Iron-55 levels in humans living in Richland, Washington-1968. BNWL-1051.
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Adult↗
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Results for “IRON, RADIOACTIVE”
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Iron-55 in the human population of the world. II. Physical sciences. 2. Radiological sciences. BNWL-1307.
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Age Factors↗
[The coefficients of iron-59 radioisotope accumulation by several species of fresh-water plants].
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Iron Isotopes↗
Determination of 90Sr in contaminated environmental samples by tuneable bandpass dynamic reaction cell ICP-MS.
A rapid method for the extraction and determination of 90Sr in natural water, plant and sediment samples was developed using extraction chromatography and dynamic reaction cell ICP-MS, with O2 as a reaction gas. While isobaric interference from the stable isotope 90Zr was efficiently removed by this method, interferences produced from in-cell reactions with Fe+ and Ni+ required suppression by tuneable bandpass, and in sediments, additional chromatographic separation. Method detection limits were 0.1 pg g-1 (0.5 Bq g-1), 0.04 pg g-1(0.2 Bq g-1), and 3 pg L-1 (5 Bq L-1) for sediments, plant and water samples, respectively, and 90Sr concentrations determined by ICP-MS were in good agreement with activities determined by Cerenkov counting and with certified reference values. While mass spectrometric determination does not rival detection limits achievable by radiometric counting, radiometric determination of 90Sr, a pure beta-emitter, is hindered by long analysis times (several weeks); the comparatively fast analysis achieved via ICP-MS enables same-day preparation and analysis of samples, making this an important technique for the environmental monitoring of areas contaminated by radioactivity.
Chromatography, Liquid↗
[A new milk formula: iron bioavailability and effect on prevention of iron deficiency in infants].
Iron bioavailability from a modified cow milk, formula (LPM) (which included additional iron as 5 mg/l ferrous sulfate and ascorbic acid, 50 mg/l) was examined in 11 adult women using the extrinsic radioactive tag method. The geometric mean absorption from LPM was 13% (reference dose absorption = 26%). The effect of this formula on iron nutrition of infants was studied in 43 healthy term infants weaned spontaneously before 3 months of age which were given LPM until 9 months of age. Another 45 infants (controls) were fed full fat, non fortified powdered cow's milk (LP) as delivered through the National Complementary Food Program (PNAC-Chile) and additional 45 infants were given fortified a cow's milk formula (LF) with ferrous sulfate (iron: 15 mg/l and ascorbic acid: 100 mg/l). Solid foods (vegetables and meat) were introduced to all these babies from age 4 months. At 9 months of age 4% infants fed LPM had evidence of anemia vs. 2% and 20% of infants given LF and LP formulae respectively. This results suggests that LPM is effective in preventing iron deficiency anemia in infants.
Adult↗
Production of free radicals arising from the surface activity of minerals and oxygen. Part I. Iron mine ores.
The excess incidence of lung cancers observed in many metal mines probably is not only correlated with radioactivity but also with the inhaled dusts. In an attempt to determine a possible mechanism of carcinogenicity related to the surface activity of dusts, using the spin-trapping agent and ESR spectroscopy, one can demonstrate that some mineral dusts from iron ore mines are very active in an oxidative process in aqueous medium, implying the formation of radical oxygen species on reducing surface sites of the solid. This reducing surface activity of the dusts depends on the presence of Fe2+ ion in the lattice and on the process of activation and passivation of the surface sites. The more simple process of activation is the dissolution of the oxidized coating on the particle surface. Among the oxides, oxyhydroxides, carbonates, and silicates, the magnesium-iron phyllosilicates (chlorite, biotite, berthierine) appear the most active. The siderite FeCO3 is also active, but the iron oxides and oxyhydroxides are generally nonactive.
Free Radicals↗
Coordination chemistry of microbial iron transport compounds: rhodotorulic acid and iron uptake in Rhodotorula pilimanae.
The mechanism by which iron uptake is facilitated by the siderophore rhodotorulic acid (RA) in the yeast Rhodotorula pilimanae was investigated with radioactively labeled Fe and RA and kinetically inert, chromic-substituted RA complexes. The weight of the evidence supports a model in which RA mediates iron transport to the cell but does not actually transport iron into the cell. It is proposed that RA exchanges the ferric ion at the cell surface with a membrane-bound chelating agent that completes the active transport of iron into the cell. Uptake of 55Fe in ferric rhodotorulate was much more rapid than uptake of RA itself. Two exchange-inert chromic complexes of RA showed no uptake.
Biological Transport, Active↗
The kinetics of iron metabolism in swine with various experimentally induced anemias.
