108 lines
6.0 KiB
Plaintext
108 lines
6.0 KiB
Plaintext
ÜÜÜÜÜÜÜÜÜÜÜÜÜ ÜÜÜ ÜÜÜÜ
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ÜÛÛÛÛÛÛÛÛßÛßßßßßÛÛÜ ÜÜßßßßÜÜÜÜ ÜÛÜ ÜÛÛÛÛÛÛÛÛÜÜÜÜÜÛßß ßÛÛ
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ßÛÛÛÛÛÛÛÛÛÛÛÛÛÛÜ ßÛÛ ÜÛÛÛÜÛÛÜÜÜ ßÛÛÛÛÜ ßÛÛÛÛÛÛÛÜÛÛÜÜÜÛÛÝ Ûß
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ßßßÛÛÛÛÛÛÛÛÛÛÜ ÞÝ ÛÛÛÛÛÛÛÛÛÛÛßßÛÜÞÛÛÛ ÛÛÛÛÛÜ ßßÛÛÛÞß
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Mo.iMP ÜÛÛÜ ßÛÛÛÛÛÛÛÝÛ ÞÛÛÛÛÛÛÛÛÛ ÞÛÛÛÛ ÞÛÛÛÛÛÝ ßÛß
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ÜÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛÝ ÛÛÛ ÛÛÛÛÛÛ
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ÜÛÛÛÛÛÛÛÝ ÞÛÛÛÛÛÛÛÛ ÞÛÛÛÛÛÛÛÛ ß ÞÛÛÛÛÛÛÜ ÜÛ
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ÜÛÛÛÛÛÛÛÝ ÛÛÛÛÛÛÛÛ ÛÛÛÛÛÛÛÛÝ ÞÞÛÛÛÛÛÛÛÛÛß
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ÜÛßÛÛÛÛÛÛ ÜÜ ÛÛÛÛÛÛÛÛÝ ÛÛÞÛÛÛÛÛÝ ÞÛÛÛÛÛÛßß
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ÜÛßÛÛÛÛÛÛÜÛÛÛÛÜÞÛÛÛÛÛÛÛÛ ÞÛ ßÛÛÛÛÛ Ü ÛÝÛÛÛÛÛ Ü
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ÜÛ ÞÛÛÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛ ßÛÜ ßÛÛÛÜÜ ÜÜÛÛÛß ÞÛ ÞÛÛÛÝ ÜÜÛÛ
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ÛÛ ÛÛÛÛÛÛÛÛß ÛÛÛÛÛÛÛÛÛÛÜ ßÛÜ ßßÛÛÛÛÛÛÛÛÛß ÜÜÜß ÛÛÛÛÜÜÜÜÜÜÜÛÛÛÛÛß
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ßÛÜ ÜÛÛÛß ßÛÛÛÛÛÛÛÛÛÛÜ ßßÜÜ ßßÜÛÛßß ßÛÛÜ ßßßÛßÛÛÛÛÛÛÛßß
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ßßßßß ßßÛÛß ßßßßß ßßßßßßßßßßßßß
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ARRoGANT CoURiERS WiTH ESSaYS
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Grade Level: Type of Work Subject/Topic is on:
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[ ]6-8 [ ]Class Notes [General Information ]
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[ ]9-10 [ ]Cliff Notes [About Chromosone Probes ]
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[ ]11-12 [ ]Essay/Report [ ]
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[x]College [x]Misc [ ]
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Dizzed: 10/94 # of Words:736 School: ? State: ?
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ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>Chop Here>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ
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=======================================================
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Chromosome Probes at the University of Toronto
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-------------------------------------------------------
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Uploaded: November 29, 1986.
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Sensitive chromosome probes recently discovered by a University of
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Toronto geneticist will make it easier to detect certain types of genetic
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and prenatal diseases, as well as being used to determine paternity and
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provide forensic evidence in criminal cases.
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Probes are short pieces of DNA which bind to, and actually pinpoint,
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particular sites on a chromosome. Because these new probes are actually
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repeated hundreds or thousands of time at a particular site, they are much
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more sensitive than previously available ones.
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Of the 23 pairs of human chromosomes, Dr. F.H. Willard has discovered
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repeated probes or markers for six plus the gender determining X and Y
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chromosomes. "What we're trying to decide now is whether to isolate probes
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for the other chromosomes, or whether we should utilize the eight we have,"
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he says.
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Dr. Willard is currently negotiating with an American company to
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develop prenatal diagnostic tests, which, because the current tests are
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time consuming and technically difficult to do, are restricted to women
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over 35 and those who have a family history of chromosomal abnormalities.
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Prenatal tests using Willard's probes would be much simpler and faster to
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perform and could be available to all pregnant women who wish to take
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advantage of the technology.
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Current prenatal testing involves growing fetal cells in vitro and
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examining them, over one or two months, to see if there are two copies of a
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particular chromosome, which is normal, or one or three, which is abnormal.
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A test using Willard's probes would require only a few cells and a few days
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to detect abnormalities. "I don't think it's beyond the realm of
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possibility that these kinds of tests could eventually be done by an
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obstetrician in the office during the early stages of pregnancy," he adds.
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The determination of gender is another possible use for the probes.
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Many diseases, such as Duschene's muscular dystrophy, show up on the X
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chromosome, manifesting only in boys. Willard thinks it is possible to
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develop a test which would quickly indicate the fetus' sex. This would
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benefit parents whose only option is to have no children or to have only
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girls.
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Confirming gender in children with ambiguous genitalia is another
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medical reason for using the test. A quick examination of the X and Y
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chromosomes of the child would indicate whether genetically the child is
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male or female.
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As yet, Willard has been unable to develop a probe for chromosome 21.
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Down's Syndrome results from three copies of chromosome 21 (trisomy 21). "I
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think we'll know within a year whether a test to detect trisomy 21 is
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feasible, " he says hopefully.
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The other six chromosome probes which Willard has developed do not
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immediately lend themselves to diagnostic tests, except for certain
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cancers, he says. "We have a probe for chromosome 7 and we know that
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trisomy 7 is a signal for certain types of cancer. Chromosome abnormalities
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of all kinds are a signpost of tumors." Theoretically, an oncologist could
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use a chromosome probe test to examine tissue and obtain a reading for a
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specific cancer. " It wouldn't suggest a mode of therapy," he points out,
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"but would be a speedy test and would have prognostic implications for the
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kind of tumor discovered."
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As a basic research tool, Willard's probes could be used to develop a
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genetic linkage map for human chromosomes. "It's important to know the
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location of genes in the human genome, particularly disease genes. The
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leading approach to try to sort out disease genes is to use genetic
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linkage. Because our sequences are at the centromere it would allow us to
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develop a map."
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The third application for the probes is in forensic biology. Willard
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believes his markers are as unique to each each individual as are
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fingerprints. According to the geneticist, it will be possible to make a
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DNA 'fingerprint' from blood or sperm, which could be used as evidence in
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rape or murder cases. "We haven't yet done the analysis which confirms that
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our probes are DNA fingerprints, but once we do, we will make them
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available for development into tests."
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As research progresses in all these areas, Willard hopes to collaborate
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with other departments at the U of T to conduct clinical trials. His work
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is funded by the March of Dimes, the Hospital for Sick Children Foundation
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and the Medical Research Council.
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