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Information regarding the quality of autologous chondrocyte implantation repair is needed to determine whether the current autologous chondrocyte implantation surgical technology and the subsequent biologic repair processes are capable of reliably forming durable hyaline or hyaline-like cartilage in vivo. We report and analyze the properties and qualities of autologous chondrocyte implantation repairs. We evaluated 66 autologous chondrocyte implantation repairs in 57 patients, 55 of whom had histology, indentometry, and International Cartilage Repair Society repair scoring at reoperation for mechanical symptoms or pain. International Knee Documentation Committee scores were used to address clinical outcome. Maximum stiffness, normalized stiffness, and International Cartilage Repair Society repair scoring were higher for hyaline articular cartilage repairs compared with fibrocartilage, with no difference in clinical outcome. Reoperations revealed 32 macroscopically abnormal repairs (Group B) and 23 knees with normal-looking repairs in which symptoms leading to arthroscopy were accounted for by other joint disorders (Group A). In Group A, 65% of repairs were either hyaline or hyaline-like cartilage compared with 28% in Group B. Autologous chondrocyte repairs composed of fibrocartilage showed more morphologic abnormalities and became symptomatic earlier than hyaline or hyaline-like cartilage repairs. The hyaline articular cartilage repairs had biomechanical properties comparable to surrounding cartilage and superior to those associated with fibrocartilage repairs. [ABSTRACT FROM AUTHOR]

Purpose.The purpose of this study was to investigate the physicochemical and structural characteristics of recombinant botulinum serotype B (rBoNTB(Hc)) under various conditions and to use the information in evaluating suitable purification process conditions.Methods. The solubility of rBoNTB(Hc) was evaluated at pH 4, 5, 6 7.5, 8, and 9. Secondary structure was evaluated using circular dichroism, and conformational stability was monitored using high-sensitivity differential scanning calorimetry. Hydrophobic interaction chromatography, size exclusion chromatography-high performance liquid chromatography (SEC-HPLC), sodium dodecyl sulfate-poly acrylamide gel electrophoresis (SDS-PAGE), peptide mapping, and UV spectroscopy were used to monitor stability under the various conditions.Results. The secondary structure of rBoNTB(Hc) consists predominantly of β-sheets. Solubility of rBoNTB(Hc) was lowest at its pI and highest at low and high pH. In the presence of NaCl, however, solubility decreased with increase in pH. Conformational and chemical stability are improved below pH 7.5. In the presence of 150 mM NaCl at high pH, conformational and chemical stability of rBoNTB(Hc) are further decreased. The study suggests that the purification process should minimize exposure of rBoNTB(Hc) to high pH and salt conditions.Conclusions. Optimal stability of rBoNTB(Hc) is achieved at low pH. The biophysical and analytical studies provide us with an understanding of rBoNTB(Hc) stability behavior in solution and assists in developing efficient purification conditions. [ABSTRACT FROM AUTHOR]