Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RADIOACTIVE WASTE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 721 records · Page 40Linked to original sources
PubMed1993

Application of the direct beta counter Matrix 96 for cytotoxic assays: simultaneous processing and reading of 96 wells using a 51Cr-retention assay.

To assess the cytotoxic activity of immune cells, we have developed a 51Cr-retention assay in which the radioactivity retained by 51Cr-labeled target cells, following coincubation with cytotoxic cells, is monitored using the automated Matrix 96 beta counter. The Matrix 96 is designed for simultaneously counting 96 samples isolated from a 96-well microplate. It uses 96 uniform and independent detectors operating on the principle of avalanche gas ionization in the Geiger-Muller mode. Samples must be dry because the detectors are of the open-window type. Therefore, samples from the 96 wells of the microplate are simultaneously harvested onto a filter using the MicroMate 196, a 96-well cell harvester, dried and quantified in the Matrix 96. Usually the 51Cr isotope is measured by the detection of gamma radiation in gamma counters. The Matrix 96, however, monitors Auger electrons, which are also emitted by 51Cr. We have shown that the retention assay can be used to monitor the cytotoxic activity of activated lymphocytes including lymphokine-activated killer cells and tumor-infiltrating lymphocytes against various tumor cell lines. This assay is most suitable for experiments in which low E/T ratios are sufficient to detect highly cytotoxic cells, such as clone screening in cloning assays or in limiting-dilution analysis assays. These assays involve processing and reading large numbers of microplates. In this case, the retention assay monitored in the Matrix 96 will improve the work flow and decrease the amount of radioactive waste.

Chromium Radioisotopes↗
PubMed2000

Aggravation of licensing procedures by doubtful thermodynamic data.

Environmental prognosis by geochemical modelling is a scientific approach to several open questions of general public interest. Two prominent fields where geochemical modelling holds an important share are the remediation of contaminated former uranium mining areas and safety assessment of radioactive waste repositories in the geosphere. In both fields, application of geochemical modelling is stipulated by public authorities. The enormous complexity of models that can be handled by computers rises the awareness on the meaningfulness of a modelling result and demands for provision of an estimate of the dependability of a calculation output by the computers. It is obvious that bias, over- and underestimation of uncertainty in input data reduces the relevance of the calculation output. Chemistry contributes important data to geochemical modelling, both from field analysis and in the fundamental physico-chemical quantities enclosed into the thermodynamic data base. Some examples will be given where progress in quality assessment of chemical data may further the predictive power of geochemical modelling.

Journal Article↗
PubMed2000

Precise and accurate isotope ratio measurements by ICP-MS.

The precise and accurate determination of isotope ratios by inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) is important for quite different application fields (e.g. for isotope ratio measurements of stable isotopes in nature, especially for the investigation of isotope variation in nature or age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, quality assurance of fuel material, for reprocessing plants, nuclear material accounting and radioactive waste control, for tracer experiments using stable isotopes or long-lived radionuclides in biological or medical studies). Thermal ionization mass spectrometry (TIMS), which used to be the dominant analytical technique for precise isotope ratio measurements, is being increasingly replaced for isotope ratio measurements by ICP-MS due to its excellent sensitivity, precision and good accuracy. Instrumental progress in ICP-MS was achieved by the introduction of the collision cell interface in order to dissociate many disturbing argon-based molecular ions, thermalize the ions and neutralize the disturbing argon ions of plasma gas (Ar+). The application of the collision cell in ICP-QMS results in a higher ion transmission, improved sensitivity and better precision of isotope ratio measurements compared to quadrupole ICP-MS without the collision cell [e.g., for 235U/238U approximately 1 (10 microg x L(-1) uranium) 0.07% relative standard deviation (RSD) vs. 0.2% RSD in short-term measurements (n = 5)]. A significant instrumental improvement for ICP-MS is the multicollector device (MC-ICP-MS) in order to obtain a better precision of isotope ratio measurements (with a precision of up to 0.002%, RSD). CE- and HPLC-ICP-MS are used for the separation of isobaric interferences of long-lived radionuclides and stable isotopes by determination of spallation nuclide abundances in an irradiated tantalum target.

Journal Article↗
PubMed2002

Determination of thiopurine S-methyltransferase phenotype using thin-layer chromatography and quantitative scanning.

