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PubMed1982

Preparative separation of intact incomplete and empty adenovirus type 2 particles.

Complete adenovirus type 2 virions containing the whole genome were resistant to while empty capsids lacking DNA were breakable at a separation procedure involving customary CsCl gradient centrifugation. A purification method was developed using CsCl density gradient centrifugation in 5% glycerol which retained the integrity of incomplete particles as well as empty capsids. This procedure enabled to study the biological and physicochemical properties of different adenovirus type 2 particles.

Adenoviruses, Human↗
PubMed1984

An ultrastructural cytochemical stain specific for neuroendocrine neoplasms.

Previous work from our laboratory has indicated that the uranaffin reaction, when run under specific conditions, will stain neurosecretory granules. In this ultrastructural cytochemical study, we analyzed the granule-staining properties of 13 normal, 10 abnormal (non-neoplastic), and 138 neoplastic tissues in an attempt to evaluate the specificity of the uranaffin reaction for diagnostic purposes when compared with routinely processed specimens. For the uranaffin reaction, previously fixed tissue stored in buffer was rinsed with 0.9% NaCl and reacted with a 4% aqueous solution of uranyl acetate (pH 3.9) for 48 hours. After three NaCl rinses, the tissue was dehydrated and processed for electron microscopy. The granules of normal or non-neoplastic neuroendocrine cells that stained positively with the uranaffin reaction included pancreatic islet cells, thyroid C cells, adrenal medullary cells, parathyroid chief cells, and the neuroendocrine cells of the intestine. All 42 neuroendocrine neoplasms studied possessed abundant uranaffin-positive granules and included carcinoids, oat cell carcinomas, islet cell neoplasms, medullary carcinomas of the thyroid, pheochromocytomas, carotid body paragangliomas, a pituitary adenoma, Merkel cell carcinomas, parathyroid adenomas, and a neuroblastoma. All 96 control neoplasms that were not classified as neuroendocrine in nature were negative for neurosecretory granules when studied with the uranaffin reaction and included 13 neoplasms derived from endocrine glands, 57 neoplasms from secretory epithelium, 10 of hematopoietic origin, and 16 miscellaneous neoplasms. It was determined that the uranaffin reaction is a useful ultrastructural cytochemical marker for neuroendocrine granules and helped distinguish these cytoplasmic organelles from ultrastructurally similar granules derived from non-neuroendocrine cells.

Adult↗
PubMed2006

Uranium(VI) reduction by Anaeromyxobacter dehalogenans strain 2CP-C.

Previous studies demonstrated growth of Anaeromyxobacter dehalogenans strain 2CP-C with acetate or hydrogen as the electron donor and Fe(III), nitrate, nitrite, fumarate, oxygen, or ortho-substituted halophenols as electron acceptors. In this study, we explored and characterized U(VI) reduction by strain 2CP-C. Cell suspensions of fumarate-grown 2CP-C cells reduced U(VI) to U(IV). More-detailed growth studies demonstrated that hydrogen was the required electron donor for U(VI) reduction and could not be replaced by acetate. The addition of nitrate to U(VI)-reducing cultures resulted in a transitory increase in U(VI) concentration, apparently caused by the reoxidation of reduced U(IV), but U(VI) reduction resumed following the consumption of N-oxyanions. Inhibition of U(VI) reduction occurred in cultures amended with Fe(III) citrate, or citrate. In the presence of amorphous Fe(III) oxide, U(VI) reduction proceeded to completion but the U(VI) reduction rates decreased threefold compared to control cultures. Fumarate and 2-chlorophenol had no inhibitory effects on U(VI) reduction, and both electron acceptors were consumed concomitantly with U(VI). Since cocontaminants (e.g., nitrate, halogenated compounds) and bioavailable ferric iron are often encountered at uranium-impacted sites, the metabolic versatility makes Anaeromyxobacter dehalogenans a promising model organism for studying the complex interaction of multiple electron acceptors in U(VI) reduction and immobilization.

Chlorophenols↗
PubMed1977

Ferrous iron oxidation and uranium extraction by Thiobacillus ferrooxidans.

