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PubMedDate not supplied

Preparation of microcapsules containing rare-earth metal elements.

Microcapsules for internal radiation therapies containing the rare-earth metal elements Dy, Ho and Cu with a diameter of 5-10 microm were successfully obtained by an interfacial polymerization method and a successive sedimentation technique was employed to fractionate the microcapsules. A triisocyanate monomer and tricresylphosphate were used for a wall forming material and a core solvent for the metals, respectively. The amount of the metal elements loaded was measured using a high frequency plasma photoemission apparatus. The beta-ray radioactivity of 1 mg of microcapsules irradiated with a common neutron source is estimated as 370 microCi, which is satisfactorily strong for usual radiotherapy, when microcapsules containing Dy are used. Differential interference microscopy indicated narrow size distribution of the fractionated microcapulses.

Algorithms↗
PubMed1999

Chemical toxicity of some actinides and lanthanides towards alveolar macrophages: an in vitro study.

PURPOSE: To compare the toxicity of lanthanides (cerium, gadolinium) with actinides (thorium, neptunium, uranium) added in soluble form to rat alveolar macrophage cultures. MATERIALS AND METHODS: The metals were added 1 day after seeding alveolar macrophages extracted by pulmonary lavage, and the metal toxicity was scored 3 days later. Cell death was measured after vital staining to distinguish between apoptosis and necrosis; relative cell density was also quantified. The physico-chemical form of the metals in the culture medium was characterized using filtration and radioactive measurements. RESULTS: Except for thorium, induction of cell death was observed for all the elements studied and the death mechanism involved was apoptosis. Graduated toxicity was observed from uranium to neptunium, cerium and gadolinium, in the range of concentration from 10(-3)-10(-6) M. From pilot experiments, it was hypothesized that soluble compounds were mainly involved in lanthanide toxicity, whereas insoluble forms were mainly involved in actinide toxicity. CONCLUSION: This study demonstrates that the toxicity of neptunium and uranium was concomitant with the presence of insoluble forms in the culture medium. Further studies are needed to characterize the cell death mechanisms involved and the potential synergistic effects of chemical toxicity and irradiation.

Actinoid Series Elements↗
PubMed2004

The FASSET framework for assessment of environmental impact of ionising radiation in European ecosystems--an overview.

The FASSET project was launched in November 2000 under the EC 5th Framework Programme to develop a framework for the assessment of environmental impact of ionising radiation in European ecosystems. It involved 15 organisations in seven European countries and delivered its final report in spring 2004. The project set out to organise radioecological and radiobiological data into a logical structure that would facilitate the assessment of likely effects on non-human biota resulting from known or postulated depositions of radionuclides in the environment. The project included an overview of 20 pathway-based environmental assessment systems targeted at radioactive substances, or at hazardous substances in general. The resulting framework includes the following fundamental elements: source characterisation; description of seven major European ecosystems; selection of a number of reference organisms on the basis of prior ecosystem and exposure analysis; environmental transfer analysis; dosimetric considerations; effects analysis; and general guidance on interpretation including consideration of uncertainties. The project has used existing information supplemented with development in some areas, e.g. Monte Carlo calculations to derive dose conversion coefficients, model development, and the building of an effects database (FRED, the FASSET Radiation Effects Database). On the basis of experience from FASSET and other recent programmes, it can be concluded that (i) there is substantial agreement in terms of conceptual approaches between different frameworks currently in use or proposed, (ii) differences in technical approaches can be largely attributed to differences in ecosystems of concern or in national regulatory requirements, (iii) sufficient knowledge is available to scientifically justify assessments following the Framework structure, but (iv) significant data gaps exist for environmental transfer of key nuclides as well as for effects data for key wildlife groups at environmentally relevant dose rates. This paper briefly describes the overall content of the FASSET Framework, as well as highlighting a few important future challenges.

Ecosystem↗
PubMed1972

Acetylcholine and lobster sensory neurones.

