*By Susan Westemeyer, with additional reporting from Cyclingnews staff *
With a verdict in the Tyler Hamilton blood doping case expected today (Monday), information has already started to leak out about the likely outcome of the case, and the nature of Hamilton’s defence. In an article in the Los Angeles Times, it appears that the “chimera theory” is being used to try to explain the mixed blood cell population in Hamilton’s body. “A theme central to Hamilton’s defence is the notion of a ‘vanishing twin’ who shared the womb when Hamilton was a fetus - a point on which there is much speculation but no proof,” wrote the LA Times.
This argument was put forward by David Housman, genetics expert and MIT professor, who presented expert testimony for Hamilton’s defence. He claimed that cells can transfer from one to unborn twin to another in the womb, “and bone marrow cells can persist for life.”
The newspaper also released specific numbers for Hamilton’s blood tests last spring. Riders are not be allowed to start a race if they receive a score of more than 133 in the Stimulation Index, a formula for profiling blood cell growth that takes into account haemoglobin and reticulocytes (immature blood cells). An explanation of the formula can be found in the footnote of Cyclingnews’ Anti-doping measures get tougher article, published in July last year.
The average SI score for professional cyclists is 90. At Liege-Bastogne-Liege last year, Hamilton scored 123.8. It was up to 132.9 the next week by the Tour de Romandie, and with it came a hematocrit level of 49.7% (the UCI’s nominal limit is 50%).
These readings caused the UCI to inform Hamilton that “he was going to be watched because his ‘blood values showed strong signs’ of ‘a possible manipulation,’” according to both the LA Times and articles in L’Equipe in 2004. The warning letters that Hamilton received were like a red card in football.
Of course its a stretch, but it may be valid. Of more concern is the last part of the article. As I understand the other test looks at the age of the cells. If you have a spike in new blood cells it can be evidence that you’ve somehow manipulated your blood. Possibly altitude would do this, but I don’t know.
Problem for TH using this seems to me to be this: it suggests a blood condition that should be as present today in his blood as it was in Athens. So has he offered to stay under observation for (say) a month (to prevent any transfusions taking place) and then offer his blood for a sample?
Chimera: In medicine, a person composed of two genetically distinct types of cells. Human chimeras were first discovered with the advent of blood typing when it was found that some people had more than one blood type. Most of them proved to be “blood chimeras” – non-identical twins who shared a blood supply in the uterus. Those who were not twins are thought to have blood cells from a twin that died early in gestation. Twin embryos often share a blood supply in the placenta, allowing blood stem cells to pass from one and settle in the bone marrow of the other. About 8% of non-identical twin pairs are chimeras.
Many more people are microchimeras and carry smaller numbers of foreign blood cells that may have passed from mother across the placenta, or persist from a blood transfusion. In vitro fertilization (IVF) is also contributing to the number of human chimeras. To improve success rates, two or more embryos are placed in the uterus so women who have IVF have more twin pregnancies than usual. More twins mean more chimeras.
That would have been the most obvious solution this whole affair.
Keep him under observation for the length of time that it takes for the red blood cells to be replaced (I think this is six weeks) if there is no change to TH’s tert results it would be pretty obvious it was a natural condition for him.
If the results change, then the blood cells had to come from an external source and then its see you in two years Tyler.
Isn’t it interesting that two guys from the same team got busted for the same thing? Could someone have messed up and switch the blood bags by mistake?
I don’t know whether he is guilty or not. All is speculation and trying to use some logic.(hopefully objective) I am not casting any evidence of the ole’blood doping. It had been a way in the past to increase hemocratic levels. Two riders of th same team getting caught for the same thing is curious to me. The other guy has been quiet on this whle thing as far as I know.
I hope Tyler didn’t do it, but something sure smells fishy.
If the test is shown to be inconclusive then Perez will have the right to appeal whether he actually is guilty or not. Lesson: don’t bring inconclusive tests to the front-line.
He is GUILTY, no matter what the out come of the trial. We have to be realistic, they all do something at that level. I have raced at the Cat 2 & 3 level in some small unimportant races. I have trained with some pros. They are amazing creatures and could wipe my sorry butt up with one leg. I respect their dedication and hours in the saddle they put in. But when you mix egos, money and corporate sponsorship together…one of the by products is cheating!
Look at all of us slow, feeble humans trying to impress the guy next door. We risk financial stability to buy a carbon, super bike because we feel it will give us a extra 3 mph on the road! We argue about wet suits and if it is truly cheating to use them. We buy any new powder mix drink that promises to make us like Lance or Norman!
Now imagine if not only your ego and self worth depended on your next race performance, but also your career and families security? We would be belying up to the performance enhancing bar and ordering a double.
So none of us are innocent! I just wish people would own up to it!
TH did have his appendix removed in 2003, and at the time of this report was probably unaware that foreign cells from any transfusion would only last 6 weeks or so. Right now it looks like a pretty dumb defense that might have been a good guess at the time.
If Tyler has some sort of medical proof he is a Chimera (sp?), I’ll be the first one to write him a letter of appology and wish him the best.
The more likely outcome isn’t that Tyler will prove he’s a Chimera (can you prove that?) - just that they (WADA) can’t prove he’s not (hence reasonable doubt, hence ‘not guilty’).
I surely hope they post a very long explanation to whatever the ruling is.