Uranyl nitrate-induced acute renal failure in the rat: micropuncture and renal hemodynamic studies.
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Acute Kidney Injury↗
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Three-dimensional reconstruction of thick filaments from Limulus and scorpion muscle.
We have produced three dimensional reconstructions, at a nominal resolution of 5 nm, of thick filaments from scorpion and Limulus skeletal muscle, both of which have a right-handed four-stranded helical arrangement of projecting subunits. In both reconstructions there was a distinct division of density within projecting subunits consistent with the presence of two myosin heads. Individual myosin heads appeared to be curved, with approximate dimensions of 16 X 5 X 5 nm and seemed more massive at one end. Our reconstructions were consistent with the two heads in a projecting subunit being arranged either antiparallel or parallel to each other and directed away from the bare zone. Although we cannot exclude the second of these interpretations, we favor the first as being more consistent with both filament models and also because it would enable easy phosphorylation of light chains. The antiparallel interpretation requires that the two heads within a subunit derive from different myosin molecules. In either interpretation, the two heads have different orientations relative to the thick filament shaft.
Animals↗
Acute accidental inhalation of U: a 38-year follow-up.
The intake and deposition of U in three men accidentally exposed to soluble natural U compounds in an explosion in 1944 were reevaluated 38 y later by the U.S. Uranium Registry. The initial lung depositions were estimated to be about 40-50 mg of U based on the fragmentary urinary excretion data obtained shortly after the accident. The initial long-term bone deposition was estimated from individual excretion curves and was 410 micrograms (5.2 Bq) in the highest exposed individual, which resulted in an integrated 40-y dose equivalent to the bone surfaces approximately 2 mSv (200 mrem). Medical and health physics examinations of two of the men 38 y after the accident revealed no detectable deposition of U nor any physical findings attributable to U exposure. One of the exposed individuals showed an altered clearance pattern for U shortly after the accident, possibly from pulmonary edema associated with concomitant exposure to acid fumes.
Accidents, Occupational↗
The structure of cytochrome b 5 at 2.0 Angstrom resolution.
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Amino Acid Sequence↗
Effect of metal ions on the lysis of yeast cells by cationic dyes and surfactants.
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Coloring Agents↗
Periplasmic cytochrome c3 of Desulfovibrio vulgaris is directly involved in H2-mediated metal but not sulfate reduction.
Kinetic parameters and the role of cytochrome c(3) in sulfate, Fe(III), and U(VI) reduction were investigated in Desulfovibrio vulgaris Hildenborough. While sulfate reduction followed Michaelis-Menten kinetics (K(m) = 220 micro M), loss of Fe(III) and U(VI) was first-order at all concentrations tested. Initial reduction rates of all electron acceptors were similar for cells grown with H(2) and sulfate, while cultures grown using lactate and sulfate had similar rates of metal loss but lower sulfate reduction activities. The similarities in metal, but not sulfate, reduction with H(2) and lactate suggest divergent pathways. Respiration assays and reduced minus oxidized spectra were carried out to determine c-type cytochrome involvement in electron acceptor reduction. c-type cytochrome oxidation was immediate with Fe(III) and U(VI) in the presence of H(2), lactate, or pyruvate. Sulfidogenesis occurred with all three electron donors and effectively oxidized the c-type cytochrome in lactate- or pyruvate-reduced, but not H(2)-reduced cells. Correspondingly, electron acceptor competition assays with lactate or pyruvate as electron donors showed that Fe(III) inhibited U(VI) reduction, and U(VI) inhibited sulfate loss. However, sulfate reduction was slowed but not halted when H(2) was the electron donor in the presence of Fe(III) or U(VI). U(VI) loss was still impeded by Fe(III) when H(2) was used. Hence, we propose a modified pathway for the reduction of sulfate, Fe(III), and U(VI) which helps explain why these bacteria cannot grow using these metals. We further propose that cytochrome c(3) is an electron carrier involved in lactate and pyruvate oxidation and is the reductase for alternate electron acceptors with higher redox potentials than sulfate.
Cytochrome c Group↗
Mechanisms of biodegradation of metal-citrate complexes by Pseudomonas fluorescens.
