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[Measurement of Fe59 and Cr51 activities on the body surface of patients after simultaneous use of these 2 isotopes].
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Recovery and estimation of radioisotopes from biologic materials; II. The electroplating apparatus. Procedures for copper, silver, zinc, mercury, iron, and cobalt.
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Iron-55 levels in humans living in Richland, Washington (1964-1967). BNWL-715. 2.
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Various radioactive tracers for the detection of brain tumors.
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Evaluation of hepatocellular and Kupffer cell function of the isolated guinea pig liver perfused by a fluorocarbon medium.
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Ferritin and intestinal iron absorption: pancreatic enzymes and free iron.
Rat intestinal mucosa gave low yields of ferritin purified by standard procedures. The resulting ferritin had less protein relative to iron and migrated faster electrophoretically than ferritin from other rat tissues. Pancreatic duct ligation reduced these differences, suggesting digestive enzyme attack during ferritin isolation. Even in ligated rats, ferritin accounted for only 5-10% of mucosal iron. However, shortly after giving 59FeCl3 orally, 50% of mucosal radioactivity occurred in cell sap, about equally distributed between ferritin and low-molecular-weight (chelated?) iron. No other cell sap components were 59Fe labeled. Iron may thus be transported as a chelate with which ferritin is in rapid equilibrium. Mucosal ferritin content increased with age and iron treatment and decreased with iron deficiency. The iron-deficient rats showed accelerated 59Fe uptake into blood with little mucosal retention. One day after administering parenteral iron to deficient rats, 59Fe transfer to blood became retarded but 59Fe now accumulated excessively in the mucosa, suggesting that iron status affects transport more rapidly at the serosal than at the mucosal cell surface. A scheme for control of iron absorption is presented.
Influence of Iron Chlorosis on Pigment and Protein Metabolism in Leaves of Nicotiana tabacum L.
Experiments were conducted on Nicotiana tabacum, L. to study the relation in the grana among chlorophylls, carotenoids, and proteins. The effect of iron chlorosis on protein and pigment synthesis was studied at different stages of chlorosis using glycine-U-C(14). Pigments were separated by thin layer chromatography.Chlorophyll a, chlorophyll b, carotenoid, and protein contents of chloroplasts from chlorotic tissue were less than those of normal tissues. A 25% decrease in protein labeling and a 45% decrease in chlorophyll labeling was noted in deficient tissue compared to normal tissue even before chlorosis was perceptible. Both normal and iron deficient leaf discs which received iron in the incubation medium incorporated higher amounts of radioactive glycine into chlorophyll a and chlorophyll b at all stages of development than their respective counterparts not supplied with iron in the incubation medium. The presence of iron in the incubation medium reduced the amount of glycine incorporated into carotenes and xanthophylls, except where the tissue was severely chlorotic. This may be attributed to active competition for glycine between the iron-dependent- (chlorophyll) and iron-independent-(carotenoid) biosynthetic pathways. Incorporation of glycine into chloroplast pigments was lowest at severe chlorosis, probably due to a reduction in the overall enzyme activity.
Distribution of storage iron as body stores expand in patients with hemochromatosis.
The relative distribution of storage iron between bone marrow and liver has not been adequately studied in patients with iron-loading disorders. To help clarify this we assessed iron metabolism in patients with iron overload and in control subjects with cirrhosis but no excess body iron. In 4 patients with advanced iron overload studied late in the course of their illness, excess hemosiderin was present in both bone marrow and liver, as expected. In contrast, 2 patients with idiopathic hemochromatosis whose excess iron had been depleted by phlebotomy subsequently developed progressive hepatic parenchymal and reticuloendothelial (RE) deposition of iron, yet marrow hemosiderin remained sparse. Moreover, surface radioactivity over the liver after an oral dose of 59Fe. These results suggest that during the initial stages of hemochromatosis there is a dissociation in the rate of iron accumulation between the bone marrow and liver. Excess hemosiderin appears to be deposited predominantly and preferentially in hepatic storage sites until the later stages of the disease.
Bathophenanthrolene disulfonic acid and sodium dithionite effectively remove surface-bound iron from Caco-2 cell monolayers.
