Search

The objective of this project was to study the influence of increased salinities on interaction processes in the system radionuclide – organics – clay – aquifer. For this purpose, complexation, redox, sorption, and diffusion studies were performed under variation of the ionic strength (up to 4 mol/kg) and the background electrolyte. The U(VI) complexation by propionate was studied in dependence on ionic strength (up to 4 mol/kg NaClO4) by TRLFS, ATR FT-IR spectroscopy, and DFT calculations. An influence of ionic strength on stability constants was detected, depending on the charge of the respective complexes. The conditional stability constants, determined for 1:1, 1:2, and 1:3 complexes at specific ionic strengths, were extrapolated to zero ionic strength. The interaction of the bacteria Sporomusa sp. MT-2.99 and Paenibacillus sp. MT-2.2 cells, isolated from Opalinus Clay, with Pu was studied. The experiments can be divided into such without an electron donor where biosorption is favored and such with addition of Na-pyruvate as an electron donor stimulating also bioreduction processes. Moreover, experiments were performed to study the interactions of the halophilic archaeon Halobacterium noricense DSM-15987 with U(VI), Eu(III), and Cm(III) in 3 M NaCl solutions. Research for improving process understanding with respect to the mobility of multivalent metals in systems containing humic matter was focused on the reversibility of elementary processes and on their interaction. Kinetic stabilization processes in the dynamics of humate complexation equilibria were quantified in isotope exchange studies. The influence of high salinity on the mobilizing potential of humic-like clay organics was systematically investigated and was described by modeling. The sorption of Tc(VII)/Tc(IV) onto the iron(II)-containing minerals magnetite and siderite was studied by means of batch sorption experiments, ATR FT-IR and X-ray absorption spectroscopy. The strong Tc retention at these minerals could be attributed to surface-mediated reduction of Tc(VII) to Tc(IV). An influence of ionic strength was not observed. The influence of ionic strength (up to 3 mol/kg) and background electrolyte (NaCl, CaCl2, MgCl2) on U(VI) sorption onto montmorillonite was studied. The U(VI) sorption is influenced by the background electrolyte, the influence of ionic strength is small. Surface complexation modeling was performed applying the 2SPNE SC/CE model. Surface complexation constants were determined for the NaCl and CaCl2 system and were extrapolated to zero ionic strength. Surface complexation in mixed electrolytes can be modeled applying surface complexation constants derived for pure electrolytes. The influence of citrate on U(VI) diffusion in Opalinus Clay was studied using Opalinus Clay pore water as background electrolyte. The diffusion parameter values obtained for the HTO through-diffusion and the U(VI) in-diffusion in the absence of citric acid were in agreement with literature data. In the presence of citric acid, U(VI) diffusion was significantly retarded, which was attributed to a change in speciation, probably U(VI) was reduced to U(IV). Larger-scale heterogeneous material effects on diffusive transport were investigated with PET. Diffusion parameters were derived by optimum fit of a FEM-model to the measurement. These parameters are in accordance with the results from 1D-through-diffusion experiments. Deviations from the simple transversal-isotropic behavior, which are identified as residuals from the model, are indications for heterogeneous transport on the mm-scale. PET measurements were also conducted in order to display the improvement of the EDZ with waterglass injections. These experiments enable to draw conclusions on the complex reactive transport process and thus an estimation of the achieved improvement of the barrier function. The image reconstruction procedure was largely improved, mainly with the aid of Monte-Carlo simulations, and now allows quantitative analysis and error estimation.

High salinity and natural organic matter are both known to facilitate migration of toxic or radioactive metals in geochemical systems, but little is known on their combined effect. We investigated complexation of Tb3+ and Eu3+ (as analogues for trivalent actinides) with fulvic acid and their adsorption onto clay in the presence of NaCl, CaCl2 and MgCl2 at ionic strengths up to saturation. 160Tb, 152Eu and 14C were employed as radiotracers, allowing invesitigations at very low concentrations according to probable conditions in far-field scenarios of nuclear waste repositories. A composite approach (linear additive model) was tested for suitability in the prediction of Kd values for solid-liquid distribution of Tb(III) and Eu(III) in the ternary system of metal ion, clay and fulvic acid based on the constituent binary subsystems. The model was found suitable in reproducing the influence of fulvic acid as a function of ionic strength for bivalent electrolyte cations. In this analysis, it could be shown that high ionic strength does not further enhance the mobilizing potential of humic matter.

