SEARCH · PubMed Health

Results for “Elements, Radioactive”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 919 records · Page 51Linked to original sources

PubMed1998

Geographical distribution of radiation risks in The Netherlands.

Risk assessment of exposure to sources of radiation is an important tool for national governments in regulating radionuclide emissions and thus reducing radiation doses for the general public. For this reason radiation doses from sources throughout The Netherlands have been analyzed. For sources with well-defined locations and doses that were thought to vary significantly throughout The Netherlands, radiation dose maps were produced. Average dose values were calculated or derived from the literature for doses considered to be evenly distributed throughout the country or for which no information on the geographical distribution of dose was available. Emission, dispersion, and individual dose were modeled for each source using various pathways and exposure routes. Indoor radon and gamma radiation from building materials generate the highest dose values. The highest human induced radiation doses for industries of which the doses showed to be geographically distributed are found in the cement industry, elemental phosphorus production, phosphoric acid production, and iron and steel production. Radiation dose from some of these sources has a very local peak and decreases rapidly with distance. The elemental phosphorus production causes relatively high radiation doses throughout a large part of The Netherlands. Cumulation of doses from various sources occurs, but these are often masked by doses from a few large industries.

Eating↗

PubMedDate not supplied

Unresolved issues, dilemmas and points of interest in thyroid cancer: a current perspective.

Thyroid cancer (TC) is the commonest endocrine malignancy. In the overwhelming majority of cases, thyroid carcinomas are well-differentiated malignancies that respond favorably to treatment; however, this outcome cannot be absolutely guaranteed. The absence of large prospective randomized clinical trials in TC-due to its low incidence and protracted clinical course in cases with persistent/recurrent metastatic disease-results in considerable debates regarding the optimal treatment and follow-up regimens in this malignancy. Some of these debates originated several decades ago, yet are still ongoing despite interim advancements in other domains of oncology. Here we discuss what we believe are the issues of major controversy in TC; these are mentioned in the following non-exhaustive list: (i) the optimal management of solitary and multiple thyroid nodules; (ii) the role of basal calcitonin measurements in the diagnostic investigation of nodular thyroid disease; (iii) the extent of the initial operation after establishment of the diagnosis of TC; (iv) the intensity and frequency of radioactive iodine (RAI; (131)I) therapies (especially in patients with persistent/recurrent metastatic disease); (v) the degree and duration of long-term thyroid hormone suppression therapy (THST) required for optimal outcomes in TC patients; (vi) the optimal management of patients with RAI-refractory disease or other "high-risk" clinicopathologic features; and, finally, (vii) the optimal algorithm for lifelong follow-up of TC patients after their initial treatment. We present elements of the above controversies as pertinent to the various types of TC. We have opted for breadth rather than depth of commentary, at the same time providing the reader with extended up-to-date bibliography.

Journal Article↗

PubMed2004

Ligand-receptor interactions in live cells by fluorescence correlation spectroscopy.

Receptor binding studies most often require the use of radioactively labeled ligands. In certain cases, the numbers of receptors are few per cell and no specific binding is detected because of a high background. Specific interactions between certain ligands (e.g. peptides, hormones, natural products) and their receptors are, therefore, often overlooked by the conventional binding technique. Fluorescence correlation spectroscopy (FCS) allows detection of the interaction of ligands with receptors in their native environment in live cells in a tiny confocal volume element (0.2 fl) at single-molecule detection sensitivity. This technique permits the identification of receptors which were not possible before to detect by isotope labeling. The beauty of the FCS technique is that there is no need for separating an unbound ligand from a bound one to calculate the receptor bound and free ligand fractions. This review will show FCS as a sensitive and a rapid technique to study ligand-receptor interaction in live cells and will demonstrate that the FCS-analysis of ligand-receptor interactions in live cells fulfils all the criteria of a ligand binding to its receptor i.e. it is able to provide information on the affinity and specificity of a ligand, binding constant, association and dissociation rate constants as well as the number and mobility of receptors carrying a fluorescently labeled ligand. This review is of pharmaceutical significance since it will provide insights on how FCS can be used as a rapid technique for studying ligand-receptor interactions in cell cultures, which is one step forward towards a high throughput drug screening in cell cultures.

