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PubMed1999

Radionuclide concentrations in underground waters of Mururoa and Fangataufa Atolls.

In 1997 an expedition to Mururoa and Fangataufa Atolls was carried out to sample underground waters from cavity-chimneys and carbonate monitoring wells. The aim of this study was to determine the prevailing concentration and distribution status of radionuclides. Elemental analysis of interstitial waters was carried out in the water fraction as well as in particles collected at 11 underground monitoring wells. 238Pu, 239,240Pu, 241Am, 137Cs, 90Sr, 3H, 125Sb, 155Eu and 60Co were analyzed in both fractions by alpha-, beta- and gamma-spectrometry. Measurements showed that at 60% of the sites, pH and Eh seemed to be related to tidal cycles; in contrast HTO was constant during the sampling time. Interstitial waters from carbonates and transition zones shared similar chemical composition that were not different from that of the surrounding seawater. Waters collected from basalt cavities left after nuclear tests, (Aristee and Ceto) have a different chemical signature characterized by a deficiency in Mg, K and SO4 as well as enrichment in Sr, Si, Al and Cl compared to the rest of the stations. Radionuclide concentrations present in both, water and particulate fractions, were significantly higher at Ceto and Aristee than at any other monitoring wells, except for Fuseau and Mitre monitoring wells (Fangataufa) where values similar to Ceto were found (e.g. 239,240Pu: > 20 mBq g-1). Considering that Pu isotopes showed high Kd values compared to non-sorbing radionuclides such as 3H, 90Sr and 137Cs it is very unlikely that migration from cavities to monitoring wells accounts for the concentration of Pu isotopes and Am at Fuseau 30 and Mitre 27. Perhaps the contact of lagoon waters with the well before sealing could be a possible source of the transuranics found at these sites. The 238Pu/239,240Pu ratios measured in the particles were similar to that of the lagoon (0.38), thus supporting this hypothesis. The fact that transuranics were found only in the particle fraction, in the water (colloids included) these radionuclides were below detection limits, may be accounted for the conspicuous quantity of iron oxy-hydroxides present in the particulate fraction that under the appropriate redox conditions may be interacting selectively with elements in solution (scavenging) resulting in the enhanced transuranic signal. While transuranics have been found in places of their origin, radionuclides with low Kd values (3H, 90Sr, 137Cs) have already been transported to monitoring wells, as well as to the atolls' lagoons and the open ocean.

Nuclear Warfare↗

PubMed2002

Transuranic biokinetic parameters for marine invertebrates--a review.

A catalogue of biokinetic parameters for the transuranic elements plutonium, americium, curium, neptunium, and californium in marine invertebrates is presented. The parameters considered are: the seawater-animal concentration factor (CF); the sediment-animal concentration ratio (CR); transuranic assimilation efficiency; transuranic tissue distribution and transuranic elimination rates. With respect to the seawater-animal CF, authors differ considerably on how they define this parameter and a seven-point reporting system is suggested. Transuranic uptake from sediment by animals is characterised by low CRs. The assimilation efficiencies of transuranic elements in marine invertebrates are high compared to vertebrates and mammals in general and the distribution of transuranics within the body tissue of an animal is dependent on the uptake path. The elimination of transuranics from most species examined conformed to a standard biphasic exponential model though some examples with three elimination phases were identified.

Animals↗

PubMed2005

Minimum speed limit for ocean ridge magmatism from 210Pb-226Ra-230Th disequilibria.

Although 70 per cent of global crustal magmatism occurs at mid-ocean ridges-where the heat budget controls crustal structure, hydrothermal activity and a vibrant biosphere-the tempo of magmatic inputs in these regions remains poorly understood. Such timescales can be assessed, however, with natural radioactive-decay-chain nuclides, because chemical disruption to secular equilibrium systems initiates parent-daughter disequilibria, which re-equilibrate by the shorter half-life in a pair. Here we use 210Pb-226Ra-230Th radioactive disequilibria and other geochemical attributes in oceanic basalts less than 20 years old to infer that melts of the Earth's mantle can be transported, accumulated and erupted in a few decades. This implies that magmatic conditions can fluctuate rapidly at ridge volcanoes. 210Pb deficits of up to 15 per cent relative to 226Ra occur in normal mid-ocean ridge basalts, with the largest deficits in the most magnesium-rich lavas. The 22-year half-life of 210Pb requires very recent fractionation of these two uranium-series nuclides. Relationships between 210Pb-deficits, (226Ra/230Th) activity ratios and compatible trace-element ratios preclude crustal-magma differentiation or daughter-isotope degassing as the main causes for the signal. A mantle-melting model can simulate observed disequilibria but preservation requires a subsequent mechanism to transport melt rapidly. The likelihood of magmatic disequilibria occurring before melt enters shallow crustal magma bodies also limits differentiation and heat replenishment timescales to decades at the localities studied.

