Can the study of individuals with autonomically complete spinal cord injuries help clarify the role of sympathetic nerves in cerebrovascular reactivity?
Bibliographic record
Abstract
Cerebral blood vessels are richly innervated by sympathetic nerves; however, their role in the control of the cerebral vasculature remains controversial. Individuals with spinal cord injury (SCI) provide a unique opportunity to study cerebrovascular control in the absence of sympathetic control. Here we studied cerebrovascular reactivity to CO 2 in individuals with cardiovascular autonomically complete and incomplete SCI, and neurologically intact controls. Cardiovascular autonomic completeness was assessed on the basis of supine plasma noradrenaline levels, blood pressure variability and lesion level. Supine beat‐to‐beat blood pressure and middle cerebral artery velocity (MCAv) were continuously recorded, as were breath‐by‐breath partial pressures of end‐tidal O 2 and CO 2 (P ET CO 2 ), during manipulation of P ET CO 2 . Low levels of P ET CO 2 were obtained by voluntary hyperventilation, and high levels by hypoventilation with increased inspired CO 2 , during normoxia (controlled on a breath‐by‐breath basis using dynamic end‐tidal forcing). MCAv reactivity was significantly different between groups (control 11.2±2.4; autonomically incomplete SCI 5.8±0.6; autonomically complete SCI 6.2±0.7 %/mmHg, p=0.025, mean±sem). These preliminary data suggest that there is impaired cerebrovascular reactivity in individuals with SCI that is independent of injury to cardiovascular autonomic pathways. This research is supported by the Heart and Stroke Foundation of B.C. and Yukon (V.E.C).
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 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".