Ferrokinetic studies were performed on 3 swine given phenylhydrazine, 3 swine deficient in pyridoxine, and 3 swine deficient in pteroylglutamic acid. Body surface radioactivity was measured in 2 pteroylglutamic acid-deficient animals. In the animals given phenylhydrazine, the mean erythrocyte survival time was 5 days. The plasma iron turnover rate was increased about fourfold, and the rate of erythropoiesis was four to five times greater than that in the control pigs. In the pyridoxine-deficient swine, the mean erythrocyte survival time was within the limits of normal. The plasma iron turnover rate was increased fourfold, but the rate of erythropoiesis was approximately one-fourth the normal mean value. These data are interpreted as indicating that the anemia associated with this deficiency is a result of an inability of the bone marrow to produce a normal number of erythrocytes. In the pteroylglutamic acid-deficient swine, the mean erythrocyte survival time was 17 days. The plasma iron turnover rate was 5 times the normal mean value. The rate of erythropoiesis was 1.6 times greater than the mean value in the control pigs. These data are interpreted as indicating that anemia develops in this deficiency as a result of a combination of a shortening of the erythrocyte survival time and a limitation of the capacity of the bone marrow to increase red cell production to the same degree as a normal marrow. The radioactivity in the liver, spleen, and bone marrow of the pteroylglutamic acid-deficient swine, as determined by measurement of the radioactivity over the body surface, declined more slowly than in control pigs.
Anemia↗
TREATMENT OF ANTRAL CARCINOMA WITH RADIOACTIVE IRIDUM.
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Anemia, Iron-Deficiency↗
Trichloroacetic acid (TCA) precipitability of 125I in the blood of mice fed 125I.
A recent study showed that after feeding 125I-labelled proteins or free 125I to mice, as much as 40% of total radioactivity in the circulation precipitated upon mixing whole blood with 10% trichloroacetic acid. We examined this potential limitation to the use of radiolabelled tracers for studies on intestinal digestion of proteins and protein uptake, and identified its mechanism. BALB/c mice were gavage-fed or injected intravenously (i.v.) with Na125I. Blood obtained at 15 min was added directly to 10% trichloroacetic acid (TCA) or was processed to obtain serum or plasma. On mixing with 10% TCA, 25-33% of the radioactivity in whole blood was precipitated; less than 2% of the radioactivity in plasma or serum was precipitated. In vitro studies identified hemoglobin as the primary carrier protein participating in this reaction. If hemoglobin was replaced by methemoglobin or cyanomethemoglobin, then the reaction with 125I did not occur, suggesting that iron in the heme group may be the site for 125I binding and that iron must be in its reduced or ferrous form (Fe2+). The administration of non-radioactive NaI in vivo or its addition to reaction mixtures in vitro completely inhibited the precipitation of 125I by hemoglobin in the presence of TCA. Thus the addition of non-radioactive iodide to TCA stock solutions may effectively prevent non-specific binding of 125I to free hemoglobin released unintentionally during venipuncture or at other stages of blood processing.
Animals↗
Micrometer-sized short-lived radioactive aerosol particles for convenient use in laboratory measurements.
For calibration and testing of radioactive aerosol measuring equipment such as continuous air monitors and cascade impactors, and other research applications, it is helpful to have a convenient and relatively safe means of producing radioactive aerosol particles of controlled size and activity. We describe a technique for producing such particles in the micrometer-diameter size range using electrostatic deposition of radon decay products onto otherwise nonradioactive powders of different sizes. An electric field focuses radon decay products (primarily 218Po) onto the surface of a powdered substrate that is then suspended by a technique such as pneumatic dry dispersion. Only a modest-activity commercial 222Rn source (e.g., containing as little as 10(5) Bq of 226Ra) is required, and issues of radioactive cleanup and contamination are minimized due to the short half-lives (26.8 min or less) of the decay products. We report representative results using powders of glass beads, iron oxide, and iron and gold metals in the size range of 0.3 to 30 microm. Yields for the deposited radioactivity per unit concentration of 222Rn gas were of the order of 5 x 10(-7) Bq (214Bi) per milligram substrate per Bq m(-3) of 222Rn for an electrostatic collection time of 30 min.
Aerosols↗
The mammalian neuroendocrine hormone norepinephrine supplies iron for bacterial growth in the presence of transferrin or lactoferrin.
