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PubMed2005

Decontamination of uranium-contaminated steel surfaces by hydroxycarboxylic acid with uranium recovery.

We developed a simple, safe method to remove uranium from contaminated metallic surfaces so that the materials can be recycled or disposed of as low-level radioactive or nonradioactive waste. Surface analysis of rusted uranium-contaminated plain carbon-steel coupons by X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy showed that uranium was predominantly associated with ferrihydrite, lepidocrocite, and magnetite, or occluded in the matrix of the corrosion product as uranyl hydroxide and schoepite (UO3 x 2H2O). Citric acid formulations, consisting of oxalic acid-hydrogen peroxidecitric acid (OPC) or citric acid-hydrogen peroxidecitric acid (CPC), were used to remove uranium from the coupons. The efficiency of uranium removal varied from 68% to 94% depending on the extent of corrosion, the association of uranium with the iron oxide matrix, and the accessibility of the occluded contaminant. Decontaminated coupons clearly showed evidence of the extensive removal of rust and uranium. The waste solutions containing uranium and iron from decontamination by OPC and CPC were treated first by subjecting them to biodegradation followed by photodegradation. Biodegradation of a CPC solution by Pseudomonas fluorescens resulted in the degradation of the citric acid with concomitant precipitation of Fe (>96%), whereas U that remained in solution was recovered (>99%) by photodegradation as schoepite. In contrast, in an OPC solution citric acid was biodegraded but not oxalic acid, and both Fe and U remained in solution. Photodegradation of this OPC solution resulted in the precipitation of iron as ferrihydrite and uranium as uranyl hydroxide.

Biodegradation, Environmental↗

PubMed2003

Analysis of uranium and its correlation with some physico-chemical properties of drinking water samples from Amritsar, Punjab.

Fission track technique has been used for uranium estimation in drinking water samples collected from some areas of Amritsar District, Punjab, India. The uranium concentration in water samples is found to vary from 3.19 to 45.59 microg l(-1). Some of the physico-chemical properties such as pH, conductance and hardness and the content of calcium, magnesium, total dissolved solids (TDS), sodium, potassium, chloride, nitrate and heavy metals viz. zinc, cadmium, lead and copper have been determined in water samples. An attempt has been made to correlate uranium concentration with these water quality parameters. A positive correlation of conductance, nitrate, chloride, sodium, potassium, magnesium, TDS, calcium and hardness with uranium concentration has been observed. However, no correlation has been observed between the concentration of uranium and the heavy metals analysed.

Chemical Phenomena↗

PubMed2000

Stabilization and solidification of metal-laden wastes by compaction and magnesium phosphate-based binder.

Bench-scale and full-scale investigations of waste stabilization and volume reduction were conducted using spiked soil and ash wastes containing heavy metals such as Cd, Cr, Pb, Ni, and Hg. The waste streams were stabilized and solidified using chemically bonded phosphate ceramic (CBPC) binder, and then compacted by either uniaxial or harmonic press for volume reduction. The physical properties of the final waste forms were determined by measuring volume reduction, density, porosity, and compressive strength. The leachability of heavy metals in the final waste forms was determined by a toxicity characteristic leaching procedure (TCLP) test and a 90-day immersion test (ANS 16.1). The structural composition and nature of waste forms were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. CBPC binder and compaction can achieve 80-wt% waste loading and 39-47% reduction in waste volume. Compressive strength of final waste forms ranged from 1500 to 2000 psi. TCLP testing of waste forms showed that all heavy metals except Hg passed the TCLP limits using the phosphate-based binder. When Na2S was added to the binder, the waste forms also passed TCLP limits for Hg. Long-term leachability resistance of the final waste forms was achieved for all metals in both soil and ash wastes, and the leachability index was approximately 14. XRD patterns of waste forms indicated vermiculite in the ash waste was chemically incorporated into the CBPC matrix. SEM showed that waste forms are layered when compacted by uniaxial press and are homogeneous when compacted by harmonic press.

Hazardous Waste↗

PubMed1994

Advances in biosorption of metals: selection of biomass types.

