Cyclic compression of cartilage/bone explants in vitro leads to physical weakening, mechanical breakdown of collagen and release of matrix fragments
Bibliographic record
Abstract
Mechanical loading of articular cartilage can produce catabolic and anabolic changes in tissue metabolism. Most previous studies in this area have focussed on aggrecan. Little information concerning load-induced collagen modifications has been obtained. We have therefore conducted studies where mechanical loads are applied in vitro to full thickness cartilage explants retaining a thin layer of bone, in order to investigate mechanically induced collagen breakdown and consequent turnover, in addition to aggrecan changes and mechanical property alterations. Tissue explant disks were subjected to unconfined compression and either immediately frozen or kept in static culture for 10 days. Mechanical tests of the disks immediately prior to and just after the cyclic loading period were also performed. They showed a weakening of the collagen network and an increased hydraulic permeability due to the cyclic loading. Load-induced alterations of the extracellular matrix was then clearly evidenced by an increase in denatured collagen in the disks frozen immediately after loading compared to unloaded controls. Loaded disks maintained in culture for 10 additional days following cyclic loading no longer expressed this increase in denatured collagen suggesting that mechanically denatured collagen II had undergone a removal process which could represent turnover or repair, or the beginning of progressive degradation. Indeed matrix fragments of collagen II and glycosaminoglycans were found to be released to post-loading culture medium in increased quantities compared to unloaded controls. Our data further demonstrates the ability of mechanical load of articular cartilage to modulate turnover and metabolism of collagen and proteoglycan in a complex and multifactorial manner that may be of particular significance in the pathogenesis of osteoarthritis and in the development of pharmacological agents to modulate its progression.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".