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PubMed1989

A novel derivative of the chelon desferrioxamine for site-specific conjugation to antibodies.

We describe the preparation of the modified chelator aminooxyacetyl-ferrioxamine, and the replacement of its iron atom by 67Ga at high specific activity. The aminooxy function of this compound was allowed to react with the aldehyde groups generated by the periodate oxidation of the oligosaccharide of a mouse IgG1 monoclonal antibody (MAb) directed against carcino-embryonic antigen (CEA). The use of the aminooxy group allowed a stable bond to be formed between the chelon and the antibody with no need for reduction. Iron was removed from the ferrioxamine moiety and replaced by 67Ga either before or after conjugation of the chelon to the antibody. In either case the labelled antibody was injected into nude mice bearing a human colon carcinoma having the appropriate antigenicity. Unoxidized antibody, labelled with 125I by conventional methods, was co-injected as an internal control. Additional control experiments were carried out with a non-immune IgG using the same 67Ga-labelled modified chelon as above. The in vivo distribution of the modified antibodies was evaluated at various times between 24 and 96 hr after injection. The methods used were gamma-camera imaging and, more quantitatively, gamma-counting of the various organs after dissection. Interestingly, with the metal-chelon-labelled antibody, the intensity and specificity of tumor labelling was comparable and in some cases superior to the results obtained with radio-iodinated antibody. In particular, there was almost no increase in liver and spleen uptake of radioactive metal relative to radio-iodine, contrary to what has been observed with most antibodies labelled with 111In after conjugation with DTPA.

Animals↗

PubMed1986

Techniques for measuring red cell, platelet, and WBC survival.

Blood cell survival studies yield valuable information concerning production and destruction of cells circulating in the bloodstream. Methodologies for the measurement of red cell survival include nonisotopic methods such as differential agglutination and hemolysis. The isotopic label may be radioactive or, if not, will require availability of a mass spectrograph. These methods fall into two categories, one where red cells of all ages are labeled (51Cr, DFP32, etc.) and those employing a cohort label of newly formed cells (14C glycine, 75Se methionine, etc.). Interpretation of results for methodology employed and mechanism of destruction, random or by senescence, are discussed. A similar approach is presented for platelet and leukocyte survival studies. The inherent difficulties and complications of sequestration, storage, and margination of these cells are emphasized and discussed.

ABO Blood-Group System↗

PubMed2002

Nuclear and isotopic techniques for addressing nutritional problems, with special reference to current applications in developing countries.

Nuclear and isotopic techniques are valuable tools in human nutritional research studies. Isotopes, both radioactive and nonradioactive, enable detailed evaluations of nutrient intake, body composition, energy expenditure, status of micronutrients, and nutrient bioavailability. In recent times, isotopic methods have been widely used in a number of coordinated research projects and technical cooperation projects of the International Atomic Energy Agency's Nutrition Programme. The doubly labeled water technique combines the use of the stable isotopes oxygen-18 and hydrogen-2 (deuterium) to measure total energy expenditure in free-living human subjects, and to investigate the magnitude and causes of both undernutrition and the emergence of obesity in developing countries. The deuterium dilution technique is a reliable tool to measure breastmilk intake and thereby infant growth and development. In collaboration with the World Health Organization's Growth Monitoring Program, this technique is being used to generate new data on growth standards for children in developing countries. This technique is also used in the measurement of body composition by the estimation of lean body mass and fat mass in individuals. Stable isotopes of iron and zinc have been successfully used to assess the nutritional impact of several nationwide food supplementation-programs conducted on pregnant and lactating women and children in both industrialized and developing countries. Isotopic techniques are especially suitable for monitoring changes in body composition, energy metabolism, and mineral status (with particular reference to osteoporosis) in the elderly. Nuclear methods have also served to develop models for a physiological reference man in Asia in support of radiological health and safety issues, for establishing elemental composition of foods, and for measurement of pollutants in the environment.

Adolescent↗

PubMed1981

Quantitative carbon-14 autoradiography at the cellular level: principles and application for cell kinetic studies.

