Dogs May Be Just What the Doctor Ordered for Worried Heart Patients
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This is SCIENCE IN THE NEWS in VOA Special English. I'm Bob Doughty. And I'm Pat Bodnar. This week, we bring you news of singing mice ...
Heart-healthy dogs ...
And a partying tortoise.
A new study finds that the animal known as man's best friend can also be a good friend to the heart. Researchers in California say they have found that even just a short visit with a dog helped ease the worries of heart patients.
Kathie Cole led the study. She is a nurse at the University of California, Los Angeles, Medical Center. The researchers studied seventy-six patients with heart failure.
The study divided the patients into three groups. In one group, a dog and a person visited each patient for twelve minutes. Patients in another group received just a human visitor for twelve minutes. And members of the third group received no visitor, human or canine.
The dogs would lie on the hospital bed so the heart patients could touch them. Kathie Cole says some patients immediately smiled and talked to the dog and the human visitor. Dogs, in her words, "make people happier, calmer and feel more loved."
The researchers examined the patients before, during and after the visits. They measured stress levels based on blood flow and heart activity. They used a measurement system called hemodynamics to rate the level of anxiety in the patients.
The researchers say they found a twenty-four percent decrease in the group visited by both a dog and a person. They reported a ten percent decrease in the group visited by a person only. There was no change in the patients without any visit. These patients, however, did have an increase in their production of the hormone epinephrine. The body produces epinephrine during times of stress.
The increase was an average of seven percent. But the study found that patients who spent time with a dog had a seventeen percent drop in their levels of epinephrine. Patients visited by a human but not a dog also had a decrease, but only two percent.
Another finding involved heart pressure. Heart pressure dropped by ten percent among patients visited by both a dog and a human. Patients with a human visitor only, however, had a three percent increase in heart pressure. And the study says there was a five percent increase in patients who received no visit.
Kathie Cole presented the research in Dallas, Texas, last month at the yearly meeting of the American Heart Association. The experiment involved twelve different kinds of dogs. All were specially trained for what is known as animal-assisted therapy. A non-profit group, the Pet Care Trust Foundation, paid for the study.
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Scientists know that male laboratory mice make unusual noises in the presence of female mice. This fact is not apparent to the human ear; the sound waves move too fast to hear without special equipment. So it has been difficult to carefully study the noises. Recently, however, scientists in the United States have established that these noises are songs.
Timothy Holy led the study. He is an assistant professor at the Washington University School of Medicine in Saint Louis, Missouri.
A song can be defined many different ways. But Professor Holy says there are usually two main qualities. A song should have a series of recognizably different musical sounds. And, he says, it should have some sounds that are repeated from time to time.
Other creatures that sing in the presence of the opposite sex include songbirds, whales and some insects.
Professor Holy worked with Zhongsheng Guo, a computer programmer in his laboratory. They were studying how the brain of male mice reacts to pheromones produced by female mice. Pheromones are chemicals that act as signals often linked to mating. Many different creatures, including humans, produce pheromones.
Professor Holy said the mouse songs are unusually difficult to record and examine. The scientists had to use computers to slow the noises down to the point where humans could make sense of them.
It sounds almost birdlike. The scientists say they were surprised by the complexity of the songs. They also found that individual male mice sing different songs. Professor Holy wonders if the mice learn to sing from a more experienced mouse, as birds do from other birds.
The findings appear in Public Library of Science Biology. This scientific publication and others can all be read free of charge at the Public Library of Science Web site. The address is p-l-o-s dot o-r-g (plos.org).
The Australia Zoo has held a birthday party in honor of a Galapagos land tortoise named Harriet. Her keepers believe she is one hundred seventy-five years old. To celebrate, they gave her a birthday cake made of hibiscus flowers.
Harriet weighs about one hundred fifty kilograms. The shell on her back measures about one square meter.
Scientists say she is the oldest living animal known. No one knows exactly when Harriet was born. But genetic tests suggest that she was born in about eighteen thirty.
A few years later, the British naturalist Charles Darwin visited the Galapagos Islands, near the coast of Ecuador. Discoveries made during the visit led Darwin to his beliefs about how human beings developed over many centuries.
Darwin collected three small, young tortoises from the islands and took them to England. Darwin noted in his writings that one of the creatures was a Santiago tortoise. Harriet fits that description, and some people think she is the one Darwin captured.
But news reports about the birthday party noted that there is no proof. In fact, no one can even be sure of her real birthday. The zoo chose November fifteenth because November is when the tortoise eggs usually hatch.
Back to the story. It is said that a former naval officer named John Wickham later took the tortoise with him from England to Australia. Wickham left it in the Brisbane Botanical and Zoological Gardens in eighteen forty-two.
The tortoise was thought to be a male. Darwin had named it Harry.
Children took rides on the back of the tortoise. Some people even cut their names into the shell. That must have hurt. The shell has feelings. The top part of it is called a carapace. The carapace is an extension of the rib bones.
In nineteen fifty-two, Harry was moved to a wildlife center on the Gold Coast of Australia. There, an animal expert from Hawaii made a surprising discovery. Harry the land tortoise was really a female. So Harry became Harriet.
After other moves, she has been living at the Australia Zoo since nineteen eighty-eight. Zoo owner Steve Irwin is known for his television program "Crocodile Hunter."
Harriet produces eggs each year. But she has not been near another of her kind for at least one hundred fifty years. They are not easy to find.
Only about fifteen thousand Galapagos giant tortoises live in the islands today. In Darwin's time, there were an estimated two hundred fifty thousand. Hunting, fishing and other animals have decreased a population thought to have lived in the islands for millions of year.
In the eighteen hundreds, sailors often captured the tortoises for food.
At one time, there were fifteen kinds of the Galapagos giant tortoises. Today there are eleven. Experts say the animals are not in immediate danger, but are threatened. Scientists are doing their part to help the population grow.
Old as she is, Harriet does not hold the record for the longest living creature. The Guinness Book of Records says a tortoise that died forty years ago holds that record. That tortoise was at least one hundred eighty-eight years old.
SCIENCE IN THE NEWS was written by Caty Weaver, George Grow and Jerilyn Watson. Cynthia Kirk was our producer. I'm Pat Bodnar. And I'm Bob Doughty. Our programs are online at voaspecialenglish.com. To send us e-mail, write to firstname.lastname@example.org. Join us again next week for more news about science in Special English on the Voice of America.