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ABSTRACT: Spallation reaction opens new additional possibilities for production of a number of medical useful isotopes. In some cases all the present world demand in produced through spallation. Because of the high transmission of targetmaterials for medium or high energy protons lower cross-sections may be more than compensated by using massive targets. The unspecific nuclear reaction as well as the radiochemical processing of such massive targets lead to several difficulties. New ways for processing of large spallation targets are required. The possibilities of modern ISOL-techniques(ISOL = Isotope Separator On-Line) for the production of medical useful radio-isotopes will be discussed in some detail. Corresponding cross-section data are reviewed and discussed in relation to physico-chemical data requirements. In detail the following radio-isotopes will be discussed: 81-Rb, 82-Sr, 123-I, 167-Tm and 211-At.
08/2008;
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ABSTRACT: This paper rewiews the research in the field of radiopharmacology of metal-ligand-complexes with radioactive central ion in the last ten years. The investigations, carried out mainly in close cooperation between radiochemists and nuclear medicine physicists, intended the elucidation of mechanisms which are responsible for the tumour accumulation of radioactive metals like 67Ga, 167Tm, 169Yb or 90Y, injected as metal-ligand-complexes. Improvement of tumour scintigraphy by means of such complexes was the practical background of our investigations. The ratio of tumour/background radioactivity obtained using these compounds depends on their biokinetics, the mechanisms by which they are accumulated in tumour tissue, and the transport processes in blood. To investigate these problems we studied possibilities to influence the biokinetics of radioactive metals, applied as metal-ligand-complexes in order to optimize the radioactivity concentration in tumours in comparison with those in other body tissues. At present we attempt to exploit our results for the therapeutic use of metal ligand complexes by testing therapeutic effective radionuclides as central ions in the complexes.
08/2008;
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ABSTRACT: A method for production of 225Ac is described. Uranium oxide was irradiated with 650 MeV protons. The radium fraction was separated by precipitation with BaSO4, the isotopically pure 225Ac as daughter product was then isolated by means of cationexchange chromatography. The biological behaviour of 225Ac as a potential candidate for radionuclide tumor therapy is compared with the behaviour of other Me3+-citrate complexes. The actinium shows the faster blood clearance and highest liver uptake in rats and tumor-bearing mice. The tumor uptake is smaller in comparison to ytterbium as a representative for the heavy rare earth elements and slightly higher compared to promethium as representative for the light rare earth elements. In general the biodistribution of actinium is in good agreement with the radiums alteration of Me3+-ions.
08/2008;
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ABSTRACT: This study demonstrates high-efficiency sterilisation of single cancer cells in a SCID mouse model of leukaemia using rituximab, a monoclonal antibody that targets CD20, labelled with terbium-149, an alpha-emitting radionuclide. Radio-immunotherapy with 5.5 MBq labelled antibody conjugate (1.11 GBq/mg) 2 days after an intravenous graft of 5.10(6) Daudi cells resulted in tumour-free survival for >120 days in 89% of treated animals. In contrast, all control mice (no treatment or treated with 5 or 300 micro g unlabelled rituximab) developed lymphoma disease. At the end of the study period, 28.4%+/-4% of the long-lived daughter activity remained in the body, of which 91.1% was located in bone tissue and 6.3% in the liver. A relatively high daughter radioactivity concentration was found in the spleen (12%+/-2%/g), suggesting that the killed cancer cells are mainly eliminated through the spleen. This promising preliminary in vivo study suggests that targeted alpha therapy with (149)Tb is worthy of consideration as a new-generation radio-immunotherapeutic approach.
European journal of nuclear medicine and molecular imaging 05/2004; 31(4):547-54. · 4.99 Impact Factor
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ABSTRACT: This study demonstrates high-efficiency sterilisation of single cancer cells in a SCID mouse model of leukaemia using rituximab, a monoclonal antibody that targets CD20, labelled with terbium-149, an alpha-emitting radionuclide. Radio-immunotherapy with 5.5MBq labelled antibody conjugate (1.11GBq/mg) 2 days after an intravenous graft of 5106 Daudi cells resulted in tumour-free survival for >120 days in 89% of treated animals. In contrast, all control mice (no treatment or treated with 5 or 300g unlabelled rituximab) developed lymphoma disease. At the end of the study period, 28.4%4% of the long-lived daughter activity remained in the body, of which 91.1% was located in bone tissue and 6.3% in the liver. A relatively high daughter radioactivity concentration was found in the spleen (12%2%/g), suggesting that the killed cancer cells are mainly eliminated through the spleen. This promising preliminary in vivo study suggests that targeted alpha therapy with 149Tb is worthy of consideration as a new-generation radio-immunotherapeutic approach.
European journal of nuclear medicine and molecular imaging 03/2004; 31(4):547-554. · 4.99 Impact Factor
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ABSTRACT: High-resolution gamma spectroscopy was applied to measure simultaneously the biodistribution of carrier-free radionuclides of several lanthanides (141Ce, 145Sm, 149Gd, 167Tm) and 225Ac in tumor-bearing nude mice. Mixtures of the radiotracers were injected in solutions containing different concentrations of EDTMP (ethylenediaminetetramethylenephosphonic acid). The strong dependence of liver uptake on the ionic radius of the radio-lanthanides was confirmed for all tracers used. The ratios of radioactivity concentrated in tumour that concentrated in liver are strongly influenced by the EDTMP concentration, reaching values close to 10 for Tm, 3 for Sm, and 1 for Ac. The optimal EDTMP concentrations, giving highest tumor-to-liver ratios of enrichment, were between 1 and 10 mM for 100 microL injected volume for the animal model used in this experiment. In radionuclide therapy using EDTMP as ligands, close control of ligand concentration will be necessary.