The microbiological oxidation of ferrous iron in batch and continuous systems has been investigated in relation to uranium extraction from a low-grade ore by Thiobacillus ferrooxidans. The influence of the parameters, agitation, and aeration on oxygen saturation concentration, rate of oxygen mass transfer, and rate of ferrous iron oxidation was demonstrated. The kinetic values, Vmax and K were determined using an adapted Monod equation for different dilution rates and initial concentrations of ferrous iron. The power requirements for initial leaching conditions were also calculated. Uranium extraction as high as 68% has been realized during nine days of treatment. Regrinding the leach residue and its subsequent leaching yielded 87% uranium solubilization.

Ferrous Compounds↗
PubMed2000

Hydrothermal synthesis of (C6N2H14)2(UVI2UIVO4F12), a mixed-valent one-dimensional uranium oxyfluoride.

A new hybrid organic-inorganic mixed-valent uranium oxyfluoride, (C6N2H14)2(U3O4F12), UFO-17, has been synthesized under hydrothermal conditions using uranium dioxide as the uranium source, hydrofluoric acid as mineralizer, and 1,4-diazabicyclo[2.2.2]octane as template. The single-crystal X-ray structure was determined. Crystals of UFO-17 belonged to the orthorhombic space group Cmcm (no. 63), with a = 14.2660(15) A, b = 24.5130(10) A, c = 7.201(2) A, and Z = 4. The structure reveals parallel uranium-containing chains of two types: one type is composed of edge-sharing UO2F5 units; the other has a backbone of edge-sharing UF8 units, each sharing an edge with a pendant UO2F5 unit. Bond-valence calculations suggest the UF8 groups contain UIV, while the UO2F5 groups contain UVI. EXAFS data give results consistent with the single-crystal X-ray structure determination, while comparison of the uranium LIII-edge XANES of UFO-17 with that of related UIV and UVI compounds supports the oxidation-state assignment. Variable-temperature magnetic susceptibility measurements on UFO-17 and a range of related hybrid organic-inorganic uranium(IV) and uranium(VI) fluorides and oxyfluorides further support the formulation of UFO-17 as a mixed-valent UIV/UVI compound.

Journal Article↗
PubMed2006

Characterization of local Egyptian iron ores for use in radiation shielding concrete.

Petrographic, physical, chemical, mechanical, and radioactive characteristics tests were performed on magnetite, limonite, and hematite found in abundance in Egypt to determine their suitability for producing radiation shielding concrete. The contents of uranium and thorium were determined using instrumental neutron activation analysis and gamma spectroscopy. The results obtained using the two methods have shown satisfactory correlation. The tests confirm that magnetite and limonite are suitable as concrete aggregate while hematite is not because of its friable nature and high contents of uranium, thorium, and cobalt.

Ferric Compounds↗
PubMed2006

The vitality of uranium molecular chemistry at the dawn of the XXIst century.

The intent of this Dalton Perspective is to highlight the recent advances in uranium molecular chemistry, with the results reported during the 2000-2006 period. This discipline is currently witnessing an impressive development, together with the theoretical chemistry and solid-state chemistry of the f-elements, and its face has profoundly changed, revealing unsuspected structural and reactivity features. This progress required and was facilitated by the use of new precursors. Studies of low-valent compounds gave a better insight into lanthanide(III)/actinide(III) differentiation and led to the discovery of unusual reactions, including activation of small molecules. A number of tetravalent uranium complexes, in particular polynuclear compounds, have been synthesized, which exhibit exciting structures and physicochemical properties. The potential of uranium(III) and uranium(IV) complexes in catalysis has been confirmed. The uranyl complexes, from mononuclear species to supramolecular assemblies, reveal a variety of novel structures, changing the generally accepted ideas on the coordination geometry and the stability of the UO2(2+) ion.

Journal Article↗
PubMed2002

Desulfitobacterium metallireducens sp. nov., an anaerobic bacterium that couples growth to the reduction of metals and humic acids as well as chlorinated compounds.

