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The penetration and permeation of the recombinant protein plasminogen activator inhibitor type 2 (PAI-2) in two formulations, one containing a penetration enhancer, into the psoriatic and uninvolved skin of eight patients with plaque-type psoriasis were investigated. Penetration and permeation of PAI-2 were measured by gamma counting and imaging following radiolabelling of a fraction of the applied PAI-2 with (123)I. The feasibility of topical delivery of drug to psoriatic plaques was confirmed by the finding that the permeability of psoriatic plaques to radiolabelled PAI-2 (P=0.007) and free (123)I (P=0.001) was approximately tenfold higher than the permeability of uninvolved skin. The addition of a penetration enhancer improved the permeation of PAI-2 into psoriatic plaques from an average of 35% to 46% (P=0.005). Occlusion decreased the permeation amount of PAI-2 from 46% to 15% due to losses on the occlusive dressing (P=0.001).

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SummaryThree immunoglobulin molecules were evaluated as infection imaging agents in a rat model of S. aureas infection:99m 99m Tc-human immunoglobulin (HIG) and 99m Tc-rat immunoglobulin (RIG). Infliximab is a chimeric monoclonal antibody specific for human tumour necrosis factor alpha (TNFa). Tc-HIG was chosen as an exogenous protein and 99m Tc-RIG as an endogenous marker. Each immunoglobulin was treated with 2-mercaptoethanol and the reduced antibody was isolated by size exclusion chromatography. In combination with Sn II -methylenediphosphonic acid, cold kit formulations were prepared. Native and reduced infliximab were tested for rat TNFa binding ability in vitro. A focal intramuscular infection of S. aureus (1 Â 10 8 colony forming units) was induced in the left thigh muscle of rats, that developed for 24 h. In separate experiments each tracer was administered by intravenous injection, then whole body scintigraphic imaging and biodistribution studies were performed at 1 and 4 h later. 99m 99m Tc-HIG and 99m Tc-RIG were prepared with 595% radiochemical purity from stable cold kits.Results from the organ assay gave infected (target) to non-infected (control) muscle ratios for 99m Tc-infliximab as 5.7 AE 0.8, 7.1 AE 1.2, 99m Tc-HIG gave 3.1 AE 1.1, 7.8 AE 1.2, and 99m Tc-RIG 7.9 AE 0.3, 12.5 AE 1.5 at 1 and 4 h, respectively. Infliximab and Sn II -infliximab did not bind to rat TNFa by the in vitro assay. Although lacking specific affinity for TNFa, 99m Tc-infliximab accumulated at infectious sites in vivo. 99m Tc-infliximab gave similar infection uptake ratios to 99m Tc-HIG at 1 and 4 h, but these proteins were inferior in comparison to 99m Tc-RIG, and is likely to be due to