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Hey, science types (doping question) . . .

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Hey, science types (doping question) . . .

Old 07-01-09, 09:34 AM
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eriksbliss
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Hey, science types (doping question) . . .

"Silence-Lotto's Thomas Dekker will miss the Tour de France after testing positive for the banned blood-booster EPO, his team announced on Wednesday. The sample was originally taken on December 24, of 2007, when Dekker was a member of the Rabobank team. The sample was re-tested using new techniques, which resulted in a positive test for EPO."

Assuming that the sample was sealed, frozen, and untouched for two years, are there any inherent concerns with testing a two-year-old sample? Degradation, contamination, something?
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Old 07-01-09, 09:38 AM
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Sorry can't provide an answer but will also add concern about
chain of custody of that sample.
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Old 07-01-09, 09:42 AM
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Old 07-01-09, 09:51 AM
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I'm not a biologist, but assuming it wasn't tampered with and stored properly, it should be fine and legit. But of course, that's a lot of assuming.
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Old 07-01-09, 09:59 AM
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Originally Posted by eriksbliss View Post
"Silence-Lotto's Thomas Dekker will miss the Tour de France after testing positive for the banned blood-booster EPO, his team announced on Wednesday. The sample was originally taken on December 24, of 2007, when Dekker was a member of the Rabobank team. The sample was re-tested using new techniques, which resulted in a positive test for EPO."

Assuming that the sample was sealed, frozen, and untouched for two years, are there any inherent concerns with testing a two-year-old sample? Degradation, contamination, something?
Many concerns from my point of view. Proteins don't do freeze/thaw cycles well, but I don't know if a denatured Epo sample would be undetectable, or if something else in the sample could pop as a false positive. I also don't know if the sample went through any freeze/thaw cycles at all for that matter.

Originally Posted by Tsuru View Post
I'm not a biologist, but assuming it wasn't tampered with and stored properly, it should be fine and legit. But of course, that's a lot of assuming.
What exactly is 'stored properly' though?
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Old 07-01-09, 10:18 AM
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As a general rule, if the sample has been well stored it is fine. We often will measure protein levels from blood that has been frozen for ten or more years.
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Old 07-01-09, 11:07 PM
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Originally Posted by rankin116 View Post
Many concerns from my point of view. Proteins don't do freeze/thaw cycles well, but I don't know if a denatured Epo sample would be undetectable, or if something else in the sample could pop as a false positive. I also don't know if the sample went through any freeze/thaw cycles at all for that matter.
Meh. It's probably stored at -80 degrees. It was no doubt thawed for the first test. It probably gets moved from one -80 freezer to another and then back about once a year due to the need to defrost freezers every so often to keep them working right. Not enough time out of the freezer to thaw. As molecular biologist who needs to use this kind of equipment, I can tell you that we take this pretty seriously - stuff will not get lost. But there isn't a lot of paperwork involved in this kind of routine lab maintenance, either. Things aren't watched at all hours. This might not sound good, but the reality is that there's just not any serious threat of things being misplaced; we're good at keeping track of things. A big deal is made about the supposed sensitivity of biological samples by people who aren't in the field. The reality: it takes some pretty serious negligence to mess up a sample. It doesn't happen too often. My take is that the scientists are that last people I would worry about in this process.
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Old 07-01-09, 11:21 PM
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Originally Posted by eriksbliss View Post
"Silence-Lotto's Thomas Dekker will miss the Tour de France after testing positive for the banned blood-booster EPO, his team announced on Wednesday. The sample was originally taken on December 24, of 2007, when Dekker was a member of the Rabobank team. The sample was re-tested using new techniques, which resulted in a positive test for EPO."

Assuming that the sample was sealed, frozen, and untouched for two years, are there any inherent concerns with testing a two-year-old sample? Degradation, contamination, something?
Worth mentioning - they only dug deep because of a history of questionable samples or borderline results for the guy, for which Rabobank had already let him go.
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Old 07-01-09, 11:21 PM
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Originally Posted by grolby View Post
Meh. It's probably stored at -80 degrees. It was no doubt thawed for the first test. It probably gets moved from one -80 freezer to another and then back about once a year due to the need to defrost freezers every so often to keep them working right. Not enough time out of the freezer to thaw. As molecular biologist who needs to use this kind of equipment, I can tell you that we take this pretty seriously - stuff will not get lost. But there isn't a lot of paperwork involved in this kind of routine lab maintenance, either. Things aren't watched at all hours. This might not sound good, but the reality is that there's just not any serious threat of things being misplaced; we're good at keeping track of things. A big deal is made about the supposed sensitivity of biological samples by people who aren't in the field. The reality: it takes some pretty serious negligence to mess up a sample. It doesn't happen too often. My take is that the scientists are that last people I would worry about in this process.

But, is this stuff really stored/watched by molecular biologists or lab techs?
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Old 07-02-09, 08:18 AM
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Originally Posted by ImRael View Post
But, is this stuff really stored/watched by molecular biologists or lab techs?
Yes... and under lock and key.
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Old 07-02-09, 10:14 AM
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I think normal urine doesn't "degrade" to the point where synthetic EPO is present.
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Old 07-02-09, 12:10 PM
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Exogenous EPO can often be detected in blood, due to slight difference from the endogenous protein, for example in features of posttranslational modification.
http://en.wikipedia.org/wiki/Erythropoietin


Which means that synthetically introduced erythropoietin (EPO) can be differentiated from naturally occurring body-produced erythropoietin through the use of mass spectrometry. The nature of this indication test pretty much eliminates the possibility of an aged sample degrading into any components which might cause a "false positive" (i.e. it's either present...or it isn't).

So as mentioned above, the chain of custody has to be demonstrably solid so that the possibility of someone intentionally sabotaging the sample by introducing synthetic EPO can be eliminated as a cause.

.

Last edited by Stray8; 07-02-09 at 12:33 PM.
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Old 07-02-09, 12:40 PM
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The chain of custody would worry me. You give a sample and two years later they find something? For two years you had no positive control over your own sample and have to trust someone else? Not a very good system.


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