Within the past decade, the potential of metal biosorption has been well established. For economic reasons, of particular interest are abundant biomass types either generated as a waste by-product of large-scale industrial fermentations or certain metal-binding algae found in large quantities in the sea. Some of these high metal-sorbing biomass types serve as a basis for newly developed metal biosorption processes foreseen particularly as a very competitive means for detoxification of metal-bearing industrial effluents. Ions of lead and cadmium, for instance, have been found to be bound very efficiently from very dilute solutions by the dried biomass of some ubiquitous brown marine algae such as Ascophyllum and Sargassum which accumulate more than 30% of biomass dry weight in the metal. Mycelia of industrially steroid-transforming fungi Rhizopus and Absidia are excellent biosorbents for lead, cadmium, copper, zinc, and uranium, binding also other heavy metals up to 25% of the biomass dry weight. The common yeast Saccharomyces cerevisiae is a 'mediocre' metal biosorbent. Construction of biosorption isotherm curves serves as a basic technique assisting in evaluation of the metal uptake by different biosorbents. The methodology is based on batch equilibrium sorption experiments extensively used for screening and quantitative comparison of new biosorbent materials. Experimental methodologies used in the study of biosorption and selected recent research results demonstrate the route to novel biosorbent materials some of which can even be repeatedly regenerated for re-use.

Absorption↗

PubMedDate not supplied

Apatite and phillipsite as sequestering agents for metals and radionuclides.

Laboratory and greenhouse studies were conducted to quantify apatite and phillipsite (zeolite) sequestration of selected metal contaminants. The laboratory batch study measured the sorption of aqueous Co2+, Ba2+, Pb2+, Eu3+, and UO2(2+). Apatite sorbed more Co2+, Pb2+, Eu3+, and UO2(2+) from the spike solution than phillipsite, resulting in distribution coefficients (Kd values) of >200,000 L kg(-1). Phillipsite was more effective than apatite at sorbing aqueous Ba2+. Results from the laboratory study were used to design the greenhouse study that used a soil affected by a Zn-Pb smelter from Pribram, Czech Republic. Two application rates (25 and 50 g kg(-1)) of phillipsite and apatite and two plant species, maize (Zea mays L.) and oat (Avena sativa L.), were evaluated in this study. There was little (maize) to no (oat) plant growth in the unamended contaminated soil. Apatite and, to a slightly lesser extent, phillipsite additions significantly enhanced plant growth and reduced Cd, Pb, and Zn concentrations in all analyzed tissues (grain, leaves, and roots). The sequestering agents also affected some essential elements (Ca, Fe, and Mg). Phillipsite reduced Fe and apatite reduced P and Fe concentrations in oat tissues; however, the level of these elements in oat leaves and grains remained sufficient. Sequential extractions of the soil indicated that the Cd, Pb, and Zn were much more strongly sorbed onto the amended soil, making the contaminants less phytoavailable.

Adsorption↗

PubMed1995

Stable isotopes of lead for source identification.

Lead is unique among all the metals in having variations among mining districts in the relative abundances of its stable (non-radioactive) isotopes. Since first described in 1927, many applications have been reported, mostly for geological uses. More recently archeological, environmental, bio-kinetic and public health uses have been found. The abundances of the four stable isotopes are usually determined with specialized mass spectrometry using rapid mass scanning cycles or multiple collectors. The relative abundances are commonly expressed as 206/204, 206/207, and 206/208 atomic ratios. Precision of 0.5% for 206/204 and even better (0.03%) for the other pairs are obtainable. The three ratios co-vary strongly and depend on when the ore was formed. This provides a tracer for following a particular batch of lead, since the ratio can only change when the lead is mixed with a different lead. A major limitation of this method is that it is useful only to those problems where the potential sources are isotopically distinct and few in number. The covariance of the ratios usually allows for only two sources to be considered. Potential sources can often be ruled out.

Animals↗

PubMed2000

Melanoma-targeting properties of (99m)technetium-labeled cyclic alpha-melanocyte-stimulating hormone peptide analogues.

