SEARCH · PubMed Health

Results for “IRON, 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 253 records · Page 14Linked to original sources

PubMed1965

Observations on iron uptake, iron metabolism, cytochrome c content, cytochrome a content and cytochrome c-oxidase activity in regenerating rat liver.

1. Differential and density-gradient centrifugation were used to fractionate mitochondria and fluffy layer from normal and regenerating rat liver. The iron, cytochrome a and cytochrome c contents and cytochrome c-oxidase activity were studied as well as the uptake of (59)Fe into protein and cytochrome c. 2. A certain degree of heterogeneity was evident between the heavy-mitochondrial and light-mitochondrial fractions, and in their behaviour during liver regeneration. 3. The specific content of light-mitochondrial iron and cytochrome a was 1.3-1.4 times that of heavy mitochondria. Changes in cytochrome c-oxidase activity closely followed those of cytochrome a content during liver regeneration, but not for light mitochondria after 10 days. 4. Radioactive iron ((59)Fe) was most actively taken up by well-washed light mitochondria during early liver regeneration. After 22 days fluffy layer became preferentially labelled. This substantiates the view that fluffy layer partially represents broken-down mitochondria. 5. During early regeneration, light-mitochondrial fractions separated along a density gradient were about 3 times as radioactive, and showed distinct heterogeneity of (59)Fe-labelling, in contrast with near homogeneity for heavy mitochondria. 6. Immediately after partial hepatectomy fractions corresponding to density 1.155 were 5-10 times as radioactive as particles of greater density. The radioactivity decreased sharply after 6 days. 7. These particles of low density possessed higher NADH-cytochrome c-reductase (1.5-5-fold) and succinate-dehydrogenase (1.1-2-fold) activities than typical mitochondrial fractions. Their succinate-cytochrome c-reductase and cytochrome c-oxidase activities were slightly lower. 8. The results are discussed in relation to mitochondrial morphogenesis, and a possible route from submitochondrial particles is suggested.

Journal Article↗

PubMed1980

The effect of metal salts on the distribution of iron-59 in rats: Manganese (II), nickel (II) and tin (II).

The disappearance and reappearance of iron-59 in plasma and blood at various time intervals has been studied in control, manganese, nickel and tin administered and anaemic rats after a single intravenous injection of an aqueous solution of radioactive iron (III) citrate. Significant difference was observed in the rate of reappearance of iron-59 in the circulation between control and manganese treated animals. The disappearance of iron-59 from the plasma of control and treated animals however did not show any appreciable difference. A significant increase in the radio-iron content was observed in bone marrow, liver and kidney of treated animals as compared to control group forty eight hours after Fe-59.

Anemia↗

PubMed1981

Ferric citrate transport in Escherichia coli requires outer membrane receptor protein fecA.

Mutants of Escherichia coli K-12 AB2847 and of E. coli K-12 AN92 were isolated which were unable to grow on ferric citrate as the sole iron source. Of 22 mutants, 6 lacked an outer membrane protein, designated FecA protein, which was expressed by growing cells in the presence of 1 mM citrate. Outer membranes showed an enhanced binding of radioactive iron, supplied as a citrate complex, depending on the amount of FecA protein. The FecA protein was the most resistant of the proteins involved in ferric irion iron translocation across the outer membrane (FhuA = TonA, FepA, Cir, or 83K proteins) to the action of pronase P. It is also shown that previously isolated fec mutants (G. C. Woodrow et al., J. Bacteriol. 133:1524-1526, 1978) which are cotransducible with argF all lack the FecA protein. They were termed fecA to distinguish them from the other ferric citrate transport mutants, now designated fecB, which mapped in the same gene region at 7 min but were not cotransducible with ArgF. E. coli W83-24 and Salmonella typhimurium, which are devoid of a citrate-dependent iron transport system, lacked the FecA protein. It is proposed that the FecA protein participates in the transport of ferric citrate.

Bacterial Proteins↗

PubMed2000

Evaluation of uncertainties in estimates of fetal doses from 59Fe kinetic studies at Vanderbilt University.