Journal Article↗

PubMed1977

Sequenced scintigraphy: a morphological and functional study of the salivary glands.

The use of scintigraphy in sequenced registration shows that there are three fundamental stages in the intraglandular turnover of the radionuclide: 1. At very early stage (between 3 min. and 15 min.), the major salivary glands could be clearly distinguished; 2. At the stage immediately following (between 20 min. and 35 min.), both the parotid and submaxillary glands were already less well defined; while in the mouth projection zone, quite intense radioactivity, connected with a progressive accumulation of the radionuclide in the minor salivary glands, was seen; 3. Within an hour after injection, maximum captation took place in the minor salivary glands, while both the parotid and the submaxillary glands were hardly distinct. These three stages are strictly related to the three phases of behavior of the radionuclide in each salivary gland; arrival, accumulation, dismissal. Then, each documented variation from the normal pattern will indicate a determined functional anomaly related to defined disease of the salivary glands. The sequenced scintigrraphy offers a functional study of the salivary glands from which it is possible to obtain many elements of practical clinical utility.

Humans↗

PubMed1991

Single photon emission computed tomography and positron emission tomography in cancer imaging.

Single photon emission computed tomography (SPECT) and positron emission tomography (PET) are now being used to improve the information available from radioisotopic imaging of patients with cancer. These nuclear medicine techniques offer the potential for studying regional function and biochemistry by using radiolabeled substrates. The chemical changes of malignancy precede anatomic changes, and PET and/or SPECT may detect these changes before anatomic changes have occurred. The superiority of SPECT compared with planar imaging has been demonstrated for cardiac and brain imaging. Radiopharmaceuticals containing technetium 99 m (99mTc) are best suited for SPECT imaging because large amounts of radioactivity are administered and the collimator-camera systems are optimized for the 140 keV photons of 99mTc. The current interest in imaging cancer with SPECT relates to the use of gallium 67 citrate and monoclonal antibodies labeled with iodine 123 or indium 111. SPECT can image these radioisotopes, but the advantages compared with planar imaging have not been clearly defined. Furthermore, the ability to quantitate the distribution of single photon emitters other than 99mTc has not been demonstrated. New SPECT systems with three heads or rings of detectors offer promise for improved, quantitative imaging. PET has the capability of imaging tracers with the biologically important elements C-11, N-13, O-15, and F-18 used for positron labeling. These radioisotopes have short half-lives and require a cyclotron close to the PET facility. The most prominently used radiopharmaceutical for PET is F-18 fluorodeoxyglucose (FDG). PET studies with FDG in patients with primary brain tumors have demonstrated the ability to determine the degree of malignancy, to differentiate necrosis from recurrent tumor after radiation therapy or chemotherapy, and to predict prognosis. Other metabolic functions of cancer have been studied, including amino acid accumulation, thymidine uptake, oxygen utilization, intermediary metabolism, and receptor status. PET has the potential to make a major impact on the characterization of a malignancy and the effect of therapy.

Fluorine Radioisotopes↗

PubMed2004

129I/(127)I as a new environmental tracer or geochronometer for biogeochemical or hydrodynamic processes in the hydrosphere and geosphere: the central role of organo-iodine.

