Novel fluorescent compound (DDP) in calf, rabbit, and human articular cartilage and synovial fluid.
Bibliographic record
Abstract
OBJECTIVE: To investigate the presence of and quantify 2,6-dimethyldifuro-8-pyrone (DDP), a novel fluorescent compound identified as in various calf, rabbit, and human tissue/fluid samples, to determine the DDP level in articular cartilage (AC) laminae, and to investigate the changes in cartilage DDP content with cartilage maturation. METHODS: Samples were obtained from calf (< 2 years), rabbit (< 2 weeks to 2 years) or human AC and synovial fluid (SF) as well as other non-cartilaginous tissues. SF and tissue samples were hydrolyzed with 6 M HCl (24 hours at 110 degrees C), lyophilized, and dissolved in HPLC mobile phase. DDP and collagen crosslink peaks were measured using a fluorescence detector at excitation and emission wavelengths of 295 and 395 nm, respectively. RESULTS: DDP was detected from calf metacarpophalangeal joint AC (362 +/- 48 pmol/mg dry weight), SF (4.5 +/- 0.3 pmol/microl SF), and intervertebral disc (24 +/- 4 pmol/mg). DDP was not detected in calf ligament, tendon, bone, ocular lens, cornea, or elastic cartilage. The DDP amount was greater in mid-deep cartilage lamina (448 +/- 63 pmol/mg) than superficial-mid lamina (129 +/- 52 pmol/mg) (p = 0.008). DDP level decreased with maturation in rabbit knee joint AC from 185 +/- 40 (< 2 weeks) to 27 +/- 3 (2 years) pmol/mg dry weight. DDP was not detected in adult rabbit ligament, tendon, meniscus, or bone. DDP was detected in human knee joint AC and SF. The DDP level in osteoarthritic lesions was present in lower concentrations (range: 0 to 96 pmol/mg dried AC) compared to intact AC (range: 63 to 236 pmol/mg) of the same knee. CONCLUSION: DDP is a hyaline cartilage specific compound present in all articular cartilage samples from various articulating joints/animal species. DDP level increases with AC depth and decreases with cartilage maturation. DDP is a potential indicator of cartilage metabolism during normal growth, ageing, and cartilage disease.
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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) | 0.000 | 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) | 0.001 | 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".