In a 1997 paper, Stabin et al. published estimates of the fetal radiation doses for women who received oral administrations of 59Fe at Vanderbilt University in the 1940's. These authors concluded that there was "considerable uncertainty... in the amount of radioactive material administered to these subjects." In an effort to quantify this uncertainty, the underlying factors in the input data used in the Stabin et al. dose estimates have been examined in detail. Such factors include (a) an absence of detailed information on, and discrepancies in, the amounts of 59Fe reported to have been administered; (b) the probability that the radioactive iron included 55Fe as well as 59Fe; (c) uncertainties as to the period of time that elapsed between the administration of the radioiron and the taking of the maternal blood samples, and the accompanying impacts of radioactive decay; (d) possible losses of 59Fe in the procedures used in preparing the blood samples; and (e) questions as to the reported efficiency of the counting equipment. Our principal conclusion is that, due to the significant uncertainties and the lack of key information, it is not possible to estimate the doses accurately. An ancillary conclusion, however, is that the doses were probably significantly higher than previously estimated. This latter possibility should be carefully considered by any investigators who subsequently seek to use these estimates to quantify the relationship between the doses to the fetus and the resulting health effects.

Beta Particles↗

PubMed1994

Reduction site of transferrin-dependent and transferrin-independent iron in cultured human fibroblasts.

Mammalian cells internalize iron as diferric transferrin (Fe2Tf) iron via receptor-mediated endocytosis (RME) and a redox mechanism under physiological condition and as an iron salt through the Tf-independent iron uptake (Tf-IU) system under morbid conditions. We have previously shown that Tf iron is reduced at the Tf molecule through a redox system on the plasma membrane prior to uptake [Oshiro, S., Nakajima, H., Markello, T., Krasnewich, D., Bernadini, I., & Gahl, W. (1993) J. Biol. Chem. 268, 21586-21591]. In the present study, the reduction site for Tf iron uptake via RME and for Tf-independent iron uptake via the Tf-IU system were examined using specific iron sources and well-characterized ferric or ferrous iron chelators in cultured human fibroblasts. At 4 degrees C for 1 h, although [55Fe]2Tf was not internalized into the cells, 55Fe from [55Fe]2Tf-Sepharose was taken up. However, under the same conditions, EDTA or dipyridyl removed the radioactive iron as a ferric or ferrous iron-chelator complex from [55Fe]2Tf bound to the Tf receptor on the cell surface. Moreover, after 55Fe-citrate was loaded into the cells at 4 degrees C for 1 h, 55Fe was removed from the cell surface by dipyridyl just as observed for [55Fe]2Tf-Sepharose. In inhibition experiments, ferric citrate showed a dose-dependent inhibition of the iron uptake of both Tf iron and Tf-independent iron. Conversely, Fe2Tf dose-dependently inhibited the uptake of 55Fe-citrate.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Membrane↗

PubMed1981

Mucosal uptake, mucosal transfer and retention of iron: reproducibility of their measurement by whole-body counting and differences between Fe(II) and Fe(III).

Iron absorption was measured with a double isotope technique which enabled investigation of initial mucosal uptake, mucosal transfer and retention of iron. Radioactivity was measured with a whole-body scanner. Absorption of 1 mg Fe2+ was studied twice in 22 healthy subjects, with an interval of almost two years. No significant difference was observed in the mean values of mucosal uptake, mucosal transfer and retention of iron. In some subjects, however, values differed considerably, despite identical experimental conditions, detailed instruction and no detectable changes in the individual iron status. In another 10 subjects absorption of 1 mg Fe3+ was compared with 1 mg Fe2+. Mucosal uptake and retention of Fe2+ were twice as high as of Fe3+ while mucosal transfer did not differ significantly. It appears that investigations of groups of subjects, receiving either the same or a different iron test dose, give reliable and reproducible results. Individual and longitudinally studied values in a single subject, however, have to be interpreted with caution.

Aged↗

PubMed1968

Studies on the partition of iron in bone marrow cells.