Iodine is a biophilic element, with several short-lived isotopes (e.g. (131)I, t(1/2)=8 days), one long-lived isotope, (129)I (t(1/2)=15.6 million years) and one stable isotope, (127)I. The inventory of (129)I in surface environments has been overwhelmed by anthropogenic releases over the past 50 years. Iodine and its isotopes are important for a number of reasons: (1) The largest fraction of the short-term and long-term dose from accidental releases and fallout from atomic bomb tests was from iodine isotopes. (2) (129)I is one of the two long-lived nuclides with highest mobility in stored radioactive waste. (3) (129)I could provide the scientific community with a new geochemical tracer and new geochronological applications in environmental science. (4) A better assessment of iodine deficiency disorders, mineralization in exploration geochemistry, and the transfer of volatile organic greenhouse-active and ozone-destroying iodine species from the oceans to the atmosphere is needed. One of the most promising future applications for the (129)I/(127)I ratio is not only as a new geochronometer, but also as a new source tracer for terrestrial organic matter with ages of 50 years or less. This is especially attractive, since radiocarbon can be, at times, an ambiguous chronometer for the 50-year time-scale, whereas (129)I concentrations during this time are overwhelming previous levels by orders of magnitude. Iodine is to a significant extent involved in the cycle of organic matter in all surface environments. Its biophilic nature is demonstrated by a relative enrichment of iodine in seaweed and dissolved macromolecular organic matter. Because of the close coupling of iodine and organic carbon cycles, our understanding of the underlying molecular mechanisms of the processes regulating iodination reactions in aquatic systems is still limited. The binding of iodine by organic matter has the potential to modify the transport, bioavailability and transfer of iodine isotopes to man. Equilibration times for (129)I in many reservoirs are likely long enough that (129)I could be used as a new source tracer for organic matter of terrestrial origin, and as a geochronometer. Current tracer applications of (129)I are limited by our knowledge of the effects of UV-radiation, microbial activity and geochemical redox conditions on organo-I compounds and overall iodine speciation. The biogeochemical behavior of iodine and its isotopes appears to be different in North America and European waters, possibly due to climatic, source and speciation differences.

Environmental Monitoring↗

PubMed2005

Versatile new ion source for the analysis of materials in open air under ambient conditions.

A new ion source has been developed for rapid, noncontact analysis of materials at ambient pressure and at ground potential. The new source, termed DART (for "Direct Analysis in Real Time"), is based on the reactions of electronic or vibronic excited-state species with reagent molecules and polar or nonpolar analytes. DART has been installed on a high-resolution time-of-flight mass spectrometer (TOFMS) that provides improved selectivity and accurate elemental composition assignment through exact mass measurements. Although DART has been applied to the analysis of gases, liquids, and solids, a unique application is the direct detection of chemicals on surfaces without requiring sample preparation, such as wiping or solvent extraction. DART has demonstrated success in sampling hundreds of chemicals, including chemical agents and their signatures, pharmaceutics, metabolites, peptides and oligosaccharides, synthetic organics, organometallics, drugs of abuse, explosives, and toxic industrial chemicals. These species were detected on various surfaces, such as concrete, asphalt, human skin, currency, airline boarding passes, business cards, fruits, vegetables, spices, beverages, body fluids, horticultural leaves, cocktail glasses, and clothing. DART employs no radioactive components and is more versatile than devices using radioisotope-based ionization. Because its response is instantaneous, DART provides real-time information, a critical requirement for screening or high throughput.

Air↗

PubMed2001

Measurement of stellar age from uranium decay.

The ages of the oldest stars in the Galaxy indicate when star formation began, and provide a minimum age for the Universe. Radioactive dating of meteoritic material and stars relies on comparing the present abundance ratios of radioactive and stable nuclear species to the theoretically predicted ratios of their production. The radioisotope 232Th (half-life 14 Gyr) has been used to date Galactic stars, but it decays by only a factor of two over the lifetime of the Universe. 238U (half-life 4.5 Gyr) is in principle a more precise age indicator, but even its strongest spectral line, from singly ionized uranium at a wavelength of 385.957 nm, has previously not been detected in stars. Here we report a measurement of this line in the very metal-poor star CS31082-001, a star which is strongly overabundant in its heavy elements. The derived uranium abundance, log(U/H) = -13.7 +/- 0.14 +/- 0.12 yields an age of 12.5 +/- 3 Gyr, though this is still model dependent. The observation of this cosmochronometer gives the most direct age determination of the Galaxy. Also, with improved theoretical and laboratory data, it will provide a highly precise lower limit to the age of the Universe.