Preliminary reports have demonstrated that (99m)technetium (Tc)-labeled cyclic [Cys(3,4,10), D-Phe7]alpha-MSH(3-13) (CCMSH) exhibits high tumor uptake and retention values in a murine melanoma mouse model. In this report, the tumor targeting mechanism of 99mTc-CCMSH was studied and compared with four other radiolabeled alpha-melanocyte stimulating hormone (alpha-MSH) peptide analogues: 125I-(Tyr2)-[Nle4, D-Phe7]alpha-MSH [125I-(Tyr2)-NDP]; 99mTc-CGCG-NDP; 99mTc-Gly11-CCMSH; and 99mTc-Nle11-CCMSH. In vitro receptor binding, internalization, and cellular retention of radiolabeled alpha-MSH analogues in B16/F1 murine cell line demonstrated that >70% of the receptor-bound radiolabeled analogues were internalized together with the receptor. Ninety % of the internalized 125I-(Tyr2)-NDP, whereas only 36% of internalized 99mTc-CCMSH, was released from the cells into the medium during a 4-h incubation at 37 degrees C. Two mouse models, C57 mice and severe combined immunodeficient (Scid) mice, inoculated s.c. with B16/F1 murine and TXM-13 human melanoma cells were used for the in vivo studies. Tumor uptake values of 11.32 and 2.39 [% injected dose (ID)/g] for 99mTc-CCMSH at 4 h after injection, resulted in an uptake ratio of tumor:blood of 39.0 and 11.5 in murine melanoma-C57 and human melanoma-Scid mouse models, respectively. Two strategies for decreasing the nonspecific kidney uptake of 99mTc-CCMSH, substitution of Lys11 in CCMSH with Gly11 or Nle11, and lysine coinjection, were evaluated. The biodistribution data for the modified peptides showed that Lys11 replacement dramatically decreased the kidney uptake, whereas the tumor uptakes of 99mTc-Nle11- and 99mTc-Gly11-CCMSH were significantly lower than that of 99mTc-CCMSH. Lysine coinjection significantly decreased the kidney uptake (e.g., from 14.6% ID/g to 4.5% ID/g at 4 h after injection in murine melanoma-C57 mice) without significantly changing the value of tumor uptake of 99mTc-CCMSH. In conclusion, the compact cyclic structure of 99mTc-CCMSH, its resistance to degradation, and its enhanced intracellular retention are the major contributing factors to the superior in vivo tumor targeting properties of 99mTc-CCMSH. Lys11 residue in 99mTc-CCMSH is critical to the tumor targeting in vivo, and lysine coinjection rather than lysine replacement can significantly decrease the nonspecific renal radioactivity accumulation without impeding the high melanoma-targeting properties of 99Tc-CCMSH. The metal-cyclized CCMSH molecule displays excellent potential for the development of melanoma-specific diagnostic and therapeutic agents.

Amino Acid Sequence↗

PubMedDate not supplied

Microwave-supported preparation of (68)Ga bioconjugates with high specific radioactivity.

The generator-produced positron-emitting (68)Ga (T(1/2) = 68 min) is of potential interest for clinical PET. (68)Ga as a metallic cation is suitable for complexation reactions with chelators, naked or conjugated, with peptides or other macromolecules. Large (68)Ga generator eluate volumes, metal traces from the generator column material, or reaction reagents, however, disturb a fast, reliable, and quantitative labeling procedure. In this paper we describe a simple technique, based on anion exchange, aiming first, to increase the (68)Ga concentration, second to purify it from competing impurities, and third to obtain a fast and quantitative (68)Ga-labeled peptide conjugate that can be applied in humans without further purification. Within 5 min one can obtain from the original 6 mL generator eluate a 200 microL (68)Ga preparation (volume reduction by a factor 30) that is suitable for direct and quantitative labeling of peptide conjugates. DOTATOC (DOTA-D-Phe(1)-Tyr(3)-octreotide, DOTA = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) was used as a test tracer for comparing the labeling properties of the different (68)Ga preparations. In combination with microwave heating, peptide conjugates of 0.5-1 nmol quantities could be labeled within 10 min with the full (68)Ga activity of a generator. Further purification of the (68)Ga-labeled peptide conjugate was no longer required since the nuclide incorporation was quantitative. The specific radioactivity (with respect to the peptide) was improved by a factor approximately 100 compared to the previously applied techniques using the original generator eluate. The commercial (68)Ge/(68)Ga generator from Obninsk in combination with this system for purification and concentration with an integrated microwave-supported labeling technology resulted in a kitlike technology for (68)Ga-tracer production. The first automated prototype using this technology is being tested.

