Nitrative stress, oxidative stress and plasma endothelin levels after inhalation of particulate matter and ozone
Bibliographic record
Abstract
BACKGROUND: While exposure to ambient air contaminants is clearly associated with adverse health outcomes, disentangling mechanisms of pollutant interactions remains a challenge. OBJECTIVES: We aimed at characterizing free radical pathways and the endothelinergic system in rats after inhalation of urban particulate matter, ozone, and a combination of particles plus ozone to gain insight into pollutant-specific toxicity mechanisms and any effect modification due to air pollutant mixtures. METHODS: Fischer 344 rats were exposed for 4 h to a 3 × 3 concentration matrix of ozone (0, 0.4, 0.8 ppm) and EHC-93 particles (0, 5, 50 mg/m(3)). Bronchoalveolar lavage fluid (BALF), BAL cells, blood and plasma were analysed for biomarkers of effects immediately and 24 h post-exposure. RESULTS: Inhalation of ozone increased (p < 0.05) lipid oxidation products in BAL cells immediately post-exposure, and increased (p < 0.05) total protein, neutrophils and mature macrophages in the BALF 24 h post-exposure. Ozone increased (p < 0.05) the formation of reactive oxygen species (ROS), assessed by m-, p-, o-tyrosines in BALF (Ozone main effects, p < 0.05), while formation of reactive nitrogen species (RNS), indicated by 3-nitrotyrosine, correlated with dose of urban particles (EHC-93 main effects or EHC-93 × Ozone interactions, p < 0.05). Carboxyhemoglobin levels in blood exhibited particle exposure-related increase (p < 0.05) 24 h post recovery. Plasma 3-nitrotyrosine and o-tyrosine were increased (p < 0.05) after inhalation of particles; the effect on 3-nitrotyrosine was abrogated after exposure to ozone plus particles (EHC-93 × Ozone, p < 0.05). Big endothelin-1 (BET-1) and ET-1 were increased in plasma after inhalation of particles or ozone alone, but the effects appeared to be attenuated by co-exposure to contaminants (EHC-93 × Ozone, p < 0.05). Plasma ET levels were positively correlated (p < 0.05) with BALF m- and o-tyrosine levels. CONCLUSIONS: Pollutant-specific changes can be amplified or abrogated following multi-pollutant exposures. Oxidative and nitrative stress in the lung compartment may contribute to secondary extra-pulmonary ROS/RNS formation. Nitrative stress and endothelinergic imbalance emerge as potential key pathways of air pollutant health effects, notably of ambient particulate matter.
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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 | 0.000 |
| 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 | 0.001 |
| 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".