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PubMed1977

Determination of radionuclide concentrations with positron CT scanning (PETT): concise communication.

A series of experiments was undertaken to evaluate the response of a positron emission transverse tomograph (PETT) to measured radionuclide concentrations similar to those encountered in human studies. The correlation between the response of the imaging system (mean PETT number/min), and the concentration of the radioactivity producing the output data, was linear with a computed sensitivity of 2720 PETT number/min, per micronCi/ml, per picture element, for a radionuclide (100% beta+) contained in either of two phantoms and imaged with a reduction of 1.5 cm. It was concluded that the output data are essentially independent of the imaged object's physical dimensions for the range of 18-28-cm diam and faithfully reflect the regional radioactivity concentration within the object, provided valid attenuation correction is achieved and the sampled area is not compromised by the imaging system's limitations of spatial resolution.

Computers↗
PubMed1984

The radioactivity content of United Kingdom coal.

Twenty samples of coal representing each of the seven major regions of the National Coal Board have been analysed for their natural radioactivity content. A variety of methods have been used to verify the results, but the major technique used was radiation spectrometry of 3 kg samples. The results indicate a mean value for uranium and radium activity in British coals of 14.5 Bq/kg, for thorium 12.5 Bq/kg and for potassium 150 Bq/kg. These are significantly lower levels of actinides than have been previously reported and represent only two thirds of those previously used as source terms for assessment of the radiological impact of fossil fuel burning in the U.K.. The content of potassium in U.K. coal is twice the accepted global mean but the radiological significance of this element is negligible. A subsidiary finding is that uranium and its daughter radium are in secular radioactive equilibrium in coal within the experimental error of the analysis.

Coal↗
PubMed1978

The movement of plutonium, americium, and curium through the food chain.

The actinides, plutonium, americium and curium, are being produced in increasing quantites as the nuclear programme is expanded. As these alpha-particle-emitting elements are hazardous to man there is considerable concern about the movement of these elements through the environment; The uptake of these elements from soil into the plants is low, as is the gastrointestinal concentration factor. Although there are complexing agents in the environment which have been shown to complex these elements there is no evidence that these complexing agents might bring about a concentration of actinides in the food chain of man.

Actinoid Series Elements↗
PubMed2003

Swedish-German actinide migration experiment at ASPO hard rock laboratory.

Within the scope of a bilateral cooperation between Svensk Kärnbränslehantering (SKB) and Forschungszentrum Karlsruhe, Institut für Nukleare Entsorgung (FZK-INE), an actinide migration experiment is currently being performed at the Aspö Hard Rock Laboratory (HRL) in Sweden. This paper covers laboratory and in situ investigations on actinide migration in single-fractured granite core samples. For the in situ experiment, the CHEMLAB 2 probe developed by SKB was used. The experimental setup as well as the breakthrough of inert tracers and of the actinides Am, Np and Pu are presented. The breakthrough curves of inert tracers were analyzed to determine hydraulic properties of the fractured samples. Postmortem analyses of the solid samples were performed to characterize the flow path and the sorbed actinides. After cutting the cores, the abraded material was analyzed with respect to sorbed actinides. The slices were scanned optically to visualize the flow path. Effective volumes and inner surface areas were measured. In the experiments, only breakthrough of Np(V) was observed. In each experiment, the recovery of Np(V) was < or = 40%. Breakthrough of Am(III) and Pu(IV) as well as of Np(IV) was not observed.

Actinoid Series Elements↗
PubMed2005

Sorption of 243Am(III) to multiwall carbon nanotubes.

Carbon nanotubes have attracted great interest in multidisciplinary study since their discovery. Herein, radionuclide 243Am(III) sorption to uncapped multiwall carbon nanotubes (MWCNTs) was carried out at 20+/-2 degrees C in 0.01 and 0.1 M NaClO4 solutions. Effects of 243Am(III) solution concentration, ionic strength, and pH on 243Am(III) sorption to MWCNTs were also investigated. The sorption is strongly dependent on pH values and weakly dependent on the ionic strength in the experimental conditions. The results show that MWCNTs can adsorb 243Am(III) with extraordinarily high efficiency by forming very stable complexes. Chemisorption or chemicomplexation is the main mechanism of 243Am(III) sorption on the surface of MWCNTs. MWCNTs can be a promising candidate for the preconcentration and solidification of 243Am(III) or its analogue lanthanides and actinides from large volumes of aqueous solution, as required for remediation purposes, and perhaps also as a sorbent for the removal of heavy metal ions from the industry wastewater.

Actinoid Series Elements↗
PubMed2006

Structural study of trivalent lanthanide and actinide complexes formed upon solvent extraction.

