[The pollutant burden of food through the environment. A hazard for man?].
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Environmental Pollutants↗
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Results for “METALS, RADIOACTIVE”
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[Pollution of food].
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Anti-Bacterial Agents↗
Characterization of a heavy metal ion transporter in the lysosomal membrane.
Lysosomes are thought to play a role in various aspects of heavy metal metabolism. In the present study we demonstrate for the first time the presence of a heavy metal ion transport protein in the lysosomal membrane. Uptake of radioactive silver both in highly purified lysosomal membrane vesicles and in purified intact lysosomes showed the typical kinetics of a carrier-mediated process. This transport was stimulated by ATP hydrolysis, and showed specificity for Ag+, Cu2+, and Cd2+. All biochemical properties of this lysosomal metal ion transporter could classify it as a heavy metal transporting P-type ATPase. Long Evans Cinnamon (LEC) rats, an animal model for the copper transport disorder Wilson disease, showed normal lysosomal silver transport.
Adenosine Triphosphatases↗
Production of free radicals arising from the surface activity of minerals and oxygen. Part II. Arsenides, sulfides, and sulfoarsenides of iron, nickel, and copper.
The excess incidence of lung cancers observed in metallic mines other than iron mines probably can be correlated not only to radioactivity, but also to dust pollution. The present work investigates the role of surface properties of sulfides and arsenides, which are present in metal mines, in oxidizing mechanisms capable of inducing oxidative stress and, possibly, of participating in carcinogenesis. Using added spin-trapping agent followed by ESR spectroscopy, it was observed that nickel and copper arsenides can be very active in the oxidation of formate or DMSO, by reducing the oxygen dissolved in a cell-free medium. Sulfides, on the other hand, are not active, except for the iron sulfides, which are very active as an air-aged powder. The process of activation and rendering the particle surface passive was investigated. Surface dissolution and moderate grinding were found to be activating factors, while air-aging generally rendered the particle surface passive. The critical factor in determining activity is the availability of reducing species of iron, copper, or nickel on the surface of the minerals.
Arsenates↗
Experimental investigation on thallium poisoning in the rat; distribution of thallium, especially in the skin, and excretion of thallium under different experimental conditions, a study with the use of the radioactive isotope Tl204.
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Animals↗
Dose-reducing effect of Lipowitz metal-embedded spacers in interstitial brachytherapy for carcinoma of the mobile tongue.
Dose-reducing effects of spacers with and without a Lipowitz metal plate for the purpose of decreasing osteoradionecrosis after interstitial brachytherapy for tongue cancers were examined experimentally and clinically. The thicker the sample or spacer and the thicker the metal plate, the greater was the dose reduction achieved. A more marked dose reduction was achieved with iridium than with radium because of lower gamma ray energy of iridium. Iridium has been used widely as a radioactive source for interstitial brachytherapy. It was concluded therefore that a metal plate should be used as a shield into the spacer in interstitial brachytherapy both to reduce the radiation dose to surrounding normal tissues and to help prevent osteoradionecrosis.
Alloys↗
The effect of calcium on DNA synthesis in pea (Pisus sativus L.) roots after treatment with heavy metals.
Cortex cells of the meristematic (1 mm) and differentiated (7 mm) zones of Pisus sativus L. roots after 144 h culture in distilled water (control), Ca2+ (10(-3) M) and/or Cd2+, Cr3+, Pb2+ solutions (10(-4) M, each) were subject of the present studies. Reductions in the number of nuclei incorporating 3H thymidine was observed in meristem in the presence of Cd2+ and in differentiated zone in Pb2+ treated roots. Intensity of DNA synthesis diminished after Pb2+ treatment but mostly in Cd2+ treated roots, mainly in meristem. Addition of calcium to the metal solutions caused an increase in the number of nuclei witch uptook the radioactive material in both studied root zones. Positive effect of calcium alone was visible also in the differentiated zone. Presence of calcium in the metal solutions caused a marked increase in 3H thymidine incorporation into nuclear DNA in meristem, although neutralizing calcium effect in this root zone was visible only in roots treated with Cr2+ and Pb2+. In the differentiated zone of roots growing in Cd2+ solution, calcium addition stimulated DNA synthesis but the intensity of this process was lower than in control (water).
Calcium↗
Effects of sodium pyridinethione on the uptake and distribution of nickel, cadmium and zinc in pregnant and non-pregnant mice.