Biodegradation of metal-citrate complexes by Pseudomonas fluorescens depends on the nature of the complex formed between the metal and citric acid. Bidentate Fe(III)-, Ni-, and Zn-citrate complexes were readily biodegraded, but the tridentate Cd- and Cu-citrate, and U-citrate complexes were not. The biodegradation of Ni- and Zn-citrate commenced after an initial lag period; the former showed only partial (70%) degradation, whereas the latter was completely degraded. Uptake studies with 14C-labeled citric acid and metal-citrate complexes showed that cells grown in medium containing citric acid transported free citric acid at the rate of 28 nmol min-1 and Fe(III)-citrate at the rate of 12.6 nmol min-1 but not Cd-, Cu-, Ni-, U-, and Zn-citrate complexes. However, cells grown in medium containing Ni- or Zn-citrate transported both Ni- and Zn-citrate, suggesting the involvement of a common, inducible transport factor. Cell extracts degraded Fe(III)-, Ni-, U-, and Zn-citrate complexes in the following order: The cell extract did not degrade Cd- or Cu-citrate complexes. These results show that the biodegradation of the U-citrate complex was limited by the lack of transport inside the cell and that the tridentate Cd- and Cu-citrate complexes were neither transported inside the cell nor metabolized by the bacterium.
Adaptation, Physiological↗
An abbreviated method of the double lead stain technique.
An enhanced staining of cellular organelles and cytoplasmic matrix is observed when ultrathin sections for electron microscopy are stained for 1-5 min in fresh Reynolds' lead citrate, rinsed in distilled water and dried prior to staining with a saturated solution of uranyl acetate (40 min) and Reynolds' lead citrate (20 min), Daddow (1983). The above procedure was recommended for tissues with poor staining qualities either from prolonged fixation or inadequacies of the buffer or the embedding medium used. Using an abbreviated method of the above (i.e., 30 sec lead citrate, 60 sec saturated uranyl acetate and 30 sec lead citrate), overfixed or normally fixed tissues show enhanced contrast. Sodium hydroxide (0.02 M), substituted for the initial lead stain, increases contrast to a lesser extent.
Animals↗
The three-dimensional structure of ribonuclease-S. Interpretation of an electron density map at a nominal resolution of 2 A.
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Acetates↗
The action of chelating agents in experimental uranium intoxication in mice: variations with structure and time of administration.
The determination of the relative abilities of 11 chelating agents to enhance the urinary and fecal excretion of uranium when administered 10 min after uranyl acetate dihydrate (UAD) in mice showed that the most effective of these were Tiron, desferrioxamine, and 1,2-dimethyl-3-hydroxypyrid-4-one. An increase in the interval between UAD administration and that of the chelating agent drastically reduces the net mobilization of the uranium by the chelating agents examined. When given shortly after UAD, Tiron produced the greatest reduction in renal and bone levels of uranium. None of the chelating agents were able to affect the bone levels of uranium when administered 24 hr or more after the administration of the UAD.
Animals↗
Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) as an antidote for acute uranium intoxication in mice.
Tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate) administered intraperitoneally was found to antagonize the lethal action of intraperitoneally induced uranium(VI) toxicity. In a comparative study Tiron was evaluated against Na3CaDTPA (sodium calcium diethylenetriaminepentaacetate). The ability of these compounds to detoxify the uranyl ion in simple and complexed form and their efficacy in delayed treatment regimens and determined. Toxicities of the complexes were assessed by the administration of uranyl acetate at levels of 40 mg/kg or 80 mg/kg complexed at a mole ratio of 3:1 or 2:1 of chelating agent to uranium, prior to injection, followed by two additional doses of chelating agent given one and three hours later at a 10:1 mole ratio of chelating agent to uranium. Therapy in delayed treatment regimens consisted of three injections of antidote given 20 minutes, one hour, and three hours, at a 10:1 mole ratio of chelating agent to uranium, subsequent to an injection of 40 mg/kg uranyl acetate. Survival rates for animals receiving multiple injections of Tiron were enhanced over those receiving Na3CaDTPA. The low inherent toxicity of Tiron may make it appropriate for possible clinical application.
1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
Excision of uranium oxide chains and ribbons in the novel one-dimensional uranyl iodates K(2)[(UO(2))3(IO(3))(4)O(2)] and Ba[(UO(2)2(IO(3))(2)O(2)](H(2)O).