Canine marrow cells were incubated with transferrin-bound (59)Fe, and the partition of cellular iron was studied by chromatographic and gel filtration methods. Splitting-off of iron from the stromal fraction was avoided by lysing the cells in Tris HCl buffer at pH 8.6. Cellular iron was divided into four major compartments: stroma, microsomes, main hemoglobin, and fraction I. The iron in fraction I was found in ferritin, heme proteins, and low molecular weight iron. With incubation times of 3-10 min, (59)Fe appeared promptly in the main hemoglobin. The entry of (59)Fe into ferritin paralleled that of hemoglobin but was smaller in amount. When the marrow cells were incubated with (59)Fe for 15-20 min and reincubated without radioactive iron, movement of (59)Fe into main hemoglobin was observed, and essentially all this iron came from the particulate fraction (stroma, mitochondria, and microsomes). In these chase experiments there was no change in the total quantity of (59)Fe in ferritin. There was no evidence of a significant hemoglobin precursor other than low molecular weight iron. DEPENDING UPON CONCENTRATION, LEAD WAS OBSERVED TO INHIBIT CELLULAR IRON METABOLISM AT SEVERAL POINTS: uptake of iron by the cell, movement of iron from stroma to the soluble intracellular compartment, and synthesis of hemoglobin. The most pronounced inhibitory effect of lead was always on hemoglobin synthesis with an increase in ferritin: hemoglobin ratio. Bipyridine appeared to trap intracellular ferrous iron and to inhibit synthesis of both hemoglobin and ferritin. It was concluded that iron moves from the stroma into the soluble intracellular compartment as low molecular weight iron, probably as a complex of ferrous iron with low molecular weight components of the cytoplasm, that serves as the source of iron for both hemoglobin and ferritin synthesis.

Animals↗

PubMed1984

Retention and distribution of iron added to cow's milk and human milk as various salts and chelates.

Iron supplementation of infant formulas is recommended by most national and international organizations, but the optimal form of supplementation has not been determined. We have compared the bioavailability and tissue distribution of iron from four iron chelates and two commonly used iron salts. Weanling C57BL/6J mice were fed for 1 week an evaporated cow's milk diet supplemented with vitamins and minerals (except for iron). Following the adjustment period, mice were divided into 12 groups of 20 each. Six groups continued to receive the cow's milk diet for 18 hours, while the other six groups were fed a similar diet based on human milk. Individual groups received a single dose of milk radioactively labeled with Fe(II)Cl2, Fe(II)SO4, Fe(III)NTA, Fe(III)EDTA, Fe(III)citrate or Fe(III)lactobionate. Wholebody retention was measured after 4 days; animals were then killed and individual tissues were counted for radioactivity. Iron from FeCl2, FeSO4 and FeNTA were the best retained from both milk diets. Fe citrate had a significantly lower iron retention than all other groups in either diet and is probably not an effective chelate for delivering iron to milk diets. Iron bioavailability was higher from the human milk diets than from the cow's milk diets from all vehicles used except citrate and lactobionate. Absorption of Fe citrate was similar from the two milk diets, while percent retention from Fe lactobionate was higher from cow's milk than from human milk. Tissue distribution of retained iron was similar for the milk diets and among the groups, indicating that, once absorbed, iron from the different vehicles is metabolized in a similar manner.

Animals↗

PubMed1981

Early events in guinea pig reticulocyte iron uptake.

Hemolysates, prepared from guinea pig reticulocytes incubated with 59Fe-labelled serum, can be resolved into five peaks utilizing molecular sieve chromatography: ferritin, transferrin, hemoglobin, an Mx 17 000 fraction, and a low molecular weight fraction. The hemoglobin peak also contains a nonhemoglobin component (III-X), demonstrated by heme extraction and by isoelectric focusing. Transferrin, the III-X component and the low molecular weight fraction are the first to accumulate radioactive iron during the reticulocyte incubation. The 59Fe in each of these also chases. Therefore, a role for these components as precursors to iron incorporation into heme is suggested.

Animals↗

PubMed2004

Role of transient receptor potential canonical 6 (TRPC6) in non-transferrin-bound iron uptake in neuronal phenotype PC12 cells.

