A CARTILAGE MATRIX DEFICIENCY EXPERIMENTALLY-INDUCED BY VITAMIN-B-6 DEFICIENCY

A vitamin B-6-deficiency-induced disorder in avian articular cartilage resembling osteoarthritis has been further characterized. We measured several parameters of proteoglycan (PG) metabolism, i.e., fixed charg e density and sulfated glycosaminoglycans (S-GAG) content in PN-defici ent versus control articular cartilage and synovial fluid from the kne e joint. Statistically significant changes were: 1) decreased content and increased extractability of total sulfated PGs from articular cart ilage with guanidine HCl; 2) elevation of S-GAG concentration in synov ial fluid; 3) increased plasma cystathionine (sulfur amino acid) level s, Pc synthesis as assessed by (SO4)-S-35 incorporation into S-GAGs wa s not impaired. A lack of cartilage swelling in 0.15 M saline and the normal water content indicated that although disturbed, the collagen n etwork was not disrupted. This finding was in agreement with a previou s microscopic study that revealed no fissures in the articular cartila ge. Previous findings of a normal aggregating Pc size-distribution and absence of elevated metalloproteases made a disturbance of aggregatin g PG metabolism unlikely. Escape into the synovial fluid of small PGs, normally bound to articular collagen, was believed to result from an alteration in collagen molecular organization that could be secondary to elevated circulating SH-compounds.