The alkali metal and alkaline-earth metal uranyl iodates K(2)[(UO(2))(3)(IO(3))(4)O(2)] and Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) have been prepared from the hydrothermal reactions of KCl or BaCl(2) with UO(3) and I(2)O(5) at 425 and 180 degrees C, respectively. While K(2)[(UO(2))(3)(IO(3))(4)O(2)] can be synthesized under both mild and supercritical conditions, the yield increases from <5% to 73% as the temperature is raised from 180 to 425 degrees C. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), however, has only been isolated from reactions performed in the mild temperature regime. Thermal measurements (DSC) indicate that K(2)[(UO(2))(3)(IO(3))(4)O(2)] is more stable than Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) and that both compounds decompose through thermal disproportionation at 579 and 575 degrees C, respectively. The difference in the thermal behavior of these compounds provides a basis for the divergence of their preparation temperatures. The structure of K(2)[(UO(2))(3)(IO(3))(4)O(2)] is composed of [(UO(2))(3)(IO(3))(4)O(2)](2)(-) chains built from the edge-sharing UO(7) pentagonal bipyramids and UO(6) octahedra. Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O) consists of one-dimensional [(UO(2))(2)(IO(3))(2)O(2)](2)(-) ribbons formed from the edge sharing of distorted UO(7) pentagonal bipyramids. In both compounds the iodate groups occur in both bridging and monodentate binding modes and further serve to terminate the edges of the uranium oxide chains. The K(+) or Ba(2+) cations separate the chains or ribbons in these compounds forming bonds with terminal oxygen atoms from the iodate ligands. Crystallographic data: K(2)[(UO(2))(3)(IO(3))(4)O(2)], triclinic, space group P_1, a = 7.0372(5) A, b = 7.7727(5) A, c = 8.9851(6) A, alpha = 93.386(1) degrees, beta = 105.668(1) degrees, gamma = 91.339(1) degrees, Z = 1; Ba[(UO(2))(2)(IO(3))(2)O(2)](H(2)O), monoclinic, space group P2(1)/c, a = 8.062(4) A, b = 6.940(3) A, c = 21.67(1), beta= 98.05(1) degrees, Z = 4.
Journal Article↗
Uranyl ion complexation by citric and tricarballylic acids: hydrothermal synthesis and structure of two- and three-dimensional uranium-organic frameworks.
The first crystal structure of uranyl citrate is reported, as well as that of uranyl sodium tricarballylate; both compounds are polymeric, with all acid groups coordinated, but they differ strongly in their coordination modes; the resulting assembly architecture is either three-dimensional with [(UO2)2(Hcit)2]2- metallacycle subunits with citrate or two-dimensional with tricarballylate.
Journal Article↗
The effect of groundwater composition on uranium(VI) sorption onto bacteriogenic iron oxides.
In this study, we investigated the effect of groundwater composition on the sorption of U(VI) onto bacteriogenic iron oxides (BIOS) and synthetic ferrihydrite (HFO). The concentration of carbonate was found to be the key factor controlling U(VI) sorption onto both BIOS and HFO. However, the efficiency of HFO to adsorb uranium(VI) was higher than that of BIOS at pH 7.0. The pH value also played an important role on the U(VI) sorption onto iron oxides. U(VI) sorption onto BIOS was optimum in the pH range 3-4.5, whereas in the same pH range, the ability of HFO to adsorb U(VI) was very low. HFO was very efficient in adsorbing U(VI) in the pH range 4.5-6.5. Zeta potential measurements have been employed to understand the different removal trends between BIOS and HFO. BIOS had a negative surface charge across the whole pH range examined, in contrast to HFO, which had point of zero charge 7.6. The sorption results have been incorporated in a surface complexation model, which predicted adequately the pH-dependent sorption of U(VI) onto both types of iron oxides.
Adsorption↗
Surface chemical characterization of 2.5-microm particulates (PM2.5) from air pollution in Salt Lake City using TOF-SIMS, XPS, and FTIR.
Particulate matter with a diameter of 2.5 microm collected in Salt Lake City (SLC PM2.5) was studied using TOF-SIMS (time-of-flight secondary-ion mass spectrometry), XPS (X-ray photoelectron spectroscopy), and FTIR (Fourier transform infrared spectroscopy). The high spatial resolution and high surface sensitivity of TOF-SIMS allow the surfaces of individual particulates to be analyzed. The high mass-resolution of TOF-SIMS provides good separation of signals from different chemical species at the same nominal mass, and the extremely high detection sensitivity of TOF-SIMS makes the detection of trace elements possible. Metallic elements such as Li, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Cu, Zn, Cs, and Bi were detected by TOF-SIMS on the surface of SLC PM25. The uranium ion U+ together with its oxide ions UO+ and UO2+ were also found. Inorganic compounds detected include oxides, hydroxides, nitrates, sulfates, silicates, borates, chlorides, etc. Organic compounds detected include hydrocarbons, alcohols, aldehydes, ethers, carboxylic acids, amines, amides, nitriles, etc. A number of polycyclic aromatic hydrocarbons (PAH) and nitrated polycyclic aromatic hydrocarbons were detected by TOF-SIMS. High-resolution XPS Cls spectrum shows functional groups such as C-O, CO2, C-CO2, C-C, and C-H and aromatic pi-pi* shake-up transitions. High-resolution XPS O 1s spectrum indicates the coexistence of different oxygen compounds on the surface of PM2.5. FTIR results confirm the presence of various organic compounds in SLC PM2.5 detected by TOF-SIMS and XPS.