Cell Membrane↗

PubMedDate not supplied

[Evaluation of the exposure levels to radioactivity in the hot-spring environment of the Island of Ischia during a year].

It is known that the decay products of the U-238 are findable in nature in certain materials (such as tufa, limestone, etc.), therefore some populations are naturally exposed to radiations originated by building materials, houses and isotopes present in drinking-waters. It is evident that, for example, the residents of Campania or Lazio will be involved, on such conditions and during their whole life, in the action of natural radiations of decay products of Uranium and consequently of Radon, which is originated and, as gas, also findable in the air of those indoor areas, at a concentration inversely proportional to the relevant ventilation factors. Furthermore, it is known that this isotope is always found in thermal waters too and sometimes at levels which make them classify as radioactive and with therapeutic properties still subjects of studies and researches. Actually, presence of Radon in warm waters is particularly evident in some basins (the Baths of Badgastein in Austria) and is also findable in some italian thermal towns such as Merano Laurisia, Abano, Baths of Lucca or the island of Ischia itself. All underground waters and especially the warm ones, including, those of Ischia basins, hold radioactive isotopes, since their composition is related to the nature of the underground, which they come from, and is strongly influenced by the kind of rocks present in that area, by the granulometry of the geological strata or by existent fractures, by flow speed and finally by solubilization capacity. On such conditions it is evident that all waters, during their scouring, will be enriched by Radon 222 (a gaseous, therefore more soluble, element); just because of its physical state, it will be more present in external environment in case of warm waters such as those ones now examined. Consequently the environmental state from a radioecological point of view of the utilized waters has to be considered, as well as any other thermal resort, fundamentally due to Radon (Rn) and to the relevant decay products. As a matter of fact, whereas from the family of Uranium come Radon (Rn 222), Lead (Pb 210) and Polonium (Po 210), these last two, respectively with halving-times of 22.3 years and 138.4 days, from the family of Thorium (Th 232) originates Radon (Rn 220 in past times defined "Toron" according to its "forebear") and Lead (Pb 212 with a halving-time of 10.6 hours).(ABSTRACT TRUNCATED AT 400 WORDS)

Background Radiation↗

PubMed1979

A computer program for simulating a distributed metabolic system. Distribution volumes in a simulated organism.

A metabolite or hormone is distributed with non-uniform concentration throughout some volume within an intact organism. Various methods involving radioactive tracers are used to estimate the total mass of the metabolite and its volume of distribution. The calculations of mass and volume are based on very simple models, and cannot usually be validated by measurements on the real animal. Hence we have developed a computer program for simulating a metabolic system with convective and diffusive transport. The tracer experiments can be simulated by solving the differential equations for convective diffusion by finite element methods. Thus the total metabolic mass and distribution volume can be both 'measured' and calculated by all the standard techniques. In this way some mathematical methods currently in general use can be seen to be patently incorrect, and others quite acceptable. The concept of a metabolic doublet was introduced, by analogy with an electrical dipole.

Biological Transport↗

PubMed2001

[Diagnosis and treatment of intraocular tumors in the child].

