R. N. Pinckard, D. Hawkins, R. Farr
Nov 1, 1973
Citations
0
Influential Citations
27
Citations
Journal
Annals of the New York Academy of Sciences
Abstract
Several years ago, investigations were initiated to study the binding properties of various urographic contrast media to plasma proteins. One particular contrast medium, 3-acetamido-2,4,6-triiodobenzoate (acetrizoate) , was especially interesting, because this anion exhibited an enhanced binding affinity for a protein in the serum from some patients with rheumatoid arthritis.lI2 Similar to many anions, acetrizoate (FIGURE 1 ) bouild loosely to albumin when equilibrium dialysis was performed at a free acetrizoate concentration of 2 X 1 0 4 M; at this concentration, the amount of acetrizoate bound by all human sera or purified human serum albumin (HSA) was directly proportional to the concentration of HSA. However, when similar binding studies were performed at a free acetrizoate concentration of 1.0 X 10-7 M, sera from rheumatoid arthritis patients bound significantly more acetrizoate than normal serum; furthermore, such enhanced acetrizoate binding could not be accounted for on the basis of the HSA concentration in the individual serum samples. Subsequent studies demonstrated that the enhanced acetrizoate binding was due to what was thought to be an abnormal albumin in some patients with rheumatoid a r th r i t i~ .~ The presence of the abnormal albumin could not be correlated with the clinical history, various laboratory tests, such as the erythrocyte sedimentation rate and rheumatoid factor, clinical progress, steroid therapy, or blood salicylate levels. The latter observation indicated that salicylate probably had not altered HSA but did not exclude the possibility that acetylsalicylate (aspirin) might be involved. Indeed, this was shown to be the case when enhanced acetrizoate binding developed in the sera of seven volunteers after the ingestion of 2.4 g aspiridday for 21-56 days.4 In addition, in vitro exposure of HSA to aspirin enhanced acetrizoate binding, whereas