[Synthesis of tumor affinity label Yb-169- and Y-90- porphyrin complexes and animal experimental investigations with various Yb-169-porphyrins]. / Synthese tumoraffiner Yb-169- und Y-90-Porphyrin-Komplexe und tierexperimentelle Untersuchung verschiedener Yb-169-Porphyrine.

AIM: It should be shown, that it is possible to insert radioactive isotopes of Yb and Y into some selected porphyrins. Besides, first informations about the biodistribution of Yb-169-por-phyrin-complexes should be obtained. METHODS: Carrier added radioactive isotopes were used for the synthesis of the metal porphyrin complexes. The animal experiments were done with mamma carcinoma bearing mice. The activity of the organs was determined 5 and 24 h after i.v. injection in a well counter. RESULTS: Four Yb-169-porphyrin complexes and Y-90-porphyrin complexes could be synthesized in non-carrier-free form. This was verified by absorption spectra, TLC and HPLC. Depending on the complex, the average tumour/background ratios were between 2 and 20. CONCLUSION: The synthesized radioactive metal-porphyrin complexes showed a clear tumour-affinity which could be used for tumour scintigraphy or perhaps therapy if the synthesis is improved (goal: reduction of carrier, other radionuclides).

Flow-injection glucose determination with long-wavelength luminescent oxygen probes.

A flow-injection method for the determination of glucose in serum is presented. It is based on the enzymatic measurement of oxygen consumption detected via oxygen quenching of the luminescence of certain metalloporphyrins. Phosphorescent water-soluble Pt2+ and Pd(2+)-porphyrins have been characterized by luminescence spectroscopy and decay-time measurements in various buffers, and found to be suitable for oxygen detection in biological systems. A new method for the flow-injection analysis of glucose has been developed based on the use of a column of immobilized glucose oxidase and the indicators Pt(2+)-coproporphyrin III and Pd(2+)-coproporphyrin I. The system has been optimized for glucose determination in aqueous samples and in whole serum with the 0.5-200 mM glucose range. Twenty assays can be performed in an hour, and the system has potential for commercial development with biotechnological and medical applications.

Fibre-optic oxygen sensor based on phosphorescence quenching.

A fibre-optic oxygen sensor is described which is based on an oxygen-sensitive luminescent film made from platinum octaethylporphyrin and polystyrene. The luminescence and quenching characteristics of such films were studied for their use in a fibre-optic oxygen biosensor. A prototype oxygen sensor was made from this material, and was tested in aqueous solutions and in the gaseous phase at physiological oxygen concentrations. Measurements of luminescence intensity and decay time were employed to determine oxygen concentration from luminescence quenching. The main working characteristics of this prototype oxygen sensor were studied.

Fibre-laser IR luminescence diagnostics of malignant tumours using rare earth porphyrins.

To eliminate the masking effect of the background luminescence of endogenic substances in biological tissues and to increase the luminescence contrast values of malignant tumours, sarcoma-implanted mice were administered with ytterbium porphyrins instead of free porphyrin radicals. This was followed by in vivo luminescence localization of tumours using fibre-laser spectrofluorometry. The luminescence contrast values obtained reached 10-45 which is evidently not a limit.

Model membrane morphology and crosslinking of oxidized lipids with proteins.

Model membranes composed of thion-phosphatidylcholine, cardiolipin, and cytochrome c have been studied by 31P NMR, polyacrylamide gel electrophoresis, gel filtration, fluorescence, and freeze-fracturing. Covalent binding of oxidized phospholipids to cytochrome c was shown to result in the formation of high-molecular-weight oligomeric complexes via Schiff base formation between a protein molecule and aldehydes produced upon peroxidation of phospholipids. The initial steps of the protein oligomerization lead to the appearance of intramembranous particles (IMPs) of various size and distribution on freeze-fractured faces of these model membranes. In the final phase of the crosslinking between cytochrome c and oxidized products of cardiolipin there is a breakdown of membrane vesicles and formation of globular lipoprotein complexes which are seen as globular particles. It is believed that the covalent linking between the products of phospholipid peroxidation and membrane proteins causes the oligomerization of membrane proteins and structural alteration in the hydrophobic region of other models also and, perhaps, in biological membranes.