PURPOSE: To remind of the absolute necessity for early diagnosis in the presence of ocular signs in children giving rise to possible intraocular tumours. METHOD: Based on our own experience of intraocular tumours in children, together with findings from the literature, diagnostic criteria and methods of treatment are presented. RESULTS: Retinoblastoma is the predominant cause of intraocular tumours in children, representing over 80% of cases under the age of 15 years. Other diseases may give rise to the same initial signs, usually leukocoria, sometimes strabismus, more rarely other atypical signs. Elements taken into account for diagnosis include age, sex, laterality, heredity, size of the globe, clinical aspect of the tumours, presence of calcifications and vitreous seeding. Full fundus examination under general anaesthetic is usually necessary. Biological examination, ultrasonography, computerized tomography and MRI enable an accurate diagnosis to be made in the majority of doubtful cases. The management of retinoblastoma is adapted for each individual case from the wide range of treatments available. Enucleation, radioactive applicators (...), brachytherapy (...), cryo- and photocoagulation represent classical measures. Primary chemotherapy, combined with other treatments such as thermotherapy, has become the treatment of choice in those cases where external beam radiotherapy has been used up to now, or in some instances before enucleation. Enucleation is usually carried out for medullo-epitheliomas, but brachytherapy may offer an alternative. CONCLUSION: Any unexplained ocular sign in children should be considered as a possible retinoblastoma, making an accurate and certain diagnosis imperative. Early treatment may save not only the life but also the vision of patients carrying this highly malignant lesion.

Child↗

PubMed1981

In-vitro uptake and metabolism of [3H] corticosterone by mammary glands from pregnant, lactating, and post-lactational rats and by parametrial adipose tissue from lactating rats.

The study was designed to determine the influence of the physiological state on the in-vitro uptake and metabolism of glucocorticoid hormone by the mammary gland. [3H] Corticosterone was accordingly incubated with minced mammary glands from pregnant, lactating and post-lactational rats. The total uptake of [3H] corticosteroid was obtained from the concentration of radioactivity by the tissue and the specific activity of the steroid substrate. The extent of 21-acylation was determined as the percentage of the radioactivity in the chromatographed tissue extracts attributable to 21-acyl-[3H] corticosterone. The results indicated that the uptake of [3H] corticosteroid increased with advancing pregnancy, attained a high plateau level during lactation, and steadily declined during the post-lactational period. The extent of 21-acylation of [3H] corticosterone varied from 10 to 40%, fluctuating widely in all physiological states, particularly during the post-lactational period. It was inferred that the stromal elements, presumably the adipocytes, of the mammary gland can also acylate the corticosteroid hormone, a view which gained experimental support from similar studies with minced parametrial adipose tissue from lactating rats.

Acylation↗

PubMed2004

Comparison of transfer and distribution of technetium and rhenium in radish plants from nutrient solution.

Tracer experiments were carried out to compare the plant uptake behavior of Tc and Re from nutrient solutions. Radish plants, transplanted to nutrient solution including various tracers, showed the same uptake and distribution of 95mTc and 183Re. The trend was the same when the 99Tc and stable-Re concentrations were increased in nutrient solution. The behavior of other elements was different from that of Tc and Re. These findings suggest the possible use of Re as the chemical analogue of Tc in soil solution to plant uptake experiments.

Industrial Waste↗

PubMedDate not supplied

Toxic agent and radiation control: progress toward objectives for the nation for the year 1990.

In 1980, the Department of Health and Human Services set national prevention objectives for 1990 in 15 health priority areas, 1 of which is the control of toxic agents and radiation. Ten objectives related to this area are priorities for the national control effort. Progress is reviewed on those priorities within the responsibilities of the Public Health Service. Six key program elements, or types of support activities, are deemed essential to preventing, identifying, and controlling toxic agent and radiation threats. Significant progress has been made toward achieving objectives for which all key program elements have been successfully implemented to provide the requisite know-how, manpower, and tools. Important advances have been made in reducing the blood lead levels of the population, reducing unnecessary exposure to medical X-rays, evaluating the toxicities of chemicals in toxic waste dumps, and improving the scientific and technical information base and its availability for prevention and control efforts. The most important priority for the forseeable future will be to expand our knowledge of potential health risks posed by toxic agents and radiation. Expanded surveillance systems and data bases are essential to determining the extent of the problems in terms of human health effects and for measuring the impact of prevention programs. Emphasis on the activities embodied in the key elements will encourage the expansion of the knowledge base and its effective application to prevention and control problems.

