Studies on the preparation of labelled compounds for γ-scintigraphy use

1. Development of 165Dy-HMA for the treatment of rheumatoid arthritis 1) Irradiation of twelve mg of 164Dy2O3 showing specific activity of 2x1013 n/cm2sec for four hours gave 165Dy2O3 showing specific activity(∼480 mCi/mg Dy2O3) and radionuclidic purity(>99.9%). 2) 165Dy-HMA was prepared in yield of 80 - 85% from the 165DyCl3 solution which was made by dissolving 165Dy2O3 with hydrochloric acid and adjusting pH to 3.0, and then followed by the treatment with aqueous sodium hydroxide solution. 3) Serial filtration using polycarbonate filter (1 - 10μm) of 165Dy-HMA suspension in saline after treatment with sonificator exhibited that the majority of particles are in the 3 - 8μm range. 4) Even though the 165Dy-HMA suspension in saline was left to stand for 24 hours at room temperature, there was no significant change in particle size resulting in high stability of 165Dy-HMA. 2. Study on the 99mTc labelling of bioactive material 1) The labelling of antibody [F(ab')2] coupled to DTPA with Na99mTcO4 in the presence of sodium dithionite(μg) gave labelling yield of 40% determined by ITLC-SG. 2) The labelling of 500μl of antibody solution in phosphate buffer(0.2M, pH 7.4, 1.5mg antibody/ml) with Na131I(3 - 5mCi) in the presence of chloramine-T(0.14mg) for 30minutes at room temperature exibited labelling yield of 60 - 70%, radiochemical purity of 97%, specific activity of 1.2 - 3.5 mCi/mg, respectively, determined by ITLC-SG. 3) The results obtained from the animal experiment in rabbit to study the specificity and sensitivity of 131I labelled antibody exhibited hot uptake until 72 hours in the case of tuberculous infection, with the highest target/background ratio(2.52) at 24 hours after injection of 131I-F(ab')2 4) In the case of rabbit infected with syphilitic orchitis, it exhibited the highest target/background ratio(3.51) at 2 hours after injection and showed fast decrease after 24 hours. (Author)