Chelating Agents↗

PubMed1989

Assessment of computed tomographic artefact in the pituitary fossa following needle implantation of radioactive rods.

Computed tomographic scans of the pituitary fossa following treatment of pituitary tumours by interstitial irradiation were reviewed for the degree of metallic artefact created by the rods. Among 50 patients treated with 90Y rods alone, none showed artefact to a degree that caused technically unsatisfactory images in coronal or axial cuts. Among the seven patients who had been treated with 198Au, either alone (two patients) or with both 198Au and 90Y rods (five patients), six had severe artefact and in five of these the images were technically unsatisfactory in both coronal and axial slices. We conclude that following implantation of 90Y rods, the currently preferred isotope, the pituitary fossa can be satisfactorily assessed by computed tomography.

Adenoma↗

PubMed2000

Physiologic determinants of radiation resistance in Deinococcus radiodurans.

Immense volumes of radioactive wastes, which were generated during nuclear weapons production, were disposed of directly in the ground during the Cold War, a period when national security priorities often surmounted concerns over the environment. The bacterium Deinococcus radiodurans is the most radiation-resistant organism known and is currently being engineered for remediation of the toxic metal and organic components of these environmental wastes. Understanding the biotic potential of D. radiodurans and its global physiological integrity in nutritionally restricted radioactive environments is important in development of this organism for in situ bioremediation. We have previously shown that D. radiodurans can grow on rich medium in the presence of continuous radiation (6,000 rads/h) without lethality. In this study we developed a chemically defined minimal medium that can be used to analyze growth of this organism in the presence and in the absence of continuous radiation; whereas cell growth was not affected in the absence of radiation, cells did not grow and were killed in the presence of continuous radiation. Under nutrient-limiting conditions, DNA repair was found to be limited by the metabolic capabilities of D. radiodurans and not by any nutritionally induced defect in genetic repair. The results of our growth studies and analysis of the complete D. radiodurans genomic sequence support the hypothesis that there are several defects in D. radiodurans global metabolic regulation that limit carbon, nitrogen, and DNA metabolism. We identified key nutritional constituents that restore growth of D. radiodurans in nutritionally limiting radioactive environments.

Amino Acids↗

PubMed2002

Experimental study of the material composition of laparoscopic ports on tumour cell adherence.

BACKGROUND: Laparoscopic resection of intra-abdominal malignancies has yet to be widely adopted, partly because of concerns over the possible increase in the rate of port-site metastasis. The aetiology of these is unclear, but the laparoscopic instrumentation used may influence the deposition of tumour cells at the port sites during operation. An in vitro model to examine tumour cell adherence to laparoscopic ports and to port sites was developed to examine this hypothesis. METHODS: A pilot study (study 1) was performed in which six smooth plastic, six ribbed plastic and six metal ports were introduced through the shaved abdominal wall of a cadaveric sheep and suspended in a water-bath containing radiolabelled LIM 1215 human colonic cancer cells for 30 min. Radioactivity on both ports and port sites was measured and the number of cells adherent to each structure was calculated. The study was expanded to include a further 36 smooth plastic ports and 36 metal ports (study 2). RESULTS: In study 1 metal ports were found to have significantly more adherent cells than plastic ports (P = 0.004), as did ribbed ports when compared with smooth ports (P < 0.05). In study 2 increased numbers of cells were again detected on metal ports (P < 0.001) when compared with plastic ports. Significantly greater numbers of cells were also detected on the sites through which metal ports had passed than on sites through which plastic ports had passed (P = 0.03). CONCLUSION: In this model, the use of metal ports as opposed to plastic ports resulted in increased deposition of tumour cells on both ports and port sites.

Animals↗

PubMed2004

Trace elements in Jamaican tobacco.

