is the VOA Special English program SCIENCE IN THE NEWS. I'm Steve Ember.
And I'm Doug Johnson. This week, we will tell about a drug treatment
for stroke victims. We also will tell
about a possible explanation for the mysterious disappearance of bees. And, we will tell about a lot of plastic waste
in the Pacific Ocean.
Strokes are a major cause of death and
disability. A stroke is a loss of blood
flow in the brain. There are two kinds
of strokes. An ischemic stroke happens
when a blood vessel in the brain gets blocked. A bleeding, or hemorrhagic, stroke happens
when a blood vessel breaks.
are more likely to die from a hemorrhagic stroke. But ischemic strokes are more common, and
doctors may be able to treat them.
A drug called tissue plasminogen
activator, or tPA, can break up blood clots. But experts generally advise against using the
drug if more than three hours have passed after the first signs of a stroke.
There is a risk that giving a patient a strong
blood thinner during a stroke can cause bleeding inside the brain. The longer the wait, experts say, the more
likely that the risks of treatment will be too great.
But recent findings suggested
that tPA may be effective in saving brain tissue even if three to four and a
half hours have passed.
studies have failed to produce clear evidence to support treatment after three
hours. But researchers reported recently
that the evidence was stronger when they combined the results of the four major
studies already done.
findings were published in the journal Stroke. The researchers said tPA improved the chances
of a successful result by thirty-one percent and produced no change in the
Scientists from Belgium and
Germany worked with Maarten Lansberg of the Stanford University School of
Medicine in California. One of the
scientists worked for a company that makes tPA for use in Europe. America's National Institutes of Health paid
for the study.
you think someone is having a stroke, you should seek help immediately. The warning signs often appear suddenly. These include trouble walking, weakness
especially on one side of the body, difficulty seeing and difficulty speaking.
people who seem healthy can suffer a stroke without even knowing it. A study published last year involved about two
thousand people with an average age of sixty-two. Brain imaging showed that nearly eleven
percent of them had suffered what is known as a silent stroke.
The study found a link between silent strokes and a condition
called atrial fibrillation. This is the
most common cause of an unusual, or abnormal, heartbeat in older adults.
Colony collapse disorder first struck honey bees in the
United States in late two thousand six. Over the next two years, beekeepers lost more than one-third of their
in the United States and other countries have been working to explain the
mysterious disappearances of bees. Now, a
new study suggests that several viruses may act together.
Scientists from the University of Illinois and the
United States Department of Agriculture carried out the study. The scientists compared bees from affected
colonies with those from healthy colonies. They were looking for differences in gene expression in the guts of the
scientists found that the affected bees had a number of viruses from a group
called picorna-like viruses. The
infections observed in the bees included Israeli acute paralysis virus and
deformed wing virus.
small insects are likely involved in spreading the viruses. Varroa mites have been causing serious
problems in bee colonies in the United States since the late nineteen
eighties. These mites carry picorna-like
The viruses appear to harm the bees' ability to use
their genes to produce proteins needed to fight infections.
of Illinois Professor May Berenbaum says it appears that bees could deal with
one or two viruses at the same time, but not three or four. She says the picorna-like viruses seize
control of the ribosome in cells. Ribosomes are structures in which proteins are made.
professor says ribosome is important to the survival of any organism. If it is compromised, then the bees could not
defend themselves against pesticide products, fungal infections, bacteria or
poor nutrition. These have all been
identified as possible causes of the collapse disorder.
Imagine a mass of floating waste two
times the state of Texas. Texas has a
land area of more than six hundred and seventy-eight thousand square kilometers. So it might be difficult to imagine anything
twice as big.
includes bags, bottles and containers. Plastic
products of all kinds -- even shoes. There
also are lots and lots of extremely small pieces of plastic.
together, this mass of waste floating in the North Pacific Ocean is known as
the Great Pacific Ocean Garbage Patch. It weighs about three million, five hundred thousand tons.
The eastern part of the Great
Pacific Ocean Garbage Patch is about one thousand six hundred kilometers west
of California. The western part is west
of the Hawaiian Islands and east of Japan. The two patches of waste are connected together in the shape of a dog
bone -- a really big bone about nine thousand kilometers long.
The waters surrounding
the Great Pacific Ocean Garbage Patch are known as the North Pacific Gyre. The area has been described as a kind of
oceanic desert, with light winds and slow moving water currents. Slow enough that garbage from all over the
world collects there.
say the garbage gets trapped in the currents for years before being pushed
out. Some of the trash finds its way to
coastal areas around the world.
recent years, there have been growing concerns about the floating garbage and
its effect on sea creatures and human health. America's Environmental Protection Agency estimates that about one
hundred thousand sea animals die each year as a result of the plastic waste. An estimated one million sea birds are also affected.
say thousands of the animals get trapped in the floating waste, resulting in
death or injury. Even more die from a lack
of food or water after swallowing pieces of plastic. The plastic can block air passages. The trash can also make the animal feel full,
lessening its desire to eat or drink.
floating garbage also can have harmful effects on people. There is an increased threat of infection and
disease from polluted waste, and from eating fish that swallowed waste. Divers can also get trapped in the plastic,
and it can get caught up in boating equipment. The plastic also releases chemicals into the water. Some of the chemicals are harmful to both
humans and animals.
existence of the North Pacific Garbage Patch first gained public attention in
nineteen ninety-seven. That was when racing
boat captain and oceanographer Charles Moore and his crew sailed into the
garbage while returning from a racing event.
years earlier, another oceanographer learned of the trash after a shipment of rubber duckies got lost at
sea. Many of those toys are now part of the
Great Pacific Ocean Garbage Patch.
Moore and his team at the Algalita Marine
Research Foundation have spent ten years studying plastic waste and testing
water from the ocean. Their studies
found up six times more plastic in the water than zooplankton, the small organisms
normally found floating near the ocean's surface. They have also found small pieces of plastic
inside the stomachs of fish like mahi-mahi.
Last month, a team from
the University of California at San Diego became the latest group to travel to
the Great Pacific Ocean Garbage Patch. The team of students and research volunteers set off on a three-week
boat trip to examine the area.
shocked by the amount of waste they saw. They gathered hundreds of sea creatures and water samples to measure the
garbage patch's effect on ocean environment. There were small pieces of plastic in every sample.
This SCIENCE IN THE NEWS
was written by June Simms and Jerilyn Watson. Our producer was Caty Weaver. Transcripts, MP3s and podcasts of our programs are at voaspecialenglish.com. I'm Steve Ember.
And I'm Doug Johnson. Listen again next week for more news about
science in Special English on the Voice of America.