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PubMed1998

Contribution of radiation chemistry to the study of metal clusters.

Radiation chemistry dates from the discovery of radioactivity one century ago by H. Becquerel and P. and M. Curie. The complex phenomena induced by ionizing radiation have been explained progressively. At present, the methodology of radiation chemistry, particularly in the pulsed mode, provides a powerful means to study not only the early processes after the energy absorption, but more generally a broad diversity of chemical and biochemical reaction mechanisms. Among them, the new area of metal cluster chemistry illustrates how radiation chemistry contributed to this field in suggesting fruitful original concepts, in guiding and controlling specific syntheses, and in the detailed elaboration of the mechanisms of complex and long-unsolved processes, such as the dynamics of nucleation, electron transfer catalysis and photographic development.

Cations↗
PubMed2004

Effect of the militarily-relevant heavy metals, depleted uranium and heavy metal tungsten-alloy on gene expression in human liver carcinoma cells (HepG2).

Depleted uranium (DU) and heavy-metal tungsten alloys (HMTAs) are dense heavy-metals used primarily in military applications. Chemically similar to natural uranium, but depleted of the higher activity 235U and 234U isotopes, DU is a low specific activity, high-density heavy metal. In contrast, the non-radioactive HMTAs are composed of a mixture of tungsten (91-93%), nickel (3-5%), and cobalt (2-4%) particles. The use of DU and HMTAs in military munitions could result in their internalization in humans. Limited data exist however, regarding the long-term health effects of internalized DU and HMTAs in humans. Both DU and HMTAs possess a tumorigenic transforming potential and are genotoxic and mutagenic in vitro. Using insoluble DU-UO2 and a reconstituted mixture of tungsten, nickel, cobalt (rWNiCo), we tested their ability to induce stress genes in thirteen different recombinant cell lines generated from human liver carcinoma cells (HepG2). The commercially available CAT-Tox (L) cellular assay consists of a panel of cell lines stably transfected with reporter genes consisting of a coding sequence for chloramphenicol acetyl transferase (CAT) under transcriptional control by mammalian stress gene regulatory sequences. DU, (5-50 microg/ml) produced a complex profile of activity demonstrating significant dose-dependent induction of the hMTIIA FOS, p53RE, Gadd153, Gadd45, NFkappaBRE, CRE, HSP70, RARE, and GRP78 promoters. The rWNiCo mixture (5-50 microg/ml) showed dose-related induction of the GSTYA, hMTIIA, p53RE, FOS, NFkappaBRE, HSP70, and CRE promoters. An examination of the pure metals, tungsten (W), nickel (Ni), and cobalt (Co), comprising the rWNiCo mixture, demonstrated that each metal exhibited a similar pattern of gene induction, but at a significantly decreased magnitude than that of the rWNiCo mixture. These data showed a synergistic activation of gene expression by the metals in the rWNiCo mixture. Our data show for the first time that DU and rWNiCo can activate gene expression through several signal transduction pathways that may be involved in the toxicity and tumorigenicity of both DU and HMTAs.

Carcinoma, Hepatocellular↗
PubMed1999

Binding properties of various metals to blood components and serum proteins: a multitracer study.

The binding affinity of various trace elements to blood components and the pH-dependence of the binding affinity of the elements to serum proteins were examined using the radioactive multitracer technique. The binding affinity of 13 elements (Be, V, Mn, Zn, Se, Rb, Sr, Ce, Eu, Gd, Tm, Yb, and Lu) was simultaneously determined by gamma-ray spectrometry. The blood drawn from rats was separated into plasma, corpuscles, and erythrocyte ghosts. It was found that Be, Sr, Mn, and Zn bind highly to the plasma proteins. V and Se were highly bound to the corpuscles, and Se to the erythrocyte ghosts as well. Similar binding percentages of rare earth elements (Ce, Eu, Gd, Tm, Yb, and Lu) were found for each of the blood components, with the highest percentages being observed for plasma proteins. Albumin, beta-globulin, gamma-globulin, apotransferrin, and holotransferrin were examined in the study on the affinity of individual serum proteins. The pH dependence of the affinity of metal ions to the serum proteins in the pH range of 6.4-8.5 was examined using ultrafiltration and gamma-ray spectrometry. Each element showed a characteristic binding affinity to each serum protein, depending on pH. The results are discussed in terms of the chelating ability of metal ions and the nature of the serum proteins.