Strain 853-15A(T) was enriched and isolated from uranium-contaminated aquifer sediment by its ability to grow under anaerobic conditions via the oxidation of lactate coupled to the reduction of anthraquinone-2,6-disulfonate (AQDS) to anthrahydroquinone-2,6-disulfonate (AHQDS). Lactate was oxidized incompletely to acetate and carbon dioxide according to the reaction CH3CHOHCOO(-)+ 2AQDS+H2O --> CH3COO(-)+ 2AHQDS+CO2. Additional electron donors utilized included formate, ethanol, butanol, butyrate, malate and pyruvate. Lactate also supported growth with Fe(III) citrate, Mn(IV) oxide, humic substances, elemental sulfur, 3-chloro-4-hydroxyphenylacetate, trichloroethylene or tetrachloroethylene serving as the electron acceptor. Growth was not observed with sulfate, sulfite, nitrate or fumarate as the terminal electron acceptor. The temperature optimum for growth was 30 degrees C, but growth was also observed at 20 and 37 degrees C. The pH optimum was approximately 7.0. The 16S rDNA sequence of strain 853-15A(T) suggested that it was most closely related to Desulfitobacterium dehalogenans and closely related to Desulfitobacterium chlororespirans and Desulfitobacterium frappieri. The phylogenetic and physiological properties exhibited by strain 853-15A(T) (= ATCC BAA-636(T)) place it within the genus Desulfitobacterium as the type strain of a novel species, Desulfitobacterium metallireducens sp. nov.

Anaerobiosis↗
PubMed2004

Synthesis and characterization of a discotic uranium-containing liquid crystal.

The synthesis of several UO(2)-alaskaphyrin derivatives functionalized with aliphatic chains is described. These compounds are found to be liquid-crystalline and form columnar mesophases, as judged from polarizing optical microscopy studies, and represent the first uranium-containing discotic mesogens.

Journal Article↗
PubMed1998

Determination of 226Ra in mineral drinking waters by alpha liquid scintillation with rejection of beta-gamma emitters.

The radiotoxicity of radium isotopes (especially the long-half-life 226Ra) requires their monitoring in drinking waters or nuclear wastes. We studied the applicability of the PERALS method of detection (photon electron rejecting alpha liquid scintillation) for radium measurement. This method combines alpha liquid scintillation with pulse shape analysis for beta rejection and specific chemical extractants included in the scintillating cocktail. Radium is separated by an extractive-scintillator cocktail called RADAEX containing 2-methyl-2-heptylnonanoic acid (HMHN) and dicyclohexano-21-crown-7 (Cy(2)21C7) as extractant molecules. The variation of the radium extraction has been studied relative to pH, salt concentrations, anion and cation effects, and the volume ratio between aqueous and organic phases. The main parameter affecting the radium extraction in mineral drinking water is its complexation by inorganic anions, especially sulfate. Due to the lack of thermodynamic data, some complexation constants had to be determined. For instance, the value reported in this paper for radium sulfate (log beta = 2.58 +/- 0.22) is in good agreement with that from the literature. The knowledge of complexation constants allows the determination of radium extraction recovery for any solution when the inorganic anion concentrations had been measured by capillary zone electrophoresis. The detection limit for this technique is found to be equal to 0.006 Bq.L-1 using only 6 mL of sample solution for analysis. Several French mineral waters have been studied and the results compared with determinations of uranium and thorium concentrations by ICPMS and time-resolved laser induced fluorescence (TRLIF).

Beta Particles↗
PubMed1996

Deliberate overdose of uranium: toxicity and treatment.

A case is described of deliberate ingestion of 15 g of uranium acetate which resulted in acute renal failure requiring dialytic therapy for 2 weeks, refractory anaemia, rhabdomyolysis, myocarditis, liver dysfunction with a disproportionate coagulopathy and paralytic ileus. Despite significant elevations in plasma uranium levels, treatment with both calcium EDTA and calcium DTPA were ineffective in promoting uranium excretion. Six months later the initial significant renal impairment exists with a persistent incomplete Fanconi syndrome. Future options for management of this unusual cause of acute renal failure are discussed.

Acute Kidney Injury↗
PubMed1997

Acquired resistance to rechallenge injury with uranyl acetate in LLC-PK1 cells.

