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At least 253 records · Page 14Linked to original sources
PubMed1994

Localization of endothelin receptors in the human prostate.

The objective of the present study was to localize endothelin receptors in the human prostate using quantitative autoradiography. Slide-mounted tissue sections 20 microns. in thickness were obtained from the transition zones of seven patients undergoing radical prostatectomies for low volume prostate cancer. Sarafotoxin (S6C) and BQ123 have been used to distinguish endothelin receptor subtypes (ETA and ETB). The prostatic tissue sections were incubated in four different stock solutions containing the following: 0.1 nM. 125I-endothelin-1 (125I-ET-1) (total ET-1 binding); 0.1 nM. 125I-ET-1 and 100 nM. S6C (total ETA binding); 0.1 nM. 125I-ET-1 and 1 microM. BQ123 (total ETB binding); and 0.1 nM. 125I-ET-1 and 1 microM. ET-1 (nonspecific ET-1 binding). Nonspecific binding accounted for only 12 and 15% of total 125I-ET-1 binding in the stroma and glandular epithelium. Autoradiograms were quantitatively analyzed using a computerized image analysis system. Specific radioactive densities (nCi/mg.) were determined for the stromal and glandular epithelial elements of the prostate. The specific radioactive densities of ETA and ETB binding sites in the stroma were 7.57 +/- 0.65 and 2.98 +/- 0.81. The specific radioactive densities of ETA and ETB binding sites in the glandular epithelium were 1.59 +/- 0.15 and 7.87 +/- 1.35. The present study demonstrates that the predominant endothelin receptors in the stroma and glandular epithelium are the ETA and ETB subtypes, respectively.

Autoradiography↗
PubMed1993

Managing radioactively contaminated infectious waste at a large biomedical facility.

Proper management of infectious waste containing radioactive material depends on three program elements. First, screening methods are required to identify medical waste containing radioactive material. Second, a means of managing the volume of waste identified has to be developed. Management includes identifying the radioisotopes, dealing with the physical requirements of the waste (e.g., the need for cold storage), and treating the material as a mixed waste. Finally, methods to limit production of waste at its source must be implemented. This includes educating the radioactive material users, enabling them with the means of reducing waste volume, and giving them feedback on how well they are implementing the waste reduction practices.

Academic Medical Centers↗
PubMed2000

137Cs and relationships with major and trace elements in edible mushrooms from Mexico.

137Cs and 40K specific activity together with major and trace elements were determined in soil samples and in different edible wild mushroom species collected from a seminatural temperate forest ecosystem located in the central part of the Mexican Volcanic Belt. The activity measurements were made using a gamma-ray spectrometer system with a high purity germanium (HpGe) detector. The major and trace elements were determined using emission spectrography and mass spectrometry, respectively. The aggregated transfer factors for 137Cs were estimated in 30 local mushroom species collected from 1993 to 1999. Differences as large as three orders of magnitude were observed. The contribution of mushrooms for the total 137Cs dietary intake by the local population was estimated to be 37%. Mushrooms also showed to be good accumulators for Rb, Cu, Cs and Se.

Agaricales↗
PubMed1999

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

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

Animals↗
PubMed1982

Stable isotopes of lithium: in vivo differential distribution between plasma and cerebrospinal fluid.

Stable and radioactive isotopes of an element have been utilized to study a variety of complex phenomena including metabolic pathways and enzyme reactions. It is generally assumed that isotopes of an element are not treated in a differential manner. Nevertheless we have demonstrated that the two stable isotopes of lithium (Li), one of mass 6 and the other with a mass of 7, are differentially taken up by red blood cells with 6-8% higher quantities of 6-lithium (6Li) being accumulated. We report here on the in vivo pharmacokinetics of Li isotopes. Nineteen adult cats were given a single dose of either 6LiCl by gastric intubation (1 meq/kg) and 2 weeks later the treatment was crossed. Plasma concentrations of the two Li isotopes were determined. In another series of studies 19 adult cats were given either 6LiCl or 7LiCl by intubation, cerebrospinal fluid (CSF) and blood samples were collected simultaneously and isotropic Li concentrations of the spinal fluid and plasma were determined. The average plasma concentration of 6Li was higher than 7-lithium (7Li) between 2 and 9 hr postadministration. The elimination curve for both isotopes had an initial fast and later slow component. For the slow component 6Li had an average half-life of 12.9 and 7Li 15.9 hr. Comparison of the CSF/plasma ratio for 6Li and for 7Li indicated that the ratios were higher for 6Li than 7Li 2-6 hr after administration. These data suggest that factors in addition to concentration gradients influence the transport of Li isotopes across the blood-brain barrier. These studies demonstrate the acute pharmacokinetics of the two Li isotopes are not the same in compartmental distribution and rate of disappearance from plasma. It is conceivable 6Li may have a greater toxic or therapeutic effect than 7Li in the treatment of manic-depressive illness.