Environmental Health↗

PubMedDate not supplied

[Structural and physicochemical characteristics of DNA from animal tissue subjected to chronic irradiation in the Chernobyl area].

The properties of animal DNAs exposed to prolonged irradiation in the Chernobyl zone, have been studied by the methods of viscometry, thermal denaturation, IR-spectroscopy, and electrophoresis. High content of low-molecular fractions have been observed in the preparations of DNA from liver and spleen, their quantities increasing with age and generation of animals. This effect is especially strong in DNA from liver. Low-molecular fraction of DNA is shown to be enriched with G-C pairs and to consist of the following four fractions: 1) approximately 500 base pairs (B.p.), 2) approximately 1.5 divided by 2 thousand B.p., 3) approximately 4 divided by 5 thousand B.p. and 4) a mixture of approximately 20 thousand B.p. fragments. Further, it has been observed that the DNA preparations from the tissues of experimental animals contain about ten times higher contents of Fe, Zn, Se and other elements as compared to the control preparations.

Animals↗

PubMed2005

A comparative radiological assessment of five European biosphere systems in the context of potential contamination of well water from the hypothetical disposal of radioactive waste.

In the framework of the BioMoSA project for the development of biosphere assessment models for radioactive waste disposal the Reference Biosphere Methodology developed in the IAEA programme BIOMASS was applied to five locations, situated in different European countries. Specific biosphere models were applied to assess the hypothetical contamination of a range of agricultural and environmental pathways and the dose to individuals, following contamination of well water. The results of these site-specific models developed by the different BioMoSA partners, and the individual normalised dose to the exposure groups were compared against each other. Ingestion of drinking water, fruit and vegetables were found to be among the most important pathways for almost all radionuclides. Stochastic calculations revealed that consumption habits, transfer factors, irrigation rates and distribution coefficients (Kd(s)) were the most important parameters that influence the end results. Variations in the confidence intervals were found to be higher for sorbing elements (e.g. (36)Cl, (237)Np, (99)Tc, (238)U, (129)I) than for mobile elements (e.g. (226)Ra, (79)Se, (135)Cs, (231)Pa, (239)Pu). The influence of daughter products, for which the distribution into the biosphere was calculated individually, was also shown to be important. This paper gives a brief overview of the deterministic and stochastic modelling results and the parameter sensitivity. A screening methodology was introduced to identify the most important pathways, simplify a generic biosphere tool and refine the existing models.

Adult↗

PubMed1998

Expression of the RNA component of telomerase in Wilms tumor and nephrogenic rest recapitulates renal embryogenesis.

Telomerase is a ribonucleoprotein enzyme associated with cellular immortality and has been detected in the vast majority of adult tumors. Wilms tumor is a histologically diverse embryonal malignancy of childhood, and the histological features of Wilms tumor and its precursor lesion, the nephrogenic rest, recapitulate the components of normal renal embryogenesis. Both the epithelial and the stromal components of Wilms tumor arise by differentiation of primitive mesodermal blastema. We compared expression of the RNA component of human telomerase (hTR) in normal developing kidneys, Wilms tumors, and nephrogenic rests and correlated expression of hTR with cell proliferation. Using a radioactive in situ hybridization method, we examined archival material from 17 Wilms tumors (including nine with nephrogenic rests), four therapeutically aborted embryos (37 to 56 days), three fetuses on whom autopsies had been performed, and one neonate for expression of hTR. Proliferative index was measured by immunohistochemical staining for MIB1. In the embryonic kidney, Wilms tumors, and nephrogenic rests, the patterns of hTR expression were similar: expression was usually maximal within the immature epithelial elements followed by the poorly differentiated blastema, but was weak or absent in the immature stroma. Mature tubules, glomeruli, and stroma were negative for hTR expression, as were differentiated heterologous elements present in post-therapy Wilms tumors. There was only a partial relationship between proliferative index and hTR expression. In the embryonic kidney, Wilms tumors, and nephrogenic rests, blastema had the highest proliferative index, whereas the indices were significantly lower in the immature epithelium and stroma. The proliferative index in mature and heterologous elements was low or zero. Thus, the pattern of hTR expression in Wilms tumor and its precursor lesion recapitulates embryogenesis precisely and may represent that aspect of the persistent fetal phenotype which predisposes to the development of malignancy.

