Following yesterday’s discussion with Dr Loh I understand better how Rapamycin reduces numbers of white blood cells in that it acts to hold back cell division.
The key question when is whether it holds back all cell division or just lymphocytes. I have asked her this in relation to stem cells.
One thing I try to measure is my nail growth rate. I do this because that is an easy mechanism for monitoring stem cell creation when it comes to nail stem cells.
Hence I also did a quick literature search and found:
and
What is interesting about these is
a) The nails grow along the whole length of the nail bed to a limited extent
b) Most of the nail growth is from the nail matrix
c) That part of the nail matrix that is visible is the lunula (or half moon)
d) Rapamycin does reduce nail growth in many people.
I have not seen a paper which indicates directly that the visibility of the matrix (presence of lunula) is an indicator of nail growth rate. I have not found anything that says it isn’t and Chat GPT is of no use in this.
It does raise a quite simple piece of research we could do which is to collate dosing and visibility of lunula. When I measure my nail growth I also check for visibility of lunulae. My thumb nail lunulae are quite big, but those on the little finger are invisible. Those on fingers 1 and 2 are easily visible, but small, those on fingers 3 are only just visitble.
My mechanistic hypothesis is that nail growth would speed up when rapamycin levels are lower. In fact today I took 6mg of Zydus combined with a grapefruit, but won’t take any more rapamycin until 1st June.
What I like about lunulae is if they are any use as a test they are an easily visible test of stem cell generation. Measuring nail growth (which I do with a groove in my thumbs) is quite difficult to do accurately as it is really slow. When I cut my nails I have growth of about 2-3 mm. I have a set of vernier calipers which measure to 0.01 mm, but measuring to the proximal distral fold (which is IMO the only really reliable place to measure to) is really hard to do accurately hence I only look for reliable measurements over a long period.
Still it remains a question as to whether people dosing weekly have less visible lunulae.
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I usually cut my nails every other week and have not felt that my finger nails grow slower but I think my toe nails is growing slower. Here is an image of my hand.
Does the lunulae logic also apply to toe nails?
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The lunulae logic does apply to toe nails. Toe nails grow slower normally anyway.
Normally nail growth slows as people get older. I think you have visible lunulae on thumb and fingers 1, 2 and 3, but the little finger may or may not be visible.
It would be helpful to know your age and rapamycin dosing schedule.
This is one of those situations where it would have been good to have a baseline, but I didn’t take a picture of my hand before I started on rapamycin.
I might start measuring my lunulae with the vernier calipers as it would be helpful to know if the length varies and what that correlates with.
The mechanism for stem cell growth is likely to be substantially much the same as any other cell type.
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I will see if I can find a old picture of my hand. Yes, the lunulae on the little finger is very small.
I’m soon 47 and my dose regime is 6 mg once weekly. Have been taking it now for around 70 weeks. On this page you can see my biomarkers pre and post rapamycin.
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I put a post on my blog about nails and Rapamycin yesterday
My own dosing is 6mg every 21 days, but with an accelerator (Grapefruit or Pomelo). If we say the multiplier is 3 and simply the half life as 3 days I start at 18, then 3 days later it is 9, then 3 days later it is 4.5. Hence for a week it is around or above the equivalent of 6mg, then follows logically your pattern then there is a week which is even lower.
I am, however, 64 and nail growth is thought to reduce on average by 0.5% per year from age 25. My left thumbnail is growing around 2.4mm per 30 days and the right 2.1 although I don’t think my measurements are that good.
When I started nail growth measurement my methodology was not that good and I probably need to do some work to try to estimate the rate of growth for the early period as I started rapamycin after that.
Edit I have just done the measurements to the PDF as the PDF is perhaps 0.5-1mm wide it would move from 0 to say 1mm merely if the lunula is visible, but these are the results (not very accurate)
Lunulae Measurements (from PDF) L T-2.81 1-2.87 2-2.39 3-1.51 4-0 R T-4.48 1-2.51 2-3.7 3-1.47 4-0
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