Iron uptake by Caco-2 cell monolayers is commonly assessed by incubating the cells under radiolabeled iron solutions, removing the radiolabeled solution, rinsing to stop uptake and measuring the radioactivity retained by the cells. It is therefore essential to differentiate between iron that is nonspecifically bound to the cell surface from that which has been taken up by the cell. We report here on a method for removal of surface-bound iron from Caco-2 cell monolayers. We used a 140 mmol/L NaCl, 10 mmol/L PIPES, pH 6.7 solution containing 5.0 mmol/L sodium dithionite (Na2S2O4) and 5.0 mmol/L bathophenanthroline disulfonic acid to reduce, remove and chelate iron bound to the cell surface. We validated our method by demonstrating the removal of 97% of an insoluble iron complex from the apical surface of Caco-2 cell monolayers. Our data indicate that the removal solution does not damage the apical membrane and thereby does not have access to intracellular iron; thus only surface bound iron is removed. The remaining cell-associated iron represents that which has been transported into the cell. We present data on the uptake and nonspecific binding of iron from iron complexes of both ferrous and ferric forms, and show that iron removal treatment resulted in uptake measurements that agree more closely with accepted principles of iron uptake by intestinal epithelium. The iron removal method used in this study should provide investigators with a valuable tool for accurately determining iron uptake by epithelial cells in culture.
[The use of radioactive isotopes in the evaluation of survival of preserved erythrocytes; experimental research with Fe59].
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Relative contribution of parenchymal and non-parenchymal cells to the hepatic distribution and metabolism of iron-poly(sorbitol-gluconic acid) complex in the rat.
The hepatic cellular distribution in rats of radioiron and radiocarbon after [14C-gluconic acid]-and 59Fe-labelled iron-poly(sorbitol-gluconic acid) complex, glusoferron (Ferastral), has been investigated. Following administration of the 59Fe-iron complex at a dose level corresponding to 10 mg of iron per kg bodyweight, the ratio of radioactivity per 10(8) cells in parenchymal (P) and non-parenchemal (NP) cell fractions, the P/NP ratio, was 3.0 after 24 hours and rose to 10.4 at day 14. After 100 mg/kg the ratio was 0.9, 10.5 and 5.7 at day 1, 4 and 14, respectively. Radiocarbon content in the different cell compartments fell steadily throughout. Radioiron from 59Fe-iron-poly(sorbitol-gluconic acid) complex was shown to be incorporated into whole liver 59Fe-ferritin. In vitro uptake studies with the different liver cells were also performed. Parenchymal cells were found to be more active than non-parenchymal cells with regard to cellular uptake of radiolabel from both iron complex and polymeric ligand without iron.
Geologic storage of radioactive waste: field studies in Sweden.
Access to a granitic rock mass in an iron ore mine in Sweden provided a unique opportunity for underground experiments related to the geologic disposal of radioactive waste. These field tests demonstrated the importance of hydrogeology and the difficulties in predicting the thermomechanical behavior of fractured granitic rocks. To characterize a site fully, measurements made from the surface must be supplemented by extensive subsurface measurements and experiments. Much effort is needed at this stage to generate the technology required for the development of waste repositories.
Effects of erythropoietin therapy on iron absorption in chronic renal failure.
The effect of erythropoietin administration on the absorption of dietary and therapeutic iron was examined in patients with anemia of chronic renal failure on maintenance hemodialysis. Absorption from test meals tagged extrinsically with iron 55, iron 59, or both was determined 2 weeks later by using incorporated red blood cell radioactivity and whole body counting. In an initial study of food iron absorption, the effect of initiating erythropoietin therapy was determined by measuring the absorption of heme and nonheme iron before and 2 weeks after the administration of 64 U/kg body weight erythropoietin (range, 46-85 U/kg body weight) three times weekly. Absorption of heme iron increased 1.6-fold from 18.6% to 30.1% (P < .05), and nonheme iron increased 3.7-fold from 1.3% to 4.9% (P < .01) after erythropoietin therapy. In a second study therapeutic iron absorption was evaluated at baseline and after erythropoietin administration (63 U/kg body weight (range, 48-74 U/kg body weight) three times weekly). The absorption of 50 mg of iron as ferrous sulfate increased 2.4-fold from 3.8% to 9.4% (P < .05) when given without food and 4.2-fold from 1.4% to 5.9% (P < .05) when given with food after erythropoietin administration. After adjusting for changes in iron stores with serum ferritin after erythropoietin therapy, the enhanced erythropoiesis associated with erythropoietin therapy increased absorption about 2-fold, which was similar to the response observed previously in normal subjects. In a final study we examined the absorption of therapeutic iron during the steadystate phase of erythropoietin therapy after an erythroid response to erythropoietin had occurred. The absorption of 50 mg of iron was lower than that occurring with the initiation of erythropoietin therapy at 2.2% when given alone and 1.3% when taken with food. We conclude that iron absorption with or without erythropoietin stimulation is unimpaired in patients with chronic renal failure.
