Rumination 9. An Experiment in Diagnostics
Rumination 9. An Experiment in Diagnostics
By Tom Vogl
September 20, 2007
My remission is holding up beautifully and I have no further formal medical workups planned until my next set of scans, PET and MRI, in early December.
That does not mean that there are not scientifically relevant and interesting things happening in which I cannot resist getting involved. In February I ran across an item (in the January 2007 issue of Optics & Photonics News, page 8), about a novel method for the detection of melanoma cells in blood plasma. Since there are not supposed to be melanoma cells circulating, any melanoma cells in the blood are malignant and potentially metastatic. I link the article here since it is short and self-explanatory
The paper whose results are described is Photoacoustic Detection of Metastatic Melanoma Cells in the Human Circulatory System, by R. M. Wright, J. A. Viator, et al., Optics Letters 31:2998 – 3000 (October 15, 2006).
This work intrigued me because I saw in it the opportunity for an early warning system for remission failure (PET scans cannot detect a metastasis smaller than 2 mm). I hoped that the opportunity to make serial determinations on a patient in remission from a rare melanoma would interest the study team. Dr. Norris kindly agreed to get in touch with the team in Missouri and make a referral. I subsequently called Dr. John Viator who invited me to come to Columbia, visit their lab, and run my blood sample through their equipment. So we arranged the visit for September 11.
Modern airlines being what they are, it takes as long to get from here to Columbia as from here to Europe, with more plane changes going to Columbia. In fact, to spend a few hours in Columbia I had to stay two nights, arriving the evening before and leaving before the crack of dawn the day after our meeting. Mercifully, the motels in Columbia are very reasonably priced.
The visit was an absolute delight. The evening I arrived I had dinner with my old friend from Westinghouse days, 'Rig' Rigler and his wife Bev. I had not seen him in 15 years and Bev in closer to 30. It was a nostalgic visit with wonderful people.
Tuesday morning I met John on the UM Cancer center where they drew two vials of blood which Melvin, John's graduate student, immediately spun down. The immediate part is important, because that is the reason I had to go to Columbia myself instead of sending a blood sample. Even though I hope it will turn out that I will be able to send samples (see below), I am glad I went because of the opportunity to meet John and spend the day with him in his lab, walking around the campus, and attending a lecture on photoacoustics by Dr. Hao Zhang. Being back in a academic environment after nine years as a chicken farmer had me worried that I could no longer do science, but I found that it all (well, almost all) came back and I was able to make a few suggestions that John found helpful. Of these, if it works out, the one of most interest to me for purely selfish reasons and possibly of the greatest use to John (because of the greatly increased potential patient pool) has to do with the processing of the samples in such a way that the patient need not go to Columbia to have the blood samples drawn.
I won't go into the details of the protocol (if you want to see it let me know), but what needs to be done is to separate the erythrocytes (red blood cells), the leukocytes (white blood cells) and other mononeuclear cells and the plasma. Centrifuging after adding appropriate reagents to the blood produces four layers – the erythrocytes, one of the added reagents as a separator, the leukocytes and other mononeuclear peripheral blood cells including any melanocytes, and the supernatant plasma.
It turns out that unless the blood is spun down within a few minutes of being collected, the breakdown of the erythrocytes will contaminate the leukocyte layer, and since the erythrocytes absorb the same wavelength used to detect the melanocytes, even a minute contamination produces false positive results. However, once the leukocyte layer has been separated from the erythrocytes, it is stable. What I plan to explore in the next few weeks is whether a local clinical pathology lab can be persuaded to perform this straightforward separation. I should note, in passing, that a modification of the system using two laser beams at two different frequencies will be able to distinguish melanocytes from erythrocytes and solve that false positive problem, but that prototype system is still in the planning stage.
Yesterday, I received e-mail from John – no melanocytes in my blood samples. Despite the fact that the clinical implications and prognostic value of this test are unknown (I am contributing my blood samples as part of a very preliminary study) this clearly is better news than if melocytes were found. Sufficiently good news to be worthy of a glass of champagne to toast John in absentia.
John also sent me the protocol for processing the blood samples and I have already started the wheels turning to see whether the lab at the MV hospital, the Falmouth hospital, or in Boston can be persuaded to do it. If this works out, I will send monthly samples to John for processing.
All in all, a great summer.