Hauptziel des Verbundprojektes war es, die Wechselwirkung von neu synthetisierten supramolekularen Komplexbildnern mit N,O,S-Donorfunktionen gegenüber d- und f-Elementen zu untersuchen. Dabei standen für das HZDR im Teilprojekt 1 die Komplexierung von N,O-Donorliganden insbesondere mit den Aktiniden U(VI) und Cm(III) und den Lanthaniden Eu(III), Ce(III) und Yb(III) in wässriger und erstmalig in organischer Lösung in Abhängigkeit vom pH-Wert bzw. Redoxspannung im Mittelpunkt. Es wurden die entsprechenden Komplexstöchiometrien und die spektroskopischen Eigenschaften der gebildeten Komplexe mittels UV-Vis-Spektroskopie, verschiedener laserinduzierter Methoden als auch IR-Spektroskopie bestimmt. Durch Anwendung der NMR-und EXAFS-Spektroskopie konnten strukturelle Aussagen zu den Metallkomplexen in Lösung gemacht werden. Mit Hilfe von UV-Vis Daten war es möglich, reproduzierbare Komplexbildungskonstanten von Aktinid- bzw.- Lanthanidkomplexen mit verschiedenen ß-Diketonen sowie Schiffschen Basen in Lösung zu bestimmen. Ergebnisse der Arbeiten des HZDR im Teilprojekt 2 zeigten, dass die Wechselwirkung von wasserlöslichen Calixarenen mit Radionuklidmetallionen sowie das Adsorptionsverhalten von Calixarenen an Geomatrizes unter naturnahen Bedingungen (pH 4 - 9) vernachlässigbar sind. Für die Flüssig-Flüssig-Extraktion von divalenten Metallionen mittels Radiotracertechnik wurden wasserunlösliche Calixarene ermittelt, die elementselektiv die Radionuklide 85Sr, 56Co, 64Cu und 65Zn aus der wässrigen Phase separieren können. Für Strontium eignet sich Bis-Salicyliden-diamino-calixaren, welches sich unter milden Bedingungen rückextrahieren lässt. Dicarboxy-calixaren extrahiert die d-Elemente quantitativ. Diese Extraktion ist nicht vollständig reversibel. Für die gebildeten Calixaren-Komplexe wurden spektroskopische Daten ermittelt. Die Extraktionsverfahren wurden für vier natürliche Wässer erfolgreich angewendet. Festphasenfixierte Calixarene sorbieren die Radionuklide quantitativ, jedoch ist eine vollständige Desorption nicht realisierbar.

Die Abteilung „Reaktiver Transport“ der Forschungsstelle Leipzig beschäftigt sich mit dem Migrations-/Sorptionsverhalten von (Schad)stoffen in geologischen Formationen. In aktuellen Projekten werden zur Zeit toxische Schwermetalle sowie langlebige Radionuklide untersucht. Für unsere Studien werden kurzlebige Radionuklide eingesetzt (64Cu, 85Sr, 56Co). Diese werden am Leipziger Zyklotron durch Protonenbeschuss von isotopenangereichertem 64Ni und 85Rb und natFe hergestellt. Die chemische Aufarbeitung erfolgt durch Flüssig-flüssig-Extraktion und Ionenchromatographie. Die Radionuklide werden mit einer chemischen Ausbeute von ca. 95 % erhalten. Das wertvolle Targetmaterial (isotopenangereichert bis zu 95 %) wird mit ~ 90 % Ausbeute wiedergewonnen. Die Targets werden entweder durch Verpressen ihrer Chloride oder durch elektrolytische Abscheidung auf Goldfolien hergestellt. Die Bestrahlung erfolgt bei einem Protonenstrom von 27 µA bei Strahlzeiten von bis zu 4 Stunden und einer Projektilenergie von ca. 12 MeV. Die produzierten Radionuklide wurden erfolgreich in Verteilungsstudien an Geomaterialien sowie in der Calixarenkomplexierung eingesetzt.

