Bexarotene treatment does not clear β-Amyloid in an AD mouse model and Beagle dogs
Bibliographic record
Abstract
In our aging society Alzheimer’s Disease (AD) is becoming more and more prevalent while effective symptomatic therapeutics remain limited and no cure is available. ApoE4 is the most important genetic risk factor for AD. Previous results by Cramer et al. [ 1 ] showed that Bexarotene treatment reduced Aβ in the brain of wild type and AD model mice via an apoE-mediated clearance mechanism. Bexarotene, an RXR agonist, is an FDA approved drug for cutaneous T cell lymphoma and hence a preferred candidate for clinical testing. In this study we attempted to replicate the data by Cramer et al. [ 1 ]. We used captisol (Cydex Pharmaceuticals), and HP-b-CD/ Tween to dissolve Bexarotene for administration in mice and dogs respectively. For acute experiments we administered a single 100 mg/kg/p.o. dose of Bexarotene (Ontario Chemical, Inc., Canada) to wild type male Swiss CD1 mice and measured endogenous levels of soluble Aβ x-37 , Aβ x-38 , Aβ x-40 and Aβ x-42 in brain at different time points. In Beagle dogs we administered 25 and 100 mg/kg/p.o. Bexarotene and measured Aβ x-37 , Aβ x-38 , Aβ x-40 and Aβ x-42 levels in CSF. For chronic experiments we administered 100 mg/kg/day/p.o. Bexarotene for 19 days to 10-months-old male hAPP/PS1 mice. In contrast to the published data, we found that acute and chronic treatment with Bexarotene had no significant effects on Aβ levels in the brain of wild type and AD model mice and in Beagle dogs, despite high penetration of the drug into the brain. Although behavioral alterations were observed in AD model mice, adverse effects of the treatment confounded these observations. Drug formulation and pharmacokinetics might explain our contradictory observations with Cramer et al. [ 1 ] at least partly. These issues need to be resolved before Bexarotene can be tested in AD.
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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 | 0.000 | 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) | 0.000 | 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".