OBJECTIVE: To develop a non-high-performance liquid chromatography method for the determination of thiopurine- S-methyltransferase (TPMT) phenotype using thin-layer chromatography and quantitative scanning. METHODS: TPMT reaction was performed using a radiochemical assay. The reaction product [(14)C]-6-methylmercaptopurine was separated using thin-layer chromatography and quantified by means of radioactive scanning. Day-to-day variance was determined to validate results. RESULTS: Determination of TPMT phenotype using thin-layer chromatography and quantitative scanning is reliable (day-to-day variance 8.5+/-1.7%, mean+/-SEM). Mean TPMT activity in 314 randomly selected patient samples was 11.8+/-3.3 units/ml red blood cells (mean+/-SD, range 3.5-25 units/ml). CONCLUSION: We developed a new assay variant for the determination of TPMT phenotype that is easy to perform, reliable and reduces production of radioactive waste. This may lead to more frequent pretreatment determination of TPMT phenotype and increase drug safety and efficacy by individualising thiopurine doses.

Carbon Radioisotopes↗
PubMed2004

Distribution, diversity and activity of microorganisms in the hyper-alkaline spring waters of Maqarin in Jordan.

The hyper-alkaline, high-Ca(2+) springs of Maqarin, Jordan, were investigated as an analogue for various microbial processes at the extremely high pH generated by cement and concrete in some underground radioactive waste repositories. Leaching of metamorphic, cementitious phases in Maqarin has produced current, hyper-alkaline groundwater with a maximum pH of 12.9. Six consecutive expeditions were undertaken to the area during 1994-2000. The total number of microorganisms in the alkaline waters was 10(3)-10(5) cells/ml. Analysis of the 16S-ribosomal ribonucleic acid (rRNA) diversity revealed microorganisms mainly belonging to the Proteobacteria. Obvious similarities between the obtained sequences and sequences from other alkaline sites could not be found. Numerous combinations of culture media compositions were inoculated with spring, seepage and groundwaters and incubated under aerobic and anaerobic conditions with various carbon sources. Assimilation studies were performed using identical radio-labeled carbon sources. Glucose seemed to be the preferred carbon source for assimilation, followed by acetate, lactate, and leucine. The results demonstrate that microorganisms from the hyper-alkaline springs of Maqarin could grow and be metabolically active under aerobic and anaerobic hyper-alkaline conditions. However, the growth and activity found were not vigorous; instead, slow growth, low numbers, and a generally low metabolic activity were found. This suggests that microbial activity will be low during the hyper-alkaline phase of cementitious repositories.

Carbon↗
PubMed2005

Radiobiology and gray science: flaws in landmark new radiation protections.

The International Commission on Radiological Protection--whose regularly updated recommendations are routinely adopted as law throughout the globe--recently issued the first-ever ICRP protections for the environment. These draft 2005 proposals are significant both because they offer the commission's first radiation protections for any non-human parts of the planet and because they will influence both the quality of radiation risk assessment and environmental protection, as well as the global costs of nuclear-weapons cleanup, reactor decommissioning and radioactive waste management. This piece argues that the 2005 recommendations are scientifically and ethically flawed, or gray, in at least three respects: first, in largely ignoring scientific journals while employing mainly "gray literature;" second, in relying on non-transparent dose estimates and models, rather than on actual radiation measurements; and third, in ignoring classical ethical constraints on acceptable radiation risk.

Dose-Response Relationship, Radiation↗
PubMed1983

Preparation and reactions of an iodinated imidoester reagent with actin and alpha-actinin.

The chemical iodination of an imidoester (methyl-p-hydroxybenzimidate, Wood et al. (1975) Anal. Biochem. 68, 339) and subsequent coupling of iodinated imidoester (IIE) to protein is an indirect method of iodinating proteins that is specific for the epsilon amino group of lysine residues and maintains the positive charge on the amino group at physiological pH. Purification of the IIE from chloramine-T and free iodine by benzene extraction eliminates the need for isoelectric precipitation and produces a more time- and cost-efficient IIE preparation and purification protocol. The separation of free from protein-bound label by chromatography, using centrifugal elution, provides a separation method that is rapid and efficient, without the generation of large volumes of radioactive wastes characteristic of conventional chromatographic and dialysis methods. To optimize the parameters of labeling protein with IIE, a systematic assessment of the effects of pH, reactant concentrations, and reaction time was made using purified cardiac actin and gizzard alpha-actinin. The parameters were defined to achieve an average labeling ratio of one IIE per protein polypeptide. The data demonstrate that both proteins appear to be labeled at the same rate and define several determining factors that limit the rate and extent of IIE incorporation into protein.