The concentrations of 28 elements, in hand-made cigars, "rope" tobacco and freshly picked tobacco leaves from the parish of Manchester in central Jamaica, were compared with locally packaged and imported cigarettes and cigars. Except for chromium and vanadium, which are lower in the imported products, the elemental concentrations of all the brands sold in Jamaica are rather similar. The means for aluminium, cadmium, caesium, cerium, chromium, iron, thorium, uranium, vanadium and zinc for the Manchester material exceed the maximum values of the other tobaccos. The significant concentrations of heavy metals, and especially cadmium, which is about 50 times that of commercial cigarettes, reflect the known high concentrations in the soils in the region. This tobacco is not filtered and the smoke contains 50% of the cadmium. This, and the concentrations of radioactive elements, may indicate an additional health risk compared with commercial cigarettes. A study of three samples of marijuana indicates a similar level of risk from heavy metals.

Cannabis↗

PubMed1996

Disulfiram and diethyldithiocarbamate intoxication affects the storage and release of striatal dopamine.

Acute intoxication and chronic therapy with the alcohol consumption deterrent dithiocarbamate disulfiram have been associated with several neurological complications perhaps involving the impairment of neurotransmitter pathways. In this study we have tested the hypothesis that dopaminergic malfunction is a critical component in disulfiram-evoked neurotoxicity. Disulfiram antagonized the in vitro striatal binding of [3H]tyramine, a putative marker of the vesicular transporter for dopamine, and the uptake of [3H]dopamine into striatal synaptic vesicles, with inhibitory constants (Ki) in the range of reported blood dithiocarbamate levels in treated alcoholics. Furthermore, disulfiram provoked a loss of radioactivity from [3H]dopamine-preloaded striatal vesicles, when added directly to the incubation mixture. Several metal-containing fungicide analogs were also potent displacers of specifically bound [3H]tyramine. Diethyldithiocarbamate (DDC), the major metabolite of disulfiram, had none of these effects. The intraperitoneal injection of a high dose of disulfiram and DDC into rats, mimicking acute intoxication, induced in vivo overflow of striatal dopamine from both a reserpine-sensitive (vesicular) and an alpha-methyl-p-tyrosine-sensitive (cytoplasmic) pool. The vesicular component of in vivo dopamine release resulted mainly from a direct activity of disulfiram, on the organelles (interaction with the carrier for dopamine plus membrane permeabilization) and indirectly through the mediation of serotonergic 5-HT3 receptors. DDC acted poorly at the vesicle membrane, and the in vivo releasing effect of dopamine was only partially prevented by the inhibition of 5-HT3 receptors, thus suggesting the role of additional mechanisms. It is concluded that disulfiram intoxication may acutely disrupt dopamine balance, an effect probably underlying some of the central neurotoxic, extrapyramidal symptoms associated with dithiocarbamate overdose.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1986

The uptake of cadmium from a dietary and soluble source by the crustacean Daphnia magna.

Daphnia were exposed to radioactively labeled cadmium in solution and in the presence of Chlorella which had been preloaded with the metal to varying extents. Illuminated algal cells retained the cadmium and greatly reduced its availability to the daphnids. Autoradiographic evidence was obtained which implicated the exoskeleton as a major sink for the cadmium taken up from solution. Cadmium in solution at a concentration close to the 48 hr LC50 level did not affect respiration during the first 6 hr of exposure. Retention patterns were similar, regardless of the source of cadmium, but ecdysis resulted in a considerable loss of body burden provided that this had been acquired via a predominantly soluble route.

Animals↗

PubMed2004

Radiocaesium and natural gamma emitters in mushrooms collected in Spain.

Mushrooms can accumulate heavy metals in general, including radionuclides found in the nature. However, little attention has been paid to the radioactive content of mushrooms collected in Spain and the dose for the population due to their ingestion. To address this, we analysed the contents of 137Cs, 40K, 226Ra and 7Be present in different species of mushrooms, according to their genus and nutritional mechanism. We observed that mycorrhizal mushrooms accumulate 137Cs more than saprophytes, and vice versa for 7Be. 40K and 226Ra are accumulated to the same degree by the two groups of mushrooms. We estimated the dose due to ingestion of mushrooms in Spain to be 2 microSv/year, and the contribution of 40K and 226Ra to be generally greater than that of 137Cs. The contribution of 137Cs to the dose was calculated by taking into account the results of an experiment carried out under the controlled laboratory conditions, which showed that approximately 98% of 134Cs was associated with the readily digestible fraction of the mushrooms.

