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No direct effect of calcitonin on rat epiphyseal cartilage
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Abstracts
No direct effect o f c a l c i t o n i n on rat e p i p h y s e a l c a r t i l a g e JANUSZ BADURSKI t , KALERVO MATSIKO*, JUHA TUUKKANEN t AND KALERVO VA.~NANEN
*Department of Anatomy University of Oulu, SF #Department of Rheumatology, Hospital Bialystok, PL, Poland Calcitonin has been proposed as a chondroprotective agents on the basis of experiments on animal models of osteoarthritis demonstrating anticatabolic and anabolic proprieties. However, the mechansism of action on articular cartilage is unclear. Calcitonin receptor on chondrocyte have not yet been found and was the aim of our study. Calcitonin binding sites were looked for on cultured rat chondrocytes using 1125 labeled salmon calcitonin (Sandoz). Chondrocytes were freshly isolated from rat epiphyseal cartilage. Another experiment
examined the influence of calcitonin on calcium movement into also cultivated chondrocytes from rat epiphysis by Fura-2 labeling. (1) Only unspecified radioactivity into chondrocytes was found and (2) no changes in cytosolic calcium concentration was o b s e r v e d . . We conclude that rat epiphyseal chondrocytes do not possess calcitonin specific binding sites and that the influence of calcitonin on cartilage is indirect.
The p r i m a r y l e s i o n o f t r a p e z i o m e t a c a r p a l osteoarthritis: a b i o c h e m i c a l and u l t r a s t r u c t u r a l study o f regional cartilage disease V. D. PELLEGRINI*, R. L. SMITHt AND C.
*University of Rochester, NY, U.S.A. tStanford University, CT, U.S.A. A correlative biochemical and ultrastructural analysis of articular cartilage was undertaken to clarify the inter-relationship of mechanical and biochemical events in the pathogenesis of trapeziometacarpal (TM) osteoarthritis, Nineteen TM joint specimens included seven obtained surgically from arthroplasty procedures and 12 from fresh post mortem material. Articular cartilage was harvested and hydroxyproline (HYP) was determined following papain digestion and hydrolysis in H C 1 . Chondroitin sulfate (CS) was quantitated by a metachromatic shift in dimethylmethylene blue. Glycosaminoglycan (GAG)from papain-digested cartilage was quantitated by optical density. Individual proteoglycans were extracted in the presence of guanidine HC1 and protease inhibitors, fractionated by gel filtration chromatography, and characterized by determination of glucuronic acid. Specimens were fixed in 2% glutaraldehyde and gold coated in a vacuum evaporator for scanning electron microscopy (SEM). Gross inspection of the joint surfaces demonstrated two patterns of disease; severe volar chondromalacia and eburnation was seen in all surgical specimens (7) and half of post mortem specimens (6), while remaining post mortem specimens (6) demonstrated well-preserved cartilage surfaces. Loss of total GAG exceeded HYP; both were depleted primarily from the volar compartment in arthritic specimens. Normalized for dry weight
Ku#.: ~
of cartilage, GAG was~ significantly (P < 0.001) decreased in areas of volar ~hondromalacia while HYP remained unchanged irresl~'ective of the anatomic compartment or degree of disease. SEM showed disruption of the fibrillar surface layer in areas of early chondromalacia and deeper erosions with empty chondrocyte lacunae in zones of more advanced arthritic disease. Gross, ultrastructural, and biochemical profiles of arthritic post mortem and surgical joints were nearly identical. GAG loss far exceeded that of HYP from chondromalacic cartilage adjacent to areas of eburnation, suggesting sequential early mucopolysaccharide depletion followed by late erosion of the collagen substructure. The occurrence of this preferential GAG depletion, in the volar compartment where shear forces are concentrated due to insufficiency of the adjacent capsular structure, suggests localization of selective biochemical cartilage destruction by an abnormal mechanical environment. Shear-dependent disruption of the surface lamina splendens may allow synovially derived regional access t o the chondrocytes of the underlying articular cartilage, thereby stimulating enzyme mediated degradation of the mucopolysaccharide matrix. This work therefore Supports ligamentous laxity as a causative factor and stabilization of the symptomatically lax TJM joint as a therapeutic intervention to prevent progressive osteoarthritic disease.
