SCIENCE IN THE NEWS #2129 - DigestBy StaffThis is Bob Doughty.And this is Sarah Long with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today, we tell about damaged heart tissue that repair itself. We tell about health problems caused by being overweight. And we tell about a Russian proposal to import nuclear waste.
For many years doctors have believed that damage to the heart after a heart attack was permanent. They said the human body could not replace cells killed by a heart attack, injury or disease. But new research has shown that human heart muscle cells continue to divide and grow after a heart attack. The New England Journal of Medicine published the study earlier this month.
Scientists say the new cell growth was not enough to repair the heart. But some scientists say the research proves a damaged heart may some day repair itself. This could result in new treatments for heart disease. Heart disease is the leading cause of death in the United States, and a major killer throughout the world.Piero Anversa of the New York Medical College in Valhalla led the research. Scientists from the United States and Italy studied muscle cells from the hearts of thirteen heart attack victims. The people had died from four to twelve days after suffering a heart attack.
The scientists examined tissue near the area of the heart attack. They also studied tissue from another part of the heart. Then they compared these damaged hearts with those of ten patients with normal hearts who had died of other causes.The researchers measured the activity of a protein in the cells needed for cell division. They also colored the heart tissue with a substance that helps show cells dividing. They used a special microscope to study the cells.
They found that the number of muscle cells dividing and growing in the diseased hearts was much higher than in the normal hearts. Doctor Anversa says these results offer an exciting possibility. He says even a few new heart cells might grow into many cells in several weeks. However, experts say the heart contains more than just muscle cells. It also includes blood vessels and connective tissue. Growth in heart muscle cells alone may not return the heart to normal.During a heart attack, a blockage forms in an artery carrying blood to the heart muscle. The heart does not receive needed oxygen and other nutrients. The tissue dies if blood does not flow again within about twelve hours. For years, doctors believed this damaged tissue proved the heart could not manufacture new cells.
Doctor Anversa has been studying cell growth in the heart for about twenty years. He and his team published a study of heart re-growth two years ago. At that time a number of other scientists said they did not believe the evidence. But several experts immediately praised the new research.
Doctor Anversa and his team have started trying to identify substances that can cause cell division in the heart. They hope such substances can some day be placed around dying heart tissue. This process might prevent permanent heart damage.
((MUSIC BRIDGE))You are listening to the Special English program SCIENCE IN THE NEWS on VOA. This is Bob Doughty with Sarah Long in Washington.
The Worldwatch Institute warns that the growing number of overweight or obese people in the world has become an international problem. The organization says obesity damages people's health. It increases the chances of heart disease, some kinds of cancer and diabetes. The Centers for Disease Control in the United States estimates that three-hundred-thousand Americans die each year from sicknesses linked to obesity. Sixty-one percent of American adults are overweight.
However, obesity is not just a problem in the United States. The Worldwatch Institute says that for the first time in history, a majority of adults in several other industrial countries are overweight. For example, fifty-four percent of the people in Russia are obese. Fifty-one percent are overweight in Britain. And in Germany, half the population weighs too much.The number of obese people is also increasing in developing countries. The Worldwatch Institute estimates that thirty-six percent of the population of Brazil is overweight. Also, fifteen percent of China's population weighs too much.
The Worldwatch Institute says obesity is more common in cities. This is because people living in cities are less active. This causes them to gain weight. For example, in China and Indonesia, there are two times as many obese people in cities as in farming areas. And in Congo, obesity is six times higher in cities.
Modern technology has reduced the amount of exercise people get. Many people drive cars every day instead of walking or riding bicycles. They also spend their free time watching television. The Worldwatch Institute says this is especially harmful for children. It says children who watch television at least five hours a day are five times more likely to be overweight than those who watch fewer than two hours a day.People gain weight when they eat more calories than they burn. Calories are a measurement of the heat and energy value of food. In industrial countries, people eat many foods rich in fat and sugar. The Worldwatch Institute says this is also happening in developing countries, especially in cities.
Most overweight people must do two things to lose weight. They must reduce the amount of calories they eat. And they must burn more calories through exercise. However, increasing exercise is not easy.
The Worldwatch Institute says cities today are designed for automobiles. It says one answer is to redesign communities with more paths for walking, running and bicycling. It says cities should have more public transportation. And there should be more public play areas. The Worldwatch Institute says exercise should become a daily activity or obesity and health problems will continue to spread around the world.
((MUSIC BRIDGE))The lower house of the Russian parliament has approved a plan to import used nuclear fuel from nuclear reactors in other countries. Under the plan, Russia would import and process about twenty-thousand tons of used nuclear fuel over the next thirty years. Supporters say the plan could help Russia earn up to twenty-thousand-million dollars. They say about one-third of the money would go to cleaning up areas in Russia where nuclear waste is buried.
Officials from the Russian Nuclear Energy Ministry say the plan is safe. They say it provides a service to Russia and other countries. Reports say the waste would be put in temporary storage for at least ten years. Then it would be reprocessed into fuel.Many environmentalists urged Russian lawmakers to vote against the plan. They say its passage would be a huge mistake for Russia. They argue that Russia should not receive the nuclear waste of other countries. They say Russia cannot guarantee the safety of its own nuclear waste. Last year, a public opinion study found that more than ninety percent of Russians questioned opposed importing nuclear waste.
The upper house of the Russian parliament will consider the proposal. The upper house and President Vladimir Putin would have to approve the measure before it could become law. Mr. Putin has not publicly expressed support for the plan. Environmentalists say they will continue to urge Mr. Putin not to sign the bill.The United States has exported nuclear reactors and nuclear fuel to many countries. Experts say the United States produced about ninety percent of the nuclear fuel covered by the Russian proposal. Countries that have used the fuel would have to get approval from the United States before sending it to Russia. The environmental group Greenpeace is urging President Bush to block the Russian plan.
This SCIENCE IN THE NEWS program was written by Jerilyn Watson, Jill Moss and George Grow. It was produced by Caty Weaver. This is Bob Doughty.And this is Sarah Long. Join us again next week for more news about science in Special English on the Voice of America.