FABRICATION OF MONODISPERSE LUCITE AND IRON OXIDE PARTICLES WITH A SPINNING DISK GENERATOR.
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The determination of ferric iron in plants by HPLC using the microbial iron chelator desferrioxamine E.
Common methods for plant iron determination are based on atomic absorption spectroscopy, radioactive measurements or extraction with subsequent spectrophotometry. However, accuracy is often a problem due to background, contamination and interfering compounds. We here describe a novel method for the easy determination of ferric iron in plants by chelation with a highly effective microbial siderophore and separation by high performance liquid chromatography (HPLC). After addition of colourless desferrioxamine E (DFE) to plant fluids, the soluble iron is trapped as a brown-red ferrioxamine E (FoxE) complex which is subsequently separated by HPLC on a reversed phase column. The formed FoxE complex can be identified due to its ligand-to-metal charge transfer band at 435 nm. Alternatively, elution of both, DFE and FoxE can be followed as separate peaks at 220 nm wavelength with characteristic retention times. The extraordinarily high stability constant of DFE with ferric iron of K = 10(32) enables extraction of iron from a variety of ferrous and ferric iron compounds and allows quantitation after separation by HPLC without interference by coloured by-products. Thus, iron bound to protein, amino acids, citrate and other organic acid ligands and even insoluble ferric hydroxides and phosphates can be solubilized in the presence desferrioxamine E. The "Ferrioxamine E method" can be applied to all kinds of plant fluids (apoplasmic, xylem, phloem, intracellular) either at physiological pH or even at acid pH values. The FoxE complex is stable down to pH 1 allowing protein removal by perchloric acid treatment and HPLC separation in the presence of trifluoroacetic acid containing eluents.
Pork meat increases iron absorption from a 5-day fully controlled diet when compared to a vegetarian diet with similar vitamin C and phytic acid content.
Meat increases absorption of non-haem iron in single-meal studies. The aim of the present study was to investigate, over a 5 d period, the potential increasing effect of consumption of pork meat in a whole diet on the fractional absorption of non-haem iron and the total absorption of iron, when compared to a vegetarian diet. A randomised cross-over design with 3 x 5 d whole-diet periods with diets containing Danish-produced meat, Polish-produced meat or a vegetarian diet was conducted. Nineteen healthy female subjects completed the study. All main meals in the meat diets contained 60 g of pork meat and all diets had high phytic acid content (1250 mumol/d). All main meals were extrinsically labelled with the radioactive isotope (59)Fe and absorption of iron was measured in a whole body counter. The non-haem iron absorption from the Danish meat diet was significantly higher compared to the vegetarian diet (P=0.031). The mean fractional absorption of non-haem iron was 7.9 (se1.1), 6.8 (se 1.0) and 5.3 (se 0.6) % for the Danish and Polish meat diets and vegetarian diet, respectively. Total absorption of iron was higher for both meat diets compared to the vegetarian diet (Danish meat diet: P=0.006, Polish meat diet: P=0.003). The absorption ratios of the present study were well in accordance with absorption ratios estimated using algorithms on iron bioavailability. Neither the meat diets nor the vegetarian diets fulfilled the estimated daily requirements of absorbed iron in spite of a meat intake of 180 g/d in the meat diets.
Iron balance in the common vampire bat Desmodus rotundus.
1. Total body iron in the common vampire bat was 80 +/- 67 mg Fe/kg body wt (mean +/- SD). 2. Mean (+/- SD) iron absorption as measured by the double isotope method was 0.068 +/- 0.0032% Fe. A typical adult bat ingests 6.1 mg Fe/day (Morton & Wimsatt, 1980) of which approximately 4.2 microgram Fe is absorbed. 3. Body iron turnover (BIT) was estimated from the decrease in specific radioactivity of the blood over more than a year. The mean (+/- SD) of the half-life of iron turnover was 379 +/- 101 days and that of the estimate of BIT. 0.14 +/- 0.04% TBI/day. This is equivalent to a loss of approximately 4.6 microgram Fe/day. 4. The common vampire bat maintains iron balance by severely limiting the percentage of iron absorbed from its very high iron diet.