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Citation
style: ProQuest Standard |
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Document 1 of 1 |
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People: |
Fry,
Bryan Grieg |
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Author(s): |
Rick
Weiss |
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Document
types: |
News |
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Section: |
Sunday Reader - Science |
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Publication
title: |
Edmonton
Journal. Edmonton, Alta.: Mar 20, 2005. pg. D.9 |
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Source
type: |
Newspaper |
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ProQuest
document ID: |
810559511 |
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Text
Word Count |
831 |
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Document
URL: |
http://proquest.umi.com/pqdweb?did=810559511&Fmt=3&clientId=17280&RQT=309&VName=PQD |
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Abstract (Document Summary) |
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More
important, it promises new drugs for cancer, heart disease and many other
ills, says Bryan Grieg Fry, a snake venom expert at the University of
Melbourne in Australia. In a landmark article published this month, Fry
traced the evolutionary roots of all the major poisons known to occur in
snake venoms -- a feat scientists said should facilitate a spectrum of
biomedical discoveries. One of those
bites launched Fry on his quest to understand the origins of snake venoms
and, with luck, discover new medical applications. The culprit was a rare
Stephen's banded snake, which Fry was trying to catch in the Australian
rainforest. To find out,
Fry did something that was relatively simple but that no one else had done
before. He knew that snake toxins are proteins, and proteins are long strings
of amino acids, whose order determines the protein's shape and function. He
compiled the amino acid sequences for all 24 of the major known snake toxins
and, with a computer program, compared them with the sequences of all the
other known proteins in snakes and other backboned creatures. |
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Full Text (831 words) |
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(Copyright Edmonton Journal 2005) Milking
venom's medicinal value: THE BITE OF LIFE / Researchers are unravelling the
secrets of snakes to develop potent new drug treatments Sixty million
years after the earliest snakes figured out how to make venom in their
salivary glands, descendants of the little mammals those snakes preyed on
have begun to figure out just how the slithering reptiles did it. And while it
is too late for those who, in the intervening epochs, found themselves
hyperventilating, paralysed or worse because of a run-in with a pair of
fangs, it is not too late for the rest of us. A better
understanding of what snake venoms are -- and how snakes cooked them up over
eons of evolution -- promises better antivenins for future snakebite victims. More
important, it promises new drugs for cancer, heart disease and many other
ills, says Bryan Grieg Fry, a snake venom expert at the University of
Melbourne in Australia. In a landmark article published this month, Fry
traced the evolutionary roots of all the major poisons known to occur in
snake venoms -- a feat scientists said should facilitate a spectrum of
biomedical discoveries. Already,
venoms from snakes and other creatures have led to the development of
important medications, including the blood pressure drug captopril, which is
a modified version of a toxin found in the green mamba of Africa. Venoms have
also proved their mettle in basic biomedical research -- their ill effects
sometimes offering the first clue that there are biological systems in the
body no one knew about. A toxin found in the deadly many-banded krait of
Southeast Asia, for example, led to the discovery of an entire component of
the human nervous system that had been unknown. "Snakes
are so inventive. Their venoms are a tremendous natural pharmacy," said
Fry, who milks venom from 2,000 to 3,000 snakes a year and feels lucky to
have been bitten only 24 times. One of those
bites launched Fry on his quest to understand the origins of snake venoms
and, with luck, discover new medical applications. The culprit was a rare
Stephen's banded snake, which Fry was trying to catch in the Australian
rainforest. "It
knocked me out very quickly," Fry said. "As I was hitting the
ground, I was thinking: 'Hmm, this is a rather unusual effect. If I survive
this, I should be able to get a PhD out of it.' " He did. After
recovering, he analysed the snake's venom and found it was loaded with
especially potent "natriuretic peptides," the class of proteins
that in many animals -- including humans -- naturally help reduce blood
pressure. "This explained the ability of the snake to knock me out so
quickly," Fry said. Fry went on to
find that many snakes have versions of natriuretic toxins in their venoms,
which are typically mixtures of toxins. He ended up with not only a doctorate
but also a patent application for a version of the poison that may have
potential as a treatment for congestive heart failure, a sometimes fatal
complication of high blood pressure. But the
finding also made Fry wonder: How many other snake toxins are "evil
twins" of molecules that are normally helpful or even necessary to life?
Biologists had long speculated that some snake toxins are chemical relatives
of pancreatic enzymes. The pancreas, after all, is famed for its ability to
digest all kinds of biological tissues, and many snakebite wounds end up
looking like errant acts of digestion. Might other
toxins have similar roots? To find out,
Fry did something that was relatively simple but that no one else had done
before. He knew that snake toxins are proteins, and proteins are long strings
of amino acids, whose order determines the protein's shape and function. He
compiled the amino acid sequences for all 24 of the major known snake toxins
and, with a computer program, compared them with the sequences of all the
other known proteins in snakes and other backboned creatures. As reported in
the March issue of the journal Genome Research, 23 of the 24 toxins were very
close matches with proteins that have important functions in the bodies of
vertebrates. Apparently
snakes have "learned" to make these proteins in their salivary or
venom glands. And not just the normal versions of those proteins but mutated
versions that in many cases make them lethally more potent than the parent
proteins. Some snakes,
for example, make modified versions of chemicals that normally help nerve
cells communicate with muscle cells -- and they do it so well they lock up
the system, causing paralysis. Other snakes produce mutated versions of
blood-clotting factors that trigger countless small clots in the victims'
blood. That uses up victims' own clotting factors and leads to deadly
bleeding. "They're throwing our natural clotting factors right back at
us," Fry said.
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