Amounts of radio-labelled substances as low as 10(-18) moles incorporated into individual cells can be measured by utilizing techniques of quantitative autoradiography. For this purpose, radioactive standard sources are processed with the labelled cells smeared to slides. Carbon-14 is a favourable isotope with regard to minimal loss of beta-disintegrations due to self-absorption, and to limited cross-fire effects complicating the attribution of silver grains to individual cells. Silver grain densities can be counted by automated microphotometry allowing on-line data processing by an interfaced computer. Rate measurements of 14C-thymidine incorporation into individual cells yield values of the DNA synthesis rate provided that the endogenous pathway of thymidine-phosphate formation has been previously blocked. From the rate values of individual cells the DNA synthesis time of a cell compartment is derived. This is an essential time parameter for the evaluation of kinetic events in proliferating cell populations. This method is applicable to human cells without radiation hazard to man, and provides an optimal source of detailed information on the kinetics of normal and diseased human haematopoiesis. Examples of application consist of thalassaemia, malaria infection, iron deficiency anaemia and acute myelogenous leukaemia.

Animals↗

PubMed1977

Performance parameters of the Hamburg 4 pi whole body radioactivity detector.

Large 4 pi whole body counters allow the use of very low doses of radioactivity in medical research and in routine diagnosis of patients. The electronics of the 4 pi whole body counter in Hamburg (HAMCO) have recently been updated. The detector contains 1360 I of liquid organic scintillator. Experiments combined with extensive computer simulations yielded quantitative information for whole body counters and comparable systems, (1) about physical parameters such as detection efficiency, energy resolution and background count rates which are important for practical performance, and (2) concerning the optical properties of the large volume scintillation counters employed here; these are of interest for the construction of future detectors of related types.

Cesium Radioisotopes↗

PubMed1998

Raised neutrophil phospholipase A2 activity and defective priming of NADPH oxidase and phospholipase A2 in sickle cell disease.

Intermittent painful crises due to vasoocclusion are the major clinical manifestation of sickle cell disease (SCD), but subclinical episodes may also occur. There is sparse evidence for the involvement of neutrophils in the pathophysiology of SCD, but production of cytokines by the damaged endothelium might influence neutrophil function and modulate responses to subsequent cytokine exposure. In addition, the activation of neutrophils in the microcirculation could itself exacerbate vasoocclusion. To test whether neutrophil inflammatory responses were altered in SCD, neutrophil phospholipase A2 and NADPH oxidase activity in response to in vitro priming by granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor-alpha (TNF-alpha) were measured both during and between painful crises. Resting levels of neutrophil phospholipase A2 activity in steady-state SCD (4.0% +/- 0. 5% of total cell radioactivity) were raised relative to control values (2.0% +/- 0.2%, n = 10, P = .008). There was no defect of agonist-stimulated phospholipase A2 or NADPH oxidase activity in steady-state SCD; however, the ability of phospholipase A2 to respond to priming with GM-CSF was attenuated to 63% +/- 17% of control values (n = 10, P = .04). Similarly, neutrophil NADPH oxidase activity after priming with GM-CSF and TNF-alpha was, respectively, 65% +/- 11% (n = 7, P = .03) and 57% +/- 7% of control (n = 10, P = .007) in steady-state disease, and was further reduced during painful vasoocclusive crises to 34% +/- 9% and 25% +/- 3% of control for GM-CSF and TNF-alpha, respectively. These data were not explained by poor splenic function or any racial factor, as normal cytokine responses were seen in splenectomized patients in remission from Hodgkin's disease and in healthy Afro-Caribbean subjects. Abnormal neutrophil cytokine priming responses were not observed in either patients with rheumatoid arthritis or iron-deficiency anemia. Our findings are indicative of an ongoing inflammatory state in SCD between painful crises involving neutrophil activation and an abnormality of cytokine-regulated neutrophil function, which may compromise the host defenses against certain microorganisms.

Adolescent↗

PubMed1999

Unidirectional transport from apical to basolateral compartment of cobalt ion in polarized Madin-Darby canine kidney cells.

