The NGF Metabolic Pathway in the CNS and its Dysregulation in Down Syndrome and Alzheimer's Disease
Why this work is in the frame
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Bibliographic record
Abstract
It is well established that individuals with Down syndrome develop Alzheimer’s disease neuropathology by middle age. Both in Alzheimer’s disease and Down syndrome, this is accompanied by the atrophy of NGF-dependent cholinergic neurons of the basal forebrain. An NGF trophic compromise in Alzheimer’s disease had been early suspected. This hypothesis was discarded with the finding of unaltered NGF mRNA synthesis and of increased NGF precursor levels (proNGF) in postmortem Alzheimer’s disease brains. The possibility of an NGF trophic disconnection has been recently revisited at the light of a newly discovered extracellular NGF metabolic pathway; where proNGF is released in an activity-dependent manner and converted by plasmin to mature NGF in the extracellular space. Mature NGF is ultimately degraded by the metalloprotease MMP-9. This pathway has been shown to be compromised in Alzheimer’s disease and Down syndrome brains, thus reviving the trophic factor hypothesis to explain the atrophy of basal forebrain cholinergic neurons in these disorders. This chapter will discuss the physiological role of NGF and its biological significance to cholinergic neurons of the CNS, and present the evidence for a dysregulation of the NGF metabolism in Alzheimer’s disease and Down syndrome. Keywords: Alzheimer’s disease, cholinergic neurons, Down syndrome, neurotrophins, inflammation, nerve growth factor, NGF metabolism, neuroserpin, matrix metallo-protease 9, plasminogen, tissue inhibitor of metallo-proteases, tissue plasminogen activator.
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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 | 0.005 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.002 |
| 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 it