Within Subject Variability and Duration of Brachial Artery Dilation in Response to GTN
Bibliographic record
Abstract
Glyceryl trinitrate (GTN) elicits an endothelium independent dilation by supplying exogenous nitric oxide to vascular smooth muscle. GTN tests are often used in conjunction with flow mediated dilation (FMD) testing to isolate impaired FMD to an endothelium dependent mechanism. The purpose of this investigation was to assess trial to trial variability in GTN induced dilation. A secondary purpose was to evaluate the duration of diameter elevation post GTN administration. A 400‐µg GTN dose was administered sublingually to 17 healthy male subjects (23±3 years) at two time points, trial 1‐ 0min, and trial 2‐ 160min. Pre GTN baseline (1min) and post GTN (10min continuously) artery diameters were measured via ultrasound. Diameter was also measured for 1min at 40min, 80min, and 140min post trial 1 GTN administration. The response to GTN was determined as the percent change from the pre GTN baseline diameter to the peak 30 second average diameter post GTN administration. The within subject trial to trial coefficient of variation (CV) (SD/Mean*100) was calculated from the percent change from baseline for each subject after GTN trial 1 and 2. Data are mean ±SD. Percent change in diameter was not different between trials (21.4± 5.7% vs. 22.4± 5.9%, p =0.153). Within subject trial to trial CV for the GTN response was 7.9± 6.7%. Brachial artery diameter remained elevated from the trial 1 baseline at 40min ( p <0.001), and 80min ( p <0.001), but not 140min (p=0.513) post GTN administration. These results suggest that there is a fairly low within subject variability in the response to GTN between trials, and that the dilatory response to GTN may have persisted for at least 80 min post GTN administration. The potential for prolonged dilation in response to GTN must be considered when planning assessments pre/post acute interventions. NSERC, CFI
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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 | 0.004 | 0.006 |
| 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 | 0.001 |
| 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".