Untersuchungen über die Verwendung von125J-markiertem Testosteron bei Proteinbindungsmethoden

The newly synthesized¹²⁵I-testosterone-3-carboxy-methyloxime-tyramide was tested for its applicability in protein binding methods. The binding of the radioactive steroid derivative to sex hormone binding globulin (SHBG), albumins and testosterone antibodies was examined. Furthermore the adsorption to florisil, charcoal and amberlite was studied. The results show:

1. ¹²⁵I-testosterone is bound to antibodies obtained by immunization with testosterone-3-oxime-albumin conjugate similarly to³H-testosterone and unlabelled steroid.
2. ¹²⁵I-testosterone and³H-testosterone show identical binding to florisil, charcoal and amberlite.

Therefore the¹²⁵I-labelled hormone is suitable in competitive protein binding methods using testosterone antibodies and it can displace the tritium labelled hormone. Since¹²⁵I-steroids have higher specific activities the sensitivity of the method is increased. Furthermore the practicability is enhanced. Special problems arise through the relatively short half-life of the isotope and the changing specific activity. Another difficulty is its decreased chemical stability when compared with the tritiated steroid.     

Latex Fractionation by Sedimentation and Colloidal Crystallization: The Case of Poly(styrene-co-acrylamide)

Poly(styrene-co-acrylamide) (PS-AAM) latex was prepared, fractionated by sedimentation under gravity, and characterized by PCS, infrared spectra, secondary and backscattered electron imaging in the scanning electron microscope, and electron spectroscopy imaging in an analytical transmission electron microscope. Three latex fractions were obtained. The lower fraction was opalescent and its particles were the more uniform, concerning size, chemical composition, and topochemical features. This lower fraction was still further fractionated by zonal centrifugation in a density gradient, yielding two fractions with similar macrocrystal-forming abilities but different sizes and chemical compositions. These results confirm those previously obtained for the PS-HEMA latex. Copyright 2000 Academic Press.     

Formation of benzynes from 2,6-dihaloaryllithiums: mechanistic basis of the regioselectivity

The key elimination step for the formation of 3-chloro- and 3-fluorobenzyne from 2-chloro-6-fluorophenyllithium displays a pronounced solvent-dependent regioselectivity. 6Li and 13C NMR spectroscopic studies on 2-chloro-6-fluorophenyllithium reveal a single monomeric aryllithium, suggested by DFT computational studies to be a trisolvate. Rate studies indicate that the elimination of LiCl and LiF proceeds via trisolvated and disolvated monomers, respectively.     

Zur Analyse von Eisen -und Stahl

Ohne Zusammenfassung