Child, Preschool↗

PubMed1997

Drosophila ecdysone receptor functions as a constitutive activator in yeast.

Transcriptional activation of the Drosophila ecdysone receptor (EcR) was studied in yeast cells, which carry a reporter plasmid containing the ecdysone response element in the absence or presence of its heterodimeric partners, ultraspiracle protein (USP) or human retinoid X receptor (RXRalpha). High constitutive transcriptional activation was detected in the yeast strain expressing EcR, but not USP or RXRalpha in the absence of ponasterone or muristerone A. Incubation of these ligands with yeast cells coexpressing EcR and USP or RXRalpha did not enhance the constitutive transcriptional activity. However, specific ligand binding using [3H]ponasterone A as a radioactive ligand was detected only in yeast extracts prepared from the yeast strain coexpressing EcR and USP, but not from yeast strains expressing only EcR or USP. The ligand binding characteristics of the EcR/USP complexes were similar to those reported in an insect cell line with a Kd value of 1.8 nM for [3H]ponasterone A. These data are in contrast to mammalian cell transfection studies, and indicate that the EcR is the only member of the nuclear receptor superfamily of ligand-activated transcription factors which functions as a constitutive transcriptional activator in yeast, although the EcR/USP complexes exhibit normal ligand binding properties.

Animals↗

PubMed1984

Uptake of radiolabeled alpha-fetoprotein by mouse mammary carcinomas and its usefulness in tumor scintigraphy.

The ability to internalize alpha-fetoprotein (AFP) and serum albumin, which is characteristic of embryonic and fetal elements undergoing differentiation, may reappear in some cultured neoplastic cells (i.e., the MCF-7 human breast cancer cell line). The in vivo uptake of AFP by spontaneous carcinomas of the CH3/Bi mouse was investigated. Nineteen mice were given i.v. injections of approximately 10 muCi of mouse 125I-AFP (0.6 to 4 micrograms of AFP according to the specific ratio of the preparation used). Four to 7 days later, the animals were sacrificed. The radioactivity concentration in the tumor was the highest among all solid tissues examined. Tumor:liver radioactivity ratios were clearly positive [3.6 +/- 0.3 (S.E.)] in 27 of 31 specimens studied. Microscopy examination of autoradiograms from various tissue sections confirmed the selective accumulation of radioactive AFP in the tumors. In order to assess the specificity of AFP uptake by mammary tumors, 4 mice were given simultaneous injections of 125I-AFP and 131I-ovalbumin, respectively. Compared to AFP, the retention of ovalbumin was very low in all tissues studied, including the tumor. The possibility of tumor localization of radiolabeled AFP by external photoscanning was also explored. Two mice were given injections of 131I-AFP, one mouse received 131I-serum albumin, and one was given 131I-ovalbumin. Images were obtained 6 days after with a standard gamma-camera linked to a computer with data display. About 50% of the total radioactivity retained was concentrated in the tumor areas of mice given injections of iodinated AFP, while it was only 15% in the mouse that received 131I-serum albumin. No tumor image could be detected in the mouse given ovalbumin. These results show that the ability to internalize AFP, common to many tissues during ontogenesis, may also be shared by neoplastic cells which develop later in life. They also prove the preferential uptake of AFP by the tumors compared to normal tissues and the usefulness of AFP as a radiotracer for mammary carcinomas. The latter represents a novel approach to tumor detection.