Norepinephrine stimulates the growth of a range of bacterial species in nutritionally poor SAPI minimal salts medium containing 30% serum. Addition of size-fractionated serum components to SAPI medium indicated that transferrin was required for norepinephrine stimulation of growth of Escherichia coli. Since bacteriostasis by serum is primarily due to the iron-withholding capacity of transferrin, we considered the possibility that norepinephrine can overcome this effect by supplying transferrin-bound iron for growth. Incubation with concentrations of norepinephrine that stimulated bacterial growth in serum-SAPI medium resulted in loss of bound iron from iron-saturated transferrin, as indicated by the appearance of monoferric and apo- isoforms upon electrophoresis in denaturing gels. Norepinephrine also caused the loss of iron from lactoferrin. The pharmacologically inactive metabolite norepinephrine 3-O-sulfate, by contrast, did not result in iron loss from transferrin or lactoferrin and did not stimulate bacterial growth in serum-SAPI medium. Norepinephrine formed stable complexes with transferrin, lactoferrin, and serum albumin. Norepinephrine-transferrin and norepinephrine-lactoferrin complexes, but not norepinephrine-apotransferrin or norepinephrine-albumin complexes, stimulated bacterial growth in serum-SAPI medium in the absence of additional norepinephrine. Norepinephrine-stimulated growth in medium containing (55)Fe complexed with transferrin or lactoferrin resulted in uptake of radioactivity by bacterial cells. Moreover, norepinephrine-stimulated growth in medium containing [(3)H]norepinephrine indicated concomitant uptake of norepinephrine. In each case, addition of excess iron did not affect growth but significantly reduced levels of radioactivity ((55)Fe or (3)H) associated with bacterial cells. A role for catecholamine-mediated iron supply in the pathophysiology of infectious diseases is proposed.
Animals↗
Energy-independent uptake of iron from citrate by isolated outer membranes of Neisseria meningitidis.
Cyanide-poisoned Neisseria meningitidis SD1C cells rapidly took up 55Fe from iron-citrate complexes during the first 2 min, after which no further iron was accumulated. [14C]citrate was not taken up concomitantly with 55Fe by these cells. The 55Fe taken up by the poisoned cells was found in the membrane fraction after cells were broken; 70% of the radioactivity was distributed in the outer membrane, and 30% was in the inner membrane. Isolated outer membranes from iron-starved cells were as capable of iron uptake from citrate as intact cells were. As with whole cells, [14C]citrate was not taken up by isolated outer membranes. A polyacrylamide gel electrophoresis analysis of the proteins from citrate-dialyzed outer membranes after the uptake of 55Fe revealed that the radioactivity was associated with a major band of 36,500 molecular weight.
Bacterial Proteins↗
Antibiotic action of N-methylthioformohydroxamate metal complexes.
The antibiotic activity of metal complexes of N-methylthioformohydroxamic acid against gram-negative Escherichia coli NIHJ and gram-positive Staphylococcus aureus 209P was investigated. The kinetically labile, square-planar, divalent (Cu, Ni, and Pd) and octahedral, trivalent (Fe, Co, and Cr) complexes displayed activity, whereas the more inert platinum(II) or rhodium(III) complex displayed no activity, or activity only at elevated concentrations. The free ligand did not suppress the growth of the above organisms, and the sulfur atom of the ligand in its metal complexes appears crucial for activity. Uptake studies of radioactively labeled N-methylthioformohydroxamic acid, its nickel(II), platinum(II), iron(III), and rhodium(III) complexes were conducted in the Escherichia coli K-12 RW193 mutant, which is defective in the production of its native iron(III) transport agent, enterobactin. Uptake of (55)Fe or (63)Ni label from their metal complexes appeared to occur as free inorganic metal ions. The antibiotic activity of the iron(III) and nickel(II) complexes was not due merely to an enhanced accumulation of metal ions by the cell. Metal complexes of [(35)S]N-methylthioformohydroxamic acid enhanced the accumulation of (35)S label compared to that of the free ligand. The antibiotic activity and uptake data are discussed in terms of possible modes of action.
Anti-Bacterial Agents↗
4-methyl-5-amino-1-formylisoquinoline thiosemicarbazone, a second-generation antineoplastic agent of the alpha-(N)-heterocyclic carboxaldehyde thiosemicarbazone series.
