Broadcast: March 25, 2003
I'm Phoebe Zimmermann with Bob Doughty, and this is the VOA Special English program Science in the News.
This week, we tell about findings that aspirin may lower the risk of colon cancer. And we report on a fifty-year-old mystery involving a picture of the moon.
Researchers have shown that aspirin can reduce the threat that a person will develop growths in the intestines. These growths, called polyps, can lead to cancer. The New England Journal of Medicine recently published two studies of people at risk for colorectal cancers.
The colon is also known as the large intestine. The colon extends to the rectum, the last part of the digestive tube. Most polyps in these areas never become cancerous. But most cancers in these areas begin as polyps. Doctors cannot tell which ones are dangerous. So they urge people to have polyps removed.
One of the new studies is based on examinations of five-hundred patients who had colorectal cancer in the past. For the study, half took a regular, three-hundred-twenty-five-milligram aspirin each day. The other half took an inactive substance, a placebo, but did not know it was inactive.
After a year, seventeen percent of the people who took the aspirin had developed new polyps. This compared to twenty-seven percent of those in the placebo group. The study ended early because the results seemed so clear. Robert Sandler of the University of North Carolina led this study.
John Baron of Dartmouth-Hitchcock Medical Center in the city of Lebanon, New Hampshire, led the other one. That study involved more than one-thousand people with a history of polyps but not cancer. After three years, thirty-eight percent of those who took a low-strength aspirin had developed polyps. This compared to forty-seven percent of those who took a placebo.
For some reason, the eighty-one-milligram low-strength aspirin did better than regular aspirin. Forty-five percent of those who took the higher strength aspirin had polyps. Both kinds, though, reduced the threat of large polyps.
Doctors are not sure of all the ways that aspirin works. But they do know it lowers the production of prostaglandin. Growths and cancers contain high levels of this natural substance.
Many people already take one low-strength or regular aspirin daily to reduce their risk of heart attack.
Experts praised the studies but urged people not to depend on aspirin to prevent colorectal cancer. They say people should be tested, especially those older than fifty and those with the disease in their family. Most cancers of this kind can be cured if found early.
Research seems to continually find possible new uses for aspirin.
Aspirin is one of the world's oldest, least costly and most widely used drugs. It is a common treatment for headaches, colds and flu. It also reduces other kinds of pain, such as pain in bone joints caused by arthritis. In addition, aspirin prevents tiny blood cells called platelets from sticking together to form clots. Clots can block the flow of blood to the heart or the brain. They can cause heart attacks or strokes.
A drug like aspirin is said to have been used in ancient Greece. More than two-thousand-four-hundred years ago, Hippocrates told his patients to ease pain by chewing the outer part of the willow tree. This bark contains the chemical salicylic acid.
In the seventeen-hundreds, people used willow bark to reduce a sick person's high body temperature. In eighteen-sixty, researchers at the Bayer Company in Germany copied the salicylic acid found in willow bark. They created acetyl salicylic acid. They called it aspirin, for the spirea plant which also contains the natural chemical. Aspirin first was made into its present pill form a century ago.
In nineteen-eighty-two, British scientist Sir John Vane shared the Nobel Prize in Medicine in part for his discoveries about aspirin. He found that aspirin blocks the body from making prostaglandins. Some cause pain and swelling in damaged tissue. Others protect the lining of the stomach and small intestine. Prostaglandins also make the kidneys, heart and blood vessels work well. The problem with aspirin is that it works against all prostaglandins -- good and bad.
So, while aspirin can reduce pain and swelling in damaged tissues, it also can harm the lining of the stomach and small intestine.
Doctors do not believe aspirin is safe for everyone. They do not believe pregnant women should take the drug. And, they say children should not take aspirin. Children who take aspirin for a sickness like flu or chicken pox may develop a serious disease called Reye's syndrome.
Even with its problems, aspirin is still considered one of the most valuable drugs ever discovered.
You are listening to the VOA Special English program Science in the News. This is Phoebe Zimmermann with Bob Doughty in Washington.
Some mysteries in science take on a life of their own.
Recently, there was news that a scientist at the Jet Propulsion Laboratory in California solved a fifty-year-old mystery. It involved an event that happened on November fifteenth, nineteen-fifty-three. A man named Leon Stuart of Tulsa, Oklahoma, was taking pictures of the moon. Mister Stuart was not a professional astronomer. He was a medical doctor. But he loved to examine the sky.
Early that morning he had a camera attached to a telescope. Suddenly, he saw a bright light on the moon. He estimated that he saw it for eight seconds or more. He took a picture.
Leon Stuart reported what he saw to the publication The Strolling Astronomer. He was sure he had captured a fireball as a piece of space rock struck the moon with great energy. Experts were not so sure. Some dismissed the picture. No one could find evidence on the surface of the moon.
Time passed, and so did Mister Stuart. He has been dead more than thirty years. He never found out what it was that he had captured on film.
Astronomers named it "Stuart's Event."
Bonnie Buratti is a scientist at the NASA Jet Propulsion Laboratory in California. Several years ago, she learned about the event observed by Leon Stuart in nineteen-fifty-three. She became interested. So Mizz Buratti and an assistant, Lane Johnson, studied pictures of the moon taken since then. These included pictures from the NASA spaceship Clementine which photographed the moon in nineteen-ninety-four.
The two also studied the picture taken by Mister Stuart. They estimated that an object about twenty-meters across had hit the moon. They estimated it would leave a crater hole in the surface between one and two kilometers across.
Bonnie Buratti and Lane Johnson have just had their findings published in the space science magazine Icarus. They offered evidence that Leon Stuart had taken the first and only picture of an object striking the moon. They said they found a fresh crater exactly where Mister Stuart had photographed the bright light.
In recent weeks many publications, including the New York Times, reported the findings. Mizz Buratti called the crater "a very good candidate." Soon, however, some experts began to question that.
John Westfall is the science editor for the Association of Lunar and Planetary Observers. He is also a geography professor at San Francisco State University. Mister Westfall examined pictures taken of the moon on five different dates. Two of the pictures were taken before nineteen-fifty-three.
John Westfall discovered that the crater in the study had existed before nineteen-fifty-three. In other words, what Leon Stuart saw could not have caused it. Mister Westfall also told VOA that the crater is not in the place where Leon Stuart had seen the light. Sky and Telescope magazine confirmed the findings by Mister Westfall.
Bonnie Buratti now agrees that what she found is not connected to "Stuart's Event." But what is more important, she told Sky and Telescope, is to find that out.
Science does solve mysteries. But there are times when further scientific work finds that explanations are just not correct. This leaves some mysteries for future scientists to solve.
Science in the News was written by Jerilyn Watson and Mario Ritter, who also produced our program. This is Bob Doughty.
And this is Phoebe Zimmermann. Join us again next week for more news about science in Special English on the Voice of America.