Actinin↗
PubMed1986

Solid-phase iodination: in vitro labeling with 125I of proteins bound to nitrocellulose and substituted Sepharose.

A solid-phase iodination method is described which employs either nitrocellulose paper, phenyl- and octyl-Sepharose beads, or octyl hydroxylapatite as matrices to adsorb proteins. Nitrocellulose lends itself to cases where denaturation of the iodinated proteins due to the use of chaotropic reagents or strong acids for protein elution can be tolerated. On the other hand, substituted Sepharoses, preferably octyl-Sepharose, should be used when preservation of the biological activity of the iodinated protein molecules is required; immunoglobulins and protein A, for instance, could be recovered as functionally active molecules because they were extracted from the hydrophobic matrices under nondenaturing conditions. Both methods are advantageous if, for example, series of fractions from column chromatographies (including HPLC) are to be iodinated and subsequently analyzed by gel electrophoresis or bioassays. Furthermore, the amount of radioactive waste can be reduced considerably.

Collodion↗
PubMed1988

Radioiodination of proteins and lipoproteins using N-bromosuccinimide as oxidizing agent.

In an attempt to improve conditions for radioiodination of sensitive proteins we used N-bromosuccinimide as a mild oxidizing agent. Under gentle conditions we increased the average labeling efficiency of a wide variety of proteins to above 97%. There was no loss of binding activity of low density lipoprotein particles, which are most sensitive to oxidation. Depending on high labeling efficiency, our method reduces preparation time as well as radioactive waste, costs, and irradiation exposure to personnel.

Animals↗
PubMed1990

A method for separating bound versus unbound label during radioiodination.

An inexpensive, highly effective, and safe method for the removal of bound versus unbound label during radiolabeling of proteins is described. The technique employs the use of membrane ultrafiltration technology and returns in one step a highly reproducible product of quality superior to that attained by gel chromatography. Advantages of this technique are a reduction in the quantity of liquid and solid radioactive waste and a significant limitation of potentially harmful manipulation and exposure times.

Chromatography, Gel↗
PubMed1975

A method for the recovery of the constituents of scintillation fluid used in the assay of steroid hormones.

A procedure for the recovery of toluene, and the fluors 2,5-diphenyloxazole, and 1,4-bis-2-(5 phenyloxazolyl)-benzene from used scintillation fluid is described. Toluene is recovered by distillation, and the accumulated residue containing the fluors is dried, and subjected to vacuum distillation and recrystallization. The recovery of the two fluors is 75 and 70%, respectively. The method is relatively simple and could be used in many endocrine laboratories for economy and to reduce volumes of radioactive waste.

Benzoxazoles↗
PubMed1987

Development and clinical application of sensitive enzyme immunoassay for macromolecular antigens--a review.

Radioimmunoassay has been a powerful tool to measure haptens and antigens which are important for the investigation and diagnosis of diseases, especially endocrine disorders. However, the use of radioisotopes in radioimmunoassay suffers from serious disadvantages. Radioisotope-labeled reagents are unstable and hazardous to health. The disposal of radioactive wastes is not easy. Furthermore, the sensitivity of radioimmunoassay is limited by the detection limit of radioisotope that depends upon the half-life. The detection limit of the most widely used radioisotope, 125I, with a half-life of 60 days is 5 to 10 amol, when it is carrier-free. By contrast, the use of enzymes has obvious advantages. Some enzymes are very stable and cause no health hazards or waste disposal problems, provided that appropriate substrates are chosen. The detection limits of some enzymes are lower than that of 125I and will be further improved in the future. Therefore, enzyme immunoassay is potentially more sensitive than radioimmunoassay. This article reviews the development and clinical application of sensitive enzyme immunoassay for macromolecular antigens, which has been replacing radioimmunoassay.

Antigens↗
PubMed1982

Technetium-99m generators--the available options.

