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Somerset East, South Africa

Rossouw D.D.,Themba LABS | Breeman W.A.P.,Erasmus University Rotterdam
Applied Radiation and Isotopes | Year: 2012

A scaled-up radiolabelling and improved post-labelling purification procedure for [ 68Ga]DOTATATE is reported, using a more than 1 year old SnO 2-based 1850MBq 68Ge/ 68Ga generator (initially double-loaded with 3700MBq 68Ge) as a source of ionic 68Ga. The elution method of choice comprised elution with 0.6M HCl in a single 4mL fraction, containing up to 95% of the total eluted 68Ga activity. The unpurified fraction was directly used for labelling after pH adjustment with 2.5M sodium acetate. Labelling efficiencies were determined at 90-95°C at various reaction times and reaction volumes of up to 5.7mL, using either 30μg or 50μg DOTATATE. Only the latter amount resulted in consistently high labelling efficiency in excess of 95%. Post-labelling purification, carried out on Sep-Pak C18, showed that 50% ethanol in saline was a superior desorption eluant than 100% ethanol. The highest and most consistent decay-corrected radiochemical yields (89%) were obtained using 50μg DOTATATE and a 20min reaction time. © 2011 Elsevier Ltd. Source

Yeremin A.V.,Joint Institute for Nuclear Research | Popeko A.G.,Joint Institute for Nuclear Research | Malyshev O.N.,Joint Institute for Nuclear Research | Lopez-Martens A.,French National Center for Scientific Research | And 24 more authors.
Physics of Particles and Nuclei Letters | Year: 2015

The results of the first experimental tests of the modernized VASSILISSA separator with the use of accelerated 22Ne ions are presented. Data has been obtained on the transmission coefficients of recoil nuclei synthesized in asymmetric combinations of the incident ion and target nuclei. Estimates from ion optical calculations performed in the design phase of the project of modernizing the separator are completely confirmed. © 2015, Pleiades Publishing, Ltd. Source

de Blois E.,Erasmus University Rotterdam | Sze Chan H.,Erasmus University Rotterdam | Naidoo C.,Themba LABS | Prince D.,Themba LABS | And 2 more authors.
Applied Radiation and Isotopes | Year: 2011

Objectives: PET scintigraphy with 68Ga-labelled analogs is of increasing interest in Nuclear Medicine and performed all over the world. Here we report the characteristics of the eluate of SnO2-based 68Ge/68Ga generators prepared by iThemba LABS (Somerset West, South Africa). Three purification and concentration techniques of the eluate for labelling DOTA-TATE and concordant SPE purifications were investigated. Methods: Characteristics of 4 SnO2-based generators (range 0.4-1GBq 68Ga in the eluate) and several concentration techniques of the eluate (HCl) were evaluated. The elution profiles of SnO2-based 68Ge/68Ga generators were monitored, while [HCl] of the eluens was varied from 0.3-1.0M. Metal ions and sterility of the eluate were determined by ICP. Fractionated elution and concentration of the 68Ga eluate were performed using anion and cation exchange. Concentrated 68Ga eluate, using all three concentration techniques, was used for labelling of DOTA-TATE. 68Ga-DOTA-TATE-containing solution was purified and RNP increased by SPE, therefore also 11 commercially available SPE columns were investigated. Results: The amount of elutable 68Ga activity varies when the concentration of the eluens, HCl, was varied, while 68Ge activity remains virtually constant. SnO2-based 68Ge/68Ga generator elutes at 0.6M HCl >100% of the 68Ga activity at calibration time and ±75% after 300 days. Eluate at discharge was sterile and Endotoxins were <0.5EU/mL, RNP was always <0.01%. Metal ions in the eluate were <10ppm (in total). Highest desorption for anion purification was obtained with the 30mg Oasis WAX column (>80%). Highest desorption for cation purification was obtained using a solution containing 90% acetone at increasing molarity of HCl, resulted in a 68Ga desorption of 68±8%. With all 68Ge/68Ga generators and for all 3 purification methods a SA up to 50MBq/nmol with >95% incorporation (ITLC) and RCP (radiochemical purity) by HPLC ±90% could be achieved. Purification and concentration of the eluate with anion exchange has the benefit of more elutable 68Ga with 1M HCl as eluens. The additional washing step of the anion column with NaCl and ethanol, resulted in a lower and less variable [H+] in the eluate, and, as a result the pH in the reaction vial is better controlled, more constant, and less addition of buffer is required and concordant smaller reaction volumes. Desorption of 68Ga-DOTA-TATE of SPE columns varied, highest desorption was obtained with Baker C18 100mg (84%). Purification of 68Ga-DOTA-TATE by SPE resulted in an RNP of <10-4%. Conclusions: Eluate of SnO2-based 68Ge/68Ga generator, either by fractionated elution as by ion exchange can be used for labelling DOTA-peptides with 68Ga at a SA of 50MBq/nmol at >95% incorporation and a RCP of ±90%. SPE columns are very effective to increase RNP. © 2010 Elsevier Ltd. Source

Migula P.,University of Silesia | Przybylowicz W.J.,Themba LABS | Nakonieczny M.,University of Silesia | Augustyniak M.,University of Silesia | And 2 more authors.
X-Ray Spectrometry | Year: 2011

Plants may use the ability to hyperaccumulate toxic metals in their defence against herbivores. Insects can counteract and feed on toxic plants. Among grazers of Ni-hyperaccumulating Berkheya coddii, some beetles tolerate Ni (Chrysolina clathrata, former name Chrysolina pardalina; Epilachna nylanderi). The adaptive mechanisms against Ni toxicity were studied in these species using micro-PIXE quantitative elemental mapping and by microscopy techniques. Distinct differences were found in mechanisms used for Ni-elimination in both species. Functional comparisons and quantification of data extracted from selected micro-areas in target organs responsible for metal circulation (digestive tract and Malpighian tubules) were made. Similar detoxification mechanism is used against metals through spheric granules, which in E. nylanderi are formed mainly in the midgut, while in C. clathrata in Malpighian tubules and midgut. Elemental maps showed positive correlations of Ni and Zn in Malpighian tubules of E. nylanderi without such effect in C. clathrata. Quantitative relations of K+ and Cl- indicate higher osmotic pressure increasing reabsorption of water necessary for Ni transportation to the intestine lumen and further rejection outside the body. © 2011 John Wiley & Sons, Ltd. Source

Mesjasz-Przybylowicz J.,Themba LABS | Przybylowicz W.J.,Themba LABS | Przybylowicz W.J.,AGH University of Science and Technology
X-Ray Spectrometry | Year: 2011

The status of micro-PIXE applications in investigations of ecophysiological aspects of the hyperaccumulation phenomenon in plants is reviewed. Measurements of elemental concentrations and distribution in organs, tissues and cells of plants hyperaccumulating Ni, Co, As, Mn, Zn and Cd, show that in most cases hyperaccumulated metals are stored in physiologically inactive tissues. However, some exceptions indicate that different physiological mechanisms are involved in metal transport, storage locations and detoxification. The influence of mycorrhiza on elemental concentration and distribution in the roots of the Ni-hyperaccumulator Berkheya coddii is also discussed. Several herbivorous insects have been found feeding exclusively on Ni-hyperaccumulating plants. A summary of micro-PIXE contribution to studies aimed at explanation of their ability to survive in such extreme conditions is given. © 2011 John Wiley & Sons, Ltd. Source

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