Renal transport of Co2+ was studied by use of cultured MDCK cells with cell polarity. Cells imported 57Co2+ from the apical membrane exclusively, while uptake from the basolateral membrane was minute. Apical uptake was time-, concentration-, pH-, and temperature- dependent and the dose-dependency curve was saturable, indicating that a carrier-mediated influx process operates in the apical membrane. The substrate specificity and other properties of this Co2+ transport process are distinct from those of a transporter DCT1, divalent cation transporter 1, with unusually broad substrate specificity including Co2+. Radioactive Co2+ added from the apical side appeared in the basolateral side, while there was only slight movement of Co2+ from the basolateral to apical side, indicating that this unidirectional transepithelial passage of Co2+ is not caused by the paracellular diffusion, but by the basolateral export of the cellular Co2+ uptake from the apical membrane. Our results may indicate the presence of a novel vectorial transport system responsible for the reabsorption of Co2+ from the glomerular filtrate.

Animals↗

PubMed2004

Hepatocellular bioactivation and cytotoxicity of the synthetic endoperoxide antimalarial arteflene.

Arteflene is a synthetic endoperoxide antimalarial. Its peroxide bridge undergoes iron(II)-mediated reduction in vitro which yields a carbon-centered cyclohexyl radical and a mixture of cis- and trans-alpha,beta-unsaturated ketones (enones). The enones are biliary metabolites in rats and therefore surrogate markers of bioactivation. Arteflene is reported to be more cytotoxic to primary rat hepatocytes than some non-endoperoxide antimalarials. Hepatic metabolism of arteflene was investigated in recirculating isolated perfused rat livers, and the drug's metabolism and cytotoxicity were compared using hepatocytes from male rats. Both preparations metabolized [(14)C]arteflene to cis- and trans-[(14)C]enone, 8-hydroxyarteflene glucuronide and an unassigned isomeric glucuronide. During a 2 h liver perfusion, the cis- and trans-enones recovered in bile represented 8.1 +/- 3.4 and 11.3 +/- 4.6% (mean +/- S.D., N=6), respectively, of the [(14)C]arteflene (52 microM) added to the perfusate. After a 3 h incubation of [(14)C]arteflene (10 microM) with hepatocytes in suspension, the cis- and trans-enones comprised, respectively, 14.8 +/- 7.1 and 2.1 +/- 1.0% (N = 4) of the recovered radioactivity; the corresponding data for cultured hepatocytes being 18.6 +/- 6.9 and 3.3 +/- 2.2%. Arteflene was significantly (P < 0.05) toxic to isolated hepatocytes with reference to extramitochondrial reductase activity (tetrazolium reduction) but not enzyme leakage when the cells were exposed to drug concentrations > or =50 microM for 24 h. Cellular glutathione was depleted under these conditions. Therefore arteflene was acutely cytotoxic, though only at relatively high concentrations, when it was metabolized via a pathway which generates carbon-centered radicals.

Animals↗

PubMed2002

Determination of ferrichrome binding to the FhuA outer membrane transport protein, periplasmic accumulation of ferrichrome, or transport of ferrichrome into cells using a three-layer oil technique.

A new method for the determination of ferrichrome binding to the FhuA transporter in the Escherichia coli outer membrane, ferrichrome accumulation in the periplasmic space, and ferrichrome transport into the cytoplasm was developed. Cells were separated from residual, soluble, radiolabeled ferrichrome by centrifugation in a micro-test tube containing three layers of nonmixable solutions of different densities. Cells in the upper aqueous layer passed through the middle silicone oil layer, but did not enter the underlying NaI layer, thereby accumulating on top of the NaI layer; soluble compounds remained in the upper aqueous layer. Cells were then easily recovered by centrifugation, and radioactivity was determined by liquid scintillation counting. Reproducible results for all applications tested were obtained without the need for any washing steps. The method was tested by determination of receptor binding and transport of ferrichrome with various FhuA mutants which, in contrast to their transport activity, showed only a weak binding of ferrichrome to FhuA and compared with the commonly used cellulose nitrate filter method. Similar transport rates were obtained with the two methods, but binding of ferrichrome to the mutated FhuA proteins and accumulation of ferrichrome in the periplasm could be measured only with the new method.