Administration, Oral↗
PubMed1976

The effect of 35SO2 binding by ammonia on sulfur incorporation into rat tissues.

Sulfur metabolism was traced in experimental investigations on rats, and the importance of the method of sulfur dioxide neutralized by ammonia was estimated. The animals were exposed to 35SO2 by means of inhalation, and radioactivity in several organs at different periods of exposure was traced. Apart from that, autoradiographic investigations were carried out in order to show the incorporation of radioactive sulfur into particular elements of the cell in different tissues. Elimination of isotope with urine and feces at different periods of time after exposure was also determined. It was found that the use of ammonia to neutralize sulfur dioxide in the air decreased the amount of sulfur which could enter the organism as a result of breathing air contaminated by SO2.

Ammonia↗
PubMed1996

Technetium, the missing element.

The history of the discovery of technetium is reviewed within the framework of the discovery and production of artificial radioactivity in the twentieth century. Important elements of this history are the accidental production of this element in a cyclotron in Berkeley, California, USA, a machine devised by Ernest Orlando Lawrence, and its subsequent discovery in 1937 by Carlo Perrier and Emilio Segrè in scrap metal parts sent by Lawrence to Palermo, Italy by mail. A detailed account is given of the steps taken; the history of the later discovery of the technetium-99m isotope in 1938 is likewise examined. Sources of natural and artificial technetium are briefly discussed.

Cyclotrons↗
PubMed1979

X-ray emission analysis of human plasma by proton excitation of thick samples in air.

Thick plasma samples have been irradiated in air by 2.3 MeV protons for trace elemental analysis by proton-induced X-ray emission spectroscopy. Accurate calibration curves were obtained for Fe, Zn and Sr and detection limits in dry plasma were estimated to be 0.08 PPM for Fe, 0.065 PPM for Zn and 0.12 PPM for Sr. Low temperature ashing of these samples improved the detection limits by a factor of 3 but reduced the precision and resulted in loss of bromine from the plasma. Mass absorption coefficients for low energy X-rays in dry plasma were measured and X-ray attenuation in the sample was found to prevent the detection of trace elements with Z less than 26. The method was used to determine Sr in plasma from a patient with bone disease, the Sr being a non-radioactive bone-seeking tracer element. The results, which were in the 3--13 PPM range, were in good general agreement with the analysis of the same samples by flame photometry.

Air↗
PubMed1997

The radioactivity of atmospheric krypton in 1949-1950.

The chemical element krypton, whose principal source is the atmosphere, had a long-lived radioactive content, in the mid-1940s, of less than 5 dpm per liter of krypton. In the late 1940s, this content had risen to values in the range of 100 dpm per liter. It is now some hundred times higher than the late 1940 values. This radioactivity is the result of the dissolving of nuclear fuel for military and civilian purposes, and the release thereby of the fission product krypton-85 (half-life = 10.71 years, fission yield = 0.2%). The present largest emitter of krypton-85 is the French reprocessing plant at Cap-de-la-Hague.

Journal Article↗
PubMed1976

Survey of radioactive agents for in vitro labeling of phagocytic leukocytes. I. Soluble agents.

Twenty-three soluble (nonparticulate) radioactive agents were screened for their ability to label leukocytes in vitro in the presence or absence of plasma and red cells. The degree of cell binding was compared with that of other agents previously reported. Leukocyte binding of 2% or more of the added radioactivity was obtained with ten of these agents. High labeling yields were obtained only with nonpolar lipid-soluble complexes capable of penetrating lipid cell membranes. Unfortunately, this type of labeling tends to be reduced by plasma protein. Some lipophilic radioactive agents tend to elute from the cells after labeling. Compared with radioactive particles, soluble radiopharmaceuticals offer the advantage of easy centrifugal separation of the cell-bound from the residual activity in the suspension fluid. However, the labeling yield tends to be lower than for radioactive particles, and other cellular elements are labeled in addition to the phagocytic leukocytes. In this survey, the most promising soluble agents were 111In or 99mTc complexes of oxine, 111In-tetraphenylporphyrin, DNA labeled with radioactive iodine, and DNA labeled with 77Br and complexed with adriamycin. The ultimate value of any of these agents must await adequate in vivo testing in experimental animals and clinical trials.

DNA↗
PubMed1982

Review of nuclear pharmacy practice in hospitals.

