Ginkgo as Memory Aid Disputed / New Findings About Deadly Skin Cancer / Hair and Sex Lives of Lions
This is Sarah Long. And this is Steve Ember with SCIENCE IN THE NEWS, a VOA Special English program about recent developments in science. Today, we tell about a new study of a product people take to improve their memory. We tell some new information about lions. We tell about an unusual side effect of an anti-cancer drug. And we tell some new research about a deadly form of skin cancer.
Memory problems are a sign of old age. A number of products claim to have the ability to improve memory and other mental activities. Many older adults around the world take a substance called ginkgo in an effort to treat the problem. Now, a new study is disputing the effectiveness of ginkgo.
Ginkgo is an herb, the part of a plant valued for its medical uses. It comes from the leaves of the ginkgo biloba tree. Ginkgo is an anti-oxidant, much like vitamins C and E. Scientists believe anti-oxidants protect the body from damage caused by harmful oxygen particles called free radicals.
Millions of Americans take ginkgo as a way to improve their memory. They spend hundreds of millions of dollars on ginkgo products. Doctors in Germany commonly suggest ginkgo for treating mental problems.
Scientists from Williams College in Williamstown, Massachusetts organized the new ginkgo study. It involved more than two-hundred people over sixty years of age. All of the people were in good mental health.
For six weeks, half the group took forty milligrams of ginkgo three times a day. The other half took an inactive substance or placebo. The people did not know which substance they were taking.
The Williams College researchers questioned a close friend of each person about any changes in mental ability. No differences were observed. Everyone in the study also took a series of tests designed to show their mental abilities including memory before, during and after the study. The scientists found no measurable improvement in memory or any other mental ability.
The Journal of the American Medical Association reported the findings. The National Institute on Aging provided money for the study.
In recent years, the American government has approved such studies to examine claims made by producers of herbal products. The Food and Drug Administration sets rules for medicines sold in the United States, but not for herbal products.
Makers of ginkgo were quick to dispute the findings. Boehringer Ingelheim Pharmaceuticals made the ginkgo products used in the study. A company official said that other studies have found that ginkgo improved people's memory. An industry trade group added that larger studies are necessary.
The lion is perhaps the most famous member of the cat family. Lions are well known for their power and beauty. Adult male lions are the only cats with manes. This long, thick hair covers the animal's head and neck.
For years, biologists have wondered why lions have manes or what purpose they serve. One suggestion is that the thick hair protects a lion's neck during fights with other males. Another idea is that the mane is a sign of the male's physical condition. This idea says the hair frightens other males and helps females choose successful mates.
Now, a new American study suggests that manes strongly influence the sex life of lions. Two University of Minnesota scientists found that female lions in Tanzania like males with dark manes. Science magazine reported their findings.
Peyton West and Craig Packer studied lions in Tanzania's world famous Serengeti National Park. They set up life-size models of lions near where the wild animals live. The models of the lions had different kinds of manes. Then, they waited to see how the lions would react to the models.
The scientists say the results were clear. Male lions were not afraid to move toward the model lions with short and light-colored manes. The females were less concerned about hair length. However, they avoided the model lions with lighter manes. Ninety percent of the time, the females moved toward the model lions with dark hair.
Mizz West said the females seemed to be reacting to the physical condition of the males. She said lions with dark manes usually have higher levels of the male hormone testosterone. She notes that such lions are more aggressive fighters. They win fights more often. Her studies show that male lions with dark manes are more likely to recover from wounds. They also are able to frighten other lions and defend their families.
A drug normally used to treat cancer has been found to have a surprising side effect. It appears to restore color to gray hair in some people.
Doctors from the Victor Segalen University in Bordeaux, France were testing the drug, called Gleevec. Last year, American officials approved Gleevec for treatment of chronic myeloid leukemia, a rare form of blood cancer.
The French doctors gave the drug to one-hundred-thirty-three leukemia patients. The drug darkened the hair of nine patients who had gray hair. The darkening effect began two to fourteen months after the patients began taking the drug.
One doctor said the effect may have been found in even more patients. It was difficult to identify the true numbers because some patients had used hair coloring products to darken their hair.
The New England Journal of Medicine published the findings. Gleevec has strong side effects. It can damage the liver and blood. So doctors say the drug should not be used as a hair-coloring product. But scientists have begun to study the unusual side effect.
Scientists have discovered a genetic change that can cause malignant melanoma, the most serious kind of skin cancer. The cancer spreads through the body. Malignant melanoma kills almost forty-thousand people around the world each year.
The new research was reported in the publication Nature. The work was done by medical scientists involved in the Cancer Genome Project at the Wellcome Trust Sanger Institute in Cambridge, England. The aim of the Cancer Genome Project is to find which of the thirty-thousand human genes are involved in cancer.
Genes contain material called D-N-A. The order of the D-N-A in a gene is represented by a series of letters. A change, or mutation, happens when the order of the letters changes. Mutations happen in two ways. Chemicals, radiation or viruses can damage D-N-A. Damage also can result from mistakes before cells divide.
Most of these mutations are harmless. However, sometimes a mutation in a gene will cause cells to act in an unusual way. For example, a changed gene will cause a cell to divide when it should stop dividing. Or the cell will move away from its normal place and into another organ. This is how cancer begins. Experts say it takes about twenty-five years from the time of the first gene mutation until a cancerous growth appears in adults.
Cancer Genome Project researchers have been examining human genes to find the abnormal genes that cause cells to become cancerous. The change that causes malignant melanoma is the first one they have found. It is in the gene called B-R-A-F, one of a group of genes that must all be turned on for a cell to grow and divide.
Scientists say when a gene causes a cell to grow and divide it is "turned on." Normally, it then "turns off" and stops the cell from dividing any more. The Genome Project scientists found that the mutation makes the gene stay turned on all the time. It causes the cells to divide and never stop. This leads to cancer.
The researchers say the finding could lead to effective drugs to treat melanoma. They have already started searching for drugs to make the gene turn off and stop the growth of the cancer. But they also say that people should try to prevent malignant melanoma from developing by staying out of the sun as much as possible.
This SCIENCE IN THE NEWS program was written by George Grow and Nancy Steinbach. It was produced by Cynthia Kirk. This is Sarah Long. And this is Steve Ember. Join us again next week for more news about science in Special English on the Voice of America.