Im Rahmen eines vom BMBF geförderten Projektes beschäftigt sich die Abteilung „Reaktiver Transport“ des HZDR in Wechselwirkungsstudien mit der Komplexbildung und dem Transportverhalten von d- und f-Elementen mit makrozyklischen Chelatliganden. Als kurzlebige Analoga für langlebige, umweltrelevante Radionuklide kommen in den Studien 56Co, 64Cu, 65Zn und 85Sr zum Einsatz. Diese werden am hauseigenen Zyklotron hergestellt. Die makrozyklischen Liganden basieren auf funktionalisierten Calix[4]arenen. Das Komplexierungsverhalten der Calix[4]arene bezüglich der genannten Radionuklide wurde in Extraktionsstudien in flüssig-flüssig Systemen untersucht. Dabei lag der Fokus auf den Reaktionsbedingungen, unter denen eine erfolgreiche Extraktion realisierbar war. Die Extraktionswirkung der Calix[4]arene wurde mit Hilfe der Radiotracertechnik verfolgt. Unter alkalischen Bedingungen konnten für zwei spezielle Calix[4]arene Extraktionsausbeuten von >90 % erreicht werden. Die entstandenen Komplexe wurden hinsichtlich ihres Bindungsverhaltens spektroskopisch untersucht. Weiterhin konnten Aussagen zur Reversibilität der Reaktionen getroffen werden. Basierend auf den Reaktionsbedingungen konnten die Extraktionsversuche der Calix[4]arene bezüglich der erwähnten Radionuklide erfolgreich auf reale Wasserproben mit komplexeren Matrizes übertragen werden.

Sr-90 is a long-lived radionuclide (T(1/2) = 28.6 a), produced as a by-product in nuclear power plants. Due to its chemically similarity to calcium, it follows the food chain from environment (e.g. aquatic systems and soil) to fauna and human in case of release in the biosphere. Strontium can be, as well as calcium, incorporated in bones. Stable isotopes of strontium might not be harmful, but radioactive strontium can lead to bone disorders and diseases, including leukaemia[1]. Calixarenes and their functionalised derivatives are research subjects in the development of extracting agents, transporters, stationary phases[2] or biosensors. We used modified calixarenes, including derivatives having carbonyl binding sites, for the extraction of strontium[3] by means of a liquid-liquid extraction in a chloroform / water system. As a simulated contamination solution with Sr-90, the aqueous strontium phase was traced using the short-lived radionuclide Sr-85 (T(1/2) = 64.9 d), which was produced and purified at the in-house 18 MeV-cyclotron[4]. Under alkaline conditions, strontium extraction yields of >(90±4)% were obtained. Furthermore, the impact of inorganic and organic impurities, competing ions like sodium, calcium, acetate or tartaric acid, to the extraction performance was studied. The used carboxy-modified calixarenes are highly potent and selective extracting agents towards strontium, under conditions near to nature (e.g. synthetic groundwater). The authors gratefully thank the German Federal Ministry of Education and Research (BMBF) for financial support of this study (project no. 02NUK014). [1] Wallova, G., N. Kandler, and G. Wallner, Monitoring of radionuclides in soil and bone samples from Austria. Journal of Environmental Radioactivity, 2012. 107(0): p. 44-50. [2] Wendel, V., Neuartige Wirt-Gast-Komplexe basierend auf Cycloheptatrienbausteinen, Mathematisch-Naturwissenschaftliche Fakultät I 1998, Humboldt-Universität zu Berlin: Berlin. [3] Casnati, A., et al., New Efficient Calixarene Amide Ionophores for the Selective Removal of Strontium Ion from Nuclear Waste: Synthesis, Complexation, and Extraction Properties. J. Am. Chem. Soc., 2001. 123: p. 12182-12190. [4] Mansel, A., et al., Production of Sr-85 at a 18 MeV-cyclotron and purification for geochemical investigations, 2012. (submitted)