Bacterial Outer Membrane Proteins↗

PubMed1995

Lipopolysaccharide-inactivating activity of neutrophils is due to lactoferrin.

Neutrophils can inactivate lipopolysaccharide (LPS), thereby blocking the ability of LPS to prime fresh neutrophils for enhanced fMLP-triggered release of superoxide. Here we show that inactivation of LPS by neutrophils was primarily due to lactoferrin. A time course for inactivating LPS showed that neutrophils (5 million/ml) took 30 min to inactivate 10 ng/ml LPS. Mononuclear cells could not inactivate LPS under the same conditions. Experiments with radioactive LPS showed that inactivated LPS remained in the medium and was not taken up or destroyed by the neutrophils during inactivation. Inactivated LPS still gelled Limulus lysate and primed monocytes. Cell-free medium from neutrophil suspensions also inactivated LPS. A single LPS-inactivating factor was purified from medium by heparin-agarose chromatography. SDS-PAGE showed a single band at 80 kDa, which was identified as lactoferrin by immunoblotting. Antilactoferrin immunoglobulin G removed the LPS-inactivating activity from purified lactoferrin and cell-free medium. Surprisingly, even purified neutrophil lactoferrin required 30 min to inactivate LPS, indicating inherently slow binding of lactoferrin to LPS.

Culture Media↗

PubMed2005

Simulations of an accelerator-based shielding experiment using the particle and heavy-ion transport code system PHITS.

In order to estimate the biological effects of HZE particles, an accurate knowledge of the physics of interaction of HZE particles is necessary. Since the heavy ion transport problem is a complex one, there is a need for both experimental and theoretical studies to develop accurate transport models. RIST and JAERI (Japan), GSI (Germany) and Chalmers (Sweden) are therefore currently developing and bench marking the General-Purpose Particle and Heavy-Ion Transport code System (PHITS), which is based on the NMTC and MCNP for nucleon/meson and neutron transport respectively, and the JAM hadron cascade model. PHITS uses JAERI Quantum Molecular Dynamics (JQMD) and the Generalized Evaporation Model (GEM) for calculations of fission and evaporation processes, a model developed at NASA Langley for calculation of total reaction cross sections, and the SPAR model for stopping power calculations. The future development of PHITS includes better parameterization in the JQMD model used for the nucleus-nucleus reactions, and improvement of the models used for calculating total reaction cross sections, and addition of routines for calculating elastic scattering of heavy ions, and inclusion of radioactivity and burn up processes. As a part of an extensive bench marking of PHITS, we have compared energy spectra of secondary neutrons created by reactions of HZE particles with different targets, with thicknesses ranging from <1 to 200 cm. We have also compared simulated and measured spatial, fluence and depth-dose distributions from different high energy heavy ion reactions. In this paper, we report simulations of an accelerator-based shielding experiment, in which a beam of 1 GeV/n Fe-ions has passed through thin slabs of polyethylene, Al, and Pb at an acceptance angle up to 4 degrees.

Aluminum↗

PubMed2005

Partitioning of radionuclides and trace elements in phosphogypsum and its source materials based on sequential extraction methods.

Phosphogypsum is a waste produced by the phosphate fertilizer industry. Although phosphogypsum is mainly calcium sulphate dihydrate, it contains elevated levels of impurities, which originate from the source phosphate rock used in the phosphoric acid production. Among these impurities, radionuclides from 238U and 232Th decay series are of most concern due to their radiotoxicity. Other elements, such as rare earth elements (REE) and Ba are also enriched in the phosphogypsum. The bioavailability of radionuclides (226Ra, 210Pb and 232Th), rare earth elements and Ba to the surrounding aquatic system was evaluated by the application of sequential leaching of the phosphogypsum samples from the Brazilian phosphoric acid producers. The sequential extraction results show that most of the radium and lead are located in the "iron oxide" (non-CaSO4) fraction, and that only 13-18% of these radionuclides are distributed in the most labile fraction. Th, REE and Ba were found predominantly in the residual phase, which corresponds to a small fraction of the phosphate rock or monazite that did not react and to insoluble compounds such as sulphates, phosphates and silicates. It can be concluded that although all these elements are enriched in the phosphogypsum samples they are not associated with CaSO4 itself and therefore do not represent a threat to the surrounding aquatic environment.