Oral administration of sodium pyridinethione together with 63Ni2+, 109Cd2+ or 65Zn2+ to non-pregnant mice resulted in very markedly increased levels of the metals in several tissues in comparison with animals given the metals alone. For 63Ni2+ the sodium pyridinethione induced a strong labelling of the pancreatic islets and of the melanin of pigmented tissues. A considerable radioactivity was also obtained in the peripheral and central nervous system. For 109Cd2+ a strong radioactivity was observed in the red pulp of the spleen and the neurohypophysis and, in addition, in the liver and the kidney. For 65Zn2+ the distribution pictures in mice given 65Zn2+ only were similar to those seen in mice given the metal together with sodium pyridinethione, although the radioactivity in all tissues of the latter animals was much higher than in the former. All 3 metals were shown to form lipophilic complexes with pyridinethione (the nickel and zinc complexes being more lipophilic than the cadmium complex) and a facilitated penetration of the complexed metals through the cellular membranes is probably important for the observed results. Differences in the stability of the complexes in the body may be one factor of importance for the marked differences in the obtained distribution pictures but other factors may also be involved, as discussed in the paper. Experiments in pregnant mice showed markedly increased levels of 63Ni2+ and 65Zn2+ in the foetuses as a result of the sodium pyridinethione administration, whereas for 109Cd2+ only a small increase was observed. Our results suggest that effects on the disposition of metals may be important for the toxicity of the pyridinethiones.
Administration, Oral↗
Identification of the serum binding proteins for iron, zinc, cadmium, nickel, and calcium.
The binding of five biologically important metals to serum proteins has been studied. After suitable radioactive isotopes were added to serum proteins separated and precipitated by two-dimensional immunoelectrophoresis, the sample plates were exposed to roentgenogram film. 59Fe bound to transferrin alone; 65Zn bound mostly to albumin, but also to another 12 proteins; 109Cd was mostly associated with alpha 2-macroglobulin, but was also present on albumin, immunoglobulins G and A, and prealbumin; 63Ni, added in high concentration, was associated with an alpha 2-mobility protein and albumin; and, finally, 45Ca was mostly bound to albumin, but seven other binding proteins were also identified, with transferrin predominant. The results are not quantitative, but the technique is simple and specific, and the information gained can direct further studies on isolated proteins.
Autoradiography↗
Dispersion modeling of PM10 released during decontamination activities.
The decontamination and decommissioning of radioactively contaminated structures and facilities, volume reduction of massive metal structures, and demolition of large concrete structures, result in release of large quantities of contaminants that become airborne and thus could be inhaled by workers and population living in the neighborhood. In order to provide adequate protection to the workers, adequate monitoring of the airborne particulates and proper models that predict the dispersion of the airborne contaminants are needed. The dispersion model will enable development of decision tools on the extent of decontamination that needs to be performed prior to dismantlement and the optimization of personal protective equipment requirements during D&D operations. The Gaussian plume dispersion model is used in this study to predict the dispersion of airborne particulate PM10 (dp<10 microm) released from: (1) a 35 m height contaminant plant where the plume is affected by the presence of 36 buildings around the emission source, (2) a building during decontamination and removal of process equipment and (3) demolition of contaminant building. The potential impact of PM10 on 180 receptors located at five downwind distances between 0.1 and 20 km around the emission source was performed. A short-term (1-48 h) prediction of average concentration of PM10 from point and area sources on receptors located at ground level was obtained. The concentrations of PM10 over 24h time period were compared to the U.S. air quality standards. The results obtained in the course of this study are used to predict the inhalation exposures of workers and population living in neighborhood.
Air Pollutants↗
Distribution of toxic and radiation components in air particulates.
The concentrations of several toxic heavy metals and volatile organic compounds (VOCs) in various types of Hungarian fly-ash fine particulates were investigated by means of instrumental neutron activation analysis, X-ray fluorescence analysis and gas chromatography, coupled with mass spectrometry. Within a power station, particulate samples were taken from the boiler zone (BO), from the electrostatic dust filter chamber (FI) and from the flue-gas at the top of the stack (ST). Enrichment rates of the toxic metals both in FI and ST particulate fractions related to the BO concentrations were calculated to enable the temperature dependence on the adsorption of the toxic components to be studied. In addition, both the total amounts of the VOCs and their partial distributions in accordance with the number of carbon atoms were also studied in fly-ash particulates. From them, 31 organic species were identified and determined. Since Hungarian brown coals have high uranium and thorium contents, the specific radioactivities of the daughter isotopes of both the 232Th and 238U decay series were also measured and are discussed.
Air Pollutants↗
Human interleukin-3 contains a discontinuous zinc binding domain.