This study was conducted to determine whether cultured renal cells exposed to previous uranium injury would be resistant to subsequent insult, and if so, the mechanisms for this resistance. The addition of a toxic dose of uranyl acetate (UA) (1 X 10(-3) mol/L) for 48 hours to the culture medium significantly enhanced the release of lactate dehydrogenase (LDH) from LLC-PK1 cells, expressed as LDH activity in the medium corrected by protein content of the cells, compared with control conditions (31.5 +/- 3.6 vs 5.5 +/- 0.6 Wroblewski unit/microg protein, p < 0.01). Pretreatment with a toxic dose of UA (1 x 10(-3) mol/L for 24 hours) or heat stress (42 degrees C for 30 minutes) significantly lessened the extent of increase in LDH after exposure to toxic doses of UA for 48 hours (15.2 +/- 1.4 and 7.6 +/- 0.6 Wroblewski unit/microg protein, respectively). Pretreatment with a nontoxic dose of UA (3 x 10(-4) mol/L for 24 hours) had no effect on the release of LDH after a toxic dose of UA treatment (38.6 +/- 7.0 Wroblewski unit/microg protein). Quercetin (100 microm ) and staurosporine (0.1 microg/ml), both known to inhibit the development of thermotolerance, hindered acquisition of the resistance to rechallenge with UA (42.5 +/- 1.1 and 38.9 +/- 1.8 Wroblewski unit/microg protein, respectively). Quercetin did not modify the UA-induced increase in the release of LDH in cells not pretreated with UA or heat stress. It follows from these findings that LLC-PK1 cells previously exposed to a toxic dose of UA are resistant to rechallenged insult and that mechanisms similar to those for thermotolerance might contribute to this acquired resistances.

Animals↗
PubMed2000

Basicity of uranyl oxo ligands upon coordination of alkoxides.

Uranium(VI) alkoxide complexes are prepared via metathesis reactions of [UO2Cl2(THF)2]2 with potassium alkoxides in nonaqueous media. The dark red compound U[OCH2C(CH3)3]6, 1, results from redistributive exchange of oxo and neopentoxide ligands between more than one uranium species. Single-crystal X-ray diffraction analysis of 1 reveals a monomer in which the uranium is coordinated in a pseudooctahedral fashion by six neopentoxide ligands. Imposition of steric congestion at the metal center prevents oxo-alkoxide ligand exchange in the reactions using more sterically demanding alkoxides. Simple metathesis between uranyl chloride and alkoxide ligands occurs in the synthesis of golden yellow-orange UO2(OCHPh2)2(THF)2, 2, and yellow UO2[OCH(tBu)Ph]2(THF)2, 3. Single-crystal X-ray diffraction analysis of 2 reveals a monomer in which the uranium is coordinated in a pseudooctahedral fashion by two apical oxo ligands, two diphenylmethoxide ligands occupying trans positions, and two tetrahydrofuran ligands. Coordination of diisopropylmethoxide allows for synthesis of a more complex binary alkoxide system. Single-crystal X-ray diffraction analysis of watermelon red [UO2(OCH(iPr)2)2]4, 4, reveals a tetramer in which each uranium is coordinated in a pseudooctahedral fashion by two apical oxo ligands, one terminal alkoxide, two bridging alkoxide ligands, and one bridging oxo ligand from a neighboring uranyl group. These compounds are characterized by elemental analysis, 1H NMR, infrared spectroscopy, and, for 1, 2, and 4, single-crystal X-ray diffraction analysis. Luminescence spectroscopy is employed to evaluate the extent of aggregation of compounds 2-4 in various solvents. Vibrational spectroscopic measurements of 2-4 imply that, in contrast to the case of uranyl complexes prepared in aqueous environments, coordination of relatively strongly donating alkoxide ligands allows for enhancement of electron density on the uranyl groups such that the uranyl U=O bonds are weakened. Crystal data are as follows. 1: monoclinic space group C2/m, a = 10.6192(8) A, b = 18.36(1) A, c = 10.6151(8) A, beta = 109.637(1) degrees, V = 1949.1(3) A3, Z = 2, dcalc = 1.297 g cm-3. Refinement of 2065 reflections gave R1 = 0.045. 2: monoclinic space group P2(1)/c, a = 6.1796(4) A, b = 15.669(1) A, c = 16.169(1) A, beta = 95.380(1) degrees, V = 1558.7(2) A3, Z = 2, dcalc = 1.664 g cm-3. Refinement of 3048 reflections gave R1 = 0.036. 4: tetragonal space group I4, a = 17.8570(6) A, b = 17.8570(6) A, c = 11.4489(6) A, V = 3650.7(3) A3, Z = 2, dcalc = 1.821 g cm-3. Refinement of 1981 reflections gave R1 = 0.020.

Journal Article↗