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D A Weerasekera

Publications and source records attributed to D A Weerasekera.

8 recordsLinked to original sources
PubMed1983

Multiple immunoassay: the simultaneous measurement of two urinary steroid glucuronides as an index of ovarian function.

Ovarian function in women may be monitored effectively by a simple, solid-phase, multiple immunoassay for the simultaneous measurement of estrone-3-glucuronide and pregnanediol-3 alpha-glucuronide in diluted urine. IgG fractions of the respective antisera are passively absorbed to the walls of polypropylene tubes. The labelled antigens are estrone-3-glucuronyl-5-aminoethyl-ethyl-isoluminol and [6,9-3H]-pregnanediol-3 alpha-glucuronide. Daily samples of early morning urine are diluted in buffer (1:200; v/v), and 200 microliters removed, in duplicate, for assay. After the binding reaction (18 h at 4 degrees C), the solution is removed by aspiration. The antibody-bound fraction is washed twice with buffer (300 microliters) is added and the mixture incubated for 50 min at 22 degrees C. Luminescence is initiated by oxidation of the label with microperoxidase/hydrogen peroxide and the signal integrated for 10 s. Subsequently, liquid scintillation fluid (4 ml) is added to the tube and the radioactivity measured. The unknown values are determined from appropriate calibration curves. The combined method has similar sensitivity, accuracy, precision and clinical utility to the values obtained from the separate measurement of the two analytes.

Antigen-Antibody Complex↗
PubMed1983

Measurement of serum thyroxine by solid-phase chemiluminescence immunoassay.

Descriptions are given of two solid-phase chemiluminescence immunoassays for the measurement of total thyroxine in serum. The antibodies were either attached to small uniform plastic microspheres (method 1) or passively adsorbed to antibody-coated tubes (method 2). The labelled antigen was thyroxine-aminobutyl ethyl isoluminol. After the antibody-binding reaction the antibody-bound fraction was washed, sodium hydroxide was added, and the mixture was incubated. Luminescence was initiated by oxidation of the label with microperoxidase/hydrogen peroxide and the signal integrated for 10 seconds. The light yield is inversely proportional to the concentration of thyroxine in the standard or sample. Both methods have similar sensitivity and precision to that obtained by a conventional radioimmunoassay.

Antibodies↗
PubMed1981

Specificity studies of monoclonal and rabbit antibodies raised against steroid glucuronides.

Monoclonal and rabbit antibodies raised against estrone-3-glucuronide and pregnanediol-3 alpha-glucuronide have been studied with respect to their ability to bind free estrone and its conjugates or free pregnanediol and its conjugates, respectively. High titre and high specificity were observed with monoclonal antibodies produced against pregnanediol-3 alpha-glucuronide, whereas the monoclonal antibodies produced against estrone-3-glucuronide were not so specific when compared with the corresponding rabbit antibodies. Both monoclonal and rabbit antibodies had affinity constants in the range of 10(9)--10(10) liter/mole.

Animals↗
PubMed1979

Seasonal differences in plasma testosterone profiles in buffalo bulls.

Testosterone was measured by radioimmunoassay in blood samples collected hourly over 10 h from two adult buffalo bulls in April, May, August and December. The basal concentrations were below 0.2 ng/ml while peak concentrations ranged from 0.35 to 1.65 ng/ml, with not more than one complete peak occurring during a 10 h period. Both bulls had similar testosterone profiles within each sampling period but differences were evident between periods, the mean concentration being highest in August and falling through December and April to the lowest levels in May. Testosterone concentrations in buffaloes are therefore lower than those in other domestic species, and appear to vary during different times of the year.

Journal Article↗