O19 H<sub>2</sub>S inhibits O<sub>2</sub><sup>−</sup> scavenger and causes oxidative damage <i>in vivo</i>
Bibliographic record
Abstract
Objective Volatile sulphur compounds (VSCs), namely hydrogen sulfide and methyl mercaptan have been demonstrated to initiate or progress periodontal disease by increasing the permeability of sulcal epithelium and the degradation of extracellular matrices. Superoxide dismutase (SOD) is one of the most important antioxidative enzymes in intracellular protection against superoxide free radicals which may cause cancer or aging process. The objectives of this study were to demonstrate that hydrogen sulfide, a major contributor to oral malodor, inhibits SOD activity, and to determine if VSCs cause oxidative damage. Methods Cu,Zn‐ and Mn‐SOD, and human gingival fibroblast (HGF) SOD activities were examined with the determination of the inhibitory activity of the production of 2‐(4‐Iodophenyl)‐3‐(4‐nitrophenyl)‐5‐(2,4‐disulfophenyl)‐2H‐tetrazolium formazan. Western blot analysis was employed to determine the effect of hydrogen sulfide on SOD molecules. Oxidative damage was determined with comet, caspase III and other assays. Results and discussion The activity of Cu,Zn‐SOD (0.01 U ml−1) was found to decrease by 83% when exposed to 52 ng/10 ml of hydrogen sulfide for 60 min (P < 0.0001 by ANOVA and P < 0.001 by Tukey's multiple comparison test) and that of HGF‐SOD decreased by 46% (P < 0.0001 by ANOVA and P < 0.001 by Tukey's multiple comparison test). The inhibition of SOD by H2S was both time‐ and concentration‐dependent. Following exposure to VSC, SOD activity resumed after incubation in air. The results suggested that the inhibition might be reversible. VSC might cleave the disulfide bonds and might produce monomeric SOD resulting in reversible inhibition. However, Western blot analysis has not demonstrated monomeric SOD. Comet assay and other examination demonstrated that VSC caused oxidative damage and apoptosis. Conclusion SOD is the body's major defence against oxidative damage. Cu,Zn‐ and Mn‐SOD, and human gingival fibroblast (HGF) SOD activities were strongly inhibited by hydrogen sulfide. The inhibition of SOD resulted in oxidative damage and apoptosis.
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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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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 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".