Tea for the heart
Tea may steep the arteries in healthy chemicals, say researchers trying to explain why tea drinkers appear to have a lower risk of heart attack.
Studies have long suggested that a cup a day of black tea, the most common tea for American drinkers, somehow lowers the risk of heart disease and stroke. But a biological explanation for the trend wasn't known.
Now researchers say that compounds in black tea relax the arteries, allowing more blood to flow into the heart. "Drinking tea reverses an important abnormality of blood vessel function," said Dr. Joseph Vita of Boston University School of Medicine. Dr. Vita presented his research during the American Heart Association's recent annual Scientific Sessions in New Orleans.
Dr. Vita asked 50 volunteers to drink four 8-ounce cups of tea a day for a month. They also drank the same amount of water for a month. The researchers then measured the effects on the participants' arteries.
Even two hours after exposure to the tea, blood vessels opened up. The water had no effect.
While the results were encouraging, the researchers said, future studies will determine whether tea will be a recommended way to lower the risk of a heart attack.
Nothing will quiet a schoolyard bully the way an even bigger bully does. The same goes for elephants that kill animals in the wild.
In the latest issue of the journal Nature, researchers report that older bull elephants can calm young males that go on rampages.
In Pilanesberg, South Africa, the researchers write, young male African elephants introduced into a park killed 40 white rhinos between 1992 and 1997. The young males were in musth, a normal state of increased aggression and sexual activity.
Musth occurs when testosterone levels surge. In natural populations of elephants, musth generally begins between the ages of 25 and 30. Initially, musth lasts a few days. By the time elephants reach 40, it can last four months.
But the male elephants in Pilanesberg, removed from their natural setting, matured earlier. Musth began at 18 years of age and lasted up to five months.
To calm the young bulls, the researchers, from the University of Natal in Durban, South Africa, and Pilanesberg National Park, introduced six older males into the herd. Musth decreased, and the rhinoceros killing stopped.
Misbehaving blood vessels may hasten the muscle deterioration that plagues patients with Duchenne muscular dystrophy, Dallas researchers have found.
Duchenne muscular dystrophy is a hereditary disease that affects about two in every 10,000 boys. It's usually diagnosed when toddlers have trouble standing. Life expectancy is about 20 years, and the disease kills when heart muscle and the muscles that aid in breathing fail.
Although the genetic flaw associated with the disease was found in the 1980s, it's still unclear how the defect translates into disease.
In an upcoming issue of the Proceedings of the National Academy of Sciences, scientists from the University of Texas Southwestern Medical Center at Dallas, Scottish Rite Hospital and the University of Copenhagen provide a clue.
The researchers studied 10 boys with the disease and found that their muscles were deprived of oxygen during exertion.
Heightened constriction of blood vessels that supply the muscle caused the deprivation, and that constriction occurs because an enzyme that helps blood vessels relax isn't working properly, said Dr. Ronald Victor, the UT Southwestern cardiologist who led the study.
If scientists can find therapies to restore the enzyme's function, doctors might be able to slow progression of the disease.