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Results for “Elements, Radioactive”

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PubMed1999

Comparison of three methods of microsatellite detection.

Examination of microsatellites is frequent in the diagnosis of cancer. Microsatellites are repeat DNA sequences scattered throughout the human genome. These repeat regions are very frequent and highly polymorphic elements. In this study we focus on dinucleotide repeats. We compared three different methods for the detection of microsatellites: use of the ABI Prism 377 fluorescence sequencer, autoradiography and silver-stained gels. DNA was extracted from various clinical samples and amplified by different polymerase chain reaction (PCR) protocols. DNA from normal and tumor tissues was analysed using each method. The fluorescence method was more sensitive than the two other methods; however, this technology is very expensive. It seems possible, when examining microsatellites on a low budget, to avoid radioactivity by using silver-stained gels as an alternative. In conclusion, we observed identical results when comparing autoradiography with the fluorescence technique. However, we observed variability in the results when interpreting a single locus comparing silver staining with autoradiography and the fluorescence technique. Classification of the tumors based on several microsatellite loci was always identical.

Autoradiography↗

PubMedDate not supplied

Geology and geochronology of the middle Miocene Kipsaramon site complex, Muruyur Beds, Tugen Hills, Kenya.

The Muruyur Beds are a substantial sedimentary deposit within a middle Miocene sequence of mafic volcanic flows associated with early stages of rifting in the central Kenyan Rift Valley. They are best represented in the Muruyur region, near Bartabwa, north of Kipsaramon, where dates range from 16.0 to 13.4 Ma. At Kipsaramon, located about 10 km south of Muruyur along the crest of the Tugen Hills, the upper Muruyur Beds are absent and the lower part can be divided into three members. Important fossil sites within Member 1 are dated between 15.8 and 15.6 Ma, and within Member 3 between 15.6 and 15.4 Ma. BPRP#89, in Member 1, is a bonebed at least 2500 m(2)in areal extent and up to 30 cm thick, which constitutes one of the richest concentrations of in situ fossil vertebrate bones in eastern Africa. BPRP#91, at approximately the same level at BPRP#89, is the source of a hominoid talus and other mammal and bird fossils. In Member 3, BPRP#122 has produced specimens of at least five individuals of the hominoid Equatorius, including a partial skeleton. The Muyuyur Beds were deposited near the western margin of a lake that was formed during the early stages of faulting and volcanism in the African Rift system. The bonebed in Member 1 appears to represent the influx of fluvially transported vertebrate and plant remains into a shallow portion of the lake. Elements of the fauna as well as stable isotopes that indicate both forest and more open environments occurred in proximity to the lake during the time of deposition of Member 1.

Animals↗

PubMed1982

Photoaffinity labeling of the N-formyl peptide receptor of human polymorphonuclear leukocytes.

Quantitative analysis of ligand-occupied receptor interactions with elements of the cytoskeleton and with intracellular compartments requires a sensitive and simple method of identifying the receptor-ligand complex in living cells. Toward this goal, we have prepared a photoactivatable arylazide derivative of the chemotactic peptide N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys, which can be radiolabeled to high specific activity with 125I. This derivative was biologically active as judged by its ability to elicit superoxide anion production by human PMNL at nanomolar concentrations (ED50 approximately 0.7 nM). When incubated at 0 degree C with whole PMNL, radioactive ligand became specifically and saturably associated with a 60-70,000-dalton species (as assessed by SDS-PAGE) after exposure to UV light. Addition of 10-100-fold excess of unlabeled parent or unlabeled azidopeptide derivative completely blocked uptake into this species. Approximately 20-40% of the available surface receptor-binding sites were covalently labeled under these conditions. Subcellular fractionation of the labeled cells on sucrose gradients after homogenization showed that the labeled species was primarily associated with plasma membrane-rich fractions. The labeled receptor could be completely solubilized with Triton X-100 in a form which eluted as a single species with a Stoke's radius of less than 50 A on Sepharose 4B columns. In addition, the solubilized receptor-ligand complex bound specifically to wheat germ agglutinin, indicating that it is probably a glycoprotein. The ability to label the receptor in living PMNL with a high efficiency should facilitate the study of receptor dynamics and receptor physiochemical properties in this system.