Journal Article↗

PubMed1979

Escherichia coli mutant strain with altered expression of the tryptophan operon: isolation and preliminary characterization.

From a strain of Escherichia coli with two copies of the tryptophan (trp) operon and one copy of the lactose (lac) operon, under control of one of the trp regulatory elements, we have isolated a mutant which does not grow in a medium containing 19 amino acids, unless tryptophan is added, and which cannot ferment lactose. The apparent pleiotropic nature of the mutation(s) is indicated by the very slow growth of mutant bacteria on minimal-medium agar supplemented with glucose and tryptophan. The amount of the trp enzymes (anthranilate synthetase and tryptophan synthetase) and trp messenger ribonucleic acid is reduced several-fold in the mutant compared to the isogenic wild-type strain, whereas the enzymes tryptophanyl-transfer ribonucleic acid synthetase and glucose 6-phosphate dehydrogenase remain the same. The incorporation of radioactive label into pulse-labeled but not into stable ribonucleic acid is significantly lower. Our results suggest that in the mutant organism the control of transcription of some operons, including the trp operon, is modified. An alternative explanation is that mutant bacteria contain a ribonuclease with increased activity for some messenger ribonucleic acid species.

Anthranilate Synthase↗

PubMed1989

Genomic footprinting in mammalian cells with ultraviolet light.

A simple and accurate genomic primer extension method has been developed to detect ultraviolet footprinting patterns of regulatory protein-DNA interactions in mammalian genomic DNA. The technique can also detect footprinting or sequencing patterns introduced into genomic DNA by other methods. Purified genomic DNA, containing either damaged bases or strand breaks introduced by footprinting or sequencing reactions, is first cut with a convenient restriction enzyme to reduce its molecular weight. A highly radioactive single-stranded DNA primer that is complementary to a region of genomic DNA whose sequence or footprint one wishes to examine is then mixed with 50 micrograms of restriction enzyme-cut genomic DNA. The primer is approximately 100 bases long and contains 85 radioactive phosphates, each of specific activity 3000 Ci/mmol (1 Ci = 37 GBq). A simple and fast method for preparing such primers is described. Following brief heat denaturation at 100 degrees C, the solution of genomic DNA and primer is cooled to 74 degrees C and a second solution containing Taq polymerase (Thermus aquaticus DNA polymerase) and the four deoxynucleotide triphosphates is added to initiate primer extension of genomic DNA. Taq polymerase extends genomic hybridized primer until its polymerization reaction is terminated either by a damaged base or strand break in genomic DNA or by the addition of dideoxynucleotide triphosphates in the polymerization reaction. The concurrent primer hybridization-extension reaction is terminated after 5 hr and unhybridized primer is digested away by mung bean nuclease. Primer-extended genomic DNA is then denatured and electrophoresed on a polyacrylamide sequencing gel, and radioactive primer extension products are revealed by autoradiography. By using this method we demonstrate that it is possible to footprint with ultraviolet light, in intact monkey cells, regulatory protein--DNA interactions along a single copy of a simian virus 40 viral genome integrated into the monkey genome.

Animals↗

PubMed1982

Membrane fusion and glycosylation in the rat hepatic Golgi apparatus.

When purified Golgi fractions were incubated with UDP-[3H]galactose in the absence of Triton-X-100, radioactivity was incorporated into an endogenous lipid and several peptide acceptors. Electron microscope analysis of Golgi fractions incubated in the endogenous galactosyl transferase assay medium revealed extensive fusion of Golgi saccules. Systematic removal of constituents in the galactosyl transferase assay medium showed enhanced (minus beta-mercaptoethanol) or reduced (minus ATP, minus sodium cacodylate buffer or minus MnCl2) fusion of Golgi membranes compared to the complete medium, Stereologic analysis revealed a correlation between membrane fusion and galactosyl transferase activity (r = 0.99, P less than 0.001). Electron microscope radioautography was carried out after incubation of Golgi fractions with UDP-[3H]galactose. Silver grains were not observed over trans elements of Golgi but were revealed mainly over large fused saccules with the number of silver grains being proportionate to membrane fusion (r = 0.92, P less than 0.001). Bilayer destabilization at points of Golgi membrane fusion may act to translocate galactose across the Golgi membrane and thereby provide a fusion regulated substrate for terminal glycosylation.

