This letter from a scientist on cyclingnews.com is pretty interesting and, unlike most of the posts here, offers some real insight. Since the isotope signature for synthetic testosterone and cortisone are the same, and given the possibility that the body can metabolize cortisone into testosterone, this is a rational non-doping explanation for the T/E imbalance as well as the synthetic testosterone....
Natural process still possible, likelihood uncertain
As a recreational cyclist and racing fan, I have followed the Tour de France and the aftermath of Floyd Landis’s positive doping test. I am writing this letter because I have not seen my view reflected in the media or other reader contributed opinions. I choose to consider Floyd Landis innocent until he has received full consideration of his defence during the due process he is granted under the rules that govern cycling. I believe that it is still possible that a natural process can explain the results that have been reported in the media for Floyd Landis’s doping controls.
I am a scientist, and I think and read the scientific literature about testosterone continuously. I do this because I conduct research on prostate cancer, and testosterone and related steroid hormones play a central role in prostate cancer treatment and progression. For me, the fact that Floyd Landis was legally treated with cortisone is a very important aspect of the case. Testosterone and cortisone are both steroid hormones with very similar chemical structures. When administered as exogenous drugs, they have similar origins and the same carbon-isotope signature that is distinct from the carbon-isotope signature of endogenous steroid hormones present in humans. Thus, a key question in this case is the following: did a natural process in Floyd Landis’s body convert the legal steroid hormone cortisone to testosterone?
Cortisone is a steroid hormone in the glucocorticoid family and testosterone is a steroid hormone in the androgen family. We are all full of enzymes that can convert one steroid hormone into another, but conversion of a glucocorticoid into an androgen would not be expected in most individuals. However, it has been documented in the scientific literature that the conversion of cortisone to other steroid hormones varies from individual-to-individual, and the conversion of cortisone to other steroid hormones can be altered by disease. For example, it has been documented that cortisone metabolism is altered by prostate cancer.
In addition, we are all hosts to many bacteria, and the conversion of glucocorticoids into androgens by intestinal bacteria isolated from healthy individuals has previously been demonstrated. The secretion of bacterial-metabolized derivatives of cortisone into the urine has also been demonstrated in the scientific literature. Thus, Floyd Landis's initial claim that he would demonstrate that the positive doping test resulted from a natural process is possible if he can prove that the cortisone he took was converted into testosterone due to unusual metabolism by his own enzymes or due to the presence of bacteria that can metabolise glucocorticoids into androgens. Because no population studies on the potential metabolism of cortisone into testosterone have been conducted (that I am aware of), the likelihood that a natural process can explain Floyd Landis's test results are impossible to judge.
If I were Floyd Landis and innocent I would do the following: (1) recognize that in the current anti-doping climate that the USADA and the Court for Arbitration in Sports are extremely unlikely to rule that any currently accepted anti-doping test is flawed, (2) hire competent doctors and scientists to determine the exact cause of my positive doping results, and (3) archive samples of my intestinal bacteria prior to taking any antibiotics that may be required during the surgery and recovery associated with my hip replacement. Good luck Floyd, I hope you prove the skeptics wrong.
Paul Marker, Ph.D
Minneapolis, MN, USA
Monday, August 14, 2006