Barium↗

PubMedDate not supplied

[ A long-term changes of macro- and microelement balance in blood serum, its ultrafiltrates and hairs after exposure to low doses of ionizing radiation].

Using inductively coupled plasma atomic emission spectrometry, we examined the level of Al, Cd, Co, Cu, Fe, Mg, Mo, P, Pb, S, and Zn in blood serum, its ultrafiltrates, and hairs of liquidators of the Chernobyl Nuclear Power Plant accident who were working in the disaster region in 1986-1987. Studies continued over a period of time provided evidence for a distinct change in the balance of macroelements and trace elements in the studied biological substrates of irradiated individuals. An increase in the level of copper in the ultrafiltrate and a marked decrease in the content of zinc in the ultrafiltrate are viewed as key factors in the generation of a response to low doses of ionizing radiation. Concerning the content of iron in hairs, we demonstrate its accelerated removal from the body of liquidators. The altered balance of biotic macroelements, phosphorus, and sulfur remained unchanged when these characteristics were studied as a function of time. We found changes in the ratios of divalent cations, magnesium and zinc, in the ultrafiltrates. The magnesium concentration in the studied biological substrates was the most stable characteristic after irradiation. The level of toxic trace elements (lead, cadmium, and aluminum) did not exceed physiologically acceptable levels, while their content in hairs may be a biological indicator of their accumulation in the body.

Adult↗

PubMed1981

Separation by counter-current distribution of rat and chicken erythrocytes of different age, and its application to the assay of enzyme activities.

The separation of cells with different ages from erythrocyte populations of adult rats and young or adult chickens have been achieved by counter-current distribution (CCD). A thin-layer CCD apparatus has been employed. Erythrocytes from blood samples taken at different times after 59Fe i.p. injection were separated by CCD. By compilation in a "composite curve" of the hemoglobin and radioactivity CCD profiles obtained for each erythrocyte population, the distribution of cells according to age can be inferred. Young erythrocytes of rats are located at the right part of the CCD curves, while older cells are distributed towards the left. An opposite distribution has been found for erythrocytes from adult or young chickens. As a first attempt for the application of the CCD procedure to the assay of enzyme activities, it was found a decrease in phytase activity as the age of chicken erythrocytes increases and an increase in phosphoglycerate kinase and phosphofructokinase as the age of rat erythrocytes increases.

6-Phytase↗

PubMed2006

Autoimmune thyroiditis and exposure to iodine 131 in the Ukrainian cohort study of thyroid cancer and other thyroid diseases after the Chornobyl accident: results from the first screening cycle (1998-2000).

CONTEXT: Due to the Chornobyl accident, millions were exposed to radioactive isotopes of iodine and some received appreciable iodine 131 (131I) doses. A subsequent increase in thyroid cancer has been largely attributed to this exposure, but evidence concerning autoimmune thyroiditis (AIT) remains inconclusive. OBJECTIVE: The objective of the study was to quantify risk of AIT after 131I exposure. DESIGN/SETTING/PARTICIPANTS: Baseline data were collected from the first screening cycle (1998-2000) of a large cohort of radiation-exposed individuals (n = 12,240), residents of contaminated, iodine-deficient territories of Ukraine. Study individuals were under the age of 18 yr on April 26, 1986, and had thyroid radioactivity measurements made shortly after the accident. OUTCOMES: AIT was defined a priori based on various combinations of elevated antibodies to thyroid peroxidase (ATPO), TSH, and clinical findings; elevated ATPO were considered to be an indicator of thyroid autoimmunity. RESULTS: No significant association was found between 131I thyroid dose estimates and AIT, but prevalence of elevated ATPO demonstrated a modest, significant association with 131I that was well described by several concave models. This relationship was apparent in individuals with moderately elevated ATPO and euthyroid, thyroid disease-free individuals. CONCLUSIONS: Twelve to 14 yr after the Chornobyl accident, no radiation-related increase in prevalence of AIT was found in a large cohort study, the first in which 131I thyroid doses were estimated using individual radioactivity measurements. However, a dose-response relationship with ATPO prevalence raises the possibility that clinically important changes may occur over time. Thus, further follow-up and analysis of prospective data in this cohort are necessary.

