Blood Pressure / Eating Study / Dinosaur Diets
I'm Bob Doughty with Phoebe Zimmermann, and this is the VOA Special English program SCIENCE IN THE NEWS.
Today -- experts take a new look at blood pressure ... a study of laboratory mice looks at the health effects of eating every other day ... and, we tell about evidence that some dinosaurs ate members of their own species.
American medical experts have a warning for many people who think their blood pressure is normal. They say these people are really in danger of developing high blood pressure, also called hypertension.
The information is in a new report by the National Heart, Lung and Blood Institute. That is part of the National Institutes of Health in the United States. The Journal of the American Medical Association published the report and new guidelines from the experts.
Until now, doctors had considered a blood pressure of one-hundred-twenty over eighty to be normal. But the new guidelines say people start to increase their chances of heart disease or stroke at readings as low as one-hundred-fifteen over seventy-five. It also says those chances go up one-hundred percent for each increase of twenty systolic points and ten diastolic points. The systolic is the number on the top. The diastolic is the number on the bottom.
The guidelines say normal blood pressure is now considered under one-hundred-twenty over eighty. People are still considered to have high blood pressure with a reading of one-hundred-forty over ninety. But, now, those with readings in between are to be considered prehypertensive -- at risk for developing high blood pressure.
Blood pressure is the force of the blood against the walls of the arteries as it moves through the body. The amount of force depends on the strength and rate of the heart movement, the amount of blood in the body and the health of the arteries.
Blood pressure is measured with a device placed around the arm or leg. The results are reported in millimeters of mercury. The systolic pressure -- the higher value -- is created by the movement of the heart muscle. It is also created by the reaction of the large artery as the blood moves through. The second number is called the diastolic pressure. It measures the resistance of all the small arteries in the body and the load the heart must work against.
High blood pressure has been called the silent killer. Many people do not know they have it until a serious health problem appears. High blood pressure damages the arteries in a way that provides less room for blood to flow. This continues to increase the pressure. High blood pressure can cause heart attack, stroke and kidney disease. It can also cause vision problems by damaging the retina at the back of the eye.
The medical experts who wrote the new report say they want people to act to improve their health before high blood pressure can develop. People can reduce their blood pressure if they stop cigarette smoking, reduce the amount of alcohol they drink, lose weight, eat less salt and exercise thirty minutes a day.
Blood pressure generally increases with age. The experts say even people with normal readings at age fifty-five have a ninety percent chance of developing high blood pressure later in life. They say these people, too, should stop smoking and should exercise and eat more fruits, vegetables and other healthy, low-fat foods to control their blood pressure.
Sometimes these life changes do not reduce blood pressure enough. Doctors can treat high blood pressure with a number of drugs. The new report says this treatment should be aggressive, and may include the use of more than one drug at a time. But the experts also say people with prehypertension do not need drugs -- they just need to take steps now that will improve their future health.
You are listening to the VOA Special English program SCIENCE IN THE NEWS. I'm Bob Doughty with Phoebe Zimmermann in Washington.
A study by the National Institute on Aging has found that mice that ate every other day appeared to improve their resistance to diabetes and brain damage. The study was published in the Proceedings of the National Academy of Sciences. Scientists now plan a study to see if fasting would work as well for people, too.
The team studied three groups of mice. One group was fed as normal. Another group was fed thirty percent less food daily than normal. The mice in the third group were permitted to eat as much as they wanted – but only every other day.
The mice fed less food daily lost a lot of their body weight. But the mice that ate every other day weighed about the same as the mice fed normally. That is because, once provided food, the mice that fasted ate as many calories as the mice that ate as normal.
Even so, the scientists found that the fasting mice had lower blood sugar levels and lower insulin levels compared with the other groups. This suggests that the mice that fasted were less likely to develop diabetes. Diabetes is caused by the body's inability to produce insulin or use insulin correctly.
At the end of the experiment, the scientists injected all three groups of mice with a chemical. This chemical damages nerve cells in a part of the brain, the hippocampus. The hippocampus is important for learning and memory. In humans, nerve cells in this area are destroyed by Alzheimer's, a brain disease mostly in older people. The scientists found that the nerve cells of the mice that ate every other day were more resistant to damage by the chemical than those of the other mice.
Doctor Mark Mattson led the study. He says he believes going without food puts mild stress on cells throughout the body. He says the cells react by increasing their ability to deal with more severe stress, like the effect of exercise.
Doctor Mattson said an earlier study showed that fasting appeared to help mice live longer. Still, he says more research is needed to learn the full effect that missing meals may have on health.
Scientists have discovered evidence that a dinosaur that lived in Madagascar more than sixty-five-million years ago ate members of its own species.
Scientists already had evidence that dinosaurs ate plants and other kinds of dinosaurs. This new research supports the idea that there were also dinosaurs that ate other members of their species -- cannibals, in other words.
Dinosaurs first appeared more than two-hundred-twenty-million years ago. They died out about sixty-five million years ago. The different species of dinosaurs were different in size. The largest dinosaur was more than twenty meters long, while the smallest was about the size of a chicken.
Raymond Rogers of Macalester College in the American state of Minnesota led the team. Nature magazine reported the findings. The scientists dug up fossil bones of two Majungatholus atopus dinosaurs in Madagascar. These remains show deep teeth marks that the researchers say could only have been made by another Majungatholus. These large creatures had sharp teeth like knives.
Several years ago, the same group of researchers discovered a head bone from this kind of dinosaur. They found that the teeth of that skull fit exactly into the marks on the recently discovered fossil bones. However, the scientists could not establish if the Majungatholus was likely to have killed its victims, or simply fed on the remains.
The team also studied the teeth of other meat-eating pre-historic animals found on the island of Madagascar, off the coast of East Africa. None of the teeth matched the marks on the two recently discovered fossil bones.
An earlier discovery suggested that a kind of small dinosaur found in the American Southwest may have eaten its young. But the team led by Raymond Rogers notes in a letter to Nature that there have been recent questions about that evidence.
Professor Rogers says the evidence found by his team is clear. He says that when Majungatholus was alive, food on Madagascar may have been hard to find. As a result, he says, the species likely turned to cannibalism to survive.
SCIENCE IN THE NEWS was written by Nancy Steinbach, Jill Moss and Cynthia Kirk, and our program was produced by Cynthia Kirk. 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.