Characterising barrier function among regions of the gastrointestinal tract in Holstein steers
Bibliographic record
Abstract
The objective of this study was to characterise the regional variation in the barrier function of the gastrointestinal tract in Holstein calves using the flux rates of mannitol and inulin as permeability markers and tissue conductance (Gt) as an electrophysiological indicator of barrier function. Six Holstein steer calves (6 months of age) fed a common diet were used. Calves were killed by captive bolt stunning and pithing, and tissues were collected from the rumen, omasum, duodenum, jejunum, ileum, caecum, proximal colon, and distal colon. Tissues were carefully washed using a pre-heated (38.5°C) buffer solution (pH 7.4) saturated with oxygen and then transported to the laboratory. The mucosa was prepared by hand stripping and mounted between two halves of an Ussing chamber (n = 3/region with an exposed surface area of 3.14 cm2 for rumen and omasum and 1 cm2 for all other tissues). All tissues were incubated under short-circuit conditions and exposed to a similar buffer solution except for the energy source; rumen, omasum, caecum, and colon tissues were incubated with buffer containing short-chain fatty acids while tissues from the small intestine were bathed in buffer containing glucose. The Gt and the serosal-to-mucosal flux rates of 14C-inulin and 3H-mannitol were measured as indicators of barrier function. The serosal-to-mucosal flux rate of mannitol was greatest (P < 0.001) in the jejunum [104.8 nmol/(cm2 × h)] and least in the rumen and omasum [20.3 and 18.6 nmol/(cm2 × h), respectively]. In contrast, the serosal-to-mucosal flux rate of inulin was greatest (P < 0.001) in the omasum [158.6 nmol/(cm2 × h)] followed by the rumen [87.3 nmol/(cm2 × h)] with no differences among the other regions [18.7 – 62.0 nmol/(cm2 × h)]. The Gt was greatest (P < 0.001) in the jejunum (34.6 mS/cm2) and least for the rumen (3.67 mS/cm2) and omasum (3.23 mS/cm2). The Gt was correlated with both inulin and mannitol flux rates in duodenum, caecum and proximal colon (P < 0.05); whereas, no such correlations existed in jejunum, ileum and distal colon. The Gt was correlated with the mannitol flux rate but not the inulin flux rate in rumen and omasum. For all regions but the rumen and omasum there was a positive correlation between mannitol and inulin flux rates. These data indicate that the translocation of a large molecule (inulin) across the omasum and rumen is greatest despite having an apparently tight epithelium based on Gt and mannitol flux rate, while the jejunum appears to have greatest potential for paracellular permeability.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 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 | 0.000 |
| 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".