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Originally Posted by Quasimoto WTF.... you say :
"The test is ready for Athens" but then in the same post say "They still won't confirm or deny if the test that is ready will be used in Ahtens." How do you know there is a test ready ? How do you know what the IOC and international community wont admit too...
There is "NO TEST FOR THE DETECTION OF EXOGENOUS HGH " according to the NEJM.
I ask the question again...This isnt like the test/epitest levels...Since when is there a way of determining levels ? NEJM performed a study a few yrs ago that part of what made a world class athlete, was the unusually high levels of hormones they created and released..."
What data do you have REX FERAL that predicates a statement that such a test exists? |
It was reported by Reuters last week. The challenging part of the question is not if the
test exists or not, because it clearly exists, its is how do they validate a
test for exogenous
GH. Remember, we quit using cadaver derived
GH somehwhere in the mid 80s in the U.S. Since then all
GH has been rHGH. It is created by E Coli. So clearly rHGH is not
HGH exactly as one is created by the human body & the other by genetically engineered bacteria. HMMM? I wonder if there is a way we can tell the difference? Logically, there has to be. And it turns out there is.
I made a typo in the post before, I'll edit it here. The second
test for
HGH which they are talking about using retroactively, just like they did w/ THG, detects up to 84 DAYS out, not hours. That clearly is a concern for some as the IOC just announced last week that they "may implement" this.
OK here goes.
There have been two approaches to developing a
test for abuse of recombinant
hGH (rhGH), indirect and direct.
Direct tests (actually measuring the
hGH in the circulation, by blood
test) are made difficult by the similarity of rhGH to naturally occurring
hGH and also by the short half life (~15 minutes) of the hormone. Further,
hGH levels fluctuate considerably during the day and in response to exertion.
Indirect tests measure levels of proteins affected by
hGH levels. These effects can be longer lasting, but also can be influenced by injury, age, gender and ethnic background.
Read on to find out how these problems are being addressed.
1. Indirect
The GH2000 consortium (funded by the EU and IOC) investigated the use of surrogate markers as indicators of rhGH abuse.
GH exerts most of its effect by increasing the levels of a protein called
IGF-1, which circulates bound to proteins called IGFBP3 and ALS. The concentration of all three of these proteins is highly
hGH-dependent.
Several other proteins have also been found to be
hGH-dependent. These include PIIIP, ICTP, osteocalcin and PICP. Moreover, the profile of increases in the levels of these proteins elicited by rhGH administration differs from that seen in response to
hGH increase caused by exercise.
Finally the pharmacodynamic endpoints of these changes are much longer than the half-life of
hGH itself;PIIIP and osteocalcin are the most promising candidates here, showing elevation above pretreament values for up to 3 months.
References: J. Clin. Endocrinol. Metab. (2000) 85, 1505-1512 and J. Clin. Endocrinol. Metab. (2000) 85, 124-133
2. Direct
Unlike rEPO, rhGH does not have conveniently different biochemical markers from its natural counterpart. However, circulating
hGH changes into a variety of subtly different derivatives, or 'isoforms', while rhGH does not - it remains homogenous. The major isoforms of
hGH are termed 22-kD (the form corresponding to rHGH),20-kD, acidic
hGH, fragmented
hGH and dimerized
hGH. There exist specific assays for each of these isoforms.
rhGH will only light up the 22-kD assay. If an athlete is taking rhGH, their 22-kd levels increase greatly but their levels of all other isoforms will remain the same. 22-kD normally constitutes 48% of total
hGH in the circulation. This result has been verified in studies involving more than 500 blinded samples, whereupon all subjects who had received rhGH within 24 hours could be identified.
Obviously, given the short half-life of
hGH the window for this method of detection is only 1-2 days.
Ref. Lancet (1999); 353, 895
Rex.