4-Methyl-5-amino-1-formylisoquinoline thiosemicarbazone (MAIQ-1) was studied to determine its potential for clinical trail as a second-generation antineoplastic agent of the alpha-(N)-heterocyclic carboxaldehyde thiosemicarbazone class. MAIQ-1 was shown to be among the most potent known inhibitors of the major target for the expression of antineoplastic activity by this class of agents, the enzyme ribonucleoside diphosphate reductase, requiring only 0.06 micronM for 50% inhibition. This potency at the enzymatic level was consistent with its antineoplastic activity against the murine neoplasms Sarcoma 180, Leukemia L1210, Leukemia P388, and the B16 melanoma. The acetylation of the 5-amino group of the model substrate 5-amino-1,4-dimethylisoquinoline was lower than that of 5-amino-1-methylisoquinoline when incubated with acetyl-coenzyme A and rat liver homogenate. This finding suggests that the presence of the 4-methyl function offers steric hinderance to enzymatic substitution of the adjacent 5-amino group. In vivo metabolism of MAIQ-1 in mice, studied with [3'-14C]MAIQ-1 showed that relatively slow excretion of this agent occurred, since the cumulative urinary excretion of radioactivity was only 35% in 48 HR. About 51% of excreted urinary radioactivity was present in chromatograms in an area corresponding to the iron chelate of MAIQ-1, and only a minor quantity of material migrating like acetylated MAIQ-1 was present in urine, a finding consistent with enzymatic data with liver homogenates. The results indicate that MAIQ-1 has the antineoplastic activity, enzyme inhibitory potency, and relative resistance to metabolic inactivation required of an agent of this class for clinical trials.
Animals↗
The (2R)-hydroxycarboxylate-viologen-oxidoreductase from Proteus vulgaris is a molybdenum-containing iron-sulphur protein.
An oxidoreductase with an extremely broad substrate specificity reducing reversibly 2-oxocarboxylates at the expense of reduced artificial redox mediators to (2R)-hydroxycarboxylates has been purified to a specific activity of up to 1800 mumol.min-1.mg-1 for the reduction of phenylpyruvate. The membrane-bound non-pyridine nucleotide-dependent enzyme appears in the form of various oligomers of the 80-kDa monomer. The isoelectric point is 5.1. Based on a molecular mass of 80 kDa the enzyme contains up to one molybdenum, four iron and four sulphur atoms. After growth on 99Mo-labelled molybdate, enzyme and radioactivity coincided as shown by gel electrophoresis. Permanganate oxidation delivers 0.7 mol pterin-6-carboxylic acid. The molybdenum cofactor is a mononucleotide. The enzyme is inhibited by cyanide. The first 20 amino acids have been determined. The enzyme belongs to the rare group of molybdoenzymes which possess no further prosthetic groups than the iron-sulphur clusters.
Amino Acid Sequence↗
Interaction of lipid peroxidation products with nuclear macromolecules.
The interaction of lipid peroxidation products with nuclear macromolecules was investigated in rat liver nuclei labelled with [3H]arachidonic acid. Lipid peroxidation reactions were driven both non-enzymatically and enzymatically by the addition of ascorbate-Fe2+ or NADPH-ADP-Fe3+, respectively, to the incubation mixtures. The extent of peroxidation was evaluated by the formation of thiobarbituric acid chromophore and of radioactive hydrophilic peroxidation products. The results obtained show that: (1) nuclear membrane lipid peroxidation products formed during incubation interact with DNA and total nuclear proteins; (2) non-enzymatic lipid peroxidation processes induced a 40% larger association of peroxidation products to DNA compared to processes driven enzymatically, whereas the corresponding interaction with total nuclear proteins was similar in both peroxidation systems; (3) the radioactivity associated with histones decreased during incubation in the presence of ascorbate-Fe2+ or NADPH-ADP-Fe3+, and increased in control samples (no additions); (4) inhibition of lipid peroxidation by the iron chelator Desferrioxamine B prevented the association of peroxidation products to nuclear macromolecules; (5) the levels of radioactivity found in DNA after 180 min of incubation would represent the formation of 0.6-1.0 adducts per 10(6) DNA bases. The results obtained provide evidence for an interaction between lipid peroxidation products and chromatin in the interior of the cell nucleus.
Animals↗
Radiopharmaceuticals for spleen and bone marrow studies.
The spleen and bone marrow have important hematologic functions. Evaluation of bone marrow alone may be incomplete, unless the function of the spleen is studied also. In addition to hematologic functions, each organ has unique characteristics that may need to be evaluated in assessing its activity. The evaluation of the distribution of reticuloendothelial cells, through the phagocytosis of radioactive particles, provides the basis for most of the morphological and functional studies of these organs. During the past three decades, a variety of radioactive agents have been prepared and examined. Among them, colloids of 99mTc, heat-damaged 99mTc labeled RBCs, and the radionuclides of iron and indium, make possible the functional and morphological examination of the spleen and bone marrow by external scintigraphy.
Animals↗