Agaricales↗

PubMed1989

The quantitative spectrum of inositol phosphate metabolites in avian erythrocytes, analysed by proton n.m.r. and h.p.l.c. with direct isomer detection.

The spectrum of inositol phosphate isomers present in avian erythrocytes was investigated in qualitative and quantitative terms. Inositol phosphates were isolated in micromolar quantities from turkey blood by anion-exchange chromatography on Q-Sepharose and subjected to proton n.m.r. and h.p.l.c. analysis. We employed a h.p.l.c. technique with a novel, recently described complexometric post-column detection system, called 'metal-dye detection' [Mayr (1988) Biochem. J. 254, 585-591], which enabled us to identify non-radioactively labelled inositol phosphate isomers and to determine their masses. The results indicate that avian erythrocytes contain the same inositol phosphate isomers as mammalian cells. Denoted by the 'lowest-locant rule' [NC-IUB Recommendations (1988) Biochem. J. 258, 1-2] irrespective of true enantiomerism, these are Ins(1,4)P2, Ins(1,6)P2, Ins(1,3,4)P3, Ins(1,4,5)P3, Ins(1,3,4,5)P4, Ins(1,3,4,6)P4, Ins(1,4,5,6)P4, Ins(1,3,4,5,6)P5, and InsP6. Furthermore, we identified two inositol trisphosphate isomers hitherto not described for mammalian cells, namely Ins(1,5,6)P3 and Ins(2,4,5)P3. The possible position of these two isomers in inositol phosphate metabolism and implications resulting from absolute abundances of inositol phosphates are discussed.

Animals↗

PubMed1980

Radiotherapy of choroidal melanoma with iodine 125.

Although specific data on patients will be useful only after a 5- to 10-year follow up, radiotherapy of choroidal malignant melanoma with 125iodine has several advantages over the other radioactive sources that are presently being used. The low gamma energy of 125iodine allows for construction of metal eye plaques that can attenuate the radiation preferentially so that the tumor is treated while the rest of the eye receives minimal irradiation. This ability to direct the radiation is not possible with high energy sources such as 60cobalt. The ability to control the dose rate as well as the total dose is yet another advantage. Exact positioning of the 125iodine seeds in a plaque allows for an even distribution of the radiation throughout the tumor. Six patients have been treated. We are enthusiastic, but consider this an experimental procedure until our follow-up is complete.

Aged↗

PubMed1985

Turnover of parenterally administered zinc and cadmium and the redistribution of metallothionein bound zinc in newborn rats.

The whole body retention, tissue distribution and protein binding patterns of 65Zn were compared with 109Cd in newborn rats during postnatal development. One-day-old pups received a single injection of either 65Zn (2.5 microCi) or 109Cd (2.5 microCi plus 1 mg Cd/kg as CdCl2). During the 22 days of age, the whole body retention of 109Cd was higher than that for 65Zn. The biological half times were 466 and 46.3 days for 109Cd and 65Zn, respectively. There were marked differences in tissue deposition of these metals. Both liver and kidney accumulated more 109Cd than other tissues while the 65Zn showed a uniform distribution, with a gradual decrease in radioactivity with age. At the time of weaning, 109Cd had accumulated mainly in liver and kidney whereas, 65Zn was found predominantly in bone and skin. The specific binding of 109Cd to hepatic MT in newborn rats did not change with growth. Although a significant amount of 65Zn initially accumulated in the MT fractions in the liver, it was transferred gradually to high molecular weight protein fractions during development. The administration of these 2 metals had no effect on the body weight, liver weight and total hepatic zinc concentration. However, a significantly high content of MT and zinc in MT fractions was detected in the livers of Cd-treated rats at 22 days of age. The results show the transfer of the essential metal, zinc from hepatic MT to other proteins and the specific binding of cadmium, the non-essential metal to MT during postnatal development in rats.

Animals↗