Estimation of true values in radioimmunoassays.

We tested the accuracy of radioimmunoassays for two hormones, progesterone and estradiol, in relation to the use of two different antisera in each assay and to the degree of purification from plasma before the assay was done. Each analyte was assayed either in a diethyl ether extract, in a zone eluted from a Sephadex LH-20 chromatographic column, or in fractions of a chromatographic zone (from Sephadex LH-20 or Celite) that passed a test of "radiochemical purity." Statistically indistinguishable results were obtained in the assay of radiochemically pure fractions of both analytes, irrespective of the antiserum used.

[Non-pigmented Serratia: utility of hydrolysis of Tween 80 in its identification].

The ability of Serratia sp. to hydrolyze Tween 80 and the usefulness of this test for differentiating it from other Gram negative bacilli was studied, comparing it with the capacity of production of DNAsa by the same strains using the O-Toluidine blue method. The total number of strains assayed was 88.