Abstracts
No direct effect o f c a l c i t o n i n on rat e p i p h y s e a l c a r t i l a g e JANUSZ BADURSKI t , KALERVO MATSIKO*, JUHA TUUKKANEN t AND KALERVO VA.~NANEN
*Department of Anatomy University of Oulu, SF #Department of Rheumatology, Hospital Bialystok, PL, Poland Calcitonin has been proposed as a chondroprotective agents on the basis of experiments on animal models of osteoarthritis demonstrating anticatabolic and anabolic proprieties. However, the mechansism of action on articular cartilage is unclear. Calcitonin receptor on chondrocyte have not yet been found and was the aim of our study. Calcitonin binding sites were looked for on cultured rat chondrocytes using 1125 labeled salmon calcitonin (Sandoz). Chondrocytes were freshly isolated from rat epiphyseal cartilage. Another experiment
examined the influence of calcitonin on calcium movement into also cultivated chondrocytes from rat epiphysis by Fura-2 labeling. (1) Only unspecified radioactivity into chondrocytes was found and (2) no changes in cytosolic calcium concentration was o b s e r v e d . . We conclude that rat epiphyseal chondrocytes do not possess calcitonin specific binding sites and that the influence of calcitonin on cartilage is indirect.
The p r i m a r y l e s i o n o f t r a p e z i o m e t a c a r p a l osteoarthritis: a b i o c h e m i c a l and u l t r a s t r u c t u r a l study o f regional cartilage disease V. D. PELLEGRINI*, R. L. SMITHt AND C.
*University of Rochester, NY, U.S.A. tStanford University, CT, U.S.A. A correlative biochemical and ultrastructural analysis of articular cartilage was undertaken to clarify the inter-relationship of mechanical and biochemical events in the pathogenesis of trapeziometacarpal (TM) osteoarthritis, Nineteen TM joint specimens included seven obtained surgically from arthroplasty procedures and 12 from fresh post mortem material. Articular cartilage was harvested and hydroxyproline (HYP) was determined following papain digestion and hydrolysis in H C 1 . Chondroitin sulfate (CS) was quantitated by a metachromatic shift in dimethylmethylene blue. Glycosaminoglycan (GAG)from papain-digested cartilage was quantitated by optical density. Individual proteoglycans were extracted in the presence of guanidine HC1 and protease inhibitors, fractionated by gel filtration chromatography, and characterized by determination of glucuronic acid. Specimens were fixed in 2% glutaraldehyde and gold coated in a vacuum evaporator for scanning electron microscopy (SEM). Gross inspection of the joint surfaces demonstrated two patterns of disease; severe volar chondromalacia and eburnation was seen in all surgical specimens (7) and half of post mortem specimens (6), while remaining post mortem specimens (6) demonstrated well-preserved cartilage surfaces. Loss of total GAG exceeded HYP; both were depleted primarily from the volar compartment in arthritic specimens. Normalized for dry weight
Ku#.: ~
of cartilage, GAG was~ significantly (P < 0.001) decreased in areas of volar ~hondromalacia while HYP remained unchanged irresl~'ective of the anatomic compartment or degree of disease. SEM showed disruption of the fibrillar surface layer in areas of early chondromalacia and deeper erosions with empty chondrocyte lacunae in zones of more advanced arthritic disease. Gross, ultrastructural, and biochemical profiles of arthritic post mortem and surgical joints were nearly identical. GAG loss far exceeded that of HYP from chondromalacic cartilage adjacent to areas of eburnation, suggesting sequential early mucopolysaccharide depletion followed by late erosion of the collagen substructure. The occurrence of this preferential GAG depletion, in the volar compartment where shear forces are concentrated due to insufficiency of the adjacent capsular structure, suggests localization of selective biochemical cartilage destruction by an abnormal mechanical environment. Shear-dependent disruption of the surface lamina splendens may allow synovially derived regional access t o the chondrocytes of the underlying articular cartilage, thereby stimulating enzyme mediated degradation of the mucopolysaccharide matrix. This work therefore Supports ligamentous laxity as a causative factor and stabilization of the symptomatically lax TJM joint as a therapeutic intervention to prevent progressive osteoarthritic disease.