"Robert Chung" <
[email protected]> wrote in message
news:
[email protected]...
> B. Lafferty wrote:
>> "Chris" <[email protected]> wrote
>>> Perhaps Tyler is not aware the transfusions from many years
>>> ago can also cause a positive.
>>
>> Can you cite to medical authority for this assertion? Otherwise you're
>> statement is ********.
>
> From:
> http://www.ncbi.nlm.nih.gov/entrez/...ve&db=pubmed&dopt=Abstract&list_uids=12765465
>
> "Persistent microchimerism can follow a blood transfusion, or can occur
> from transfer between twins in utereo."
This abstract does not define persistent. See:
http://www.niwi.knaw.nl/en/oi/nod/onderzoek/OND1270763/toon
"HLA-matched BT led to longer persistence of microchimerism than unmatched
BT, regardless of how the packed cells were prepared. In patients treated
before 1995, the difference between matched and unmatched BT was most
pronounced one week after BT (p<0.05, Fisher's exact test), and this trend
continued till at least 4 weeks after BT. Transfusates prepared after 1995,
using automated blood separation, gave rise to fewer cases of
microchimerism, and shorter duration of microchimerism, than transfusates
prepared by the manual method. This difference is probably due to the lower
number of leukocytes in the packed red cells produced by the Compomat® as
compared to manually prepared packed cells (mean ± SD respectively 5.0 ± 2.6
x 100 milion and 7.7 ± 3.5 x 100 million, two-tailed P value <0.0001 by
unpaired t-test with Welch correction). "
>
> From:
> http://www.ncbi.nlm.nih.gov/entrez/...ve&db=pubmed&dopt=Abstract&list_uids=14996783
>
> "Iatrogenic chimerism has been investigated in transplantation and
> following blood transfusion."
This abstract in no way addresses the length of time one would test as a
chimera after a transfusion.
I think you're clutching at straws. It has been mentioned that Tyler's
attorney is most likely to look at the methods by which the test was carried
out. An interesting article was sent to me that appeared on the Bicycling
web site (of all places).
http://www.bicycling.com/article/0,3253,s1-10361,00.html?category_id=367
.....In the last study on the test, published in the Italian medical journal
Haematologica, Ashenden and other study authors noted that the quality of
antisera available had a significant impact on the accuracy of the test and
said that this issue remained unresolved. In a phone interview last week,
Dr. Ashenden declined to elaborate on whether the issue had in fact been
addressed, citing that Hamilton's case with the UCI was still open.
Some news reports, including here on BICYCLING, have mentioned a
low-probability reason for a positive test: that Tyler is a natural chimera,
or possesses two distinct genetic lineages.
Dr. Margot Kruskall, a pathology professor at Harvard Medical School and
Director of Beth Israel Deaconness' hospital's Division of Laboratory and
Transfusion Medicine, told me in an e-mail exchange that chimerism was a
possible, but highly unlikely, reason for Hamilton's positive test.
"Chimerism has been known for centuries," she wrote, "and there's ample
literature on it in the last 100 years." While chimerism sometimes has no
outward signs and thus avoids detection, Dr. Kruskall said that even if it
is underdiagnosed the condition is still exceedingly rare. But, she added,
chimerism is not always a natural process. "Chimerism can be created
artificially, through bone marrow transplantation, or transplantation of
other tissues," she pointed out.
Disease, another possibility for a false positive, is unlikely in this case
as infection alone would not be a potential culprit--only diseases of the
blood, such as leukemia. "And in such cases, the illness itself is usually
quite apparent," she wrote. Kruskall added that if she were trying to
establish whether or not Hamilton is chimeric, she would test him again in
four months (after the red blood cells from any potential transfusion have
died) and if the result was still positive begin testing other tissues for
two cell lines and investigate his family history.........
