[en] The preliminary steps for a radio-immunoassay of Thyrotropin Releasing Hormone (TRH) are described. Rabbit antiserum at dilution 1:10000 is used with radioiodinated TRH (¹²⁵I). It is possible to assay from 5 to 1000 pg unlabeled TRH with an intraassay reproducibility varying from 7 to 4% and the lowest detectable amount in this system is 10 pg TRH. TRH mean and standard deviation in normal subjects are 136,9 and 52,9 pg/ml

[en] Proteoglycans (PG) have been purified by classical methods from human articular cartilage in order to set up a radioimmunoassay. Conditions of labelling, purification of labelled PG, and optimal conditions of buffer, temperature, duration of incubations and dilution of antiserum are described. Separation of free and bound PG is performed by immunoprecipitation. It is demonstrated that human articular PG can be assayed quantitatively by RIA procedure, with a sensitivity of +- 2 femto-moles (+- 5 ng) per tube

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[en] Short communication

[en] In radioimmunological analysis using tritiated tracers the specific activity is limited for certain commercial products, prohibiting the determination of compounds such as PGE(I) (110Ci/mmole which has been found at a concentration below 2pg/ml in human peripheral plasma. An attempt was made to see whether this problem could be solved by the use of iodinated PG of much higher specific activity. The method employed is described, and shows a greatly improved sensitivity in the radioimmunological analysis of the PG tested owing to the use of an iodinated (iodine 125) tracer. In the case of PGE(I) for instance the sensitivity was increased by a factor 25

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[en] A conjugate was obtained by covalent bond coupling of penicilloyl groups to bovine serum albumine (BSA) previously labelled with iodine 125. The reaction takes place in alkaline solution without intervention of carbodiimide. By its immunoreactivity and specific activity this conjugate is a suitable tracer in radioimmunology. The sensitivity and specificity of the determination were analysed on standard curves

[en] For the treatment of cancer, the therapeutic potential of short-range, low-energy Auger-electron emitters, such as ¹²⁵I, is getting progressively wider recognition. The potency of Auger-electron emitters is strongly dependent on their location in close vicinity to DNA. We have developed a new two-step targeting strategy to transport ¹²⁵I into cancer-cell nuclei using PEG-stabilized tumour-cell targeting liposomes named ''Nuclisome-particles''. In the present study, epidermal growth factor (EGF) was used as a tumour-cell-specific agent to target the EGF-receptor (EGFR) and the liposomes were loaded with ¹²⁵I-Comp1, a recently synthesized daunorubicin derivative. As analysed with cryo-TEM, the derivative precipitates inside liposomes at a drug-to-lipid molar ratio of 0.05:1. Receptor-specific uptake in cultured U-343MGaCl2:6 tumour cells of EGFR-targeting liposomes increased with time while non-specific and receptor-blocked uptake remained low. Nuclisome-particles were able to target single U-343MGaCl2:6 cells circulating in human blood during 4 h, with low uptake in white blood cells, as demonstrated in an ex vivo system using a Chandler loop. Autoradiography of targeted cells indicates that the grains from the radiolabelled drug are mainly co-localized with the cell nuclei. The successful targeting of the nucleus is shown to provide high-potency cell killing of cultured U-343MGaCl2:6 cells. At the concentration used, Nuclisome-particles were up to five orders of magnitude more effective in cell killing than EGFR-targeting liposomes loaded with doxorubicin. The results thus provide encouraging evidence that our two-step targeting strategy for tumour cell DNA has the potential to become an effective therapy against metastasizing cancer cells in the bloodstream. (orig.)