Posted by Larry Hoover on March 6, 2006, at 10:41:14
In reply to Re: NASA's , SSRI, SNRI, etc. » Larry Hoover, posted by SLS on March 5, 2006, at 10:23:47
> Hi Larry.
>
> Nice to see your smiling face.
>
> :-)Thank you, kind sir. Always a pleasure, Scott. Though, I'm posting on Admin right now, and that ups the stakes considerably.
> > > CSF might be a better source of chemical markers.
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> > Keyword "might". I only wish cerebro-spinal fluid was more accessible. The risks attaching to lumbar puncture are far too great to be adopted as part of routine practise. Unless some real evidence is available that way.
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> LPs ain't much fun (unless they're made of vinyl). I had a handful performed on me when I was a research patient at the NIMH. You are right.Talk about guinea pig! Sir, your sacrifice in our collective need is genuinely appreciated.
> I don't see any putative markers yet identified in CSF to act as a practicable test for anything relating to the diagnosis and treatment of affective disorders. There are some associations between low MHPG and the effectiveness of NE reuptake inhibitors (TCAs), but not much else when last I looked, and I don't know what the coefficient of correlation was.
CFS provides an integrated measure of brain function, not specific to any mechanism or target section of the brain. Global measures just don't tell us anything useful....so far.
> Actually, I think low urine MHPG might be just as reliable (or unreliable) a marker.
I really don't think fluid testing will ever yield what we seek. fMRI. PET. I think those are the real deal. When we get those fine-tuned, we'll be doing non-invasive testing that yields not only site-specific data, but continuous data.
> > > If it is found that the etiologies of some mental illnesses are to be found in abnormal gene expression, perhaps microarrays will be helpful in diagnosing and determining treatment. We really aren't all that far from that now. (I guess it's all relative. It is still too far away to suit me).
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> > If it's genetic, though, blood suits as a test medium. Saliva, even. Those genes, they be everywhere.
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> Yes. However, it might be necessary to assay gene activity in a site-specific manner, which would mean taking samples of brain tissue. A gene can be turned on in one cell but not in another.Quite so. However, we can construct probe molecules, methinks. Ones which differentiate between e.g. non-methylated and methylated DNA. Or, perhaps better yet, transfer RNA, which is only active during protein synthesis, as I understand it. Combine the probe with imaging technology, and you have a real time measure of rate of protein synthesis?
> In addition, the proteins expressed by changes in gene activity might never appear extracellularly.
I think you need to be in the cytoplasmic realm, so that's why I think probes are the thing to use. If you take out t-RNA with your probe, there will still be the original homeostatic mechanism in operation, to ensure full expression of the activation signal. There's lots of redundancy, I would think.
> I really don't know enough about this stuff to speculate any further regarding the need to sample specific tissues to assay gene activity.
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> Maybe I'm way off...
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> - ScottI think we are on the threshold of non-invasive tissue sampling.....inferential tissue sampling.
Lar
poster:Larry Hoover
thread:613775
URL: http://www.dr-bob.org/babble/20060304/msgs/616585.html