CARTILAGE BOUNDARY LUBRICATING ABILITY OF PRG4 (LUBRICIN) MONOMERS AND MULTIMERS WITH HYALURONAN
Notice bibliographique
Résumé
INTRODUCTION Proteoglycan 4 (PRG4), or lubricin, is a glycoprotein that exists in synovial fluid (SF) as monomeric and disulfide-bonded multimeric forms [1,2]. PRG4 functions as a critical boundary lubricant on the surface of articular cartilage [1,3]. Hyaluronan (HA) is another lubricant that lubricates at a cartilage-cartilage interface alone, and synergistically with PRG4 to reduce friction levels near that of SF [4]. Previously PRG4-multimers (PRG4-multi) have been shown to lubricate considerably better than PRG4 monomers (PRG4-mono) using an in vitro cartilage-on-cartilage friction testing system [5]. However, it is unknown if the difference in structure of PRG4-multi/-mono affects the synergism with HA. Therefore, the objective of this study was to evaluate the cartilage boundary lubricating ability of PRG4-multi & PRG4-mono with HA. METHODS Samples: PRG4 was purified from media conditioned by mature bovine cartilage explants [4]. PRG4 multi-mono was prepared via size exclusion chromatography [5]. HA (1.5MDa) was obtained from Lifecore Biomedical. Cartilage boundary lubrication: Lubricants of interest were assessed using a previously described in vitro cartilage-cartilage friction test [6]. Briefly, bovine osteochondral samples (n=8) were incubated with test lubricants overnight, compressed by 18%, allowed to stress relax then rotated at an effective velocity of 0.3 mm/s with pre-sliding durations (Tps) of 1200, 120, 12, and 1.2s. Phosphate buffered saline (PBS) and bovine SF served as negative and positive controls, respectively. All samples were prepared at a physiological concentration [4]; PRG4 at 450 μg/mL and HA at 3.33 mg/mL, in PBS. Test sequence: PBS, PRG4-mono+HA, PRG4-multi+HA, PRG4+HA, SF. Static (μ static,Neq ) and kinetic ( ) friction coefficients were calculated [4,6]. ANOVA was used to assess the effect of lubricant and Tps, as a repeated factor, on μ static,Neq and , with Tukey post-hoc on at Tps=1.2s. RESULTS Cartilage boundary lubrication: PRG4-mono/-multi+HA, functioned as effective friction-reducing cartilage boundary lubricants. However, they did not lubricate as well as PRG4+HA or SF. μ static,Neq values increased with Tps; they were highest in PBS and lowest in SF, with PRG4-mono+HA, PRG4-multi+HA, and PRG4+HA being intermediate. For clarity, values at Tps=1.2s are shown since values at Tps=1.2s were within 13.0±2.7% of those at Tps=1200s. values for PRG4-mono+HA and PRG4-multi+HA were similar (p=0.96). PRG4+HA and SF were similar (p=0.53). All other combinations were significantly different from each other (p<0.05). DISCUSSION AND CONCLUSIONS Previous studies have shown that PRG4-multi lubricates better than PRG4-mono [5]. However the results from this study show that PRG4-mono/-multi with HA lubricate in a similar manner. Interestingly, PRG4+HA lubricates better than PRG4-mono/-multi+HA, and close to that of SF. These differences could be due to a potential PRG4+HA “link molecule” [7] being purified from the PRG4-mono/-multi preparations.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».