Cells take up transferrin-bound iron or NTBI (non-transferrin-bound iron). After treatment with NGF (nerve growth factor), PC12 cells exhibited a neuronal phenotype and an increase in the NTBI uptake (55Fe2+ or 55Fe3+). We loaded the cells with the dye calcein, whose fluorescence increases in the presence of Ca2+ but is quenched with Fe2+ or Fe3+. When examined using calcein fluorescence or radioactive iron, DAG (diacylglycerol)-stimulated NTBI entry was more in NGF-treated PC12 cells compared with untreated cells. All experiments were performed at 1.5 mM extracellular Ca2+. Nramp2 (natural-resistance-associated macrophage protein 2) mRNA expression did not change after the NGF treatment. Expression of the bivalent cation entry protein TRPC6 (transient receptor potential canonical 6) was detected only in the NGF-treated cells. To verify that increased NTBI uptake depended on TRPC6, we examined whether transfecting HEK-293 (human embryonic kidney 293) cells with TRPC6 also increased the NTBI (55Fe) uptake. We also cotransfected HEK-293 cells with two plasmids, one expressing TRPC6 and the other expressing the fluorescent protein DsRED2 to identify the transfected cells. Challenging the calcein-loaded HEK-293 cells (which intrinsically express the a1-adrenergic receptors) with phenylephrine or a cell-permeant DAG increased the fluorescence signal more rapidly in transfected cells compared with untransfected cells. However, when iron (Fe2+ and Fe3+) was added before adding phenylephrine or DAG, the fluorescence intensity decreased more rapidly in transfected cells compared with untransfected cells, thereby indicating a greater stimulation of the NTBI uptake in cells expressing TRPC6. We postulate that the increase in the NTBI entry into neuronal PC12 cells is through TRPC6, a pathway that is unique since it is receptor-stimulated. Since neuronal cells express TRPC6, this pathway may have a role in neurotoxicity.

Animals↗

PubMed1991

Reduced hepatic iron uptake from rat aglycotransferrin.

Rat aglycotransferrin (rAgTf) was produced from the disialosyl diantennary fraction of rat transferrin (rTf) by treatment with peptide: N-glycosidase F. Following removal of the enzyme by gel filtration and isolation of the deglycosylated protein by lectin chromatography, rAgTf was compared to rTf both in vitro and in vivo. No significant differences were found between the two proteins with respect to affinity for iron and kinetics of Fe release from the N-lobe and C-lobe. The fluorescence emission spectrum of apo-rTf was red-shifted by approximately 3 nm relative to diferric rTf; however, no spectral difference was detected between rTf and rAgTf when the analogous forms (apo or diferric) were compared. Plasma clearance of radioactive iron administered to rats as either rTf or rAgTf was comparable. Reticulocytes took up iron from rAgTf slightly faster than from rTf. In contrast, Fe acquisition by the liver from rAgTf was significantly reduced relative to rTf. This finding contrasts sharply with earlier observations with asialotransferrin (rAsTf) and provides a basis for discounting charge loss as the mechanism of enhanced hepatic Fe uptake from rAsTf. It is suggested that the glycan complement of rTf, while unimportant for interaction of the protein with specific receptors, probably plays a role in the interaction with low-affinity hepatic binding sites.

Animals↗

PubMed1976

Iron-binding activity of female-specific serum proteins of rainbow trout (Salmo gairdneri) and chum salmon (Oncorhyncus keta).

The differences of serum proteins between mature male and female rainbow trout (Salmo gairdneri) and chum salmon (Oncorhyncus keta) were studied electrophoretically and immunologically. Female-specific serum proteins were seen only in females of both species, in the same region as beta-globulin on cellulose acetate membrane electrophoresis and agarose gel immunoelectrophoresis. One of the female-specific serum proteins bound radioactive iron. This protein was partially purified by precipitation by lowering the ionic strength of the serum. The purified material also showed the iron-binding property.

