he used himself as a subject and what he found was that protein S varied

He used himself as a subject and what he found was

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he used himself as a subject and what he found was that protein S varied depending on the AA (range 70-1029 mg protein synthesize/ kg/ hr). He was in N balance so remember, his C rates = S rates). o Used Ala, Gly, Leu, Lys, Gln, Asp o A few of the AAs behave funny e.g.- If 15 N-Arg used, Arg goes into synthesis of protein but we also know that Arg is used a lot in the UC and for NO synthesis (non-protein related cycles) Same with Glu which is used as an N donor But most other AAs aren’t like that, if you get rid of all those ones that we know enter into other significant metabolic pathways you get unusual results But Phe, Gly and Leu will have results that are closer together ** Reproducibility is the most important thing - The usefulness of this labeled AA-method is to look at fold changes from one treatment to another not absolute #s. As long as using same AA pre- and post-; you just want to know the direction o Researchers may say using AA x, produced Q 2x that of another AA, but those are absolute #s It doesn't matter what AA you use, the absolute # may be different but the trends will be the same o If a treatment or disorder leads to a fold change in Q it doesn't depend on what AA you use. The fold change wont change but the absolute # will 20. FLOODING DOSE TECHNIQUE - There are 2 ways to get the tracer into the subject faster than continuous infusion: IV or orally o Gavage stress hormone release which alters Q and protein metab and can only happen once - Flooding dose technique: occurs when you give a large amount of a single AA (3-4 g in a human; i.e.- cold Gly) with some labeled AA o This labels all the pools of the body almost instantaneously b/c you’re flooding the body with huge amounts of a single AA so much that it quickly gets into the bloodstream. Blood levels will and the label spreads out all over the body and labels/ flood all the body tissues with this AA in a very short period of time and then watch the decay of the label You end up with graph; see notebook Al you do is take samples at 0, 5, 10 and 15 minutes (longer in humans because our Q rate is slower because it takes slower than small animals b/c our metabolic rate is smaller) The 3 points should be linear and you can take that back to 0, and that value will be the protein S rate at time 0 o Major criticism: perturbs metabolic pool by pushing in a large amount of a single AA and imbalances the AA pool. You’ll have great excess of a single AA and thus affects protein synthesis
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SFLORES_2/27/2014 15 21. COMPARING FDM vs. CONTINUOUS INFUSION - Using the same AA comparing continuous infusion with priming vs flooding method and calculating Q: the FDM gives you higher values vs CI o A gain, this doesn't really matter if you’re not interested in absolute numbers but instead the direction of Q/overall change due to the condition [ J Nutr 136: 1504, 2006] 22. DETERMINING C RATES in MUSCLE W/O USING LABELED AAs via 3-MH - Synthesis of muscle protein could be obtained by giving label, collecting excreta, and getting Q
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  • Spring '14
  • Knutson,MitchellD
  • NRG

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