Haem Oxygenase Activity in Human Umbilical Cord and Rat Vascular Tissues
Bibliographic record
Abstract
Carbon monoxide (CO) has been shown to affect vascular tone in smooth muscle cells and thus, may regulate regional or systemic blood pressure as well as fetoplacental vascular tone and fetal blood delivery. To assess the potential of vascular tissue to produce CO, we determined haem oxygenase (HO) activity through in vitro quantitation of CO production with gas chromatography and its inhibition by 33-66 microm of chromium mesoporphyrin (CrMP) in homogenate preparations of rat aorta and vena cava and human umbilical cord tissues. We compared these results to HO activity in rat heart and liver. We also discuss normalization of HO activity on a per mg protein as well as per g fresh weight (FW) tissue basis. We found that both rat vascular tissue HO activities (per g FW) were equal, but greater than that of heart (x3) and less than that of liver (x0.2). For human cord tissues, HO activities of artery and vein were equal, but greater than that of Wharton's jelly. Also, HO activity in rat vascular tissues was 3x greater than that of the human cord tissues. HO activity was completely inhibited by CrMP in rat heart (90 per cent) and liver (96 per cent), but incompletely (50-66 per cent) in both rat and human vascular tissues. We established that it is unlikely that other non-haem CO-generating processes account for this unique insensitivity of HO to CrMP inhibition. In fact, high concentrations of other potent metalloporphyrin inhibitors affected vascular tissue HO even less. We found that the degree of in vitro HO inhibition appeared to be related to the concentration of haem in the reaction medium. We conclude that the presence of HO activity in cord tissues supports the possibility that CO plays a role in fetoplacental blood flow regulation.
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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) | 0.002 | 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".