Dynamic cerebral pressure‐flow relationships in aging and long‐term heart transplant recipients (1068.11)
Bibliographic record
Abstract
Long‐term heart transplant recipients (HTR) provide a unique opportunity to examine the relationship between the cerebrovascular and cardiovascular systems. We examined the hypothesis that HTR would have cerebral pressure‐flow responses more comparable to control subjects matched to the age of their cerebrovasculature than their donor hearts. Eight male clinically stable HTR (62 ± 8 yrs of age and 9 ± 7 yrs post transplant), 9 male age‐matched controls (AM: 63 ± 8 yrs) and 10 male donor controls (DC: 27 ± 5 yrs), were tested. Each test involved: seated rest (5‐min), and squat‐stand maneuvers at 0.05 and 0.10 Hz. The BRS and pressure‐flow responses were assessed with TFA. BRS TFA revealed that the HTR had reductions in R‐R interval PSD and LF gain (P<0.01) compared to both control groups. There were comparable TFA cerebral pressure‐flow responses for all groups at all frequencies with coherence and phase. The pressure‐flow gain was significantly greater in DC than both AM and HTR at all frequencies (P<0.05). Cerebrovascular resistance (CVR) was negatively correlated with pressure‐flow gain at all frequencies (P<0.05). These results reveal that pressure‐flow coherence and phase are comparable throughout aging, potentially helping HTR compensate for reductions in BRS. Although pressure‐flow gain did decrease in the HTR and AM, it was related to changes in CVR highlighting the need cautiously interpret this metric. Grant Funding Source : Supported by NSERC
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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".