Experiments are presented in support of the hypothesis that acetylcholine functions as a sensory transmitter in the lobster nervous system.1. Several different peripheral sensory structures incorporate radioactive choline into acetylcholine. The preparation most enriched in sensory as opposed to other nervous elements (the antennular sense organs of the distal outer flagellum) does not incorporate significant amounts of glutamate, tyrosine or tryptophan into any of the other major transmitter candidates.2. There is a parallel between the distribution of the enzyme choline acetyltransferase and the proportion of sensory fibres in nervous tissue from many parts of the lobster nervous system.3. Isolated sensory axons contain at least 500 times as much choline acetyltransferase per cm of axon as do efferent excitatory and inhibitory fibres.4. Abdominal ganglia and root stumps show a decline in the rate of incorporation of choline into acetylcholine 2 to 8 weeks after severing the first and second roots bilaterally (leaving the connectives and third roots intact). Extracts of the root stumps exhibit a significantly lower level of choline acetyltransferase 2 weeks after this operation.5. Curare and atropine partially block an identified sensory synapse in the lobster abdominal ganglion.

Acetylcholine↗
PubMed2004

Selenocysteine-containing proteins in anaerobic benzoate metabolism of Desulfococcus multivorans.

The sulfate-reducing bacterium Desulfococcus multivorans uses various aromatic compounds as sources of cell carbon and energy. In this work, we studied the initial steps in the aromatic metabolism of this strictly anaerobic model organism. An ATP-dependent benzoate coenzyme A (CoA) ligase (AMP plus PPi forming) composed of a single 59-kDa subunit was purified from extracts of cells grown on benzoate. Specific activity was highest with benzoate and some benzoate derivatives, whereas aliphatic carboxylic acids were virtually unconverted. The N-terminal amino acid sequence showed high similarities with benzoate CoA ligases from Thauera aromatica and Azoarcus evansii. When cultivated on benzoate, cells strictly required selenium and molybdenum, whereas growth on nonaromatic compounds, such as cyclohexanecarboxylate or lactate, did not depend on the presence of the two trace elements. The growth rate on benzoate was half maximal with 1 nM selenite present in the growth medium. In molybdenum- and/or selenium-depleted cultures, growth on benzoate could be induced by addition of the missing trace elements. In extracts of cells grown on benzoate in the presence of [75Se]selenite, three radioactively labeled proteins with molecular masses of approximately 100, 30, and 27 kDa were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The 100- and 30-kDa selenoproteins were 5- to 10-fold induced in cells grown on benzoate compared to cells grown on lactate. These results suggest that the dearomatization process in D. multivorans is not catalyzed by the ATP-dependent Fe-S enzyme benzoyl-CoA reductase as in facultative anaerobes but rather involves unknown molybdenum- and selenocysteine-containing proteins.

Amino Acid Sequence↗
PubMed1997

Bridging nerve defects with differently treated muscle grafts: assessment of microsphere technique for measurement of blood flow in rats.

OBJECTIVE: To select advanced points from differently treated muscle grafts and explore a new conduit to bridge nerve defects. METHODS: A total of 70 Sprague-Dawley rats were employed in this experiment. We applied a frozen probe to freeze the muscle in situ to disrupt any cellular elements of the local muscle grafts, but blood vessels to the muscle were carefully preserved. Radioactive microsphere technique was employed to visualize the blood supply to the muscle grafts. Immunohistochemical staining and ultrastructural observation were also carried out to assess the results of nerve regeneration. RESULTS: The in-situ frozen muscle grafts were revascularized within the first 3 days, which led to fast migration of macrophages and Schwann cells. That was really reflected in the final results: the early incursion of regenerating axons, more regenerating axons at the early stage both in the grafts and distal stumps, and thicker myelin sheath of regenerating axons. CONCLUSIONS: The in-situ frozen autogenous muscle graft is useful in the repair of sciatic nerve of rats. In the thicker and longer grafts the benefits will be more remarkable. It will be the most useful technique for nerve repair, especially in the repair of a large nerve gap in a poor recipient bed.

Animals↗
PubMed2003

Preparation of "high specific activity" radiochemical forms of vanadium, manganese and thallium for metallo-toxicological studies.

