Natural Abundance Carbon Isotopic Analysis Indicates the Equal Contribution of Local Synthesis and Plasma Uptake to Palmitate Levels in the Mouse Brain
Bibliographic record
Abstract
Abstract Saturated fatty acids are the most abundant fatty acids in the brain, however, there has been some debate regarding the ability of intact dietary saturated fatty acids to be incorporated into the brain. In the present study, we use compound specific isotope analysis to measure the natural abundance carbon isotopic signature of brain, liver, and blood palmitic acid (PAM) and compare it to the dietary PAM and sugar isotopic signatures to calculate the relative contribution of both the incorporation of intact and endogenously synthesized PAM to these pools. Mice were equilibrated to the study diet, and extracted fatty acids were analyzed with gas chromatography isotope ratio mass spectrometry to determine the carbon isotopic signature of PAM (δ 13 C PAM ). Liver, serum total, and serum unesterified fatty acid δ 13 C PAM ranged between −20.6 and −21.1 mUr and were approximately 8.5 mUr more enriched in 13 C when compared to the dietary PAM signature. Brain δ 13 C PAM was found to be more enriched than liver or blood pools (−16.7 ± 0.2 mUr, mean ± SD ). Two end‐member‐mixed modeling using the carbon isotopic signature of dietary PAM and dietary sugars determined the contribution of synthesis to the total tissue PAM pool to range between 44% and 48%. This suggests that endogenous synthesis and dietary PAM are near equal contributors to brain, liver, and blood PAM pools. In conclusion, our data provide evidence that brain PAM levels are maintained by both local endogenous synthesis and through the uptake of intact PAM from the blood.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".