Accurate Myoglobin Oxygen Saturation by Optical Spectroscopy Measured in Blood-Perfused Rat Muscle
Bibliographic record
Abstract
Optical spectra were acquired from myoglobin and hemoglobin solutions and from the tibialis anterior muscle of Sprague-Dawley rats in the visible region (515 to 660 nm). Validation studies were performed on the in vitro spectra to demonstrate that partial least squares analysis of second-derivative spectra yields accurate measurements of myoglobin saturation in the presence of varying hemoglobin concentrations and saturations. When hemoglobin concentrations were varied between 0.25 and 4 times that of myoglobin, myoglobin saturations were measured with a root mean squared error (RMSE) of 4.9% (n = 56) over the full range from 0 to 1. Myoglobin saturations were also shown to be largely unaffected by hemoglobin saturation. RMSE values of only 1.7% (n = 77) were found when hemoglobin saturations were varied independently from myoglobin saturations. These in vitro validation studies represent the most complete and rigorous done to date using partial least squares analysis on myoglobin and hemoglobin spectra. Analysis of reflectance spectra from the rat hind limb yielded accurate measures of volume-averaged myoglobin fractional saturation in the presence of hemoglobin in vivo. Hemodilution showed that myoglobin fractional saturation measurements in the rat leg are not sensitive to changes in hematocrit, thereby confirming the results from solutions in vitro. Decreases in optical density of 11.3 +/- 3.0% (n = 3) were achieved while myoglobin saturation decreased by only 3.1 +/- 3.8%. Myoglobin saturation was significantly increased when the fraction of inspired O(2) was increased, showing that manipulations of myoglobin saturation are detectable and that myoglobin is not fully saturated in resting muscle. Together, these in vitro and in vivo studies show that cellular oxygenation derived from myoglobin fractional saturation can be measured accurately with little cross-talk from hemoglobin in the visible wavelength region, thereby extending optical spectroscopic studies of cellular and vascular oxygenation beyond the near-infrared regions previously studied.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 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) | 0.000 | 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".