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Intracellular localization of cerium. A microanalytical study using an electron microprobe and ionic microanalysis.
Radioactive cerium is a nuclear toxicant. Metallic cerium is used in industry. Aspects of the intracellular metabolism of this element were studied following intraperitoneal injection and aerosol exposure in rat. Two microanalytic methods, an electron microprobe and ionic microanalysis, enabled the sites of incorporation and the process of intracellular concentration of cerium to be determined in the liver, lung, kidney, bone marrow and bone tissue. The very high sensitivity of ionic analysis enabled very low concentrations of cerium to be detected with a spatial resolution of 0.5 microns. Microanalysis by electron microprobe permitted: (i) the lysosomal localization of cerium to be determined; and (ii) the lysosomal coprecipitation of cerium with phosphorus to be demonstrated. Results are discussed in relation to aspects of radiological protection.
The miseries of passive smoking.
Passive smoking is defined as an involuntary exposure to a combined but diluted cigarette sidestream smoke (SS, gas and particle phases that are evolved from the smoldering end of a cigarette while the smoker is not puffing) and the exhaled smoke from smokers. SS contains numerous cytotoxic substances such as polycyclic aromatic hydrocarbons (PAHs), aromatic amines, nitrosamines, heavy metals, poisonous gases, pesticide residues, and radioactive elements in quantities much higher than those found from the cigarette mainstream smoke (MS) which is puffed by smokers. Passive smoking is found to be the cause of death from cancers and cardiac disease. Furthermore, it damagingly involves reproductive organs, the nervous system, genetic materials, and is particularly hazardous to mother and child during pregnancy and to those with a history of asthma, chronic infections, induced or earned immune deficiency, or predisposed susceptibility.
Generation of polluted waters from mining wastes in a uranium deposit.
Dump consisting of 9500 tons of rich-in-pyrite mining wastes located in the uranium deposit Curilo, Western Bulgaria, was, after rainfall, an intensive source of acid drainage waters. These waters had a pH in the range of about 1.7-4.5 and contained radionuclides (uranium, radium), heavy metals (copper, zinc, cadmium, lead, nickel, cobalt, iron, and manganese), arsenic and sulphates in concentrations usually much higher than the relevant permissible levels for waters intended for use in the agriculture and/or industry. The generation of these polluted waters was studied under real field conditions for a period of about seven years during different climatic seasons. It was found that the dump was inhabited by a diverse microflora in which some acidophilic chemolithotrophic bacteria were the prevalent microorganisms. The solubilization of the above-mentioned pollutants from the dump material was connected mainly with the oxidation of pyrite and other sulphide minerals by these bacteria. Their activity depended on some essential environmental factors such as temperature, pH, and water, oxygen and nutrient contents in the dump.
[Current separation technics used in environmental radiochemical analysis--simple preconcentration method using supportive materials].
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Radioactive colloidal solutions and suspensions for medical use.
Radioactive colloidal solutions and suspensions are being widely used in the diagnosis and treatment of various diseases. The author considers the behaviour or radioactive disperse preparations in the body and devotes particular attention to the reasons for isotope transition from the colloidal to the ionic state. Questions concerned with producing and investigating radioactive colloidal solutions are discussed. In the light of the physical and chemical properties of the radioisotopes and of the disperse systems themselves, the author considers methods of producing the more important radioactive disperse preparations: colloidal solutions of noble metals; colloidal solutions containing phosphorus-32, yttrium-90 and isotopes of the rare-earth elements; colloidal solutions with with indium-113m, gallium-68, technetium-99m and rhenium-186; suspensions (macroaggregates and microspheres) for the diagnosis of lung diseases; and radioactive colloidal solutions based on quaternary ammonium base compounds.
The Chinese total diet study in 1990. Part I. Chemical contaminants.
The Chinese total diet study in 1990 estimated the dietary intake of 24 chemical contaminants and 72 nutrients from 4 market baskets collected and prepared in 12 provinces. Twelve food group composites were made for each regional market basket. The overall dietary Pb, Cd, Hg, hexachlorocyclohexane HCH, and DDT intakes were well below their corresponding acceptable daily intakes. However, the Pb content of eggs from the 2 southern regions exceeded the tolerance limit. The Hg content of legumes just reached the tolerance limit, and Hg in eggs from the North 1 region exceeded the tolerance limit. The dietary HCH intake has decreased significantly since the 1980s, but dietary DDT intake has decreased rather slowly. Five organophosphorus pesticides were detected out of a total of 12 organophosphorus pesticides analyzed. Among them, methamidophos was the most outstanding. The intake of total committed dose equivalents (CDEs) of the 6 radionuclides was 0.24 mSv/a; only 1.5% was accounted for by 90Sr and 137Cs. 210Pb, 210Po, 226Ra, and 228Ra accounted for 98.5% of the total CDEs. The main food sources of those radionuclides were cereals, vegetables, and aquatic foods. Aflatoxin B1 was detected at very low levels only in the cereal composite of the North 1 region. Aflatoxin M1 was not detected in any of the milk and milk products. The overall results show that there is no significant environmental contamination of the average Chinese diet.
