Editorial: Does Circulating Leptin Have the Ability to Cross the Blood-Brain Barrier and Target Neurons Directly?
Bibliographic record
Abstract
It is in general agreement that proteins with high molecular weights do not cross the blood-brain barrier (BBB), because of the tight junctions between endothelial cells that characterize the cerebral microvasculature. The tight junctions are indeed essential features of the cerebrovascular system, which filtrates water-soluble molecules and protects parenchymal elements of the brain against potentially toxic substances. In addition to be the critical defense wall for neurons, the cerebral endothelium acts as a secretory membrane. There are, however, profound differences in the permeability of the blood vessels within specific regions of the brain. This is actually the case for the circumventricular organs (CVOs), in which the numerous vascular loops are relatively permeable to soluble proteins, pathogens, and even cells of the immune system (1). The vascular system of the brain is composed of penetrating arterioles, small capillaries, and venules that, all together with the blood, constitute approximately 8–10% of the total volume of the brain and spinal cord. The capillary density is also highly variable between regions and nuclei. For example, white matter contains 260 mm blood vessels/mm3 of total tissue, whereas the paraventricular and supraoptic nuclei of the hypothalamus are composed of 2000 mm/mm3 (2). These hypothalamic nuclei are among the most vascularized regions of the organism, explaining their crucial role in the control of most homeostatic systems.
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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 | 0.004 | 0.014 |
| Meta-epidemiology (narrow) | 0.004 | 0.001 |
| Meta-epidemiology (broad) | 0.004 | 0.002 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.004 | 0.001 |
| Research integrity | 0.014 | 0.018 |
| Insufficient payload (model declined to judge) | 0.008 | 0.007 |
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".