Air Pollutants↗
Combined action of uranium and stress in the rat. II. Effects on male reproduction.
The effects of stress on the potential reproductive toxicity of long-term exposure to uranyl acetate dihydrate (UAD) were assessed in adult male rats. Six groups of animals were given UAD at 10, 20, and 40 mg/kg/day in the drinking water during 3 months. Animals in three of these groups were also subjected to restraint for 2 h/day during the same period. Control groups included restrained and unrestrained male rats not exposed to UAD. To evaluate the fertility, male rats were mated with untreated females for 2 weeks. Although body weight was not affected by uranium at any dose, there was a significant (not dose-related) decrease in the pregnancy rate. Moreover, spermatid number/testis was significantly decreased by uranium administration. Histopathological examination of the testes in rats killed after 3 months of treatment revealed few differences in the tubule and interstitial alterations (focal atrophy, binucleated cells) between control and uranium-exposed animals. The results of this investigation show that at the current UAD doses, restraint stress did not enhance the uranium-induced adverse effects on reproduction in male rats.
Animals↗
Comparative effects of the chelators sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) and diethylenetriaminepentaacetic acid (DTPA) on acute uranium nephrotoxicity in rats.
Sodium 4,5-dihydroxybenzene-1,3-disulfonate (Tiron) and diethylenetriaminepentaacetic acid (DTPA) are two chelating agents that have been demonstrated to be effective in the treatment of experimental poisoning by a number of heavy metals. In this study, the effects of Tiron and DTPA on uranium-induced nephrotoxicity were evaluated in a rat model. A series of four Tiron or DTPA injections was administered intraperitoneally to adult male Sprague-Dawley rats immediately after a single subcutaneous injection of uranyl acetate dihydrate (5 mg/kg) and at 24, 48 and 72 h thereafter. Positive and negative control groups received 0.9% saline with or without uranyl acetate, respectively. Tiron effectiveness was assessed at 400, 800 and 1600 mg/kg, whereas DTPA was administered at 250, 500 and 1000 mg/kg. Although the urinary excretion of uranium was significantly enhanced by Tiron administration, significant amounts of uranium still remained in the kidney at the end of the treatment. However, the partial reduction of the renal uranium concentrations was in accordance with the amelioration noted in some urinary and serum indicators of uranium nephrotoxicity. Moreover, Tiron administration also reduced the severity of the uranium-induced histological alterations in the kidney. According to these results, Tiron offers only a modest encouragement with regard to its possible therapeutic potential to treat acute uranium-induced nephrotoxic effects. In turn, DTPA was less effective than Tiron in protecting against the nephrotoxicity of uranium in rats.
1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
Carbonate effects on hexavalent uranium adsorption by iron oxyhydroxide.
Carbonate dramatically affects the adsorption of uranium (U(VI)) onto iron hydroxides and its mobility in the natural environment. Batch tests, zeta potential measurements, and Fourier transform infrared (FTIR) spectroscopic studies were utilized to characterize the nature of U(VI) adsorption on ferrihydrite. Adsorption isotherms demonstrated that carbonate had a negative effect on U(VI) adsorption on ferrihydrite at pH > 6. Zeta potential measurements indicated that U(VI) was adsorbed as a cationic species (SO-UO2+) in the absence of carbonate and as anionic U(VI) complexes in the presence of carbonate at neutral pH. FTIR spectroscopic measurement of adsorbed U(VI) suggested that it was retained as uranyl carbonate complexes in the presence of carbonate. An increase in carbonate concentration caused a shift in the antisymmetric stretching vibration of the uranyl (UO2(2+)) U-O bond toward lower wavenumbers, which indicated an increasing carbonate effect in the adsorbed uranyl carbonate complexes. The adsorbed U(VI) species were successfully incorporated into a surface complexation model to describe the adsorption of U(VI) by ferrihydrite from artificial solutions and contaminated water.
Adsorption↗