Hypoxia‐regulated phenylethanolamine N‐methyltransferase expression
Bibliographic record
Abstract
Hypoxia is being used to identify mechanisms for stress‐induction of the epinephrine synthetic enzyme, phenylethanolamine N‐methyltransferase (PNMT). When PC12 cells transfected with a PNMT promoter‐luciferase reporter gene construct are exposed to hypoxia (5% oxygen), luciferase activity rapidly rises (6 hr) and is sustained for 72 hr. Signaling pathway inhibitor pre‐treatment prior to oxygen reduction abrogates induction and identifies two major signaling pathways, cAMP and phospholipase C (PLC). Downstream hypoxia inducible factor‐1α (HIF‐1α) and PNMT activators Egr‐1 and Sp1 are elevated. HIF‐1α co‐transfection or HIF‐1α activation by CoCl 2 and desferoxamine stimulate the PNMT promoter. While HIF‐1α is constitutively expressed, inclusion of the RNA synthesis inhibitor actinomycin D and protein synthesis inhibitor cycloheximide inhibit their induction. Hypoxia elevates Egr‐1 and Sp1 mRNA, protein and protein‐DNA binding complex formation as well. Stimulation is rapid but transient for Egr‐1 while sustained for Sp1 (24 hr). Egr‐1 binding site mutation in the PNMT promoter prevents activation by hypoxia. However, hypoxia generates long and short forms of PNMT mRNA, which produce inactive and active enzyme respectively. Thus, hypoxic stress transcriptionally activates PNMT but post‐transcriptional controls limit expression of functional enzyme.
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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 | 0.000 |
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 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".