Authors:S. Muddukrishna, D. Narasimhan, and C. Desai
A column-extraction generator based on the adsorption of alkaline sodium molybdate on an acid alumina column is described. Generators containing 1 to 3.2 g of molybdenum /99Mo/ absorbed on 12–15 g of acid alumina, with activities ranging from 0.52 to 5.2 GBq /14 to 140 mCi/, have been prepared and evaluated. The results indicate that99mTc can be quantitatively eluted from such columns with about 10 ml of MEK. The yields were found to be in the range of 70 to 90% over 3–6 days.
Authors:S. Muddukrishna, D. Narasimnan, and C. Desai
A new technique for the separation of99mTc from low specific activity99Mo is reported. A separation based on the principle of precipitation of99Mo as calcium molybdate has been investigated. On precipitating99MoO
from alkaline solution as calcium molybdate under controlled conditions, the99mTcO
is found to remain quantitatively in the supernatant solution with little carry-over of99Mo. This calcium molybdate (99Mo) could be redissolved and reprecipitated at regular intervals, yielding99mTc quantitatively in aqueous neutral solutions. Calcium molybdate precipitates containing up to 1.5 GBq of99Mo and 130–180 mg of molybdenum were prepared and evaluated. The performance in terms of repeated99mTc separation gave yields of 75–93% with acceptable readionuclidic and radiochemical purity.
Authors:M. Pillai, U. Nagvekar, C. Desai, and R. Mani
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).
Authors:S. Muddukrishna, D. Narasimhan, Saraswathy Iyer, and C. Desai
A method based on the sorption of99mTc in MEK on an acid alumina column has been investigated. A number of parameters as column dimension, amount of alumina, MEK volumes, etc. is found to affect the extent of adsorption and the final purity of99mTc solution. These parameters have been standardized and a method for rapid recovery of MEK-extracted99mTc has been developed. The final characteristics of the99mTc is found to conform to pharmacopoeia specification.
Authors:G. Samuel, M. Pillai, U. Singh, C. Desai, and R. Mani
We describe a radioimmunoassay procedure for human somatotropin using second antibody — polyethylene glycol (PEG) combination for the separation of antibody bound and free antigen. The assay is done by a single incubation of 18 hours or with one hour pre-incubation and 3 hours post-incubation at room temperature (25 °C) and uses 0.1 m of serum sample. The assay covers a range of 0–40 g/ and has a sensitivity of 0.6 g/ of somatotropin. The assay is validated by inter-assay and intra-assay variations, recovery and parallelism tests.
Authors:A. Rathinaswamy, U. Nagvekar, S. Borkute, S. Balakrishnan, and C. Desai
The need for defining the assay conditions assumes greater significance for the manufacturer of RIA kits. This stems from the consideration that despite high quality of kit reagents in the kits, it is the definition of optimum conditions of assay that makes them effective and also permits to evaluate the limits of the sensitivity and precision. In this connection we have studied in detail a number of parameters mainly to define the stability of the assay system to changes in the protein concentration, the influence of polyethylene glycol in various ionic media, incubation parameters for systematic error analysis in three separation systems based on dextran coated charcoal, plain polyethylene glycol and polyethylene glycol assisted second antibody. Second antibody in a preprecipitated form was found to be readily adaptable as a reagent. Among the three methods of separation studied, the second antibody employed as a complex with primary antibody assisted by polyethylene glycol had superior separation without any specific criticality, characteristics as judged by the variations at various dose levels over an extended period and provided a practical procedure for routine assays.
Authors:T. Jyotsna, M. Pillai, N. Pal, Jyoti Gupte, C. Desai, and R. Mani
A simple and reliable technique for the simultaneous estimation of serum triiodothyronine (T3) and thyroxine (T4) is discussed. T3 assay was done by the solid phase technique using antibody coated Eppendorf pipette tips. T4 assay was done by the polyethylene glycol separation system. The assay used 50 l of serum sample. Inter-assay and intra-assay coefficient of variation are less than 12% throughout the assay range, for both assays.
Authors:H. Dang, H. Desai, S. Kayasth, D. Jaiswal, C. Wadhwani, and S. Somasundaram
The daily intakes of trace elements by infants showing optimal pattern of growth are used as the basis to estimate the requirements of Fe, Co and Se during infancy. Since milk is the only food and source of nutrition in the first few months of life, the requirements of these elements are calculated from their average concentrations in human milk and the volume of milk required to supply sufficient amount of energy for maintenance and healthy growth of infants. The concentrations of the three elements in human milk were determined, using the technique of neutron activation followed by radiochemical separation.