Correlation of the presence of blood-brain barrier tight junctions and expression of zonula occludens protein ZO-1 in vitro: a freeze-fracture and immunofluorescence study.
Bibliographic record
Abstract
Tight junctions are regarded as the primary anatomical structure responsible for the blood-brain barrier (BBB). The molecular components that have been defined include ZO-1, a peripheral membrane protein associated with the cytoplasmic surface of the tight junction in epithelial and endothelial cells. It has been localized to the points of membrane contact with the fibrils seen by freeze-fracture. Examination of passaged endothelial cells with freeze-fracture failed to locate the intramembrane specializations associated with tight junctions. For this reason, immunocytochemistry and freeze-fracture were used to study the correlation of ZO-1 expression with the presence of tight junctions in bovine brain and aorta endothelial cells. Indirect immunofluorescence analysis showed ZO-1 to be localized at sites of cell-cell contact. Images of freeze-fractured sites of endothelial cell-cell contacts in identical passage numbers did not display characteristic tight junctions. When bovine aorta endothelial cells were cultured in astrocyte-conditioned medium on a complete extracellular matrix, platinum replicas displayed profiles of tight junctions. The elements of tight junctions were arranged as parallel ridges which displayed free ends. The immunofluorescence staining of ZO-1 was identical to that obtained on the endothelial cells that displayed no tight junction profiles. These results suggest that ZO-1 may be present at putative junction-containing sites before the junctional structures appear in the surface membrane. Therefore, ZO-1 expression does not a priori reflect assembly of the tight junctions identified by freeze-fracture.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".