Animals↗

PubMed1975

Plasma iron transport during egg laying and after oestrogen administration in the domestic fowl (Gallus domesticus).

The concentrations of 59Fe and of radioiodinated transferrin and albumin were measured in the blood, liver, spleen, bone marrow and ova at different times after the injection of transferrin-bound 59Fe and the labelled proteins into non-laying, laying and oestrogen treated chickens. In the egg-laying and oestrogen-treated birds the 59Fe of the plasma was rapidly transferred from transferrin to another component with the properties of th phosphoprotein, phosvitin. Radioactive iron, and labelled transferrin and albumin to a lesser extent, entered the ova only while they were in the ovary. Relatively more labelled transferrin than albumin was found in all the tissues studied except in the ova, in which the two labelled proteins were present in the same relative concentration as in the plasma. It is concluded that, during egg laying and after oestrogen treatment, plasma iron bound to transferrin is taken up by the liver, incorporated into phosvitin and is then secreted into the plasma leading to elevation of the plasma iron concentration and transfer of iron to the ova.

Animals↗

PubMed1978

Erythropoietin assay: present status of methods, pitfalls, and results in polycythemic disorders.

Mammalian erythropoiesis is regulated primarily by the hormone erythropoietin (ESP). Studies of ESF have provided information about its biochemistry and its role in regulating hemoglobin synthesis. Such studies rely on assays for erythropoietic activity in biological fluid. The assay which has proven most valuable and is used most widely is based upon the incorporation of radioactive iron into newly-formed red cells of polycythemic mice. While this assay has gained wide acceptance, it is expensive, cumbersome, imprecise, and insensitive, capable of reliably detecting no less than 50 milliunits of erythropoietin. Improvements in assay techniques will require new methodology relying primarily on immunologic recognition for the determination of hormone activity. Currently under development and in experimental use are radioimmunoassays and a hemagglutination inhibition assay. While work has progressed in these areas, these assays are not of proven value at present and meaningful physiological correlations have not emerged from their use. Alternatively, assays for hormone activity using suspensions of hematopoietic cells and the measurement of incorporation of radioactive isotopes into hemoglobin have provided both improvement in sensitivity and precision. The disadvantage of these types of assays is that they are sensitive to factors other than ESF and may give misleading information, depending on whether the factors present stimulate or inhibit cellular proliferation and hemoglobin synthesis. While such techniques may provide a temporary solution to some problems associated with assaying ESF for purification or physiological studies, they are not the best answer to the overall problem of hormone detection and characterization. The most important contribution to this field will be the availability of large amounts of highly purified and well-characterized ESF.

DNA↗

PubMed1981

Changes in the characteristics and distribution of ferritin in iron-loaded cell cultures.

When Chang liver cells are grown in an iron-rich medium for up to 20 weeks, iron loading up to 50 times the normal cellular iron content may be obtained, although ferritin increases only to about 10 times normal. Ferritin has been isolated from such cells, and the isoferritin pattern found on elution from DEAE-Sephadex A-50 by increasing chloride concentrations has been used as a basis for studying changes in the properties of ferritin under conditions of cellular loading. A consistent shift of peak ferritin-elution position to higher chloride concentrations (lower pI) occurs when cells are loaded with ferric nitrilotriacetate for increasing lengths of time. A change in immunoreactivity also takes place on loading, the ratio of ferritin reacting with heart and spleen ferritin antibodies increasing at any particular value of pI. Cells were pulse-labelled with [59Fe]ferric nitrilotriacetate and [3H]leucine followed by non-radioactive iron in the same form. During the 72 h after the synthesis of new protein and its incorporation of iron, there is a slight acid shift in its isoelectric point. This effect is seen in both normal and loaded cells, with the whole spectrum being shifted towards lower pI in the loaded state. These findings suggest that the shift to more acidic ferritins on iron loading and the associated changes in antigenicity may be unrelated to subunit composition.

Cells, Cultured↗

PubMed1991

Transferrin Receptor Expression and Iron Uptake in the Injured and Regenerating Rat Sciatic Nerve.

