Stimulus Control Minimizes the Impact of Baseline Diameter on the Endothelial Dependent Dilation Response
Bibliographic record
Abstract
2026 Non-invasive tests to quantify endothelium dependent flow-mediated dilation (EDFMD) have important clinical and basic research applications. With the current EDFMD test which employs reactive hyperemia (RH) as a shear stress stimulus, both the peak stimulus and the peak response vary inversely with the subject's baseline brachial artery diameter (BAD). PURPOSE: To create a uniform stimulus in all subjects regardless of baseline diameter and determine the relationship between baseline diameter and peak response compared with the RH test (RHT). METHODS: BAD and mean blood velocity (MBV) were measured with Doppler ultrasound in 8 healthy subjects. RHT: transient, uncontrolled shear rate (SR) stimulus (estimate of shear stress; SR = MBV/BAD) created via release of 5 min of forearm occlusion. Controlled hyperemia test (CHT): precise, maintained target SR stimulus created by controlled release of brachial artery compression upstream of heat-induced forearm vasodilation. 2 trials of each test were performed on 3 separate days. RESULTS: The CHT SR stimulus was on target and maintained for 5 min. The between subjects CV for the shear rate stimulus in the CHT was only 4.87% vs. 36.61% in the RHT. Thus the CHT was successful in creating a uniform stimulus between subjects. Subjects demonstrated a range of brachial artery diameters (3.35–5.19 mm) and the RHT showed an inverse relationship between baseline diameter and both the shear rate stimulus and the dilation response (slope = 1.05, r2 = 0.47, P < 0.001 and slope = −4.75, r2 = 0.64, P < 0.01 respectively). Conversely, the CHT showed no relationship between baseline diameter and the shear rate stimulus(slope = −1.02, r2 = 0.018, P = 0.36) and only a very small relationship between baseline diameter and the peak response (slope = − 0.77, r2 = 0.14, P < 0.01). CONCLUSIONS: Controlling the shear rate stimulus virtually eliminates the relationship of baseline diameter to the EDFMD response. This will facilitate the comparison of EDFMD sensitivity in groups with significantly different diameters e.g. men vs. women. Supported by NSERC; CFI New Opportunities Fund
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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) | 0.004 | 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".