UBC-Nepal Expedition: Cerebrovascular Responses to Exercise in Sherpa Children Residing at High Altitude
Bibliographic record
Abstract
Abstract Understanding the process of successful adaptation to high altitude provides valuable insight into the pathogenesis of conditions associated with impaired oxygen uptake and utilization. Prepubertal children residing at low altitude show a reduced cerebrovascular response to exercise in comparison to adults, and a transient uncoupling of cerebral blood flow to changes in the partial pressure of end-tidal CO 2 (P ET CO 2 ); however, little is known about the cerebrovascular response to exercise in high-altitude native children. We sought to compare the cerebral hemodynamic response to acute exercise between prepubertal children residing at high and low altitude. Prepubertal children ( n = 32; 17 female) of Sherpa descent (Sherpa children [SC]) at high altitude (3800 m, Nepal) and maturational-matched ( n = 32; 20 female) children (lowland children [LLC]) residing at low altitude (342 m, Canada). Ventilation, peripheral oxygen saturation (S p O 2 ), P ET CO 2, and blood velocity in the middle and posterior cerebral arteries (MCA v and PCA v ) were continuously measured during a graded cycling exercise test to exhaustion. At baseline (BL), P ET CO 2 (−19 ± 4 mmHg, p < 0.001), S p O 2 (−6.0% ± 2.1%, p < 0.001), MCA v (−12% ± 5%, p = 0.02), and PCA v (−12% ± 6%, p = 0.04) were lower in SC when compared with LLC. Despite this, the relative change in MCA v and PCA v during exercise was similar between the two groups ( p = 0.99). Linear regression analysis demonstrated a positive relationship between changes in P ET CO 2 with MCA v in SC ( R 2 = 0.13, p > 0.001), but not in LLC ( R 2 = 0.03, p = 0.10). Our findings demonstrate a similar increase in intra-cranial perfusion during exercise in prepubertal SC, despite differential BL values and changes in P ET CO 2 and S p O 2 .
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 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 | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 teacher head, 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".