Does simulated apnea elicit respiratory long term facilitation?
Bibliographic record
Abstract
Respiratory plasticity following acute intermittent hypoxia may help to prevent apneas and hypopneas during sleep. Long term facilitation (LTF) is a progressive increase in respiratory motor output following acute intermittent hypoxia. LTF is most frequently studied in anesthetized rats following three, 5‐min episodes of isocapnic hypoxia with 5‐min intervals. Since spontaneous apneas are shorter than 5‐min, and result in hypercapnic hypoxia, we determined whether simulated apneas also induce LTF in anesthetized rats. We hypothesized that repetitive 25‐sec pump apneas at 5‐min intervals would elicit LTF in both phrenic and hypoglossal (XII) motor output. Phrenic and XII activity were recorded in anesthetized, vagotomized and ventilated Sprague Dawley rats (Harlan, 217) before and 60‐min after 6, 25‐sec pump apneas, separated by 5‐min of control, hyperoxic conditions (PaO 2 > 200 mmHg). 60‐min after the final pump apnea, LTF was observed in both phrenic (53±7% baseline; n = 6; p < 0.05) and XII activity (53±6% baseline; p < 0.05). Both were significantly greater than time controls (phrenic: 5±7%; and XII: 8±13% baseline; n = 3; p < 0.05). The magnitude of pump‐apnea induced LTF is similar to values observed after 3, 5‐min episodes of isocapnic hypoxia. Thus, 6 25‐sec pump apneas are sufficient to produce a robust respiratory LTF in both phrenic and XII motor output. Although all aspects of a spontaneous apnea were not simulated by this protocol, we speculate that LTF has the potential to play an important role in stabilizing breathing during sleep, minimizing the recurrence of apneas. Such an effect may help explain the evolution of obstructive sleep apnea syndrome as it progresses from tolerable, when LTF mechanisms are sufficient, to intolerable, when LTF is either absent or no longer adequate to prevent further apneas. Supported by NIH HL65383, HL 89209 and CIHR (Canada).
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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 | 0.001 |
| 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".