Autoradiographic study of distribution patterns of metals which occur as corrosion products from dental restorations.
Radioactive chromium, cobalt, gold and mercury, all of which may occur as corrosion products from dental restorations, were injected in single doses via the tail vein of mice and an in vivo analysis of their distribution was performed using whole-body autoradiography. Gold seemed to be inert and went mainly to the liver and bones. The other elements studied were distributed widely in the body and remained for a long period of time in specific target organs and tissues.
A simple solution to prevent the loss of radioactive spot markers.
OBJECTIVE: Most nuclear medicine technologists have experienced the misplacing and/or the loss of a radioactive spot marker. We report on a simple solution to prevent or at least minimize the loss of radioactive spot markers. METHODS: One end of a metallic beaded chain was attached to the side of 57Co spot marker using repair putty. The other end of the beaded chain was attached to a lead shield that housed the radioactive source when not in use. RESULTS: This design has allowed easy, unobstructed use of the 57Co spot marker for marking the right or left side and anatomical position during imaging while preventing its loss. CONCLUSION: A radioactive spot marker that is attached to a lead shield by a beaded chain is a simple way to prevent its loss while allowing it to be used easily during imaging.
The use of non-radioactive chromium as an alternative to 51Cr in NK assay.
A novel method to measure target cell cytolysis based on the use of 'cold', non-radioactive chromium and on the determination of metal release by graphite furnace atomic absorption spectroscopy (FAAS) is proposed. Natural killer (NK) assays were performed by labelling target cells with chromium as Na2CrO4, and results were compared with those obtained by conventional overnight labelling with 51Cr of targets killed by the same effectors. The cytotoxic capacity of peripheral blood lymphocytes from healthy subjects was evaluated, and NK activity measured with both methods showed a good agreement at each of the tested effector to target cell ratios (between 100:1 and 1:1), with a high and significant coefficient of correlation (r = 0.931, p < 0.0001). The selection of the appropriate Cr concentrations for labelling target cells took into account both the sensitivity of our instrumentation and the possible toxic effects of the metal. A study of the effects of Cr on the cell line (K562) which is usually employed as a target in NK tests showed that Cr could have a detrimental effect on cellular function, with significant numbers of cells with depolarised mitochondria and reduced DNA synthesis after 24 h incubation using Cr levels higher than 15 mumol/l (780 micrograms/l). The method proposed here has a number of advantages, including the use of a non-radioactive tracer, limited costs, high sensitivity and reproducibility, and the possibility of storing samples. In addition, the technique uses a fixed Cr concentration which is known to be non toxic.
[On distribution of radioyttrium and radioactive rare earths in the mammaliam body. III. Metabolism studies on mice and guinea pigs with radiocerium (Ce-144-Pr-144)].
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[Study on decontamination of radioactive ruthenium by steel wool in waste solution (author's transl)].
Tracer experiments were done in order to establish a decontamination process of 106Ru in radioactive waste solution by column method paying special attention on the solution of nitratonitrosyl complex of Ru which is often encountered as a low level radioactive waste solution. It turned out that metallic iron was the most effective decontaminating agent among the several tens of materials tested. The decontamination factor (DF) of 106Ru increased in proportion to the total surface area of iron and it sensitively depended on the oxidation state of the surface as revealed by the batchwise and columnwise tests. Iron samples with high corrosiveness gave a much larger DF than those with low corrosiveness. The decontamination process proceeded as iron was being oxidized via Fe(metal)leads toFe(II)leads toFe(III). As the results, the DF initially increased after initiating the passage of water through the column but it then decreased as the oxidation process became inactive. An excellent durability up to 10000 bed volumes was demonstrated by the column method at a high average DF of 150.
Characterization of metal and nucleotide liganded forms of adenylate kinase by electrospray ionization mass spectrometry.
Complexes of adenylate kinase from Escherichia coli, Bacillus subtilis, and Bacillus stearothermophilus with the bisubstrate nucleotide analog P1,P5-di(adenosine 5')-pentaphosphate and with metal ions (Zn2+ and/or Mg2+) were analyzed by electrospray ionization mass spectrometry. P1,P5-di(adenosine 5')-pentaphosphate. adenylate kinase complex was detected in the positive mode at pH as low as 3.8. Binding of nucleotide to adenylate kinase stabilizes the overall structure of the protein and preserves the Zn2+ chelated form of the enzyme from the gram-positive organisms. In this way, it is possible in a single mass spectrometry experiment to screen metal-chelating adenylate kinases, without use of radioactively labeled compounds. Binding of Mg2+ to enzyme via P1,P5-di(adenosine 5')-pentaphosphate was also demonstrated by mass spectrometry. Although no amino acid side chain in adenylate kinase is supposed to interact with Mg2+, Asp93 in porcine muscle cytosolic enzyme, equivalent to Asp84 in the E. coli adenylate kinase, was proposed to stabilize the nucleotide.Mg2+ complex via water molecules.
PAMAM dendrimer based macromolecules as improved contrast agents.