An operational profile for nuclear pharmacy practice is presented, and the technical and professional role of nuclear pharmacists is reviewed. Key aspects of nuclear pharmacy practice in hospitals discussed are the basic facilities and equipment for the preparation, quality control, and distribution of radioactive drug products. Standards for receiving, storing, and processing radioactive material are described. The elements of a radiopharmaceutical quality assurance program, including the working procedures, documentation systems, data analysis, and specific control tests, are presented. Details of dose preparation and administration and systems of inventory control for radioactive products are outlined.

Facility Design and Construction↗
PubMed1989

Kinetic modeling of selenium metabolism in nonpregnant ewes.

The kinetics of selenium metabolism in three nonpregnant ewes were studied by the intravenous injection of 75Se-sodium selenite and measurement of radioactivity responses in blood, tissues and excreta. Stable selenium measurements were also made to determine selenium intake, excretion in feces and urine, and mass of selenium in tissues. Immediately following tracer injection, there was a rapid disappearance of radioactivity from plasma reflecting the uptake of the element by the liver and blood cells. The decrease in plasma radioactivity ceased abruptly by 30-45 min, and was followed by an increase to a peak by 3-4 h and a more gradual biphasic decline thereafter. A kinetic model of selenium metabolism in the whole animal was constructed employing the SAAM/CONSAM computer program. The multiphasic response of plasma radioactivity during a physiological steady state was explained on the basis of rapid hepatic uptake of selenium and its subsequent reappearance in the circulation in protein-bound form followed by further metabolism and excretion of the element. The model provides reference parameter values for 75Se-sodium selenite kinetics in selenium-replete, mature nonpregnant ewes for comparison with the kinetics in animals whose selenium status may be altered.

Animals↗
PubMedDate not supplied

[Accumulation of uranium, plutonium and americium by granulated microbial biosorbent].

A possibility of efficient extraction of 238U, 239Pu and 241Am by microorganisms from solutions with activity 520-3200 Bq/l has been shown on the example of microbial biosorbent (MBS). MBS presents water-resistant granules consisting of living microorganisms and nutrient substances. The ratio MBS:solution being equal to 1:100 and 1:20, microorganisms extracts 98.9 and 99.8% of 238U; 99.1 and 99.8% of 239Pu, 241Am, respectively. The worked out MBC granules may be utilized by burning with the 4-8 decrease of the volume. It is foreseen to use MBS in industrial processes of treatment of liquid radioactive waste (LRW) for uranium and transuranium elements.

Absorption↗
PubMed2005

Impacts of stable element intake on 14C and 129I dose estimates.

The purpose of this study was to evaluate and provide insights related to the influence of the intake of stable isotopes of carbon and iodine on the committed doses due to the ingestion of (14)C and (129)I. This was accomplished through the application of two different computational approaches. The first was based on the assumption that ground (drinking) water was the only source of intake of (14)C and (129)I, as well as stable carbon and stable iodine. In the second, the intake of (14)C and (129)I was still assumed to be restricted to that in the ground (drinking) water, but the intake of stable carbon and stable iodine was expanded to include that in other components of the diet. The doses were estimated using either a conversion formula or the applicable dose coefficients in Federal Guidance Reports No. 11 and No. 13. Serving as input for the analyses was the estimated maximum concentrations of (14)C or (129)I that would be present in the ground water due to potential releases from the proposed Yucca Mountain high-level radioactive waste repository during the first 10,000 y after closure. The estimated contributions of stable carbon and iodine through the consumption of ground water were based on analyses of samples collected in the Amargosa Valley, NV. The contributions through dietary intake were based on surveys conducted in the United States. Based on the accompanying analyses, it was noted that stable isotope intake has a significant effect on the estimated doses due to the intake of radioactive isotopes of the same element. While this is a well-known fact, this observation has international implications in terms of dose estimates for key radionuclides, such as (14)C and (129)I, a primary reason being the wide variations in the intakes of stable carbon and iodine in various countries. For this reason, analysts planning to apply the dose coefficients developed by the International Commission on Radiological Protection (ICRP) should either confirm that the average total intake in their country of stable isotope(s) of the radioactive isotope being evaluated is in reasonable agreement with the value assumed by the ICRP or suitably modify the ICRP dose coefficients to account for any differences. If such a procedure is to be implemented, there is a need for periodic updates of the dietary intakes of various stable elements in countries throughout the world. The importance of this is documented by recent surveys in Asia that revealed that their average total daily intake of stable iodine was less than half of the ICRP value for Reference Man. In this case, application of the ICRP dose coefficients, without modification, would underestimate the dose due to ingested (129)I by a factor of more than two. A related situation exists in the United States where the latest surveys indicate that the daily intake of stable iodine is 75% of the ICRP value.

Administration, Oral↗