The coordination of the trivalent 4f ions, Ln = Nd3+, Eu3+ and Yb3+, as well as the trivalent 5f ion, Am3+, with diamide and dialkylphosphoric acid extractants, individually and in combination, was studied by use of X-ray absorption spectroscopy. These studies provide metrical information about the interatomic interactions between the f-ions (M3+) and the ligands, dihexylphosphoric acid (HDHP) and N,N'-dimethyl-N,N'-dioctylhexylethoxymalonamide (DMDOHEMA), that is of practical relevance to the control of metal-ligand binding in liquid-liquid extraction systems for the separation of trivalent actinide ions, An3+, from trivalent lanthanide ions, Ln3+. Through systematic variations of extraction conditions and extractant combinations, we have found that the HDHP complexes with M3+ involve MO6 coordination and distant M...P interactions, whereas the DMDOHEMA complexes with M3+ involve MO8 coordination. The combination of the EXAFS results with ancillary extraction data and IR results facilitates descriptions of the stoichiometries and structures of the molecular species formed in solution upon liquid-liquid extraction and leads to a new understanding of the binary extraction systems in terms of the strength and selectivity of An3+- vs. Ln3+-ligand interactions. This fundamental structure information affords insight into solvent extraction processes that are of contemporary and practical importance in heavy element chemistry and to environmentally related issues arising from the separation and disposal of radioactive materials, particularly actinides and selected fission products, in the field of nuclear waste reprocessing research.

Journal Article↗
PubMed1975

Simultaneous efflux of K+ and Na+ from frog sartorius muscle freed of extracellular fluids: evidence for rapidly exchanging Na+ from the cells.

After removal of radioactivity trapped in the extracellular space and correcting for the contribution of connective tissue elements, the K+ -efflux curve of frog sartorius muscles becomes a perfect straight line in a semilogarithmic plot. The simultaneously recorded Na+-efflux curve from the same muscles remains strongly curved, and can be resolved into a slow fraction (which conventionally has been regarded as representing the entire cell Na+) and at least one fast fraction. The fast fraction of Na+ could not have originated from a sarcoplasmic reticulum or any other extracellular space extensions; otherwise a similar fast fraction should exist for K+. The data agree with the interpretation that it is the fast fraction that is rate limiting by cell permeability and the slow fraction by desorption from intracellular adsorption sites.

Adsorption↗
PubMedDate not supplied

[The formation of the catecholaminergic system of the hypothalamus in rats. Dopamine uptake and release].

The development of the hypothalamic catecholaminergic (CA) system during ontogenesis in rats has been studied with the isotopic biochemical technique in vitro. It has been demonstrated, that at the 15th fetal day, the CA system was functionally inactive at least in its ability for the uptake and K(+)-stimulated release of catecholamines. Since the 16th fetal day, hypothalamic neuronal elements gained an ability for specific uptake and K(+)-stimulated release of the exogenous radioactively labeled dopamine increased significantly. The specific uptake doubled from the 20th fetal till the 9th postnatal day, whereas K(+)-stimulated release doubled between the 9th 45th postnatal days.

Aging↗
PubMed1997

Total thyroidectomy for Graves' disease.

BACKGROUND: Therapeutic options for treatment of hyperthyroidism caused by Graves' disease remain controversial. There are three main options: thiourea drugs, radioactive iodine ablation, and thyroidectomy. Each treatment has significant advantages and potential problems. METHODS: The present study is a retrospective analysis of our experience with total thyroidectomy in Graves' disease. Sixty-two patients underwent this procedure in 11 years' time and were followed for a minimum of 2 years after surgery. All had measurement of total thyroxine, T3 uptake, and radioactive iodine (RAI) uptake and scanning. Sixty-three percent of all patients had some element of hyperthyroid eye signs. All patients were rendered euthyroid with pharmacologic therapy prior to surgery. Postoperatively, the patients were evaluated for improvement in eye signs, incidence of recurrent laryngeal nerve injury, and hypoparathyroidism. RESULTS: None of the patients in this study have developed recurrent hyperthyroidism. All patients are maintained on levothyroxine. None of our patients incurred bilateral vocal cord paralysis. One patient (1.6%) demonstrated an immobile vocal cord more than 1 year following surgery. Ten patients (16%) demonstrated impaired mobility of one vocal cord in the immediate postoperative period. Nine of these patients recovered full vocal cord mobility within 6 months after surgery. Only one patient (1.6%) still required calcium and vitamin D therapy 1 year following surgery. However, in the immediate postoperative period, 23 patients (37%) required supplemental calcium and vitamin D. In 12 patients, calcium and vitamin D was discontinued within 1 month. In an additional 6 patients, calcium and vitamin D were discontinued within 4 months; 3 patients, within 6 months; and 1 patient, within 12 months after surgery. Incidental papillary carcinoma was found in 3 patients (5%). CONCLUSIONS: Total thyroidectomy for Graves' disease is an effective and safe therapy. When performed by an experienced head and neck surgeon, it carries a low morbidity rate. It should be presented to patients as a therapeutic option within the context of a comprehensive discussion of the risks and benefits of radioactive iodine, pharmacologic therapy, and surgery.