Dendrimers are an attractive platform for macromolecular imaging due to the presence of multiple terminal groups on the exterior of the molecule. Through application of appropriate metal ion chelates, large numbers of metal ions for imaging (paramagnetic or radioopaque) and therapy (radioactive particle emitters) may be conjugated to the dendrimer in combination with a targeting vector, through classic organic synthetic techniques. Thus, a large amount of these metal ions potentially may be site specifically delivered directly into the body with the dendrimer as the vehicle with the targeting vector directing the modified dendrimer. The development of targeted macromolecular agents with acceptable blood retention times and selective organ uptake then has the potential for various biological applications. A review of comparative studies of dendrimers with various externally appended imaging and targeting agents is presented herein.
Binding of metals to cell envelopes of Escherichia coli K-12.
As representative of gram-negative bacteria, the isolated and purified envelopes of an Escherichia coli K-12 strain were used to determine metal-binding capacity. The envelopes were suspended in 5 mM metal solutions for 10 min and 23 degrees C, separated and washed by centrifugation, and analyzed for metal by either atomic absorption or X-ray fluorescence spectroscopy. Of 32 metals tested, large amounts (> 0.9 mumol/mg [dry weight]) of Hf and Os, intermediate amounts (0.1 to 0.4 mumol/mg [dry weight]) of Pb, Zn, Zr, Fe III, Mn, Mo, Mg, Co, and Ce IV, and small amounts (< 0.1 mumol/mg [dry weight]) of Na, K, Rb, Ca, Sr, Cu, Sc, La, Pr, Sm, U, Fe II, Ru, Ni, Hg, Pt, Pd, Au, and In were detected Li and V were not bound to the envelopes. Electron microscopy of unstained, thin-sectioned material provided an electron-scattering profile for localizing the bound metal within the envelope. Energy-dispersive X-ray analysis of thin sections detected all metals in single envelope vesicles. These data suggest that most metal deposition occurred at the polar head group regions of the constituent membranes or along the peptidoglycan layer. No leaching of envelope components was detected by monitoring radioactive probes within the lipopolysaccharide and peptidoglycan layers during metal uptake experiments, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins from metal-loaded envelopes, or protein and carbohydrate determinations on the wash fluids. These results suggest that membrane integrity was not disturbed under these ionic conditions.
[The immunological reactivity of children living under conditions of the action of low doses of ionizing radiation and of industrial waste].
We undertook the present studies to gain insights into the immunological reactivity of children exposed to small doses of ionizing radiation and salts of heavy metals. A total of 1500 children were examined who live in Sumy Province areas affected by varying levels of radioactive contamination. Increased morbidity, with thyroid hyperplasia being noted more often than not, has come to be recorded among children residing in the territories contaminated with discharges of salts of heavy metals and small doses of ionizing radiation. Imbalance of the thyroid and immune systems has been disclosed. The degree of immunological disorders was found to be related to specificities of activity of the hypophysis-and-thyroid system. Those children who are permanent residents in health-hazard localities exhibit a significant rise in blood level of interferones. Doing away with thyroid insufficiency will, we believe, help in returning the immune disorders in children to normal.
Engineering Deinococcus geothermalis for bioremediation of high-temperature radioactive waste environments.
Deinococcus geothermalis is an extremely radiation-resistant thermophilic bacterium closely related to the mesophile Deinococcus radiodurans, which is being engineered for in situ bioremediation of radioactive wastes. We report that D. geothermalis is transformable with plasmids designed for D. radiodurans and have generated a Hg(II)-resistant D. geothermalis strain capable of reducing Hg(II) at elevated temperatures and in the presence of 50 Gy/h. Additionally, D. geothermalis is capable of reducing Fe(III)-nitrilotriacetic acid, U(VI), and Cr(VI). These characteristics support the prospective development of this thermophilic radiophile for bioremediation of radioactive mixed waste environments with temperatures as high as 55 degrees C.
A new bis(3-hydroxy-4-pyridinone)-IDA derivative as a potential therapeutic chelating agent. Synthesis, metal-complexation and biological assays.
A new bis(3-hydroxy-4-pyridinone) derivative of iminodiacetic acid, imino-bis(acetyl(1-(3'-aminopropyl)-3-hydroxy-2-methyl-4-pyridinone)), IDAPr(3,4-HP)(2), has been prepared and studied in its interaction with a set of hard metal ions. This tetradentate ligand presents a much higher chelating efficiency for trivalent hard metal ions (Fe, Ga, Al) than the monodentate derivative Deferriprone, namely at the diluted conditions prevailing in physiological conditions and at low clinical doses. A similar behaviour was also observed for the complexation with Zn(II) but at a significantly lower extent. This compound presents a moderate hydrophilic character at physiological pH (logD=-1.72). In vivo assays showed much more rapid clearance of (67)Ga from most tissues of metal-loaded mice than the drug Deferriprone and the radioactivity excretion occurs mostly through the kidneys. Therefore, results from in vitro and in vivo studies indicated good perspectives for this compound to be a potential decorporating agent for hard metal ions in overload situations without depletion of essential metal ions such as zinc.