The review describes the three most commonly used methods of separating 99mTc from 99Mo, namely chromatography, sublimation and solvent extraction. General comparisons are made between the various generator systems and their respective advantages and weaknesses. The method of producing the parent radionuclide 99Mo often dictates which of the generator options is more appropriate to a particular 99mTc user. Although the use of fission-produced 99Mo is widespread, this technique is not ideal since it requires considerable capital investment and gives rise to large quantities of long-lived radioactive waste. In certain countries such resources cannot be presumed and as a result alternative methods of producing 99mTc from neutron-activation-produced 99Mo are attractive. Recent advances in generator technology indicate that neutron-activation-produced 99Mo may eventually replace the need for fission-produced 99Mo. The review mentions one method of achieving this goal.

Kinetics↗
PubMed1985

A new design for a liquid scintillation counter for micro samples using a flat-bed geometry.

A new design for a liquid scintillation counter based on a flat-bed geometry is described. Micro-samples are dried or filtered onto transfer membranes or glass fibre filters in a 6 X 16 matrix, compatible with 96-well micro-titration plate filtration assays of labelled cells. A prototype counter without lead shielding had low background countrates (2-3 cpm for 3H) giving a figure of merit of 1325 (and 1292 for 14C). Only 5-15 ml of scintillant/96 samples are required and thus the volume of radioactive waste is low.

DNA↗
PubMed1984

A small scale indirect 125iodine-labelled protein A binding assay for detection of monoclonal antibodies against avian oncoviral proteins.

A small scale solid-phase radioimmunoassay employing 125I-labelled protein A is described which is suitable for screening large numbers of monoclonal antibodies directed against antigens which can be prepared in small amounts only, for example oncoviral proteins. The use of polystyrene Terasaki microtest plates instead of 96-well microtitre plates reduces the amount of antigen required for screening hybridoma supernatants to less than 30 ng/well. This method facilitates washing procedures and reduces the quantity of radioactive waste. The sensitivity and specificity of the method is demonstrated by the isolation and initial characterization of monoclonal antibodies specific for avian oncoviral transforming, structural and polymerase proteins.

Animals↗
PubMed1983

16 alpha-iodo-3,17 beta-estradiol: a stable ligand for estrogen receptor determinations in tissues with high 17 beta-hydroxysteroid dehydrogenase activity.

Recently, the successful synthesis of radioiodinated 16 alpha-iodo-3,17 beta-estradiol-[125I] [125I]E2 was reported [1]. This new ligand has similar binding characteristics to the estrogen receptor (ER) [2-5] as the currently used tritium labeled estradiol [3H]E2. However, it offers several advantageous features: (a) high specific activity (theoretically 2,000 Ci/mmol) [1]; (b) minor problems with radioactive waste due to its short half life and (c) the possibility of simultaneous determination of ER and progesterone receptors (PgR) by double labeling with [125I]E2 and [3H]R5020 [6, 7]. As we are presently trying to determine ER and PgR in human placental cytosols we were interested in the stability of different labeled estrogens under the conditions of ER-assay. Placental cytosols [8] as well as cytosols of other tissues such as endometrium [9, 10], ovary [11] or mammary carcinomas [12] have been reported to contain significant amounts of 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity. Conversion of labeled estradiol to estrone during incubation for ER-quantification would diminish the amount of labeled estradiol thus leading to errors in ER-concentrations, as estrone has only about 10% of estradiol's binding activity [13].

17-Hydroxysteroid Dehydrogenases↗
PubMed1982

Double antibody immunoradiometric assay of hGH employing a terminal labeling technique.

A method is described, and validated for hGH, using a double antibody immunoradiometric assay and a universal antibody coupled to a chelating moiety that can be labeled as the terminal step in the assay procedure. This technique, usable for any antigen, precludes the need for radiolabeled specific antibodies, and because of the short-lived radionuclide used in the terminal labeling step, generates no radioactive waste. The assay itself uses a specific first antibody coupled to a solid support (paper disc) to which the antigen binds. A specific second antibody from a second species is then attached to the solid phase retained antigen. Now a third antibody is attached, which has been generated from a third species against the second antibody acting as an antigen, and which carries transferrin as a chelating moiety. This final complex is labeled with 113mIn and the plot of the percentage of the total activity bound against the hGH concentration provides the derived values for the antigen levels present in the assay solution.

Antibodies↗