Anna-Marja Säämänen

Proteoglycan Alterations in Rabbit Knee Articular Cartilage Following Physical Exercise and Immobilization

Rabbit knee articular cartilage was studied after the joint was submitted to immobilization, running or increased weight bearing for 24-27 days. Immobilization with a plastic splint reduced the fraction of proteoglycans not extractable with 4 M guanidinium chloride (GdnHCl). In the immobilized joints the chondroitin sulfate content was elevated as calculated from the galactosamine/glucosamine ratio. The ability of these proteoglycans to reform aggregates with endogenous hyaluronic acid in Sepharose CL-2B chromatography was reduced. Increased exercise was associated with an elevation of proteoglycans extractable with 4 M GdnHCl. The increased weight bearing occurring in the contralateral knee elevated the content of proteoglycans not extractable with 4 M GdnHCl. Other effects of weight bearing included increased glucosamine concentration, suggesting accumulation of keratan sulfate-rich proteoglycans, and an elevated hydroxyproline concentration.

Maturation of proteoglycan matrix in articular cartilage under increased and decreased joint loading. A study in young rabbits.

The right knees of 4-month-old NZW rabbits were splinted in extension for 1 to 8 weeks. Biochemical changes of the knee articular cartilage were noted after decreased (splinted leg) and increased loading (created by the shift of body weight onto the left, contralateral limb). Increased loading accelerated changes associated with maturation of articular cartilage, which include accumulation of hyaluronic acid (HA) and keratan sulfate-rich proteoglycans (KS, PG) that are tightly bound to the tissue. After 8-weeks of splinting the content of extractable PGs in the tibial medial condyle decreased. The lost material was apparently replaced by PGs with a higher degree of sulfation of the chondroitin sulfate (Ch-S) chains. Reduced loading disturbed normal maturation as evidenced by inhibition of the accumulation of KS-rich, non-extractable PGs. Collagen content increased in all samples of different joint sites and groups during the 8-week experiment. The content of extractable PGs decreased slightly, while the content of non-extractable, especially KS-rich PGs increased. The greatest changes occurred in the tibial medial condyle, where the KS content was highest.

Influences of Joint Immobilization and Running Exercise on Articular Cartilage Surfaces of Young Rabbits

The influences of joint immobilization and running exercise on the articular cartilage surfaces of the patella and lateral tibial condyle of young rabbits were investigated by the semiquantitative stereomicroscopic and scanning electron microscopic methods during a period of 8 weeks. The smoothness of the articular surfaces was disturbed already 1 week after the onset of immobilization. Leafy, slightly rough and rough surface qualities associated with superficial splits were observed. The changes were of the same nature after a longer period of immobilization. Running exercise on the treadmill (150-300 m twice a day, 12-24 min per turn, 5 times a week) led to an increase of the striated surface quality at 1 to-2-week intervals as compared with the controls. It was apparent that during immobilization remarkable changes of the articular cartilage took place within the first week, while running exercise up to 8 weeks elicited only transient or minor alterations of the articular surface.

Determination of unsaturated glycosaminoglycan disaccharides by spectrophotometry on thin-layer chromatographic plates

Chondroitin sulfate isomers and hyaluronate, digested with chondroitinase AC II and separated as unsaturated disaccharides by thin-layer chromatography on cellulose, were quantitated with scanning spectrophotometry using reflectance measurement at 232 nm. The sensitivity of the assay was increased by one order of magnitude as compared to previous modifications of the disaccharide analysis on cellulose. The method allowed quantitation of 0.2-20 micrograms of glycosaminoglycan uronic acid. Since the elution of the disaccharides from the plate could be omitted, the speed and reproducibility of the assay was enhanced.

A sensitive GLC-method for component sugars andO-glycosidic linkage monosaccharides of cartilage proteoglycans

A method is described for the measurement ofN-acetylgalactosamine,N-acetylglucosamine, galactose, mannose and xylose present in the different carbohydrate chains of cartilage proteoglycans (PG). Bovine articular cartilage PG samples corresponding to the minimum of 1 nmol of each monosaccharide were reproducibly quantified following hydrolysis with 2 M HCl and derivatization into alditol acetates. An on-column injection mode and an OV-1701 fused silica capillary column were used for chromatography.Alkaline borohydride treatment of the PG was exploited to reduce the acid labile xylose in the base of the chondroitin sulphate chain into more stable xylitol, allowing the assay of chondroitin sulfate chain length as anN-acetylgalactosamine/xylose ratio. A novel procedure is described for the measurement of the galactosaminitol evolving from the protein linkage of oligosaccharides and of keratan sulphate.

Superficial zone of articular cartilage after immobilization and running training: is proteoglycan depletion the clue to the pathogenesis of osteoarthrosis

Superficial zone of articular cartilage after immobilization and running training: is proteoglycan depletion the clue to the pathogenesis of osteoarthrosis