Nuclear Medicine and Biology 08/1997; 24(5):367-72. · 3.02 Impact Factor
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ABSTRACT: The influence of the ligands ethylenediaminetetramethylene phosphonic acid (EDTMP) and citrate (CIT) on the biodistribution of radio-yttrium in rats bearing a DS-carcinosarcoma was compared. 88Y-EDTMP and 87Y-CIT were i.v. injected into the same animals. Faster blood clearance and higher renal excretion were observed for the EDTMP-ligand. Of high practical interest is the reduced liver uptake of radio-yttrium (by one order of magnitude) with the EDTMP complex. Since bone and tumour accumulation is only weakly influenced, high tumour-to-liver ratios (up to 14) were observed. We propose to use EDTMP or similar complex ligands for liver blocking when radionuclides like 90Y, 169Yb, 225Ac or other group 3 elements are to be applied in endoradionuclide therapy technique.
International Journal of Radiation Applications and Instrumentation Part B Nuclear Medicine and Biology 03/1992; 19(2):201-3.
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ABSTRACT: In several studies different pathogenetic mechanisms of metabolic and/or cardiovascular origin were shown depending on the type of hypoxic or hypoxic/hypercapnic stress and conditions of animals (normal developed or intrauterine growth retarded newborn piglets). Thus, in normal-weight piglets the prevention of compensatory hyperventilation owing to severe hypoxia (artificially ventilated animals) leads to critical, i.e. lethal acidosis. In intrauterine growth retarded piglets, a severe hypoxia cannot be vitally compensated because of the restricted circulatory centralization. Moreover, a limited cerebrovascular dilatation during moderate hypoxia/hypercapnia produces a critical state of the metabolic supply in those animals.
Experimental pathology 02/1991; 42(4):197-203.
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ABSTRACT: An experimental approach is presented, where for the first time positron emission tomography (PET, the most important method for in vivo measuring the key functions of brain physiology and metabolism) was applied together with other techniques for quantitative-topological estimation of key parameters such as rCMRGlu in normal and disturbed brain function states in the newborn period.
Experimental pathology 02/1991; 42(4):229-33.
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Acta radiologica. Supplementum 02/1991; 376:119-20.
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Acta radiologica. Supplementum 02/1991; 376:81-4.
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ABSTRACT: In order to understand the thermal processes occurring within a water target we carried out calculations of heat transfer of the beam energy absorbed from the target water to the target back wall, and compared them with the temperatures measured during irradiations. It was shown, by both the experimental results and the heat transfer calculations, that, at high beam currents, static small volume water targets have a working temperature at the boiling point of the target water. The heat transfer occurs only by movement of the water molecules generated by the boiling target water and not by heat conduction or free convection alone. There is no heat transfer arising from vaporization and reflux.
International Journal of Radiation Applications and Instrumentation Part A Applied Radiation and Isotopes 02/1990; 41(8):753-6.
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ABSTRACT: Scintigraphy using labelled myocardial metabolism precursors makes possible a noninvasive qualitative--and increasingly also quantitative--evaluation of global and regional myocardium, both normally and insufficiently perfused, with normal and disturbed metabolism. Among the labelled precursors, free fatty acids appear as most important, especially the omega-123I-heptadecanoic acid. The experience with the use of this myocardial metabolism precursor in 23 examinations of 11 patients is described.
Cor et vasa 02/1988; 30(1):18-26.
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ABSTRACT: After incubation of both serum and HSA solutions with radioactive lanthanide complexes the binding constants of the corresponding lanthanide-protein complexes formed in the protein solutions under physiologic conditions, pH: 7.4, temperature: 310 K, isotonic ionic strength: 0.15 mol/L, were determined. The association constants of the lanthanide-protein complexes formed both in serum and HSA-solutions are equal within the experimental error. In conclusion, serum albumin binding predominates for the radiolanthanides. With the decrease of the ionic radii from 1.034 A (Ce) to 0.858 (Yb) the association constants increased by five orders of magnitude from 1 g Kpr = 4.90 (Ce) to 1 g Kpr = 9.54 (Yb). Further, a serum fractionation with alcohol was carried out to prove that the albumin fraction of serum is responsible for the lanthanide binding in blood.
International Journal of Radiation Applications and Instrumentation Part A Applied Radiation and Isotopes 02/1988; 39(3):261-4.
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Radiologia diagnostica 02/1988; 29(3):477-86.
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Radiobiologia, radiotherapia 02/1987; 28(6):839-43.
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Radiobiologia, radiotherapia 02/1987; 28(6):835-9.
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Radiobiologia, radiotherapia 02/1987; 28(6):823-7.
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Radiobiologia, radiotherapia 02/1986; 27(1):83-8.
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ABSTRACT: The influence of carrier amounts of Fe, Ga, and Tm on the biodistribution of 67Ga-, 59Fe-, and 167Tm-citrate in mice was investigated. Our results suggest that 167Tm, unlike 67Ga and 59Fe, is not transported by transferrin in the blood. Of the three radioisotopes tested, 167Tm had the highest tumor/background ratio (10 h after the injection). The application of Fe carrier led to an enhancement of the elimination of 67Ga from the blood and muscles, resulting in a better tumor/background ratio.
European Journal of Nuclear Medicine 02/1986; 11(9):345-9.