Iron-saturated transferrin is a ubiquitous growth factor that plays a critical role in cellular iron uptake, growth and proliferation. Here we have studied the expression and distribution of transferrin receptors and iron uptake following injury of the rat sciatic nerve. Axotomy led to a massive but transient increase (days 2 - 9, maximum day 4) in [125I]transferrin binding at the site of the injury and in the distal, denervated part of the crushed or resected sciatic nerve, shortly preceding the time course of cellular proliferation (Friede and Johnstone, Acta Neuropathol, 7, 218 - 231, 1967; Jurecka et al., Acta Neuropathol, 32, 299 - 312, 1975). An additional, transient increase in specific binding was observed during reinnervation after reconnection of the resected sciatic nerve. Immunocytochemistry using the Ox-26 monoclonal antibody revealed strong and simultaneous expression of the transferrin receptor protein on two different cell types: on a subpopulation of blood-borne macrophages invading the injured peripheral nerve and on Schwann cells reacting to denervation and reinnervation. In addition, studies using intravenously injected radioactive iron (59Fe3+) showed a massive increase in endoneural iron uptake confined to the lesion site and to the distal part of the axotomised sciatic nerve, parallel to the time course of reactive transferrin receptor expression. Since iron is an essential cofactor of a number of key enzymes needed in energy metabolism and DNA synthesis, these data suggest that the induction of transferrin receptor expression may play an important role in the regulation of cellular growth and proliferation during peripheral nerve regeneration.

Journal Article↗

PubMed1976

A complement independent erythropoietic inhibitor acting on the progenitor cell in refractory anemia.

An erythropoietic inhibitor was detected in the serum of a patient with refractory anemia. Using an in vitro heme synthesis method, the patient's serum produced tenfold inhibition of erythropoietin-stimulated radioactive iron (Fe59) incorporation into heme of normal human marrow at 72 hours, as compared with AB serum. In a separate experiment the patient's serum produced threefold inhibition, whereas immunoglobulin G (IgG) prepared from the same serum sample produced 12-fold inhibition. To identify the site of action of the inhibitor, serum was tested in a cell culture system whereby human marrow cells, grown in a plasma clot, respond to exogenous erythropoietin with the appearance of nucleated erythroid colonies. Each colony arises from a committed erythroid progenitor. The patient's serum produced a two- or tenfold reduction in the number of colonies from normal human marrow. The effect was also demonstrated on autologous marrow obtained when the patient was in "partial clinical remission". Serum samples obtained at various times during the course of the patient's illness all demonstrated a suppressive effect on colony growth. All serums were heat-inactivated, and total hemolytic complement could not be detected in either culture system. It is concluded that the anemia is due to an inhibitor, probably of IgG class, that acts on the erythroid progenitor cell. The absence of heat-labile complement components in the culture systems suggests that the mechanism is not due to immune cytolysis.

ABO Blood-Group System↗

PubMed1983

Biochemical studies on the toxicity of hematite dust.

Biochemical alterations in guinea pig lungs caused by hematite dust were followed at 150 days after intratracheal administration of the dust. In vivo dust exposure caused a significant increase in mitochondrial protein content and cytochrome c oxidase activity whereas diaphorase activity remained unaltered. Mitochondria from the exposed animals were apparently in a swollen state and their contraction profile upon the addition of ATP reflected permeability changes. However, in vitro dust caused no significant alterations. Significant increases in glycogen content along with an insignificant decrease in glycogen phosphorylase activity were also observed in hematite-treated guinea pig lungs. Decrease in drug-metabolizing enzymes such as aniline hydroxylase and tyrosine aminotransferase activities were also evident in the postmitochondrial fraction of the siderotic lungs. [3H]Leucine-incorporation studies showed increased protein synthesis in the postmitochondrial fraction. Increase in protein synthesis in mitochondria was only marginal whereas in whole homogenate it decreased considerably. Experiments employing dust tagged with radioactive iron indicated the rapid mobilization of iron from lung and its distribution to various organs. The presence of iron-binding protein was confirmed by employing Sephadex gel-filtration techniques.

Animals↗