Mechanisms of Action of External Volume Expansion Devices
Bibliographic record
Abstract
BACKGROUND: External volume expansion by suction has been proposed to improve the survival of fat grafting by preparing the recipient site. In previous experimental work, external volume expansion demonstrated the capacity to stimulate cell proliferation, vessel remodeling, and adipogenesis. This study investigated possible mechanisms underlying these observed changes. METHODS: A miniaturized external volume expansion device was applied to the dorsum of mice for 2 hours. Hypoxia during stimulation was assessed with pimonidazole hydrochloride, and tissue perfusion was measured for up to 2 days using hyperspectral imaging. Treated tissues were evaluated by microscopy for edema, inflammation, and the effects on cell proliferation and vessel remodeling. RESULTS: External volume expansion-treated tissues were grossly expanded with 2 hours of stimulation, developing a macroscopic swelling that regressed slowly over the course of hours following stimulus cessation. This gross swelling was reflective of histologic signs of intense edema, persistent for at least 1 hour after external volume expansion. Tissues were hypoxic during stimulation, and hyperspectral imaging demonstrated decreased tissue content of both oxygenated and deoxygenated hemoglobin in the first hour after external volume expansion release. The onset of inflammation was already apparent by the end of stimulation and remained elevated through 2 days after external volume expansion. At this time point, epidermal and dermal cell proliferation and vascular density were significantly increased. CONCLUSION: External volume expansion sets in motion various mechanisms, including mechanical stimulation, edema, ischemia, and inflammation, that over distinct time periods maintain an environment conducive to cell proliferation and angiogenesis, which can be elicited even by a single 2-hour external volume expansion cycle.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".