Hydrolysis of Hyaluronic Acid of Human Joint Fluid in vivo.

There is present in joint fluid a polysaccharide which Meyer 1 had named hyaluronic acid. This polysaccharide is believed to be the substance which is responsible for the increased viscosity of synovial fluid. One may obtain a rough estimate of the amount of polysaccharide present in the joint fluid from the relative viscosity of the fluid. A specific enzyme which hydrolyzes this polysaccharide has been recovered from bacterial filtrates and from various animal organs. 2 The enzyme has been shown to have many properties, similar to the spreading factor of Duran-Reynals. 3 , 4 The enzyme has been found to be active in vitro and so an attempt was made to determine its activity in vivo. In the experiments to be reported here the enzyme was injected directly into the joint space.

Methods. Four patients were taken by chance as they were seen in the clinic or hospital. The enzyme was concentrated by Dr. Karl Meyer, who kindly furnished us with the material. It was derived from bulls' testes. An aqueous solution of the enzyme was made up in small volume. The solution was then passed through a Seitz filter. Fluid was removed from the knee, and the enzyme was immediately injected into the joint space. At varying times thereafter, fluid was again removed from the knee. The joint fluid was cooled, the clot separated by slow centrifugation and the viscosity determined on the supernatant fluid, using an Ostwald viscosimeter under standard conditions. Viscosity values are expressed as multiples of the viscosity of water. The total protein content of the synovial fluid was determined by a specific gravity-gradient method. 5

Results. As shown in Table I, in all instances in which a potent enzyme was injected, the viscosity of the joint fluid was markedly reduced.