Regional brain uptake of ketone bodies and glucose in elderly humans: A<sup>11</sup>C-acetoacetate and<sup>18</sup>F-FDG PET study
Bibliographic record
Abstract
The brain relies on glucose as its primary energy substrate. However, ketone bodies, i.e. acetoacetate and hydroxybutyrate, are the main replacement fuels for brain activity during fasting or on a ketogenic (very high fat, low carbohydrate) diet. We report here a study of ketone and glucose metabolism in human brain in young (mean 26 years) and aged (mean 73 years) healthy individuals as measured with positron emission tomography (PET), using the radiotracers11C-acetoacetate and18F-fluorodeoxyglucose (FDG). Three blood samples were withdrawn during the two scans and were analyzed for plasma radioactivity and for concentration of acetoacetate, hydroxybutyrate and glucose. In the eighteen selected brain regions for this study, although the standard uptake values (SUV) were lower in the elderly subjects compared to the young subjects, the ratio of SUV in aged on young were almost similar in glucose and ketone metabolism. This protocol for brain fuel measurement by PET can be combined with treatment or on ketogenic diet to further study brain metabolism in neurodegenerative pathologies.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".