Adenocarcinoma↗

PubMed2005

Accumulation and distribution of samarium-153 in rat brain after intraperitoneal injection.

It is well known that rare earth elements (REEs) have come into extensive use in a number of fields. As a result, REEs are becoming closely related to human's daily life. However, until now, the distributions of REEs in the brain are not yet very clear. In this study, Sprague-Dawley male rats were intraperitoneally injected with 0.25 mL of (153)SmCl(3) solution (containing 10 microg Sm). The brains were perfused with saline to minimize the blood influence. The radioactivities of (153)Sm in the five brain regions (hypothalamus, cerebellum, hippocampus, corpus striatum, and cerebral cortex) were counted. The results suggested that Sm did enter into the brain. Although only about 0.0003% of the given dose was accumulated in the brain, Sm seemed to be remain in the brain for a long time. The highest amounts and lowest concentrations of (153)Sm were found in the cerebral cortex, and the highest concentrations of (153)Sm were found in the hypothalamus.

Animals↗

PubMed1987

Further evidence supporting the concurrent influence of aflatoxin and manganese.

Trace elements, including manganese may afford protection from deleterious effects of aflatoxin. Young male Fischer rats received ip injections of aflatoxin B1 (AFB1) in dimethyl sulfoxide (DMSO), 1 mg/kg, 2 mg/kg or 4 mg/kg. Control groups received DMSO ip or no injection. All animals were intubated with 3 microCi of [54Mn]-MnCl2 12 hr post-injection. Sacrifice occurred 72 hr after gavage of the radiolabel. All tested levels of AFB1 affected the loss of total body radioactivity. This response was observed within 12 hr when toxin-treated groups excreted almost 4 times more counts than controls. From 12-36 hr following radiolabel administration, AFB1 appeared to enhance excretion; by 72 hr, toxin-treated animals (especially those receiving higher doses) appeared to conserve the metal. Aflatoxicosis manifested itself through reduced body weight gain. The data provide support evidence that Mn and AFB1 biointeract.

Aflatoxin B1↗

PubMed2005

Benchmark studies of induced radioactivity produced in LHC materials, Part II: Remanent dose rates.

A new method to estimate remanent dose rates, to be used with the Monte Carlo code FLUKA, was benchmarked against measurements from an experiment that was performed at the CERN-EU high-energy reference field facility. An extensive collection of samples of different materials were placed downstream of, and laterally to, a copper target, intercepting a positively charged mixed hadron beam with a momentum of 120 GeV c(-1). Emphasis was put on the reduction of uncertainties by taking measures such as careful monitoring of the irradiation parameters, using different instruments to measure dose rates, adopting detailed elemental analyses of the irradiated materials and making detailed simulations of the irradiation experiment. The measured and calculated dose rates are in good agreement.

Benchmarking↗

PubMed2006

The distribution and transport of Sellafield derived 137 Cs and 241 Am to western Irish Sea sediments.

Sellafield derived (137)Cs and (241)Am were analysed in surficial sediments at 23 sites in the western Irish Sea. Concentrations varied between 3-175 Bq (137)Cs/kg and 1-147 Bq (241)Am/kg. There are two distinct basins in the western Irish Sea separated by an area of restricted depth and this bathymetry is reflected in the radionuclide concentrations. Highest concentrations were found in the northerly samples and substantially lower concentrations further south. This pattern of distribution can be explained by the predominantly northerly residual flow and the existence of seasonal stratification in this area of weak tides. (137)Cs/(241)Am ratios were also highest in the northern basin, and it is suggested that this is caused by differences in the mechanisms of transport of the two elements. The direct physical migration of contaminated particles from the eastern Irish Sea is the dominant transport mechanism in the north of the study area, whereas transport in the dissolved phase is most important to the southern region. Concentrations of both elements were best correlated with the percentage <15 microm particulate fraction suggesting that particles within this range are most important for direct transport and scavenging from the soluble phase.

Americium↗