Animals↗
PubMed1989

Authorized limits of radon daughter products in Polish underground metal-ore mines in the light of experience.

The paper presents the results of measurements of individual exposures of miners to radioactive radon daughter products, naturally existing in air of metal-ore mines. Results concern the three year period between 1985 and 1987, during which the observed annual average concentrations were stable and have been recognised as values corresponding to the steady state. They are presented and analysed assuming several possible values of the Authorized Limit of the exposure of miners to radon daughter products. The values: 1 WLM, 2.5 WLM, 3.5 WLM (Working Level Month) were considered and compared with the value of 5 WLM, which is currently the basic limit recommended by the International Commission on Radiological Protection (ICRP), and approved by the WHO, ILO and IAEA. Though the value of 3.5 WLM is presently adopted and officially authorized in Poland as the Authorized Limit of annual individual miners' exposure, the results presented in this paper lead to the conclusion that the value of 2.5 WML could be adopted instead of the current one. This means that the present limit could be decreased by about 30% and without causing any social, technological and economic problems in Polish metal-ore mines.

Air Pollutants, Occupational↗
PubMed1994

A newly designed radioimmunoconjugate releasing a hippurate-like radiometal chelate for enhanced target/non-target radioactivity.

Target-to-non-target ratio of radioactivity can be enhanced by the injection of monoclonal antibodies (MoAbs) labeled with metallic radionuclides, if some modality to accelerate the urinary excretion of radioactivity accumulated in non-target tissues could be introduced. In this study, a radioimmunoconjugate chemically designed to release a hippurate-like radiometal chelate was synthesized and tested in vivo. A 67Ga chelate of succinyldeferoxamine (SDF) was conjugated with a MoAb against osteogenic sarcoma (OST7, IgG1) through an ester bond using a new metabolizable MESS linker, N-[I4-(maleimidoethoxy)succinyl]oxy]succinimide (67Ga-DFO-MESS-OST7). When injected into normal mice, 67Ga-DFO-MESS-OST7 exhibited faster clearance of radioactivity from circulation with less accumulation in the liver, kidney and spleen than those observed with 67Ga-DFO-EMCS-OST7, which was prepared under identical conditions to 67Ga-DFO-MESS-OST7 except for using a non-metabolizable linker holding no ester bond to release 67Ga-SDF. Size exclusion HPLC analysis of the liver homogenate obtained from mice 24 h after injection of 67Ga-DFO-MESS-OST7 indicated that all the radioactivity was eluted in the high molecular weight fraction with most of it being present as the 67Ga-DFO-MESS-OST7 fraction. Reverse-phase HPLC analysis of urine sample from the same mice showed a single radioactivity peak at the same retention time as that of 67Ga-SDF. In athymic mice bearing osteogenic sarcoma, 67Ga-DFO-MESS-OST7 exhibited higher tumor-to-blood and tumor-to-organ ratio of radioactivity when compared with 67Ga-DFO-EMCS-OST7. These results indicated that 67Ga-DFO-MESS-OST7 achieved enhanced target-to-non-target ratio of the radioactivity, due to preferential cleavage of the ester bond in non-target tissues, followed by rapid urinary excretion of the resulting chelate (probably as 57Ga-SDF). These results also suggest that the present design would become an applicable modality for enhancing the target-to-non-target ratio of radioactivity by MoAbs.

Animals↗
PubMed1987

Induction of superoxide dismutase isozymes in rabbit lung due to aniline exposure.

Single exposure of rabbits to aniline vapors caused induction of superoxide dismutase isozymes and activity as evidenced by the incorporation of radioactive amino acids and prosthetic group metals into enzymatic protein zones of electrophoreograms. Induced of a new cytosolic isozyme following aniline exposure was also evident. Xenobiotic stress indicated a close relation between free radical processes and lung biotransformation mechanisms.

Aniline Compounds↗
PubMed2006

Adsorption of biometals to monosodium titanate in biological environments.

