Bibliographic record
Abstract
Abstract Background Monitoring tau propagation in the living brain has important pathophysiological and therapeutic implications. As tau imaging agents are dependent on tau conformations, we aimed to determine the tau species amenable to in vivo imaging. Previously we demonstrated that ex vivo tau preparations may be used to image tau seeds in living murine systems, as opposed to recombinant preparations. As such, the goal of this work is to examine the dose‐dependent relationship of patient derived AD‐tau fibrils on PET imaging outcomes. Method A total of two 15‐month‐old (2 wild‐type, one male and one female) rats were used. All animal had a baseline scan with [18F] MK6240 before the stereotaxic injections. We tested tau PHFs from AD brains using ultracentrifugation of sarkosyl‐insoluble brain fractions. AD‐tau preparations were stereotaxically injected in the dorsal hippocampus. We tested injection volumes of 1 and 3 uL of equal concentrations (80 ng/uL). Contralateral hemispheres were injected with equivalent amounts of PBS, the solvent for tau preparations. All PET images were coregistered to the Waxholm Space Atlas of the Sprague Dawley Rat Brain sMRI using a linear transformation. The non‐displaceable binding potential (BPND) images were generated using cerebellar grey as a reference region based on Simplified Reference Tissue Method (SRTM). Result Injection of sarkosyl‐insoluble brain fractions from AD patients displayed positive BPnd outcome in both volumes tested. Control hemispheres injected with PBS showed potential off‐target binding. Reliability of this outcome was investigated using peak normalized TACs. Hemispheres receiving AD‐tau injections showed visible divergence in retention, as compared to baseline. The hemisphere that was inoculated with 3uL of AD‐tau showed separation during washout. A similar effect was seen in the control hemisphere. Conclusion These results continue to suggest ex vivo tau preparations may be used to image tau seeds in living murine systems. The reliability of PET and kinetic outcomes are dependent on the volume injected. Further investigation will aim to evaluate AD‐tau concentration as the dosage variable instead of injection volume. Cerebellar tissue from patients used to extract AD‐tau species should be as a control injection to account for the reagents used for protein extraction, instead of PBS alone.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".