Kinetics of the reaction between testosterone and antitestosterone antiserum.

In order to characterize from a kinetic viewpoint the antibody population mainly involved in the binding of testosterone by its homologous antiserum, the kinetics of the association reaction between [1,2,6,7-3H]-testosterone and rabbit antiserum anti-testosterone-3-(O-carboxymethyl)oxime-bovine serum albumin (Ab R2603-1) was followed at pH 7.4 and at constant ionic strength, at temperatures ranging from 2 degrees C to 37 degrees C and at concentration near to work conditions for testosterone radioimmunoassay; dextran coated charcoal suspension was used for the bound/free separation. In the examined concentration range, the observed kinetics trends can be explained by assuming the existence of two classes of antibody binding sites, Ab1 and Ab2. The kinetics of the dissociation reaction of the testosterone-antibody complex was also followed after the addition of a large excess of unlabeled testosterone. At 22.0 degrees C, association and dissociation rate constants are 2.1.10(7) s-1M-1 and 3.7.10(-3) s-1, respectively, for the Ab1 class of antibody binding sites, and 3.6.10(6) s-1M-1 and 7.0.10(-4) s-1 for the Ab2 class. Equilibrium constants obtained from kinetic data were very similar for both classes of antibody binding sites and in good agreement with the equilibrium values obtained from linear Scatchard plot. The order of magnitude of the second order rate constants and the high activation enthalpy for the forward and reverse reaction suggest a mechanism more complex than a simple second order.

[Frequency of goiter and urinary iodine in the Peidmont school children. Data on iodine contents in some local food]. / Frequenza del gozzo e valori di ioduria negli scolari del Piemonte. Dati sul contenuto iodico di alcuni alimenti locali

The frequency of thyroid alterations was examined and dietary iodine intake was assessed via urinary iodine in 6-15 yr-old schoolchildren from 145 towns in Piedmont and the Aosta Valley. Local food iodine values were also determined in 56 towns. Alteration frequency and daily urinary elimination of iodine were inversely proportional, even within individual school populations. The endemic goitre urinary iodine threshold (around 40-50 mug I/g creatine) varied from area to area, with as much as double this value in some instances. Drinking water iodine was usually from 0 to 3 mug/l, with relatively low values in high localities. Much higher levels were noted in the presence of salsobromoiodic hot springs. Local Piedmontese foods contained less iodine than those bought in city markets.