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On Thu, 29 Apr 2004 09:34:15 +0000 (UTC), (maff),
Message ID: <18510aff.0404290138.6252e141@posting.google.com> wrote in
alt.atheism;
A Glimpse at the Future of DNA: M.D.'s Inside the Body
http://www.nytimes.com/2004/04/29/science/29DNA.html
http://www.taipeitimes.com/News/world/archives/2004/04/30/2003138611
DNA key to in-body device to aid diagnosis, treatment
SOLUTIONS IN SOLUTION: The `computer' is a liquid that changes its state
based on a single variable, and then its `sticky ends' slice off
offending DNA segments
NY TIMES NEWS SERVICE , NEW YORK
Friday, Apr 30, 2004,Page 7
Scientists have developed what they say could become the world's
smallest medical kit: a computer made of DNA that can diagnose disease
and automatically dispense medicine to treat it.
The computer, so small that a trillion would fit into a drop of water,
now works only in a test tube, and it could be decades before something
like it is ready for practical use.
But it offers an intriguing glimpse of a future in which molecular
machines operate inside people, spotting diseases and treating them
before symptoms appear.
"Eventually we have this vision of a doctor in a cell," said Ehud
Shapiro of the Weizmann Institute of Science in Rehovot, Israel, who led
the research, whch was published online Wednesday by the journal Nature.
DNA's role is to store and process information, the genetic code. So it
is not surprising that DNA can be used for other computing tasks as
well, and scientists have used it to solve mathematical problems.
However, the Israeli scientists said theirs was the first DNA computer
that could have a medical use.
The computer, a solution of DNA and enzymes, was programmed to detect
the kind of RNA (a DNA cousin) that would be present if particular genes
associated with a disease were active.
In one example, the computer determined that two particular genes were
active and two others inactive, and therefore made the diagnosis of
prostate cancer. A piece of DNA, designed to act as a drug by
interfering with the action of a different gene, was then automatically
released from the computer.
Experts called the work ingenious but pointed out that it had been done
in a test tube to which the RNA corresponding to the disease genes was
added. It is not clear, they said, whether such a computer could work
inside cells, where there would be an abundance of DNA, RNA and
chemicals that could interfere with the reactions.
"I think it's very elegant -- it's almost like a beautiful mathematical
proof," said George Church, professor of genetics at Harvard Medical
School. "But it's not working in human cells yet."
DNA has intrigued some computer scientists since 1994, when Len Adleman
of the University of Southern California showed it could be used to
solve a mathematical problem.
People in the field then began envisioning billions of pieces of DNA
undergoing chemical reactions, solving problems too complex for more
conventional computers.
Some scientists have since concluded that it will be difficult to get
DNA computers to match the power of electronic computers.
But Shapiro, who is also in the Weizmann Institute's department of
biological chemistry, decided to focus on a DNA computer for use in the
body, where silicon would have a hard time competing.
And rather than trying to build the DNA equivalent of a supercomputer,
or even a wristwatch calculator, he made a device so simple that it can
barely be called a computer.
It has two states, "yes" and "no," and changes from one to the other on
the basis of a single variable, like the presence or absence of the RNA
it is looking for. If at the end of a series of steps it is in the "yes"
state, the diagnosis is positive.
The Weizmann DNA computer encodes both the software and the data in the
four letters of the genetic code, A, C, G and T.
The "hardware," the part of the computer that does not change, is an
enzyme that cuts the strands of DNA in a particular way.
The computer is made of double-stranded DNA with ends that are
single-stranded. These so-called sticky ends can bind to specific other
strands of DNA or RNA in the solution under the usual rules of DNA
pairing.
If binding occurs, the enzyme cuts the DNA a certain distance away,
exposing new sticky ends. If those ends find something to bind to, the
enzyme cuts in yet another location, and so on.
If the chain reaction proceeds in a certain way, the enzyme eventually
slices off the piece of DNA that acts as the drug.
After the DNA encoding the problem is made and put in the test tube, the
computer works automatically and arrives at the answer in minutes.
"Basically," Shapiro said, "we just drop everything in solution and see
what happens."
(c) 2004 New York Times
Stoney
"Designated Rascal and Rapscallion
and
SCAMPERMEISTER!"
When in doubt, SCAMPER about!
When things are fair, SCAMPER everywhere!
When things are rough, can't SCAMPER enough!
/end humour alert
alt.atheism military veteran #11
{so much for the 'no atheists in foxholes' rubbish}
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