VOICE ONE:
This is SCIENCE IN THE NEWS in VOA
Special English. I'm Bob Doughty.
VOICE TWO:
And I'm Faith Lapidus. This week, we will tell about a brain injury
known as silent stroke. We will also
tell about melanoma -- the most deadly form of skin cancer. And, we will tell you about the healthful
effects of vitamin D.
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VOICE
ONE:
Stroke
is a serious problem that can lead to death.
Usually the warning signs appear suddenly. But a recent study found that seemingly healthy middle-aged
people could suffer a stroke without immediately knowing it. The finding was reported in "Stroke:
Journal of the American Heart Association."
The
study involved about two thousand people.
They were the children of men and women who took part in the Framingham
Heart Study. The Framingham Heart Study
began sixty years ago in Framingham, a town in the American state of
Massachusetts. Much of what doctors
know about heart disease has resulted from this research project.
VOICE
TWO:
The average age of men and women in the
new study was sixty-two years. The
group's members received medical examinations every four to eight years. They were given magnetic resonance imaging
tests to inspect for damaged brain tissue and signs of stroke.
The imaging tests showed that nearly
eleven percent of those with no sign of stroke had suffered a silent cerebral
infarction, or silent stroke. Silent
strokes are brain injuries likely caused by a blockage that limits blood to the
brain.
Eighty-four
percent of those who suffered silent strokes had a single wound, or lesion, in
the brain. This kind of damage can lead
to increased risk of future strokes and long-term memory loss.
VOICE
ONE:
For
the first time, the researchers found a link between silent stroke and the
condition atrial fibrillation. Atrial
fibrillation is the most common cause of unusual heartbeat in older adults.
Sudha Seshadri works at the Boston
University School of Medicine. She says
atrial fibrillation increased the risk of suffering a stroke more than two
times. High blood pressure and systolic
blood pressure were also linked to an increased risk of silent stroke. Blood pressure readings are usually given in
two numbers. The upper number is
systolic blood pressure.
VOICE
TWO:
Doctor
Seshadri says the findings show the need for early testing and treatment of
conditions that could lead to heart disease in middle-aged people. Experts say nothing special needs to be done
to reduce the risk of silent stroke.
But they are urging people to watch for risk factors. They include atrial fibrilation, high blood
pressure, heart disease, diabetes and cigarette smoking.
The American Stroke Association says
people who think they are having a stroke should seek emergency medical
help. The warning signs include sudden
weakness, especially on one side of the body, and difficulty speaking or
understanding. Other warning signs are
trouble seeing in one or both eyes, trouble walking, loss of balance and severe
head pain.
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VOICE ONE:
An American study shows that
increasing numbers of young women are developing melanoma, the most deadly form
of skin cancer. The study did not
identify causes of the increase.
However, the lead researcher says it could be the result of young women
seeking to make their skin darker.
The
American Cancer Society says about sixty-two thousand cases of melanoma are
found each year in the United States.
The disease will kill more than eight thousand four hundred Americans
this year.
The biggest risk for developing melanoma
is ultraviolet radiation. However,
genetics could also be important.
People with light or fair skin are most at risk. Yet melanoma affects people of all races and
skin colors.
VOICE TWO:
Results of the new study were
reported last month in the Journal of Investigative Dermatology. The increase in melanoma cases is nothing
new. Other studies have shown the rate
of new cases increasing in the general population. But federal researchers did not know about the sharp increase
among young women.
Mark Purdue of the National Cancer
Institute led the study. His team
examined rates of melanoma for a thirty-year period -- from nineteen
seventy-three to two thousand four.
They found more than twenty thousand melanoma cases in Americans between
the ages of fifteen and thirty-nine years.
The researchers say they found that the
rate among young women rose fifty percent since nineteen eighty. For men of the same age, however, the rate
stayed the same.
VOICE ONE:
One reason for the rise in cases could
be an increase in early discovery of the disease. But the researchers believe that is not the only reason because
more serious forms of the cancer are being found.
Some experts say the study's
results could be a sign of an even greater problem in the future. This is because melanoma can develop over
years and become deadly later in life.
The number of older adults with the disease has been increasing for many
years.
VOICE TWO:
Mark Purdue says the findings
suggest that public education campaigns about the dangers of skin cancer do not
seem to be helping. He believes the
increase may be connected to women spending more time under the sun and in
tanning salon beds. Tanning beds
produce ultraviolet radiation that can damage the skin.
The tanning salon industry
disputes the idea that its treatments are to blame for the rising melanoma
rates.
People
can reduce their risk of developing the disease by avoiding the sun when it is
strongest. Wearing protective clothing
and sunblock products can also reduce the risk.
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VOICE ONE:
Vitamin D helps bones and muscles grow
strong and healthy. Low levels of
vitamin D can lead to problems such as rickets, a disorder mainly found in
children. Osteoporosis, the thinning of
bone, is a common problem as people, especially women, get older. But more and more research is suggesting
that vitamin D might also help prevent many diseases.
VOICE
TWO:
The
easiest way to get vitamin D is from sunlight.
The sun's ultraviolet radiation reacts with skin cells to produce
vitamin D. But many people worry about
getting skin cancer and skin damage from the sun. As a result, they cover their skin, wear sunblock products or
stay out of the sun.
Also, darker skinned people produce less
vitamin D than lighter skinned people.
Production also decreases in older people and those living in northern
areas that get less sunlight.
Not many
foods naturally contain vitamin D.
Foods high in this vitamin include fish liver oils and oily fish such as
salmon, tuna and mackerel.
VOICE
ONE:
Boston
University researchers reported last year that farmed salmon had only about
one-fourth as much vitamin D as wild salmon.
Small
amounts of the vitamin are found in beef liver, cheese and egg yolks. And some people take dietary supplements
containing it. But most of the vitamin
D in the American diet comes from foods with D added, like milk.
In
nineteen ninety-seven, the United States Institute of Medicine established
levels for how much vitamin D healthy people need. It set the daily amount at two hundred international units from
birth through age fifty. It set the
level at four hundred I.U.s through age seventy, and six hundred for age
seventy-one and over.
But some groups say these amounts are
not high enough. They are hoping that
the new study findings will lead to new suggestions.
VOICE TWO:
Research in the past several years has
shown that low levels of vitamin D may increase the risk of heart attacks in
men and deaths from some cancers. Other
studies have shown that people with rheumatic diseases often have low levels of
vitamin D.
More
doctors are now having their patients tested for their vitamin D levels. But as research continues, some experts
worry that if people take too much vitamin D, it might act as a poison. Also, skin doctors warn people to be careful
with sun exposure because of the risk of skin cancer.
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VOICE ONE:
This
SCIENCE IN THE NEWS program was written by Lawan Davis, Caty Weaver and Brianna
Blake, who also was our producer. I'm
Bob Doughty.
VOICE TWO:
And I'm Faith Lapidus. Read and listen to our programs
at voaspecialenglish.com. Join us at this time next
week for more news about science on the Voice of America.