Monosodium titanate (MST) is an inorganic sorbent/ion exchanger developed for the removal of radionuclides from nuclear wastes. We investigated the ability of MST to bind Cd(II), Hg(II), Au(III), or the Au-organic compound auranofin to establish the utility of MST for applications in environmental decontamination or medical therapy (drug delivery). Adsorption isotherms for MST were determined at pH 7-7.5 in water or phosphate-buffered saline. The extent of metal binding was determined spectroscopically by measuring the concentrations of the metals in solution before and after contact with the MST. Cytotoxic responses to MST were assessed using THP1 monocytes and succinate dehydrogenase activity. Monocytic activation by MST was assessed by TNFalpha secretion (ELISA) with or without lipopolysaccharide (LPS) activation. MST adsorbed Cd(II), Hg(II), and Au(III) under conditions similar to those in physiological systems. MST exhibited the highest affinity for Cd(II) followed by Hg(II) and Au (III). MST (up to 100 mg/L) exhibited only minor (<25% suppression of succinate dehydrogenase) cytotoxicity and did not trigger TNFalpha secretion nor modulate LPS-induced TNFalpha secretion from monocytes. MST exhibits high affinity for biometals with no significant biological liabilities in these introductory studies. MST deserves further scrutiny as a substance with the capacity to decontaminate biological environments or deliver metals or metal compounds for therapeutic applications.

Adsorption↗
PubMed1987

A qualitative study on vanadate effects in the tetrahydrofolate-dependent formate transfer in vitro and in vivo in mice.

Parenteral administration of sodium vanadate (NaVO3, 22 mg/kg b.w., i.p.) to mice depresses the oxidation rate of [14C]formate to [14C]CO2, as determined by radioactive breath analysis. The heavy metal-induced inhibition is relatively fast in onset, fairly intense (up to 80% inhibition), of short duration (about 2 h) and strongly correlated to the presence of vanadate (in the pentavalent state) in plasma. The [14C]CO2 exhalation rate from [14C]bicarbonate is less affected by vanadate in vivo, thereby suggesting a specific interference of vanadium in the intermediate step of formate oxidation to HCO3-. In vitro in mouse liver cytosolic fractions vanadate inhibits the enzymatic transfer of formate to tetrahydrofolic acid. The inhibition is accomplished by a vanadate-dependent oxidative degradation of tetrahydrofolate. In contrast, the concentrations of N5-methyltetrahydrofolate, dihydrofolate and folate remain unchanged upon in vitro-exposure to vanadate. The in vitro studies thus might explain the observed inhibition of formate oxidation to carbon dioxide in vivo by a vanadate-evoked depletion of its biological carrier tetrahydrofolic acid. Whether the interference in tetrahydrofolate metabolism also occurs under in vivo conditions, remains to be elucidated.

Animals↗
PubMed1998

The effect of growth conditions on the biodegradation of tributyl phosphate and potential for the remediation of acid mine drainage waters by a naturally-occurring mixed microbial culture.

The biodegradation of tributyl phosphate (Bu3-P, TBP), releasing phosphate at a high enough concentration locally to precipitate uranium from solution, was demonstrated by a mixed culture consisting primarily of pseudomonads. The effect of various parameters on Bu3-P biodegradation by growing cells is described. Growth at the expense of Bu3-P as the carbon and phosphorus source occurred over a pH range from 6.5 to 8, and optimally at pH 7. Bu3-P biodegradation was optimal at 30 degrees C, reduced at 20 degrees C and negligible at 4 degrees C and 37 degrees C. Incorporation of Cu or Cd inhibited, and Ni, Co and Mn reduced its degradation. Inorganic phosphate (above 10 mM) and kerosene (up to 1 g/l) reduced Bu3-P biodegradation significantly, but nitrate had no effect. Sulphate (10-100 mM) was inhibitory. When pregrown biomass was used the fastest rates of tributyl and dibutyl phosphate biodegradation were 25 mumol h-1 mg protein-1 and 37 mumol h-1 mg protein-1 respectively. Microcarrier-immobilised biomass decontaminated uranium-bearing acid mine waste water by uranium phosphate precipitation at the expense of Bu3-P hydrolysis in the presence of 35 mM SO(4)2-. At pH 4.5, 79% of the UO2(2)+ was removed at a flow rate of 1.4 ml/h on a 7-ml.test column.