Adolescent↗
PubMed2006

Influence of lanthanum on the accumulation of trace elements in chloroplasts of cucumber seedling leaves.

Influence of La3+ on the accumulation of trace elements (75Se, 56 Co, 83 Rb, 48 V, 95 mTc, and 67Ga) in chloroplasts of cucumber seedling leaves was studied by a radioactive multi-tracer technique. At the same time, chloroplast contents of different concentrations of La3+ treatment were calculated. It was observed that chloroplast contents peaked at 0.02 mM La3+ treatment and that the uptake and distribution of these trace elements in chloroplasts of cucumber seedling leaves are different under different La3+ treatments. With the increase of lanthanum concentrations from 0.002 to 2 mM, the uptake percentages of 75Se, 56 Co, and 83 Rb presented an obvious increase and then sharply decreased in contrast to the non-lanthanum treatment, whereas there appeared a sharp decrease and then restored control level in the uptake of 48 V. The other two trace elements, namely 95 mTc and 67Ga, were accumulated only in the presence of 0.02 mM La3+. The results indicate that lanthanum treatments to growing the cucumber lead to the change of trace element uptake in the chloroplasts of leaves, which suggest that lanthanum might influence the accumulation of trace elements in chloroplasts of cucumber seedling leaves by regulation of various ion transport mechanisms, thus affecting the photosystem of leaves.

Chloroplasts↗
PubMed1992

Erythrocyte antioxidant activity, serum ceruloplasmin, and trace element levels in subjects with alcoholic liver disease.

Erythrocyte antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) and reduced glutathione, serum ceruloplasmin, and serum trace elements (copper, zinc, iron, and selenium) related to antioxidant enzymes were assayed in subjects with alcoholic liver disease of different degrees of severity. The erythrocytes of subjects with moderate and severe alcoholic liver cirrhosis had an unbalanced antioxidant system (normal superoxide dismutase, low catalase and glutathione peroxidase activities, and low glutathione content). Serum ceruloplasmin levels were in the normal range. Levels of the serum trace elements zinc and selenium were significantly low in subjects with moderate and severe cirrhosis, whose red cell half-life was also significantly short, as measured by radioactive chromium. These data suggest that the erythrocytes of subjects with moderate and severe alcoholic liver cirrhosis are less protected against oxidant stress. The particular erythrocyte antioxidant system and serum trace element pattern may play a role in the genesis of hemolytic disorders and of alcoholic hepatic damage.

Adult↗
PubMed2002

"High specific activity" radiotracers for metallo-toxicological studies: cyclotron and nuclear reactor production, radiochemical separation and "quality control": platinum, iridium, gold, copper and gallium.

Very High Specific Activity RadioNuclides, HSARN, are a powerful tool to label a wide variety of chemical elements and compounds present in the biosphere in ultra-trace amounts. Medium and high Z radionuclides, can be produced by irradiation in light-ions accelerator and sometimes nuclear reactor. If the nuclear reaction product has atomic number different from irradiated target, it is possible separating the radioactive nuclide from irradiated target, without addition of isotopic carrier. These kinds of radionuclides are named No Carrier Added, NCA, and their specific activity is very high and can reach values close to the theoretical Carrier Free one. The true specific activity must be determined by use of very sensitive radioanalytical techniques. If a low isotopic dilution factor is obtained, these radiotracers are used to label inorganic species and complexes of elements, which are presently introduced into the echo-systems by human activities. New production methods for NCA Pt, Ir, Au, Cu and Ga radiotracers are presented, with some details on radiochemistry and quality controls.

Copper↗
PubMed2005

Natural radioactivity in Brazilian groundwater.