Affinity Labels↗

PubMed1977

Subcellular localization of the alterations in phosphatidylinositol metabolism following glucose-induced insulin release from rat pancreatic islets.

The subcellular localization of the incorporation of 2-(3H)-myoinositol into lipids has been studied in isolated pancreatic islets of the rat. The recovery of lipid-bound myoinositol increased with time in the nuclear, mitochondrial, microsomal, and secretory granule fractions. The utilization of a filtration technique for the more complete separation of mitochondrial and secretory granule elements permitted us to show that the recovery of lipid-bound 2-(3H)-myoinositol increased most rapidly in the secretory granule fraction. A 30-minute exposure of prelabeled islets to a stimulatory concentration of D-glucose (3.0 mg./ml.) resulted in a statistically significant decrease in the amount of lipid-bound 2-(3H)-myoinositol that was recovered from the secretory granule fraction (p less than 0.001). In contrast, exposure of islets to the elevated glucose concentration had no statistically significant effect on the recovery of lipid-bound radioactivity from other subcellular fractions. Since the majority of lipid-bound radioactivity associated with the secretory granule fraction could be recovered with the presumptive secretory granule membranes, these data suggest that the hydrolysis of phosphatidylinositol that accompanies glucose-induced insulin secretion from the rat pancreatic islet may be localized to the beta granule and, in particular, to its limiting membrane.

Animals↗

PubMed1989

Morphological characterization of the pathway of endocytosis and intracellular processing of transferrin and alpha-fetoprotein in human T lymphocytes stimulated with phytohemagglutinin (PHA).

Covalent conjugates of transferrin (Tf) and alpha-fetoprotein (AFP) with horseradish peroxidase (HRP) have been used to follow, at the ultrastructural level, the uptake and the intracellular pathway of these proteins in peripheral blood human lymphocytes stimulated by phytohemagglutinin (PHA) to blast formation. Both proteins enter specifically the cells via vesicles (60-70 nm in diameter) and endosomes. They are then observed in multivesicular bodies and tubular vesicular elements in the Golgi region. AFP is thus found in the same subcellular compartments as Tf and is probably also recycled, as most of the 125I-labeled protein leaves the cells undegraded. Unstimulated lymphocytes do not internalize significantly AFP-HRP. The uptake of a noncovalent conjugate of AFP-HRP and [3H]-arachidonic acid [3H-(20:4)] is usually poor, at 37 degrees C, in unstimulated lymphocytes as well as, at 4 degrees C, in lymphocytes stimulated for 72 h. Stimulated lymphocytes incubated at 37 degrees C with the radioactive conjugate show a heavy labeling of cell organelles and more particularly of lipid droplets. AFP could regulate the intracellular delivery of fatty acid molecules.

Endocytosis↗

PubMed1994

[Trans-uranium elements in food products (review)].

The data of Russian and foreign authors concerning of level environmental contamination and migration of transuranic elements in food chains, metabolism and biological danger of nuclides entering in human body with foods are reviewed. A level of radionuclide load of population and doses of radiation are discussed and the danger is estimated. The doses of radiation from radionuclide ingestion are lower than level of allowed radiation safety standards.

Animals↗

PubMed2005

Enhanced parameter estimation from noisy PET data: Part II--evaluation.

RATIONALE AND OBJECTIVES: Positron emission tomography (PET) is a minimally invasive imaging modality that provides three-dimensional distribution data for a radioactive tracer concentration within the body. Local functional parameters are estimated from these images by fitting tracer kinetic data with mathematical models. However, in some applications, the reliability of parameter estimates may be hindered by the presence of noise. In the accompanying report in this issue of Academic Radiology, a novel method using principal component analysis (PCA) was presented and used for deriving parametric images of lung function from imaged tracer kinetics of intravenously injected nitrogen 13 (13NN) in saline solution. The PCA method averages 13NN concentrations from groups of voxels (volume elements) selected for their similarity in kinetics, rather than their spatial proximity. The goal of this study is to conduct a Monte Carlo simulation to evaluate the robustness to noise of parameters derived by means of the PCA method. MATERIALS AND METHODS: This evaluation involved: (1) generating "noise-free" synthetic PET images from experimental PET data, (2) adding noise to these images, (3) applying the PCA method to yield parametric images, and (4) comparing these parametric images with original noise-free images. RESULTS: Local parameters recovered by using the PCA method deviated from noise-free parameters on average by less than 1% for up to 32-fold of expected noise levels. These deviations were much less than those (>10%) recovered by using a direct curve-fitting method. CONCLUSION: The novel PCA approach provides robust parametric lung functional images while preserving the spatial resolution of the original images.