Anions↗
PubMed1992

Presence and implications of chemical contaminants in the freshwaters of the Canadian Arctic.

Hydrocarbons, stable organochlorines, metals and radionuclides are widespread in the freshwaters of the Canadian Arctic. Petroleum-associated hydrocarbon sources include natural seepage, wastes and effluents from exploration, production and refining at Norman Wells and spills. Hydrocarbons also originate from combustion of carbon-based fuels, generally at lower latitudes and then reach the Arctic with air movements. Organochlorine compounds also move throughout the hemisphere by aerial pathways and have become distributed widely in Arctic fish. The organochlorine at highest concentration in Arctic freshwater is alpha-HCH, while those generally at highest concentrations in the fish are toxaphene, PCBs and chlordane. Metals are ubiquitous in Arctic freshwaters, with inputs of several metals by precipitation superimposed on natural geologic backgrounds. Mercury is found in muscle of fish from Arctic freshwaters at concentrations up to about 0.5 ppm. Radionuclides are also widespread at levels below those acceptable in food, with some local elevations near former mines. The implications of these contaminants for the northern ecosystems and the people dependent upon them are still not clear. Preliminary studies of inducible enzymes in fish suggest that the thresholds for biological damage have not been reached.

Animals↗
PubMed1995

Non-radioactive, isomer-specific inositol phosphate mass determinations: high-performance liquid chromatography-micro-metal-dye detection strongly improves speed and sensitivity of analyses from cells and micro-enzyme assays.

A microbore high-performance liquid chromatographic (HPLC) method is presented allowing rapid and sensitive mass analysis of inositol phosphates from cells and tissues. An analysis starting from inorganic phosphate up to inositol hexakisphosphate displaying a similar isomer selectivity as compared to the standard metal-dye detection system takes about 15 min. The detection sensitivity was about 15 pmol for inositol trisphosphate, about 10 pmol for inositol tetrakisphosphate, about 5 pmol for inositol pentakisphosphate and less than 5 pmol for inositol hexakisphosphate. The method was validated regarding day-to-day variations and variations at the same day of retention times and peak areas of standard inositol phosphates. Standard deviations of retention times ranged from 0.25 to 0.62% (same day) and from 0.64 to 1.61% (day-to-day variations). Ranges of standard deviations of peak areas were between 2.24% and 3.91% (same day) and 6.13% and 13.8% (day-to-day variations). Linearity of the post-column complexometric metal-dye detection system was demonstrated in the range of a few picomoles and at least 800 pmol. The method was applied to the analysis of inositol phosphates in Jurkat T-lymphocytes and assays from minute amounts of enzymes interconverting inositol phosphates. While measurements of inositol phosphates from cell extracts are now possible using significantly reduced cell numbers, micro-enzyme assays are feasible in reasonable repeated analysis times and with sufficient isomer selectivity. In conclusion, a substantial improvement towards speed of analysis and detection sensitivity of inositol phosphate mass analysis was achieved by microbore metal-dye detection HPLC.

Animals↗
PubMed1987

Sensitive detection of genes by sandwich hybridization and time-resolved fluorometry.

Europium has been used as a non-radioactive marker in immunoassays as this metal can be detected with high sensitivity by time-resolved fluorometry. In this work streptavidin labeled with europium was used to detect biotinylated probes in a sandwich nucleic-acid hybridization assay with microtitration strips as the solid phase. pBR 322 plasmids were detected with a sensitivity of 4 x 10(5) molecules. As the sample is added in solution in sandwich hybridization, fast and simple sample pre-treatment can be used without encountering background problems. The method was applied to test bacterial samples of uropathogenic Escherichia coli strains for the presence of the beta-lactamase gene.

Animals↗
PubMed2006

Biosorption of no-carrier-added radionuclides by calcium alginate beads using 'tracer packet' technique.