In this paper are presented the production methods for very "high specific activity" radionuclides (HSA-RN) of vanadium, manganese and thallium which have been developed in our laboratories for labelling different chemical forms of these elements present in the echo-systems in ultra-trace amounts, for metallo-toxicological and bio-kinetic studies. Use was made of both cyclotron and thermal 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. This kind of radionuclide is named No Carrier Added, NCA, and his specific activity, As is very high and can reach values close to the theoretical Carrier Free one, CF. The experimental determination of specific activity, chemical and radiochemical purities is mandatory for all these kinds of applications.

Cyclotrons↗
PubMed2000

A new phosphospecific cell-based ELISA for p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK, protein kinase B and cAMP-response-element-binding protein.

Assaying activation of signal transduction is laborious and does not allow the study of large numbers of samples, essential for high-throughput drug screens or for large groups of patients. Using phosphospecific antibodies, we have developed ELISA techniques enabling non-radioactive semi-quantitative assessment of the activation state of p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK, protein kinase B and the transcription factor cAMP-response-element-binding protein (CREB) in 96-well plates. This assay has been termed PACE (phosphospecific antibody cell-based ELISA) and was used successfully for both adherent and suspension cells. Various stimuli induced dose-dependent enzymic activity of which the kinetics closely correlated with those measured via classical methodology. Using PACE we have now characterized for the first time the concentration-dependent effects of various inflammatory prostaglandins on CREB phosphorylation in macrophages. PACE is a straightforward and novel technique enabling the large-scale analysis of signal transduction.

Animals↗
PubMed1999

Radionuclides and trace elements in fish collected upstream and downstream of Los Alamos National Laboratory and the doses to humans from the consumption of muscle and bone.

The purpose of this study was to determine radionuclide and trace element concentrations in bottom-feeding fish (catfish, carp, and suckers) collected from the confluences of some of the major canyons that cross Los Alamos National Laboratory (LANL) lands with the Rio Grande (RG) and the potential radiological doses from the ingestion of these fish. Samples of muscle and bone (and viscera in some cases) were analyzed for 3H, 90Sr, 137Cs, totU, 238Pu, 239,240Pu, and 241Am and Ag, As, Ba, Be, Cr, Cd, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Most radionuclides, with the exception of 90Sr, in the muscle plus bone portions of fish collected from LANL canyons/RG were not significantly (p < 0.05) higher from fish collected upstream (San Ildefonso/background) of LANL. Strontium-90 in fish muscle plus bone tissue significantly (p < 0.05) increases in concentration starting from Los Alamos Canyon, the most upstream confluence (fish contained 3.4E-02 pCi g-1 [126E-02 Bq kg-1]), to Frijoles Canyon, the most downstream confluence (fish contained 14E-02 pCi g-1 [518E-02 Bq kg-1]). The differences in 90Sr concentrations in fish collected downstream and upstream (background) of LANL, however, were very small. Based on the average concentrations (+/- 2SD) of radionuclides in fish tissue from the four LANL confluences, the committed effective dose equivalent from the ingestion of 46 lb (21 kg) (maximum ingestion rate per person per year) of fish muscle plus bone, after the subtraction of background, was 0.1 +/- 0.1 mrem y-1 (1.0 +/- 1.0 microSv y-1), and was far below the International Commission on Radiological Protection (all pathway) permissible dose limit of 100 mrem y-1 (1000 microSv y-1). Of the trace elements that were found above the limits of detection (Ba, Cu, and Hg) in fish muscle collected from the confluences of canyons that cross LANL and the RG, none were in significantly higher (p < 0.05) concentrations than in muscle of fish collected from background locations.

Animals↗
PubMed1976

Uptake of iodinated human kidney alpha-D-mannosidase by rat liver- Association with membrane elements and stability in vivo and in vitro.