The primary structure of human interleukin-3 contains two amino acid consensus sequences at Glutamate 22- Histidine 26 and Histidine 95-Histidine 98, that are characteristic for zinc binding proteins. Therefore, the hypothesis was tested that human interleukin-3 binds zinc specifically by either one or both sequences. Protein dotblotting, followed by probing with radioactive zinc demonstrated specific zinc binding of interleukin-3. Metal specificity was confirmed by competition experiments with 12 other divalent- and trivalent metal ions. Protease treatment combined with plasma desorption mass spectrometry was used to localize the zinc binding domain. Specific zinc binding was restricted to a fragment composed of Threonine 11-Lysine 28 and Asparagine 80-Lysine 100. It was found to decrease by a factor of five when either of these two amino acid stretches was missing. It is concluded that human interleukin-3 is a zinc binding protein. Interleukin-3 zinc binding capacity is largely determined by both moieties of the protein that contain the consensus sequences. In addition we propose that the zinc binding of hIL-3 is involved in (de)phosphorylation of the hIL-3 receptor.
Amino Acid Sequence↗
Distribution of various labeled thioglucoses in rodents.
Gold, silver and lead thioglucose were evaluated in rodents to determine the value of organo-metallic compounds in the study of metabolic abnormalities. Increased radioactivity concentration was noted in the hypothalamus with all compounds. Gold thioglucose concentrated in the kidneys and thymus, and 203Pb-thioglucose concentrated in the pancreas and thymus.
Adrenal Glands↗
111Indium labeling of cultured human tumor cells.
At least one microCi of 111indium oxine (111InOx) could be incorporated into 10(6) human tumor cells without cytotoxicity as determined by colony assay or by trypan blue staining. 111In bound to prekilled cells was removed preferentially by washings, and prelabeled cells killed with diphtheria toxin released radioactivity much more rapidly than did viable cells. The metal chelator calcium disodium edetate did not facilitate 111In removal from either viable or dead cells. High sensitivity can be obtained for in vitro or in vivo cytotoxicity assays using human cells prelabeled with 111InOx.
Animals↗
Use of non-absorbable markers in studies of human nutrient absorption.
Neutron activation analysis signifies a new era in the methodology of studies on nutrient utilization in humans. Yet the classical metabolic balance technique incorporating inert, non-absorbable markers will continue to be an invaluable tool for such studies. This review describes the use and abuse of a number of 'classical' inert markers, and describes the potential use of radioactive and naturally-occurring isotopes, and of heavy metals. The paucity of data critically appraising markers in infant balance trials is apparent. The comparative merits of conventional markers--carmine, polyethylene glycol 4000, chromium oxide--should be assessed. Indeed, it might be argued that the advancing knowledge on the use of naturally occurring isotopes in adults should make similar studies on infants a priority.
Absorption↗
[Radiometric studies of eye tissues in experimental cobalt intoxication].
Accumulation of cobalt in eye tissues were examined in rabbits which received the radioactive isotope 60Co Cl2. The studies revealed that this metal is accumulated at first in iris, choroid and ciliary body and, in smaller amounts, in cornea, sclera and retina. The least amounts of cobalt were found in lens. The contents of uveal tract was comparable with that found in heart and lungs, i.e. the organs in which lesions are the most frequent in cobalt intoxication.
Animals↗
Bone marrow transplantation in dogs after radio-ablation with a new Ho-166 amino phosphonic acid bone-seeking agent (DOTMP).
beta-emitting 166Ho (t1/2 = 26.78 hours, E(beta)max = 1.8 MeV) complexed with the phosphonic acid chelator, 1,4,7,10 tetraazacyclododecane-1,4,7,10-tetra(methylene phosphonic acid) (DOTMP) at a ligand-to-metal ratio of 1.5:1 binds to bone. This radioactive complex is a marrow-ablating radiopharmaceutical that appears useful for preparation of bone marrow (BM) transplant recipients without the morbidity usually associated with total body irradiation preparatory regimens. We have found with seven splenectomized young adult beagle dogs that a 166Ho radiopharmaceutical dosage of 370 MBq/kg body weight provides an initial skeletal radioactivity burden of at least 1.5 GBq/kg skeleton and results in complete ablation of hematopoietic marrow cell populations within 7 days. The beta particle flux distribution in BM-forming skeletal tissue is not uniform. Red marrow radiation doses varied from 30 to 115 Gy as estimated by direct radioassay and autoradiographic analyses of both bone biopsies and postmortem samples; the median value of 61 Gy agreed with our theoretical expectations. In vivo radioactivity distribution was evaluated with nuclear imaging methods. Apparently, normal hematopoiesis was restored in three dogs with autologous BM transplants performed 5 to 6 days after administration of the marrow ablative radiopharmaceutical, 166Ho-DOTMP. BM biopsies at 7 to 10 months posttransplantation indicate continued normal hematopoietic activity.
Animals↗