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- Author or Editor: K. Kothari x
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Abstract
Preparation and purification of radioiodinated progesterone derivatives for the development of a radioimmunoassay of progesterone is described. We have standardized two procedures for preparing radioiodinated progesterone conjugate. In the first procedure125I labeled histamine was conjugated to progesterone 11
hemisuccinate by the mixed anhydride method. In the secod procedure, tyrosyl methyl ester was conjugated to progesterone 11 hemisuccinate and iodination of the conjugate was carried out. Purification of the iodinated products was carried out by solvent extraction and thin layer chromatography techniques. The radiochemical purity of the tracers prepared by both methods were more than 95%. Labeled progesterone derivatives prepared were used for developing a radioimmunoassay procedure. The non-specific binding of the tracer was about 2–3%, while up to 80% binding could be obtained in the presence of excess antibody. The radioiodinated tracer could be used up to four months in the assay.
Abstract
The standardisation of a direct radioimmunoassay for progesterone using an125I labeled progesterone prepared by iodinating the tyrosine methyl ester (TME) conjugated to a progesterone hemiphthalate derivative and an antibody prepared using progesterone linked to bovine serum albumin through 11α hemisuccinate derivative is described. The hemiphthalate derivative of progesterone was prepared by reacting 11α-hydroxy progesterone with phthalic anhydride which was then conjugated to TME by using isobutyl chloroformate. The conjugate was iodinated with125I using chloramine-T as oxidising agent and purified by thin layer chromatography. Radiochemical purity of the tracer was >95% in all batches. The tracer gave 70–75% binding with excess antibody. Assays were optimised with 8-anilino-1-naphthalene sulphonic acid (ANS) and sodium salicylate as blocking agents to release the progesterone from binding proteins. The assay optimised with sodium salicylate as blocking agent has a sensitivity of 0.25 ng/ml and a working range of 0.25–50 ng/ml, whereas the assay with ANS has a sensitivity of 0.75 ng/ml and a working range of 0.75–100 ng/ml. Serum samples were analysed and compared with the values obtained with a homologous bridge assay.
Abstract
Electrolytic labelling procedures have been reported for various99mTc radiopharmaceuticals which differ widely in the choice of the electrodes, working pH, applied voltage and the quantity of current passed. The authors have studied the electrolytic labelling of99mTc EHDP, gluconate and glucoheptonate with MEK extracted99mTc using tin electrodes under different experimental conditions. The results have, shown that these compounds can be efficiently labelled with99mTc in a single step procedure avoiding multiple pH adjustments. Labelling of human serum albumin microspheres suitable for lung imaging with99mTc by the electrolytic method is also reported.
