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Medical Forum / General / Nutrition / February 2006monty's missing matter: HHMI working on it.
Perspectives Home > Literature > Perspectives > Glomset, pp. pe6 Sci. STKE, Vol. 2006, Issue 321, pp. pe6, 7 February 2006 [DOI: 10.1126/stke.3212006pe6] Role of Docosahexaenoic Acid in Neuronal Plasma Membranes John A. Glomset* Howard Hughes Medical Institute, Departments of Medicine and Biochemistry, and Regional Primate Research Center, University of Washington, Seattle, WA 98195-7370, USA. Summary: The omega-3 fatty acid docosahexaenoic acid (DHA n-3) has long been known to be a major component of phosphoglycerides in the gray matter of mammalian brains. Furthermore, early studies of synaptosomes that had been isolated from gray matter showed that the plasma membranes of the synaptosomes contained DHA n-3 that was selectively esterified to phosphatidylethanolamine, plasmenylethanolamine (alkenylacyl-glycero-phosphorylethanolamine), and phosphatidylserine. In contrast, the phosphatidylcholine in these membranes contained esterified oleic acid, and the sphingomyelin and glycolipids in the membranes contained amide-linked stearic acid instead of a mixture of this acid with other, amide-linked fatty acids. The full implications of this unusual distribution of lipid head groups, esterified fatty acids, and amide-linked fatty acids are unclear, but the phosphoglycerides and sphingosine-containing lipids appear to be distributed asymmetrically between the two leaflets of the plasma membrane lipid bilayer and are likely to contribute to a dynamic lipid substructure. Because very few neuronal plasma membranes have been isolated and characterized to date, a major challenge for the future will be to investigate the composition of the lipid bilayers of different neuronal plasma membranes and identify effects of DHA n-3-containing phosphoglycerides on the ability of the plasma membranes to perform their many different functions. The aim of this Perspective is to stimulate further work in this important area by discussing recent evidence related to the role of neuronal plasma membrane phosphoglycerides in cell signaling. It is all assumption-based, but I guess you just don't understand that. Why not take me up on my offer if you think I am wrong? We will feed a dozen mice fish oil and canola oil at 30% calories and the other group will get 30% fresh coconut oil, and thus have no source of omega 3 PUFAs. If the coconut oil group lives the same amount of time, or longer, you pay for all expenses; otherwise, I will. There may be some omega 3s in the brains of various animals, depending upong diet, but that does not mean this is optimal. A properly controlled experiment would do what I suggest, or something similar, but that has not been done. Instead, "experts" talk of "rapid DHA turnover" in the brain without evidence of any kind, and in spite of it being physically impossible. As I've said, I've avoided nearly all omega 3s for several years now, and have experienced only benefits. My great grandparents lived to be 96 and 100 without any source of omega 3s (beyond the tiniest of trace amounts that one might find in dairy, which they ate plenty of). Neither they, I, nor biochemist Ray Peat could have "rapid DHA turnover in the brain" under such conditions. When I was young, nobody was talking about omega 3s, and we consumed no oily fish (and rarely any kind of fish), no canola oil, no pumpkin seeds, no flax seeds, etc. Their claims about "lipid bilayer membranes" shows how little they know. You can wash the fatty acids off a cell, and the cell still holds together just fine. The water molecules are bound to the cytoskeletal proteins, which are energized by ATP to do so. Go to www.gilbertling.org and educate yourself about this, and perhaps you will begin to understand that what you have cited here is typical of the nonsense that passes for "science" these days. > It is all assumption-based, What is? Are you talking about your theories? > Why not take me up on my offer if you think I am wrong? Your offer has nothing to do with the DHA content of synaptic membranes so why mention it? > There may be some omega 3s in the brains of various animals, depending > upong diet, but that does not mean this is optimal. A properly > controlled experiment would do what I suggest, or something similar, > but that has not been done. Instead, "experts" talk of "rapid DHA > turnover" in the brain without evidence of any kind, I've cited evidence before. > Neither they, I, nor biochemist Ray Peat > could have "rapid DHA turnover in the brain" under such conditions. With no external supply of DHA (or linolenic acid) the brain DHA will hang around until it is oxidised beyond normal function. One of the reasons cells can live so long is regular turnover of their constituents so damaged molecules are replaced with undamaged ones. > Their claims about "lipid bilayer membranes" shows how little they > know. You can wash the fatty acids off a cell, and the cell still > holds together just fine. Rubbish. If you add detergent to a cell you permeabilise it and lose soluble molecules. What's left still has the shape of a cell because the assembled cytoskeleton is insoluble. > The water molecules are bound to the > cytoskeletal proteins, which are energized by ATP to do so. Please explain that in molecular level detail. I've never heard of ATP-driven water magnets before. It sounds very energetically wasteful. MattLB > It is all assumption-based Absolutely! See here: http://groups.google.com/support/bin/answer.py?answer=14213&topic=250 MattLB refuses to state his claims about "essential fatty acids" as a scientific hypothesis, yet accuses me of making assumptions. Try not putting the cart before the horse next time, Matt old boy. I have stated my understanding of the evidence in such a way AND I've suggested experiments to demonstrate it. This is called the "scientific method," Matt, though it appears you've never heard of it before. One needs to demonstrate claims in a particular way, or else it is just opinion, and I think many people on this group are tired of hearing your opinions - let's hear some science for a change. > MattLB refuses to state his claims about "essential fatty acids" as a > scientific hypothesis, yet accuses me of making assumptions. Try not > putting the cart before the horse next time, Matt old boy. > I have > stated my understanding of the evidence in such a way AND I've > suggested experiments to demonstrate it. Unfortunately your understanding of any kind of biochemical or chemical evidence is not up to your desires to revolutionize the scientific world, and the "experiments" you suggested 1) have been done already and have been shown to you. 2) You are not able to perform the experiments (training, facilities, money,..). 3) You refused to submit your experiment proposal to a grant institution (which would make it free for you AND you would have your proposal reviewed). > This is called the "scientific method, No it isnt. You have demonstrated quite clearly how little grasp you have on what "scientific method" means.. You constantly quote the daily newspaper and random books or websites- those are NOT valid sources in a scientific discussion. You refuse to let your experiment be evaluated by senior scientists. You refuse to provide evidence for your claims. You fail to provide molecular level detail as you always claim you do provide. > One needs to demonstrate claims in a particular way, or else > it is just opinion, Right, so: Why don't you make a simple blood test to proove *your* claims about having no w3 and w6 in your body? > and I think many people on this group are tired of > hearing your opinions - let's hear some science for a change. You have been asked, in the last post by MattLB to provide some scientific, molecular level, explanations- until now you were not able to do that.. so: lets hear some science from you. > MattLB refuses to state his claims about "essential fatty acids" as a > scientific hypothesis, yet accuses me of making assumptions. You state your claims as (what you interpret to be) a scientific hypothesis first, so we can all see what you mean. Your definitions of terms like trans fat and essential show you have a different set of meanings to the scientific world and hypothesis may well be the same. > I have stated my understanding of the evidence in such a way If that's true then you *do* have your own definition of what a scientific hypothesis is. > This is called the "scientific method," Matt, though it appears you've never > heard of it before. Not your take on it, no. > One needs to demonstrate claims in a particular way, or else > it is just opinion, and I think many people on this group are tired of > hearing your opinions - let's hear some science for a change. My opinion is that you are misguided and lack basic biochemical knowledge and/or understanding. Other comments are based on published scientific findings or direct laboratory experience. Here's some science for you: EFA-deficient kidney cells are structurally and functionally abnormal, a condition reversed by adding omega6 to the growth medium http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstra ct&list_uids=8614299&query_hl=2&itool=pubmed_docsum Cultured skin cells preferentially take up LA over oleic acid and uptake is scaled to how EFA-deficient the cells already are http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstra ct&list_uids=10025727&query_hl=7&itool=pubmed_docsum MattLB > Other comments are based on published > scientific findings or direct laboratory experience. direct laboratory experience.??? Ooooh! That biz phrase is starting to get tiresome. It is NOT a selling point in my book. If anything it is a big NEGATIVE. Just thought that unnecessary duplicant might want to know just how stupid his bragging sounds. |
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