1. Human kidney alpha-D-mannosidase (form A) was labelled with 125I to a specific radio-activity of approx. 2250muCi/mg of protein, essentially without loss of enzymic activity. The enzymic activity and radioactivity of the iodinated material also co-migrated in gel filtration and gel electrophoresis. 2. The binding of 125I-labelled mannosidase in vitro to particulate material in liver and kidney homogenates was of the other of 2 pg/mg of particulate material in liver and kidney homogenates was of the order of 2pg/mg of particulate protein withing 16h at 37 degrees C, and essentially zero in intervals of up to 60 min. The degradation in vitro of labelled exogenous mannosidase was of the order of 10-20pg/ 16th per mg of protein in postnuclear supernatant, and it was saturated entirely within 1h at 37 degrees C. 3. The binding of labelled mannosidase in vivo to particulate elements of liver homogenates 60 min after intravenous injection was at least 10 times higher in terms of specific radioactivity than the highest value attainable in vitro. Virtually all exogenous enzyme bound to liver particulate material could be recovered in macromolecular form after disruption of membranes by detergents. 4. The radioactive enzyme bound to liver particulate material could be detached almost completely by shearing, repeated freezing and thawing, and exposure to strong detergents under conditions that do not eliminate rough-endoplasmic-membrane structure. It could bot be released, however, by high salt concentration (0.5M-KC1) or by exposure to weak detergents such as Tween 80. The particle-bound enzyme should thus be associated with plasma membranes and lysosome-like elements. 5. Of the rat tissues studied, only liver could approach, within 60 min after the injection, the concentration of exogenous mannosidase found in the blood serum. The activity per g tissue weight fell progressively from liver (60% of serum value) to kidney (16% of serum value), lung (8% of serum vlaue), spleen (6% of serum value) and brain (0.9% of serum value). Most of the radioactive enzyme found in tissues other than liver appeared to be present in a free form, whereas in liver more than 50% of the labelled enzyme was associated with membrane elements.

Animals↗
PubMed1982

Tissue localization of stable and radioactive nuclides by secondary-ion microscopy.

Images of the distribution of a given nuclide in a section of biological tissue can be obtained at the microscopic level by "secondary-ion mass analysis." In this method, the images are formed by an ion-emission microscope wherein the specimen's atoms are progressively sputtered from the surface and the ions are selectively visualized by mass spectrometry according to their mass-to-charge ratios. Such images are obtained at the cost of the destruction of the specimen, which is progressively eroded at the rate of 1-10 atomic layers per second. The spatial resolution is better than 1 micrometer for an imaged area 250 micrometer in diameter and a section thickness of 1-2000 nm; thus, the analytical images are element distributions representative of 3-6000 atomic layers. Distributional images can be obtained for many nuclides, whether stable or radioactive, natural or artificially administered.

Aluminum↗
PubMed1997

Health impacts of large releases of radionuclides. Internal exposure of populations to long-lived radionuclides released into the environment.

This chapter discusses the events that led to the contamination of environments with the long-lived radionuclides of caesium, strontium and other elements, and to the internal exposure of populations living in contaminated areas. Among these events are radioactive releases into the river Techa from the Soviet nuclear weapons facility Mayak in 1949-1956, thermonuclear weapons tests in the 1950s and 1960s, the Kyshtim and Windscale accidents in 1957, and the Chernobyl and Tomsk-7 accidents in 1986 and 1993, respectively. Methods of environmental monitoring and individual internal dose monitoring of inhabitants are described. These are based on measuring the content of radionuclides not only in the air, drinking water and local food products, but also in humans using whole-body counters and analysing excreta and autopsy samples. The dynamics of internal exposure of people of different ages to radionuclides of caesium, strontium and plutonium from the environment are considered. Examples of radionuclide distributions in the environment, and of individual/collective internal doses and related medical effects are presented.

Americas↗
PubMed1981

Clathrin is axonally transported as part of slow component b: the microfilament complex.

During axonal transport, membranes travel down axons at a rapid rate, whereas the cytoskeletal elements travel in either of two slow components, SCa (with tubulin and neurofilament protein) and SCb (with actin). Clathrin, the highly ordered, structural coat protein of coated vesicles, has recently been shown to be able to interact in vitro with cytoskeletal proteins in addition to membranes. The present study examines whether clathrin travels preferentially with the membrane elements or the cytoskeletal elements when it is axonally transported. Guinea pig visual system was labeled with tritiated amino acids. Radioactive SDS-polyacrylamide gel electrophoresis profiles from the major components of transport were coelectrophoresed with clathrin. Only SCb had a band comigrating with clathrin. In addition, radioactive clathrin was purified from guinea pig brain containing only radioactive SCb polypeptides. Kinetic analysis of the putative clathrin band in SCb revealed that it travels entirely within the SCb wave. Thus we conclude that clathrin travels preferentially with the cytoskeletal proteins making up SCb, rather than with the membranes and membrane-associated proteins in the fast component.