The aim of this study was to determine the adsorption behaviour of various micronutrient elements e.g., (61)Cu, (62,63)Zn, (66,67,68)Ga, (66,67,69)Ge, (71,72)As present in no-carrier-added state, with calcium alginate (CA) using 'tracer packet' technique. High Ge and Ga and moderate Cu removal were achieved at pH 7 and pH 5, respectively. Results on the studies to recover all the three radionuclides from the calcium alginate beads using desorbing reagents, HCl, thiourea, ammonium oxalate and sodium nitrite showed that 0.1 M HCl and 0.1 M ammonium oxalate removed Cu and Ge moderately. The amount of Ga desorbed by all the washing liquids was almost negligible, except sodium nitrite.

Adsorption↗
PubMed2006

Phylogenetic and functional biomakers as indicators of bacterial community responses to mixed-waste contamination.

Few studies have demonstrated changes in community structure along a contaminant plume in terms of phylogenetic, functional, and geochemical changes, and such studies are essential to understand how a microbial ecosystem responds to perturbations. Clonal libraries of multiple genes (SSU rDNA, nirK, nirS, amoA, pmoA, and dsrAB) were analyzed from groundwater samples (n = 6) that varied in contaminant levels, and 107 geochemical parameters were measured. Principal components analyses (PCA) were used to compare the relationships among the sites with respect to the biomarker (n = 785 for all sequences) distributions and the geochemical variables. A major portion of the geochemical variance measured among the samples could be accounted for by tetrachloroethene, 99Tc, No3, SO4, Al, and Th. The PCA based on the distribution of unique biomarkers resulted in different groupings compared to the geochemical analysis, but when the SSU rRNA gene libraries were directly compared (deltaC(xy) values) the sites were clustered in a similar fashion compared to geochemical measures. The PCA based upon functional gene distributions each predicted different relationships among the sites, and comparisons of Euclidean distances based upon diversity indices for all functional genes (n = 432) grouped the sites by extreme or intermediate contaminant levels. The data suggested that the sites with low and high perturbations were functionally more similar than sites with intermediate conditions, and perhaps captured the overall community structure better than a single phylogenetic biomarker. Moreover, even though the background site was phylogenetically and geochemically distinct from the acidic sites, the extreme conditions of the acidic samples might be more analogous to the limiting nutrient conditions of the background site. An understanding of microbial community-level responses within an ecological framework would provide better insight for restoration strategies at contaminated field sites.

Bacteria↗
PubMed1996

Overview of radiation safety in the tin by-product (amang) industry of South East Asia.

Processing of by-product heavy minerals (amang) from tin mining involves potential exposure to external and internal sources of radioactivity. The radioactivity arises through the presence of thorium and uranium series radionuclides in the various minerals. Monazite is the most radioactive mineral, containing 3% to 7% thorium by weight, while ilmenite is generally the least radioactive mineral containing typically less than 0.05% thorium. External exposure occurs when workers are in close proximity to accumulations or stockpiles of the radioactive minerals, whereas internal exposure occurs when workers are involved in dusty processes. This paper summarizes the nature of the amang industry in South East Asia and presents the results of preliminary measurements of external radiation and airborne radioactivity in twelve Malaysian and Thai plants. Although constrained by a paucity of exposure data, it is concluded that radiation doses to some amang plant workers may approach or exceed international standards and that appropriate control measures are required as a matter of priority, Radiation doses may approach or exceed 100 mSv in situations where workers are exposed to excessive levels of ambient dust and no protective measures are used. Observations and recommendations are made relating to monitoring and surveillance, instruction and training, and engineering and administrative protection measures.

Air Pollutants, Radioactive↗
PubMed2003

Anomalous 235U/238U ratios and metal elements detected in the black rain from the Hiroshima A-bomb.

Contents of black rain from the A-bomb are important to clarify the health and environmental hazard caused by nuclear warfare. We analyzed the only existing physical remains of the black rain from Hiroshima A-bomb (Little Boy), a plastered wall with black streaks. Excess 137Cs and anomalous 235U/238U ratios detected in the black residues on the wall confirmed that the black streaks on the wall originated from Little Boy. The results also showed that excess 235U could be used as a fingerprint to clarify the distribution of materials discharged from Little Boy into the environment. High concentrations of lead and zinc, which may have caused a degree of heavy metal pollution in the area where the rain fell, were also detected in the black rain sample.

Environmental Exposure↗