Animals↗

PubMed1989

Countermeasures for reducing the transfer of radiocesium to animal derived foods.

The nuclear reactor accident in Chernobyl stimulated new discussions and experiments on the question, how and to what extent the radiocesium-concentration in animal derived foods can be reduced. In a brief review this paper describes the use of two groups of feed additives as already applied in laboratory experiments during the period of atmospheric atomic weapons tests to prevent radiocesium absorption in the gastro-intestinal tract: 1) Iron (III) -Hexacyanoferrates and 2) Clay minerals. In the post-Chernobyl-period pilot studies were initiated to test similar feed additives under practical farming conditions with "naturally" radiocesium-labeled feedstuffs. Since then it is obvious that the colloidal Prussian blue analogue Ammonium-Ferric-Cyanoferrate (AFCF) can be considered as a leading antidote against radiocesium, while Bentonite or Bolus alba are 88-266 times less effective, when compared on a weight basis. Additionally clay materials cause losses of minerals and trace elements and pose logistic problems when feeding millions of large animals. Because of the small doses needed AFCF appears as a substance of choice to reduce radiocesium burdens in animal derived foods, which gained full recognition by health authorities in W-Germany and Austria supported by an official clearance for the use as feed additive.

Accidents↗

PubMed1991

Chernobyl fallout in southern and central Finland.

To study the levels and distributions of radionuclides released in the Chernobyl accident, we sampled surface peat from 62 sites in Southern and Central Finland and measured 131I, 134Cs, 137Cs, 132Te, 140Ba, 103Ru, 90Sr, 141Ce, and 95Zr. The distribution of fallout activities was highly uneven, depending on movement of the contaminated air mass and rainfall distribution during the critical days. The highest values observed were 420 kBq m-2 of 131I and 70 kBq m-2 of 137Cs. The nuclide ratios showed wide and partly unexpected variations. The high-boiling-point, or nonvolatile, elements Ce and Zr were spread mostly on a 200-km-wide zone extending across Finland from southwest to northeast. The more volatile elements, I, Ce, and Te, showed quite a different, more widespread, fallout distribution, while an intermediate behavior was observed for Ba, Ru, and possibly Sr. These results can be explained by assuming that pulverized nuclear fuel material released in the reactor explosion on 26 April reached Finland via Poland and the Baltic Sea and traversed the country along the above-mentioned narrow zone, while volatile material, evaporated in the reactor fire from 26 April to 5 May, arrived in several waves and was consequently more widely and evenly spread. From their elemental melting and boiling points, Ru and Mo would appear to belong to the nonvolatile group and Sr to the volatile. Yet, their actual behaviors were opposite; Ru in particular was found in the nonvolatile as well as the volatile fallout, possibly because Ru activities were present in the fuel partly in the metallic state and partly as volatile oxides.

Accidents↗

PubMed2001

Biologic dosimetry of bone marrow: induction of micronuclei in reticulocytes after exposure to 32P and 90Y.

UNLABELLED: Bone marrow is the dose-limiting organ in targeted radionuclide therapy. Hence, determination of the absorbed dose to bone marrow from incorporated radionuclides is a critical element in treatment planning. This study investigated the potential of the micronucleus assay in peripheral blood reticulocytes (MnRETs) as an in vivo biologic dosimeter for bone marrow. METHODS: After intravenous administration of 32P-orthophosphate or 90Y-citrate in Swiss Webster mice, DNA damage induced in bone marrow erythroblastoid cells was measured by subsequent scoring of MnRETs in peripheral blood. The response to exponentially decreasing dose rates was calibrated by irradiating animals with external 137Cs-gamma-rays. The gamma-ray dose rate was decreased exponentially, with the dose-rate decrease half-time corresponding to the effective clearance half-time (Te) of the radioactivity from the femoral bone (Te = 64 h for 90Y-citrate and Te = 255 h for 32P-orthophosphate). RESULTS: The maximum MnRETs frequency occurred on the second and third day after injection of 90Y-citrate and 32P-orthophosphate, respectively. The same pattern was observed for exponentially decreasing dose rates of 137Cs-gamma-rays. For each type of exposure, the maximum MnRETs frequency increased in a dose-dependent manner. Using the calibrated dosimeter, the initial dose rates to the marrow per unit of injected activity were 0.0020 cGy/h/kBq and 0.0026 cGy/h/kBq for 32P-orthophosphate and 90Y-citrate, respectively. CONCLUSION: Micronuclei in peripheral blood reticulocytes can be used as a noninvasive biologic dosimeter for measuring absorbed dose rate and absorbed dose to bone marrow from incorporated radionuclides.