90Sr is a long-lived radionuclide (T1/2 = 28.6 a), which is produced as a by-product in nuclear power plants in the decay chain of uranium. In case of release in the biosphere, it can be concentrated in aquatic systems or in soil. It follows the food chain from environment to fauna and human. Due to its chemically similarity to calcium, it can be incorporated in bones. Stable isotopes of strontium might not be harmful, but radioactive analogues can lead to bone disorders and diseases, including leukaemia [1]. Calix[4]arenes represent an important class of supramolecules having various applications, e.g. in the recovery of nuclear fission products of uranium, like cesium or strontium.[2] We synthesised and structurally analysed calix[4]arene-based extractants as shown in Fig. 1 in order to investigate their binding ability towards strontium in liquid-liquid extraction systems. An aqueous phase was traced using the short-lived radionuclide 85Sr (T1/2 = 64.9 d), which was produced and purified at the in-house 18 MeV-cyclotron [3]. To quantify the extraction behaviour of the calix[4]arenes, the remaining amounts of 85Sr in the aqueous phases after the extraction, were recorded using gamma spectrometry. We systematically investigated the influence of various experimental parameters. Figure 1 shows extraction behaviour of various calix[4]arene derivatives depending on the pH of the aqueous strontium phase. Under alkaline conditions of the aqueous strontium phase, extraction yields of >(90±4)% were obtained for calix[4]arenes derivatives having carbonyl binding sites. Furthermore, the competition of inorganic and organic impurities to the extraction performance was studied. The impurities are in naturally occurring concentrations of ions like sodium, calcium, acetate or tartaric acid as groundwater ingredients. By simulating a synthetic groundwater, extraction of strontium was per-formed in yields up to (86±6)%. In further experiments, the calix[4]arene-strontium complex is going to be analysed spectroscopically with the aim to investigate the complex formation behaviour. The authors gratefully thank the German Federal Ministry of Education and Research (BMBF) for financial support of this study (project no. 02NUK014). [1] Wallova, G., N. Kandler, and G. Wallner, Monitoring of radionuclides in soil and bone samples from Austria. Journal of Environmental Radioactivity, 2012. 107: p. 44-50. [2] Otho, K., Review of the extraction behavior of metal cations with calixarene derivatives. Solvent Extraction Research and Development, 2010. 17: p. 1-18. [3] Mansel, A., et al., Production of 85Sr at a 18 MeV-cyclotron and purification for geochemical investigations, 2012. (submitted)

Clinical outcome of penile squamous cell carcinoma (PSCC) largely depends on the presence of lymph node metastasis. In search of a valuable marker predicting the risk for metastasis, the expression of Ki67 was investigated immunohistochemically in primary tumors and compared to presence of inguinal lymph node metastasis. As human papilloma virus (HPV) is thought to affect Ki67 expression, we evaluated whether occurrence of HPV DNA correlates to Ki67 score or metastatic potential. Samples originated from patients subjected to resection of invasive SCC of penis. Immunohistochemistry was done on paraffin-embedded sections using a monoclonal antibody against Ki67. After DNA isolation from paraffin embedded tissue the presence of HPV 6/11, HPV 16 and HPV 18 DNA was analyzed by PCR. Statistical analysis was done using two tail unpaired t test and Chi-square test. Four of 28 patients showed a weak Ki67 expression, without displaying lymph node metastasis. Among 17 patients showing an intermediate Ki67 index, eight exhibited metastases while in all seven patients with a strong expression of Ki67 lymph node metastases were found. The median Ki67 expression in metastastic lesions was significantly different (50.3%) from tumors without lymph node metastasis (31.8%) (p=0.024). Furthermore, a correlation between presence of HPV DNA and strong Ki67 expression was determined (p=0.009). Since our study demonstrated a strong Ki67 labeling index significantly associated to positive lymph nodes, we suggest Ki67 expression as a prognostic marker for lymph node metastasis in penile squamous carcinoma.

