the light had done something nasty to them.
Their laboratory experiments, using beams of pure UV light, gave them confidence that the spores were responding in a predictable way. Shorter wavelength UV light put the spores out of action faster, but even the milder regions did harm.
In fact, the pattern of damage resembled the way DNA absorbs light, which scientists know is one reason why UV light can be so lethal. DNA absorbs this energetic short wavelength light, causing chemical reactions that can irreversibly damage it. Once its DNA is changed, the cell is mutated and will probably die. The Germans' biofilm may help them monitor the effects of the "ozone hole" as well as giving a deeper insight into why it should be taken so seriously.
Meriel Jones, Photochemistry and Photobiology
ТЕКСТ 8
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