Animals↗

PubMed1992

A regulatory cis element and a specific binding factor involved in the mitogenic control of murine ribosomal protein L32 translation.

The mRNA encoding ribosomal protein L32 redistributes from untranslated subribosomal particles into polysomes after mitogenic activation of quiescent T-lymphocytes and fibroblasts. To identify the regions of the L32 mRNA which are important in regulating its cytoplasmic location we constructed a plasmid containing the murine L32 cDNA under the control of the Rous sarcoma virus (RSV) long terminal repeat promoter and introduced this construct into murine 3T3 fibroblasts. The mRNA transcribed from the RSV-L32 construct redistributed from subribosomal particles into polysomes in response to mitogenic activation in a manner similar to endogenous L32 mRNA. A conserved polypyrimidine region present at the 5' terminus of all ribosomal protein mRNAs is required for translational regulation of L32 mRNA since deletion of this sequence resulted in a mRNA that was not sequestered in subribosomal particles in quiescent cells. A radioactive RNA probe containing the first 34 nucleotides of the L32 5'-untranslated region, including the polypyrimidine region, specifically interacted with a protein of about 56 kDa. This protein did not bind detectably to RNA probes lacking the polypyrimidine sequence. Binding activity was similar in protein extracts made from resting and activated cells, suggesting that binding of the 56-kDa protein as measured in this assay is not regulated. This protein is a member of what may be an emerging family of polyribopyrimidine-binding proteins with diverse biochemical functions.

3T3 Cells↗

PubMed2007

Micro-reactors for PET tracer labeling.

Miniaturization of PET radiosynthesis devices (micro-reactors or microfluidic systems) is an emerging area that has the potential to deliver many advantages, such as more efficient use of hot-cell space for production of multiple radiotracers; use of less non-radioactive precursor for saving precious material and a reduced separation challenge; highly controlled, reproducible and reliable radiotracer production; and cheap, interchangeable, disposable and quality-assured radiochemistry processors. Several 'proof of principle' examples along with basics of micro-reactor flow control, mixing principle and design, and device fabrication are discussed in this chapter.

Animals↗

PubMed1996

Localization of mRNA for the muscarinic M1 receptor in rat stomach.

Cholinergic stimulation of receptors in the oxyntic mucosa results in secretion of mucus, pepsinogen and hydrochloric acid. There has been speculation as to the cellular localization of these receptors in the mucosa and as to which subtype is present in the different cell types. In the present study, utilizing radioactive riboprobes for the M1 muscarinic receptor subtype, we carried out in situ hybridization to determine which cells of the gastric corpus transcribe mRNA for this receptor. The antisense M1 probe hybridized strongly on the zymogen cells and, to a lesser extent, on the surface mucous cells and the muscle layers. Control sections from brain also displayed specific hybridization.

Animals↗

PubMed2005

Measurement of 224Ra uptake in a fern actively accumulating radium.

A method is proposed for determining the level of 224Ra in plant samples by measuring its descendant nuclide 212Pb at 239 keV by gamma-ray spectrometry. Variations of 224Ra and 212Pb over time during sample preparation and counting were delineated prior to gamma-ray measurement. The 224Ra concentrations in plant samples were measured by their direct uptake from soil, which could be determined and distinguished from that resulting from decay of 228Th inside the plants. We propose that a field-growing Dicranopteris linearis, which actively accumulates radium, can be used as an indicator of the nutritional transportation and metabolic rate of radium and other alkaline earth elements. We investigated the influence of rainfall on 224Ra concentrations in fronds of D. linearis and the corresponding uptake rates. 224Ra could serve as a natural tracer of growth in plants over a several days. Its presence and content in plants implies a temporal mineral metabolic rate, which can provide useful information for plant physiological and environmental investigations.

Ferns↗