Humans↗

PubMed1994

Replication of a Bacillus subtilis oriC plasmid in vitro.

We constructed an in vitro replication system specific for a Bacillus subtilis oriC plasmid using a soluble fraction derived from cell extracts of B. subtilis. DNA polymerase III and two initiation proteins, DnaA and DnaB, were required for in vitro replication as observed in vivo. Both upstream and downstream DnaA box regions of the dnaA gene were required as cis-elements for in vitro synthesis of the B. subtilis oriC plasmid as well as for in vivo activity. The replication was semi-conservative and only one round of replication occurred within 15 min. These results indicate that in vitro replication faithfully reproduced in vivo replication. To elucidate the site of initiation and the direction of replication, we analysed replicative intermediates generated in vitro in the presence of various concentrations of ddGTP by two methods. First, analysis of restriction fragments around the dnaA gene showed a high level of incorporation of the radioactive substrate, indicating that replication began within the vicinity of the dnaA gene. Second, using 2-dimensional gel electrophoresis, bubble arcs were detected only on fragments containing the DnaA box region downstream of the dnaA gene, indicating that the initiation site resided within this region. The distribution of the bubble arcs suggested that both bidirectional and undirectional replication occurred in vitro.

Bacillus subtilis↗

PubMedDate not supplied

Gut retention of metals in rats.

In sucklings, a high fraction of orally administered metals and radionuclides is retained in the gut. The location of elements in the gut is of interest because of their potential local health effect. The purpose of this work was to evaluate the influence of chelation therapy on gut retention and location of cadmium, mercury, and cerium in suckling rats. Radionuclides 115mCd, 203Hg, and 141Ce were administered orally to 6-d-old rats. Chelating agent Zn-DTPA (3.64 mmol/kg) was administered to animals that received 115mCd or 141Ce and Na-DMPS (375 mumols/kg) to those that received 203Hg, immediately and 24 h or 24 and 48 h after radionuclide administration. Radioactivity was determined in the whole body and gastrointestinal tract 6 d later. Both early and delayed chelation treatment very effectively reduced whole body retention, and this was mainly owing to reduced gut retention. Although chelation therapy reduced gut retention of administered radionuclides 3-30 times, the site of metal accumulation and retention in the intestine remained unchanged. For all 3 radionuclides, both after early and delayed therapy, the site of metal accumulation was always the lower part of small intestine-ileum.

Animals↗

PubMed2003

How Daphnia copes with excess carbon in its food.

Animals that maintain near homeostatic elemental ratios may get rid of excess ingested elements from their food in different ways. C regulation was studied in juveniles of Daphnia magna feeding on two Selenastrum capricornutum cultures contrasting in P content (400 and 80 C:P atomic ratios). Both cultures were labelled with (14)C in order to measure Daphnia ingestion and assimilation rates. No significant difference in ingestion rates was observed between P-low and P-rich food, whereas the net assimilation of (14)C was higher in the treatment with P-rich algae. Some Daphnia were also homogeneously labelled over 5 days on radioactive algae to estimate respiration rates and excretion rates of dissolved organic C (DOC). The respiration rate for Daphnia fed with high C:P algae (38.7% of body C day(-1)) was significantly higher than for those feeding on low C:P algae (25.3% of body C day(-1)). The DOC excretion rate was also higher when animals were fed on P-low algae (13.4% of body C day(-1)) than on P-rich algae (5.7% of body C day(-1)). When corrected for respiratory losses, total assimilation of C did not differ significantly between treatments (around 60% of body C day(-1)). Judging from these experiments, D. magna can maintain its stoichiometric balance when feeding on unbalanced diets (high C:P) primarily by disposing of excess dietary C via respiration and excretion of DOC.