Adolescent↗

PubMed2005

Vitrified metal finishing wastes I. Composition, density and chemical durability.

Durable phosphate glasses were formed by vitrifying waste filter cakes from two metal finishing operations. Some melts formed crystalline components during cooling. Compositional analysis of dried, heat treated and vitrified samples was made using energy-dispersive X-ray spectroscopy, X-ray fluorescence spectroscopy, inductively-coupled plasma spectroscopy and Leco induction furnace combustion analysis. Hydrolytic dissolution, measured by an adapted product consistency test, was reduced by up to 3 orders of magnitude upon heat treatment or vitrification, surpassing the performance of borosilicate glass in some cases. This was attributed to the high levels of iron and zinc in the wastes, which greatly improve the durability of phosphate glasses. One of the wastes arose from a metal phosphating process and was particularly suitable for vitrification due to its high P2O5 content and favourable melting behaviour. The other waste, which arose from a number of processes, was less suitable as it had a low P2O5 content and during heating it emitted harmful corrosive gases and underwent violent reactions. Substantial volume reductions were obtained by heat treatment and vitrification of both wastes. Compositions and performances of some vitrified wastes were comparable with those of glasses which are under consideration for the immobilisation of toxic and nuclear wastes.

Crystallization↗

PubMed1975

In vitro labelling of platelets: an experimental study on healthy asplenic subjects using two different incubation media.

Duplicate platelet survival studies, using autologous platelets labelled in vitro with radioactive sodium chromate, were performed on six young healthy asplenic men. In the first experiment plasma, and in the second a Ringer-citrate-dextrose (RCD) solution (Abrahamsen, 1968), was employed as incubation medium. The uptake of chromate by the platelets was about 2.5 times higher in the RCD compared to the plasma experiments. An identical pattern for the immediate behaviour of infused labelled platelets was observed in the duplicate studies, and the recovery of platelet-bound radioactivity remained stable at the 90% level during 2 h post-infusion. In these experiments the means for platelet mean life span (MLS) were identical, 7.2 +/- 0.5 and 7.2 +/- 0.4 days, respectively. These values slightly, but not significantly, exceeded the mean platelet MLS for a control group consisting of 10 young healthy males (6.9 +/- 0.4 days). The means for platelet production rate (P) at the duplicate studies made on the asplenic subjects were 19 +/- 2 X 10(10) and 21 +/- 2 X 10(10) platelets per day, respectively, and did not differ from the mean for P obtained in the control group (22 +/- 2 X 10(10).

Adult↗

PubMed1994

Role of redox systems on Fe3+ uptake by transformed human intestinal epithelial (Caco-2) cells.

Caco-2 cells were used as a model of human intestinal epithelium to investigate the role of redox systems in transepithelial transport of 59Fe3+. The cells reduced Fe3+ present in the apical medium; the reduction was 50% inhibited by adriamycin and p-chloromercuribenzoate. Addition of [14C]ascorbate to the basolateral medium resulted in accumulation of 14C radioactivity in both cells and apical medium; apical radioactivity increased with time and was probably caused by paracellular flux. The cells provided Fe3+ reduction capacity to the apical incubation medium. Addition of ascorbate to the basolateral medium increased this reduction capacity 2-fold and the cellular uptake of 59Fe3+ 1.8-fold. Adriamycin significantly inhibited both cellular 59Fe uptake and Fe transport into the basolateral side. The results indicate that Caco-2 cells reduce apical Fe3+ by two parallel mechanisms: by a plasma membrane ferrireductase and by the secretion of reductants of either cellular or basolateral origin. The data support a model for Fe3+ intestinal absorption in which cell-mediated Fe3+ reduction occurs before cellular Fe uptake.

Ascorbic Acid↗