Abstract TP275: Brain Cell Volume Reductions After Severe Ischemic and Hemorrhagic Strokes in Rat
Bibliographic record
Abstract
Background: Raised intracranial pressure (ICP) following severe strokes can impede blood flow to the brain, causing injury or death. There are compensatory mechanisms regulating ICP, but they are often inadequate. Interestingly, our recent observations in intracerebral hemorrhage (ICH) suggest that a volume reduction in remaining brain may serve a compensatory role after large strokes. We observed neurons well outside the hematoma reduce their volume and intercellular space 7 days after the bleed. Here, we tested the hypotheses that this volume reduction would occur sooner in both ischemic and hemorrhagic insults. Methods: Rats received either an ICH via stereotaxic infusion of collagenase or a sham procedure. Euthanasia and perfusion fixation occurred either 1 (N=12), 3 (N=12), or 7 (N=12) days following the ICH. Following histological processing, cellular volume, density, and cortical thickness were assessed with stereological techniques in representative brain regions such as hippocampus, striatum, and primary somatosensory cortex (S1). In a separate experiment, rats received either a middle cerebral artery occlusion (MCAO) via intraluminal suture occlusion (N=8), or a sham procedure (N=7). Rats were euthanized and perfusion fixed 1 day following the MCAO, with brains processed and assessed as described above. Results: After ICH, the decrease in neuronal volume (up to 60%) compared to shams had the largest effect one day following the insult in hippocampal layers CA1 and CA3 (p<0.0001), striatum (p<0.001), and S1 (p<0.05). The largest increase in cellular density occurred one day following the insult in CA1 and CA3 (p<0.0001), and striatum (p<0.001). Cortical thickness was significantly decreased on day 1 (p<0.0001). Following MCAO, cellular volume was significantly decreased compared to shams in areas CA1 (p<0.01) and S1 (p<0.05). Cellular density was significantly increased compared to shams in areas CA1 and S1 (p<0.01), and striatum (p<0.05). Discussion: Our data challenges the assumption that ‘healthy’ brain tissue outside the injured area maintains its volume after stroke. Given the magnitude of cell volume reductions, we posit that this is an important intracranial compliance mechanism invoked after severe strokes.
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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 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 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".