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A.
New Insight into How Early Humans Adapted to Colder
Climates
Narrator:
This is Science Today. A new study finds mutations
in the mitochondrial DNA of human cells may have
helped migrating, early humans from Africa adapt
to colder, northerly climates. Douglas Wallace,
co-leader of the University of California, Irvine
study, says mitochondria are the power plants of
cells, generating heat to maintain body temperature
and synthesizing ATP, a chemical form of energy.
Wallace:
These mitochondria are actually ancient symbiotic
bacteria that entered our cells about 3 billion
years ago and as a result, they have their own genome,
their own DNA. Therefore, we've been able to reconstruct
the origin and migration by actually examining the
sequence variation of the mitochondrial DNA.
Narrator: Researchers discovered that a key
change in the mitochondrial DNA of early humans
may have resulted in successful adaptation to the
cold.
Wallace:
By changing this energy balance of their mitochondrial
power plants from primarily work ATP production,
to a high percentage of heat production to survive
the cold winters.
Narrator:
For Science Today, I'm Larissa Branin.
B.
Researchers to Study the Use of Medications to Treat
ADHD
Narrator:
This is Science Today. Researchers at the University
of California, Berkeley have received a 900 thousand
dollar federal grant to study the use of medications
to treat attention deficit hyperactivity disorder,
or ADHD. Stephen Hinshaw, a professor of psychology
and one of the nation's leading experts on ADHD, describes
the basic symptoms.
Hinshaw:
It's referring to a syndrome that has two main constituent
parts - one is inattention and disorganization and
the other is hyperactivity and impulsivity. The big
question for the clinician is when is this normal
childhood and when is this a clinically significant
disorder?
Narrator:
ADHD is diagnosed in 3.5 percent of school-age children
in this country. Because it's a behavioral and emotional
disorder based in the brain, Hinshaw says some people
are skeptical of the diagnosis.
Hinshaw:
Thorough evaluation is really probably the key
step towards distinguishing normal childhood, difficult
environmental situations from the syndrome we call
ADHD.
Narrator:
The newly funded three-year study seeks to better
understand the use of medications to treat ADHD. For
Science Today, I'm Larissa Branin.
C.
Acupuncture Research Gets a Big Federal Boost
Narrator:
This is Science Today. Acupuncture has become one
of the most popular forms of complementary medicine
in the United States, yet there's still some skepticism
in the Western medical community about this ancient
Eastern healing treatment. John Longhurst, a cardiologist
at the University of California, Irvine, has been
studying acupuncture for over a decade and says there
are several reasons for this skepticism.
Longhurst:
We in medical school, in the past at least, have
not been taught about these various treatment modalities.
And then secondly, they're not really very familiar
with the type of research that has gone in these areas
and then finally, the little that they do know about
it - much of that literature is not particularly high
quality.
Narrator:
Longhurst received a two million dollar, federal grant
- the first of its kind - to continue studying how
acupuncture influences the cardiovascular system.
Longhurst:
It's very clear that acupuncture can lower what we
call the sympathetic outflow and the sympathetic outflow
comes from the brain and causes constriction of the
blood vessels and increased activity of the heart.
Narrator:
For Science Today, I'm Larissa Branin.
D.
What Everyone Should Know about Advance Directives
Narrator:
This is Science Today. Planning for end of life
care often includes an advance directive, a written
document that indicates particular treatment preferences
and designates individuals who can make decisions
for us. But According to Felicia Cohn, director of
medical ethics at the University of California, Irvine
College of Medicine, advance directives are not always
sufficient by themselves.
Cohn:
Advance directives are a good idea in theory.
The problem with advance directives is that most of
us can't predict the things we will actually face
as we approach the ends of our lives.
Narrator:
To bridge the gaps, Cohn urges discussing and
documenting your wishes with family and doctors, in
addition to an advance directive.
Cohn:
It's always good to document those conversations with
your physician, so that he can include a note in your
chart along with an advance directive. Doctors certainly
feel more comfortable when there is something in writing
that you can draw on and it's nice if you can document
those conversations because some states require a
higher level of evidence should your situation end
up in court.
Narrator:
For Science Today, I'm Larissa Branin.
E.
A Call for New Guidelines for Prenatal Diagnostic
Testing
Narrator:
This is Science Today. Although pregnant women
of all ages and risk levels are routinely offered
prenatal screening tests, current guidelines recommend
the more invasive testing, such as amniocentesis,
be reserved for women age 35 and older. Dr. Miriam
Kuppermann of the University of California, San Francisco,
says this threshold is based on the belief that the
likelihood of carrying an affected fetus is equal
to the small risk of procedure-related miscarriage.
Kuppermann:
There would be clearly reluctance to do a procedure
that was more likely to cause a miscarriage than to
identify a fetus with Down syndrome. But the problem
with that threshold is there is an implicit assumption
that those two outcomes would be equally burdensome
for the average woman.
Narrator:
In a study of pregnant women of all ages, Kuppermann
found this was not the case.
Kuppermann:
My hope is that the guidelines will be expanded
to enable women to make their own informed choices
about which test, if any, makes sense for them to
undergo.
Narrator:
For Science Today, I'm Larissa Branin.
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