Animals↗
PubMedDate not supplied

Effect of heterogeneity on radionuclide retardation in the alluvial aquifer near Yucca Mountain, Nevada.

The U.S. Department of Energy is currently studying Yucca Mountain, Nevada, as a potential site for a geological high-level waste repository. In the current conceptual models of radionuclide transport at Yucca Mountain, part of the transport path to pumping locations would be through an alluvial aquifer. Interactions with minerals in the alluvium are expected to retard the downstream migration of radionuclides, thereby delaying arrival times and reducing ground water concentrations. We evaluate the effectiveness of the alluvial aquifer as a transport barrier using the stochastic Lagrangian framework. A transport model is developed to account for physical and chemical heterogeneities and rate-limited mass transfer between mobile and immobile zones. The latter process is caused by small-scale heterogeneity and is thought to control the macroscopic-scale retardation in some field experiments. A geostatistical model for the spatially varying sorption parameters is developed from a site-specific database created from hydrochemical measurements and a calibrated modeling approach (Turner and Pabalan 1999). Transport of neptunium is considered as an example. The results are sensitive to the rate of transfer between mobile and immobile zones, and to spatial variability in the hydraulic conductivity. Chemical heterogeneity has only a small effect, as does correlation between hydraulic conductivity and the neptunium distribution coefficient. These results illustrate how general sensitivities can be explored with modest effort within the Lagrangian framework. Such studies complement and guide the application of more detailed numerical simulations.

Actinoid Series Elements↗
PubMed1977

[Fluorescence of dental ceramics by means of non-radioactive materials].

In order to improve the aesthetics of dental ceramics under all lighting conditions, uranium and cerium are added as fluorescent additives. However, studies have shown that the fluorescent behavior of dental ceramics is still not identical to that of natural teeth in all cases. A further disadvantage of the use of uranium are its radioactive and poisonous properties. This study was undertaken in order to investigate the possibility of using elements of the rare earth family as fluorescent additives for dental ceramics. The rare earths were added to a potassium feldspar glass host and emission spectra were measured. As a result it is recommended that divalent europium and trivalent dysprosium be further investigated as possible fluorescent additives for dental ceramics, as they show intense blue-white and yellow fluorescence respectively.

Dental Porcelain↗
PubMed1987

5'-Fluorosulfonylbenzoyl derivatives of therapeutic nucleoside analogs.

Several fluorosulfonylbenzoyl /FSB/ purine and pyrimidine nucleoside analogs of the clinically useful antimetabolites which belong to endo affinity labeling compounds were synthetized. Structures were confirmed by both 1H NMR and UV spectroscopy and by elemental analysis. Procedure for preparation of microamount of [3H] FSB-araC was developed. Bonding of radioactive FSB-araC to nucleotide utilizing enzymes in K562 myeloblasts soluble protein extract was compared with araCTP-degradating activities in this extract after DEAE-cellulose column chromatography. There was found that five major peaks of the radioactivity bound to the protein coincident with peaks of araCTP degradation. Bonding of [3H] FSB-araC in CCRF-CEM lymphoblasts exhibits only 3 major peaks of the bound radioactivity. This result correlates with the higher sensitivity of the CEM cells to araC.

Antimetabolites, Antineoplastic↗
PubMedDate not supplied

[Contents of plutonium and microelements in the hair of Belarus inhabitants living in the areas contaminated during the Chernobyl AES accident].

The levels of plutonium were studied in the body of inhabitants of the Minsk and Gomel Regions. Their hair was used as the indicator of its levels. The hair concentrations of plutonium correlated with its content in the ribs. The hair levels of lead in the inhabitants of some populated localities of the Gomel Region were found to be higher than those in the residents of unpolluted areas and industrial centers of the Republic of Belarus.

Adolescent↗