Adaptation, Physiological↗

PubMed2002

About the assumption of linearity in soil-to-plant transfer factors for uranium and thorium isotopes and 226Ra.

The linearity assumption for soil and plant concentrations of radionuclides is usually a good approximation for use in food-chain models. To verify this assumption, different samples of plant and substrate were collected from a granitic zone located near a disused uranium mine in order to cover a large range of concentrations. In all of the samples, the activity concentration of 226Ra and of different isotopes of uranium (238U and 234U) and thorium (232Th, 230Th and 228Th) were determined. The results indicate that the linearity assumption can be considered valid when the range of concentrations taken into account is large (approx. two orders of magnitude). Otherwise, there is a clear deviation from linearity. Also, the influence of different stable elements on the soil-plant transfer factors was studied by using multivariate regression methods. The uptake of uranium, thorium and radium was found to be mainly associated with the concentration of iron in the plant and the phosphorus and alkaline earths in the substrate.

Food Chain↗

PubMed2003

A chemoenzymatic approach toward the rapid and sensitive detection of O-GlcNAc posttranslational modifications.

We report a new chemoenzymatic strategy for the rapid and sensitive detection of O-GlcNAc posttranslational modifications. The approach exploits the ability of an engineered mutant of beta-1,4-galactosyltransferase to selectively transfer an unnatural ketone functionality onto O-GlcNAc glycosylated proteins. Once transferred, the ketone moiety serves as a versatile handle for the attachment of biotin, thereby enabling chemiluminescent detection of the modified protein. Importantly, this approach permits the rapid visualization of proteins that are at the limits of detection using traditional methods. Moreover, it bypasses the need for radioactive precursors and captures the glycosylated species without perturbing metabolic pathways. We anticipate that this general chemoenzymatic strategy will have broad application to the study of posttranslational modifications.

Acetylglucosamine↗

PubMed1978

Sulfated compounds in the zymogen granules of the guinea pig pancreas.

Sulfate incorporation into the guinea pig pancreas was investigated by light (LM) and electron microscope (EM) autoradiography using a system of minilobules incubated in vitro for 60 min in Krebs-Ringer bicarbonate medium (KRB) containing 35SO4(-2). In acinar cells, examined by EM autoradiography, the label was found concentrated over Golgi elements (including condensing vacuoles) and zymogen granules. 35SO4(-2) was also incorporated by the epithelial cells of the entire pancreatic duct system, the incorporation being surprisingly high in the epithelium of the major ducts. In all ductal epithelia, autoradiographic grains appeared over the Golgi complex and the plasmalemma. Since a contribution of duct epithelium to the sulfated compounds found in the discharged secretion could not be ruled out, a purified zymogen granule fraction was used as a source material for the isolation of sulfated compounds of acinar origin. The presence of 35S-radioactivity in the zymogen granules and condensing vacuoles of this fraction was ascertained by autoradiography (of sectioned pellets). From a lysate of this zymogen granule fraction, a soluble sulfated compound of low isoelectric point and high molecular weight was isolated by gel filtration under conditions that allowed its satisfactory separation from the bulk of the secretory proteins.

Animals↗

PubMed2001

Development of a sensitive multi-well colorimetric assay for active NFkappaB.

The transcription factor nuclear factor kappaB (NFkappaB) is a key factor in the immune response triggered by a wide variety of molecules such as inflammatory cytokines, or some bacterial and viral products. This transcription factor represents a new target for the development of anti-inflammatory molecules, but this type of research is currently hampered by the lack of a convenient and rapid screening assay for NFkappaB activation. Indeed, NFkappaB DNA-binding capacity is traditionally estimated by radioactive gel shift assay. Here we propose a new DNA-binding assay based on the use of multi-well plates coated with a cold oligonucleotide containing the consensus binding site for NFkappaB. The presence of the DNA-bound transcription factor is then detected by anti-NFkappaB antibodies and revealed by colorimetry. This assay is easy to use, non-radioactive, highly reproducible, specific for NFkappaB, more sensitive than regular radioactive gel shift and very convenient for high throughput screening.

Animals↗

PubMed1978

Accumulation of radionuclides by plants as a monitor system.

