OC-044 Antisecretory effects of <i>Lactobacillus rhamnosus</i> -conditioned medium prompts the notion of lactobacilli species as probiotics of the upper gastrointestinal tract
Bibliographic record
Abstract
Introduction The Lactobacillus genus has evolved over thousands of years together with humans through its9 natural role in milk and dairy products. However, recent attention of the gastro-intestinal (GI) probiotic effect has concentrated on intestinal function rather than on gastric function. The antibacterial properties of Lactobacilli in controlling gastric colonisation by Helicobacter pylori are well recognised1 but little is known about the effects of these acidophilic bacteria on gastric physiology. Recent evidence that Lactobacillus species have been found in the stomachs of animals and humans suggests that they may also modulate acid secretion. Methods Lactobacillus rhamnosus (LRH) was chosen because its probiotic properties are well documented, it has been isolated from healthy human gastrointestinal mucosa and its genome was completely sequenced recently.2 LRH was grown in liquid medium for 48 h and conditioned medium (CM) was obtained by centrifugation and micro filtration. The effect of LRH CM was studied using a mouse gastric gland preparation with 14C-aminopirine accumulation as the indirect method for measurement of acid secretion. Culture medium alone was used as control. Results LRH CM inhibited 0.1 M histamine stimulated acid secretion by 100% at dilution of 1/40 while the control medium showed only marginal non-significant effect at this dilution (n=4). The IC50 (50% of acid inhibition) was ∼1/120 dilution and at this concentration LRH CM did not cause a shift in the histamine dose response curves indicating that histamine H2-receptor antagonism is not involved although the efficacy of the response was inhibited by 47.7% (n=5). Furthermore, LRH CM inhibited 0.01 M carbachol and 1.0 M cAMP stimulated acid secretion by 100% and 95%, respectively (n=5), the latter also being suggestive of a post receptor effect. This raises the possibility that bioactive bacterial products secreted into the culture medium act directly on the proton pump or other aspects of parietal cell physiology/metabolism. Conclusion This is the first report showing that Lactobacillus or its products exert a gastric antisecretory effect. This prompts the notion that colonisation of the gastric mucosa by these acidophilic bacteria or ingestion of their products may modulate acid secretion with the possibility of a beneficial impact on acid related diseases. Future in vivo and clinical studies on the role of Lactobacillus sp on gastric physiology are needed to explore the potential role of these probiotics in the stomach.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".