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- Author or Editor: M. Pillai 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
Application of extraction chromatographic technique to the analytical separation of Th/IV/ and U/VI/ has been investigated. The stationary phase was a macroporous resin Amberlite XE-270 impregnated with undiluted trin-n-butylphosphate /TBP/ and the mobile phase was either 5.OM HNO3 or 6M HCl. Separation of traces of Th/IV/ from large quantities of U/VI/ was achieved on a laboratory column by elution of the absorbed Th/IV/ with 6M HCl.
Abstract
A solid phase radioimmunoassay for triiodothyronine (T3) has been developed using antibody-immobilized serum albumin microspheres. Antibody albumin microspheres were prepared using a 
spinning disc aerosol generator
. The low density of the antibody-albumin microspheres gives greater mobility for the particles there by ensuring better kinetics to the antigen-antibody reaction. The assay has a single incubation of one hour at 37° C and the separation of the antigen-antibody complex is accomplished by centrifugation. The sensitivity of this assay is 0.3 ng/cm3 and has a range of 0.3–4 ng/cm3.
Abstract
Sea water is observed to be a good desorbing agent for137Cs from marine sediments. Investigations on the sites of137Cs binding and their abundance by desorption over extended periods indicated that, whatever the time of contact of sorption,137Cs has three modes of desorption: fast component with desorption half-time of 30–50 min, medium component with desorption half-time of 25–50 h and slow component with desorption half-time of 31–112 days. These are expected to be sites of ion exchange, slower exchange and trapped Cs in the clay mineral layer lattices.
Abstract
A direct radioimmunoassay for the measurement of progesterone in human serum is described. Progesterone 11
-hemisuccinate was conjugated to tyrosine methyl ester (TME) by the mix anhydride method and then iodinated using chloramine-T. The radiochemical purity of different batches of125I-progesterone was greater than 95% and showed 70–75% binding with excess antibody. Progesterone 11-hemisuccinate was coupled with BSA and injected to rabits. Antisera collected after three booster injections and having aK value of 1·1091/M was selected for the assay. Significant reduction in binding with antibody was seen when hormone free serum was used in the assay system. Various blocking agents were tried to reduce the serum effects and none of them were found satisfactory. From a series of optimization experiments, an assay was developed without the use of blocking agents. This assay used a much higher concentration of antibody along with lower amount of serum sample (50 
l). The optimized assay has a sensitivity of 0.5 nj/ml and a working range of 0.5 to 100 ng/ml. Serum samples were analyzed analysis showed good correlation between the results obtained from the present system and the DPC kit. (Y=0.93X+0.5,r=0.93, forn=25).
Abstract
Cerebral amino acid metabolism is known to be associated with various psychosomatic disorders. 3-(123I)iodo-L-alpha methyl tyrosine (123I-L-AMT) is an alternative to the PET radiopharmaceutical, 11C- thymidine, for brain SPECT studies. Radioiodination of L-alphamethyl tyrosine using chloramine T as well as iodogen has been standardized using 125I as the first step towards the development of the SPECT imaging agent 123I-L-AMT. Purification of the iodinated product was carried out over Sephadex LH-20 column. A quick and easy purification method using Sep-pak column also has been standardized. Quality control of the 125I-L-AMT was carried out by estimating the radiochemical purity and stability of the product. Biodistribution studies of the product were carried out in mice. Time dependent pharmacokinetic studies and activity distribution pattern in the different parts of the brain were also carried out.
A sensitive high-performance thin-layer chromatographic (HPTLC) method has been developed for estimation of amentoflavone, an important bioactive biflavonoid found in many medicinal plants. Amentoflavone was isolated from Biophytum sensitivum , characterized, and used as reference standard. The HPTLC method was validated for precision (intra- and inter-day), repeatability, and accuracy. The method was found to be precise — intra-day and inter-day RSD , for different concentrations, were 0.52–1.36% and 1.87–3.41%, respectively. Instrumental precision and repeatability of the method were found to be 0.098 and 2.1 (% CV ), respectively. The accuracy of the method was checked by performing a recovery study at two levels; average recovery was found to be 98.86%. The method was used for the estimation of amentoflavone from B. sensitivum and Putranjiva roxburghii . The method was found to be accurate and precise and could be used for the estimation of amentoflavone from plant materials.
Abstract
We discribe the development of a simplified radioimmunoassay for triiodothyronine (T3) using pre-incubated labelled T3 and antibody. The assay is carried out by adding 50 
l of standard or sample to 0.4 ml of pre-incubated reagent dispensed in assay tubes. The reaction is allowed to proceed for about four hours and the antigen-antibody complex precipitated by the addition of 1 cm3 of 22% polyethylene glycol solution. Due to the high dissociation constant of T3-antibody complex at 37° C (2.83·10–4 S–1), the labelled antigen-antibody complex dissociates and thereby the unlabelled antigen binds with the antibody. With a four hour incubation the sensitivity of this assay is comparable to an assay done by the equilibrium method using the same antibody. Sixty serum samples were analyzed using this method and compared with the equilibrium assay (Y=0.94x+0.046 ng/cm3, r=0.98).
Ion exchange in organic solvents
IV. Separation of plutonium from uranium in 30% TBP on amberlyst-15
Abstract
Studies on the partitioning of plutonium from 30% TBP by ion-exchange absorption on macroporous cation exchanger Amberlyst-15 have been described. Detailed loading experiments indicate that the resin absorbs plutonium in preference to uranium from loaded organic phase at low organic phase acidities (around 0.2M). Absorption behaviour of some fission products on the resin in 30% TBP is also reported. Possibility of using this procedure as an alternate method for plutonium partitioning from IAP stream of Purex process has been discussed.