The accumulation of radionuclides by plants acting as a monitoring system in the environment may occur by two modes; foliar absorption by the leaves and shoot of the plant, or by root uptake from the soil. Data on plant accumulation of radionuclides may be obtained from studies of fission product radionuclides deposited as worldwide fallout, and from tracer studies of plant physiology. The epidermal features of plant foliage may exert an effect upon particle retention by leaves, and subsequent uptake of radionuclides from the surface. The transport of radionuclides across the cuticle and epidermis of plant leaves is determined in part by the anatomy of the leaf, and by physiological factors. The foliar uptake of fallout radionuclides, 99Sr, 131I, and 137Cs, is described with examples from the scientific literature. The environmental half-life of 131I, for example, is considerably shorter than its physical half-life because of physical and biological factors which may produce a half-life as short as 0.23/day. 99Sr and 137Cs are readily taken up by the leaf, but 137Cs undergoes more translocation into fruit and seeds than 99Sr which tends to remain in the plant part in which it was initially absorbed. Soil-root uptake is conditioned primarily by soil chemical and physical factors which may selectively retain a radionuclide, such as 137Cs. The presence of organic matter, inorganic colloids (clay), and competing elements will strongly affect the uptake of 99Sr and 137Cs by plants from the soil. The role of plants as monitors of radionuclides is twofold: as monitors of recent atmospheric releases of radionuclides; and as indicators of the long-term behavior of aged deposits of radionuclides in the soil.

Absorption↗

PubMed2004

Parametric study of pellets for elemental analysis with laser-induced breakdown spectroscopy.

The effect of various parameters on the accuracy of the laser-induced breakdown spectroscopy (LIBS) data taken from pellet samples has been investigated. The dependence of the standard deviation of the LIBS data on the amount and nature of the binder used, pressure used to press the powder into a pellet, and the position of the focal spot on the pellet has been investigated. Pellets made from industrially important materials such as silica, alumina, and lime with polyvinyl alcohol, sucrose, and starch as binders have been studied. The results thus obtained are tested by preparation of the calibration curves for Si, Fe, and B in the pellets made from the powder glass batch used as a surrogate for the batch employed for the vitrification of radioactive waste.

Journal Article↗

PubMed1986

Food iron and lead absorption in humans.

Food iron and lead absorption were measured simultaneously in 28 subjects by extrinsically labeling three consecutive meals with the radioactive tracers, iron 59-sulfate and lead 203-chloride. Absorption was measured directly in all subjects by whole-body counting and indirectly in 15 subjects by assessing subsequent levels of tracer in blood. Iron status of the subjects ranged from iron deficient to replete, thus providing a wide range of iron absorption. Statistically significant positive correlations were obtained between food-iron and lead absorption measured by whole-body counting and also between the tracer levels of iron and lead in the blood. However, the correlation between the absorption of the two elements was not strong, as evidenced by the fact that only 50% of the subjects who hyperabsorbed iron also hyperabsorbed lead.

Administration, Oral↗

PubMed2001

Radionuclides in Peconic River fish, mussels, and sediments.

For regulatory oversight and quality control of Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) actions, fish, mussels, and sediments were analyzed from the Peconic River system on Long Island, NY, downstream of the Brookhaven National Laboratory, as well as from control locations. The analyses were for photon-emitting radionuclides (notably 60Co and 137Cs), uranium, plutonium, and americium. Sediments were cored in 4 sections to 0.37 m depth, whole fish were analyzed, and mussels were separated into flesh and shells. Radioisotopes of the cited elements were detected in sediment, some of the fish contained 137Cs, 241Am, and uranium, and mussel flesh contained 137Cs and uranium. All of the 60Co, 233U, and enriched uranium, and some of the 137Cs and 241Am, can most likely be attributed to Brookhaven National Laboratory. The other radionuclides (and some of the 137Cs and 241Am) are believed to have either fallout or nature as their origin. The New York State Department of Health (NYSDOH) evaluated the radiological data in terms of adverse health implications due to consumption of fish with the levels of reported radioactivity. The NYSDOH determined that the added radiation doses likely to result from eating this fish are a small fraction of the radiation dose that normally results from radionuclides present in the body from natural sources.

Animals↗