More than 220 groundwater samples were analyzed for 228Ra, 226Ra, 222Rn, 210Pb, U(nat), Th(nat), pH, conductivity, fluoride and some additional elements determined by ICP-MS. Since samples from several Brazilian states were taken, involving areas with quite different geologies, no general trend was observed relating the chemical composition and the natural radionuclide content. On the other hand, 210Pb strongly depends on the water content of its progenitor, 222Rn. The values obtained during the present work were compared with those reported by Hainberger et al. [Hainberger, P.L., de Oliveira Paiva, I.R., Salles Andrade, H.A., Zundel, G., Cullen, T.L., 1974. Radioactivity in Brazilian mineral waters. Radiation Data and Reports, 483-488.], when more than 270 groundwater samples were analyzed, mainly, for 226Ra. Based on the results of both works, it was possible to build a database including the results of both works, generating a set with the radium content of circa 350 groundwater sources. It was demonstrated that 228Ra, 226Ra, 222Rn, 210Pb and U(nat) content in Brazilian groundwater follows a lognormal distribution and the obtained geometric mean were 0.045, 0.014, 57.7, 0.040 BqL(-1) and 1.2 microgL(-1), respectively.

Brazil↗
PubMed1982

Tropolone: a lipid solubilizing agent for cationic metals.

Lipid soluble agents which chelate radioactive cations have several potential uses in nuclear medicine including: brain imaging, labeling of blood elements, and identifying fatty infiltration of organs. A tropolone-gallium complex has been characterized by the determination of in vitro partition ratios correlated with in vivo organ distribution in the rat. Partition ratios were determined for gallium-67 citrate, indium-114m chloride, and iron-59 chloride cations complexed with tropolone in chloroform + water, octanol + water, olive oil + water, and olive oil + plasma two-phased systems. Tropolone proved to be highly effective in the lipid solubilization of these metal cations. Distribution studies in animals of these cations complexed with tropolone demonstrated an increased concentration of these cation complexes in tissues of high lipid content when compared with appropriate controls.

Animals↗
PubMed1996

Gamma-ray spectrometric analysis of neutron irradiated golden sands.

A nondestructive method has been used for the qualitative and quantitative determination of elements such as Au, Cu, Ag in minerals and especially in golden sand. The induced radioactivity has been analyzed with a high resolution gamma spectrometer containing a Ge(Li) semiconductor detector type and a multichannel analyzer. The samples have been collected from the alluvia of the Mureş and Someşul Mic river basins, proving the presence of gold and copper in small concentrations. These results have been correlated to previous data showing the existence of some gold mines in these zones. This nondestructive, rapid and highly sensitive method can be used for industrial processes [1] control and prospections. The use of a NaI(Tl) scintillation crystal for routine measurements of the (198)Au radioisotope type and the interferences by copper, silver and indium in the irradiated samples are discussed.

Journal Article↗
PubMed1997

Protein interactions at the carboxyl terminus of p53 result in the induction of its in vitro transactivation potential.

The tumor suppressor protein p53 is a transcription factor frequently inactivated in human cancers. We have studied the DNA binding potential and the transcriptional activity of p53 variants and p53 protein complexes in in vitro transcription assays. p53 specific transcription was measured via introduction of radioactive UTP into G-free cassette transcripts regulated by promoter sequences containing p53 response elements. Latent and activated p53 fractions were prepared from insect cells infected with p53 encoding baculoviruses by chromatography on heparin columns. p53 fractions distinguishable by their specific DNA binding activities and their recognition by monoclonal antibody PAb421 were obtained. Specific DNA binding and binding to PAb421 are mutually exclusive. The C-terminus of p53 can be phosphorylated by casein kinase II, protein kinase C and cyclin dependent kinases. The antibody PAb421 binds within the PKC phosphorylation site of p53 and is able to activate DNA binding of latent p53 in vitro. Activation of p53 by PAb421 also results in enhanced transactivation in vitro. Dephosphorylation of latent p53 with phosphatase 2A does not change these properties. This suggests that a conformational change in the carboxyl terminal domain of p53 controls the transactivation potential of p53.

Animals↗
PubMed2003

Bcl-2 protein is required for the adenine/uridine-rich element (ARE)-dependent degradation of its own messenger.

We have shown previously that the decay of human bcl-2 mRNA is mediated by an adenine/uridine-rich element (ARE) located in the 3'-untranslated region. Here, we have utilized a non-radioactive cell-free mRNA decay system to investigate the biochemical and functional mechanisms regulating the ARE-dependent degradation of bcl-2 mRNA. Using RNA substrates, mutants, and competitors, we found that decay is specific and ARE-dependent, although maximized by the ARE-flanking regions. In unfractionated extracts from different cell types and in whole cells, the relative enzymatic activity was related to the amount of Bcl-2 protein expressed by the cells at steady state. The degradation activity was lost upon Bcl-2 depletion and was reconstituted by adding recombinant Bcl-2. Ineffective extracts from cells that constitutively do not express Bcl-2 acquire full degradation activity by adding recombinant Bcl-2 protein. We conclude that Bcl-2 is necessary to activate the degradation complex on the relevant RNA target.

3' Flanking Region↗