Observations of time-based measures of flow-mediated dilation of forearm conduit arteries: implications for the accurate assessment of endothelial function
Bibliographic record
Abstract
Endothelium-dependent flow-mediated dilation (FMD) is measured as the increase in diameter of a conduit artery in response to reactive hyperemia, assessed either at a fixed time point [usually 60-s post-cuff deflation (FMD(60))] or as the maximal dilation during a 5-min continuous, ECG-gated, measurement (FMD(max-cont)). Preliminary evidence suggests that the time between reactive hyperemia and peak dilation (time to FMD(max)) may provide an additional index of endothelial health. We measured FMD(max-cont), FMD(60), and time to FMD(max) in 30 young healthy volunteers, 22 healthy middle-aged adults, 16 smokers, 23 patients with hypertension, 40 patients with coronary artery disease, and 22 patients with heart failure. As previously reported, FMD(max-cont) was similar in healthy cohorts and was significantly blunted in smokers and all patient groups, whereas FMD(60) was significantly blunted only in heart failure patients. There was a wide within-group variability between measures of time to FMD(max) with no significant difference between normal and patient groups. Intra-arterial infusion of the nitric oxide synthase inhibitor N(omega)-monomethyl-l-arginine in eight healthy subjects resulted in a blunting of FMD(max-cont) (P < 0.001) and FMD(60) (P = 0.02) but not time to FMD(max). Both FMD(max-cont) and FMD(60) demonstrated good repeatability in 30 young healthy volunteers studied on two separate occasions (P < 0.01 for both), whereas time to FMD(max) varied widely between visits (P = not significant). In conclusion, although time to FMD(max) does not appear to be a useful adjunctive measure of endothelial health, the use of continuous diameter measurements provides important data in the study of endothelial function in healthy subjects and patients with cardiovascular disease.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".