Skp2 (S-phase kinase associated protein 2) controls progression from G- to S-phase by promoting the proteolysis of the cyclin dependent kinase inhibitor p27KIP1. Despite the fact that a p27KIP1 decrease has been documented in melanoma progression, the role of Skp2 in these tumours is unknown. We therefore examined by immunohistochemistry the expression of Skp2, p27KIP1 and Ki-67 in 10 naevi (Ns), 15 superficial spreading melanomas (SSMs), 10 nodular melanomas (NMs) and 14 melanoma metastases (Ms). Nuclear Skp2 expression augmented with increasing malignancy (Ns: 1.4%, SSMs: 5.6%, NMs: 17.3%, Ms: 19.1%). In all tumours nuclear Skp2 expression correlated with Ki-67 (p=0.024) and inversely with p27KIP1 (p=0.007). A cytoplasmic reaction for Skp2 was also observed in most tumours and its expression decreased from Ns (12.3%) to SSMs (7.9%) and NMs (4.5%). In contrast, Ms showed an increase of cytoplasmic Skp2 (11.9%) that correlated with its nuclear expression (p=0.016). While nuclear Skp2 expression correlated with the pT-level (p=0.023), Clarklevel (p=0.023) and Breslow index (p=0.019), the cytoplasmic Skp2 expression might be of biological significance only in NMs since it correlated with tumour depth (p=0.02) and pT-level (p=0.025). Our data suggests that Skp2 could contribute to melanoma progression. This is further highlighted by the fact that vertical growth phase (VGP) melanomas show significant higher nuclear Skp2 expressions when compared with the harmless radial growth phase (RGP) (p=0.047). Also nuclear Skp2 expression correlates with a reduced survival time (p=0.025) in melanoma.

The detection of structural and numerical chromosomal aberrations is an important part of the characterization of tumors and genetic diseases. The direct demonstration of DNA sequences in interphase nuclei and metaphases by fluorescence in situ hybridization (FISH) has been termed interphase cytogenetics. It has been proven as a powerful technique to detect specific aberrations in a wide variety of cell types, including paraffin-embedded tissue. Nowadays a standard method in leukemia and lymphoma, interphase cytogenetics contributes mainly to the diagnosis in these tumors and helps to classify soft tissue tumors. Therefore FISH is mandatory for the choice of therapy in these tumors. In contrast to the aforementioned, up to now, the value of FISH in solid tumors is mostly limited to pure research and contributes in this way to our understanding of tumor biology. But with the use of paraffin-embedded tissue and the first results obtained, it seems very likely that a direct correlation between histological classification and cytogenetic characteristics of solid tumors can be achieved in the near future. This information might not only provide insights into tumor biology, but could also contribute to a different tumor classification, a sort of risk estimation, where we might predict the possible biological behavior of solid tumors. This could greatly influence further therapeutic decisions thus establishing the FISH technique as an indisputable part in the diagnosis of solid tumors.

A number of neoplastic disorders are characterized by recurrent chromosome aberrations. One of these is the translocation t(2;5), which is found in a considerable percentage of large-cell anaplastic lymphomas. This translocation results in the fusion of two genes, alk and npm. The recent discovery of alk/npm mRNA in 11 of 13 cases of Hodgkin's disease has caused a controversial discussion concerning the question of whether t(2;5) is also present in Hodgkin and Reed-Sternberg cells. We tackled this problem on the molecular cytogenetic level by combined CD30 immunophenotyping and interphase cytogenetics. Using a pair of DNA probes flanking both sides of the npm gene breakpoint at 5q35 we were able to prove, at least in 12 of 13 cases of Hodgkin's disease, that all CD30-positive Hodgkin and Reed-Sternberg cells lacked the translocation t(2;5). Fifteen to forty-five Hodgkin/Reed-Sternberg cells were analyzed per case (mean, 27). Our findings indicate that this translocation is not a primary event in the development of Hodgkin's disease.