@Norman E. Booth, thank you for taking the time to comment on this thread, and for clarifying some of the intricacies of this research. It is very much appreciated. It always raises the spirits of ME/CFS patients here when researchers graciously spend a moment communicating on the forum.
Thanks for identifying the issues and errors in my original post; I have now edited this post to fix these.
And thanks very much for offering to supply further information; there are in fact some aspects of your published papers which I am unclear about, and so if I may, I have asked a few questions below to try to clear up some things.
Hip says that the ATP Profile measures the efficiency of five metabolic pathways. The Profile does provide at least five numerical figures but these all refer to the textbook pathway of starting with glycolysis of glucose
I have now replaced the incorrect term "
energy metabolism pathway" with "
energy metabolism process." I hope that is better (if there is more appropriate terminology, please let me know, and I will use it).
Also, it forced us to modify our definition of Mitochondrial Energy Score. This is a good example of the importance of having better statistics and also more careful scrutiny.
I did try to understand the new definition of the Mitochondrial Energy Score (MES) detailed in the
2012 paper, but I was struggling with the newly introduced parameter
% ATP inhibited. Perhaps you could kindly explain this a little bit, as I would like to get to grips with it.
I understand the concept of multiplying the 5 efficiency factors together to get an overall efficiency figure for the MES (which is a valid approach as all five were found to be largely independent and uncorrelated factors). So in the original MES definition, we have:
MES = ATP Concentration × ATP Ratio × Oxidative Phosphorylation × TL OUT × TL IN
In the 2012 paper it says:
Ox Phos, a parameter related to the efficiency of the oxidative phosphorylation process which recycles ADP (adenosine diphosphate) back into ATP. In order to measure this, the inhibitor sodium azide is added to a buffer solution containing the neutrophils. After 3 min. an aliquot is taken and the ATP measured. The ratio gives us % ATP inhibited.
we take into account the measurement % ATP inhibited and use it to replace the TL IN factor in the calculation of MES
So then the new definition of MES, which is named MES
inh, is given by:
MES
inh = ATP Concentration × ATP Ratio × Oxidative Phosphorylation × TL OUT × %ATP Inhibited
What I am unclear about is what % ATP Inhibited actually measures and represents, and how it differs from Oxidative Phosphorylation. The Oxidative Phosphorylation figure represents the efficiency by which mitochondria recycle ADP back to ATP; but what does % ATP Inhibited represent?
Later in the 2012 paper it says:
It is important to note that the value of % ATP inhibited is also the percentage of ATP generated by oxidative phosphorylation in the ETC and this can be as low as about 20% for both cohorts.
We are forced to conclude that, for patients with low values of % ATP inhibited, the ETC is already partially inhibited (or BLOCKED, and hence the introduction of the category label ‘B: 'HI Blk'). This could be due to blockages within the Krebs Cycle or ETC, or of the TL protein.
So this seems to indicate that the value of % ATP Inhibited relates to the efficiency of the electron transport chain (ETC), or to a process closely tied to the ETC like the Krebs cycle; but I am still not very clear on the difference between the % ATP inhibited and Oxidative Phosphorylation figures (and whether these are largely independent of each other, which is necessary for the MES
inh multiplication of all the efficiency values to be valid mathematically).
It is certainly interesting, though, that you found that the % ATP Inhibited value can be as low as just 20% in ME/CFS patients.
Another thing I am unclear on in the 2012 paper is the N
fn factor, which is an integer from 0 to 6 representing the number of energy metabolism factors that are running at normal efficiency, out of the six factors: ATP Concentration, ATP Ratio, Oxidative Phosphorylation, TL OUT, TL IN and % ATP Inhibited.
As I understand it (and please correct me if I am wrong), this N
fn number is a simpler, rough and ready alternative to the MES
inh calculation.
But what I don't understand is why MES
inh is plotted against N
fn (in
figure 1 of the 2012 study). I can't see what this graph would represent or indicate.
In the original 2009 paper, in
figure 4a you plot MES against the patients' severity of illness, as measured on the Bell scale, and this makes sense to me (and it is astounding how well the MES correlates to the Bell scale severity of illness score).
But I don't really understand the significance of the MES
inh against N
fn graph. I would have expected the new MES
inh value to be plotted against the Bell scale severity of illness score.
A further question if I may: I understand that glycolysis remains anaerobic (leading to lactic acid build up) if the glycolysis product pyruvate cannot be transported to the mitochondria and burnt with oxygen. But if everything is fine with the mitochondria, then I understand glycolysis works in tandem with the mitochondria (with the pyruvate being burnt in the mitochondrial Krebs cycle), and it becomes aerobic glycolysis where no lactic acid is produced.
What is it in ME/CFS that prevents aerobic glycolysis from taking place? Might there be a problem with the pyruvate transporters (mitochondrial pyruvate carrier, MPC), or is it just that the mitochondria are running very inefficiently, so they cannot effectively burn the pyruvate?
I am very wary of the idea of comparing mitochondria or ATP molecules to batteries.
I changed the analogy to one of ATP/ADP molecules being like petrol/gasoline trucks delivering fuel energy. I think that's a better analogy anyway.
By the way, if you would like to quote any paragraph of text in this post in your reply, you can just highlight the paragraph in question, and click on the pop-up "Reply" button that appears, and that will insert the paragraph into the text editor box.