[The balance of hemoglobin iron patrimony in dogs during pregnancy, studies with a radioactive isotope of iron].
Explore the source record for details and available documents.
Animals↗
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.
Iron dynamics in the ruminant.
We have compared the plasma clearance rate of radioactive iron in cows both as ferric chloride and as iron specifically bound to transferrin. We have also repeated the transfusion experiment of Dern et al. (Dern, R.J., Monti A. and Glynn, M.F. (1963) J. Lab. Clin. Med. 61,280-291) using goats. The results show that neither non-specificity bound iron (Bates, F.W. and Schlabach, M.R. (1973) J. Biol. Chem. 248, 3228-3232) nor the iron bound to the two different sites in transferrin (Awai, M., Chipman, B. and Brown, E.B. (1975) J. Lab. Clin. Med. 85,769-784) can be identified as distinguishable iron pools by this technique.
Animals↗
Patterns of food iron absorption in iron-deficient white and indian subjects and in venesected haemochromatotic patients.
The absorption of radioactive iron from a solution of ferrous ascorbate, and from a standard meal containing intrinsically labelled haemoglobin and wheat, was measured in 12 Indian housewives, 18 white hospital patients and 12 subjects with idiopathic haemochromatosis. Eight of the latter had been fully treated by multiple venesections, so that their serum ferritin concentrations were below 25 mug/1. Since the serum ferritin concentrations of the housewives and the hospital patients were comparable, their body iron stores were considered to be depleted to a similar degree. There were no significant differences between the absorptions of ferrous ascorbate or of the haem iron in the standard meal by each group, but the housewives and the hospital patients absorbed significantly less of the non-haem food iron. The mean non-haem food iron absorptions were 36.4%, 5.8% and 18.9% for the treated haemochromatotic subjects, the Indian housewives and the white hospital patients respectively. The discrepancies between the absorptions of the different forms of food iron were highlighted by calculating the ratios between them. The mean non-haem: haem food iron absorption ratio for the group of treated haemochromatotic subjects was 0.98, and for the Indian housewives only 0.18. The white hospital patients did not form a homogenous population: the ratios of the five males and three of the females were greater than 1.0, whereas those of the remaining 10 females were less than 0.5. The results of this study suggest that mal-absorption of non-haem iron from a meal containing bread, presumably due to a defect at the luminal level, may be an important factor in the pathogenesis of iron deficiency in some subjects. The abnormality appears to be particularly prevalent among Indian women living in Durban.
Adolescent↗
Fusarinines and dimerum acid, mono- and dihydroxamate siderophores from Penicillium chrysogenum, improve iron utilization by strategy I and strategy II plants.
Cucumber, as a strategy I plant, and Maize as a strategy II plant, were cultivated in hydroponic culture in the presence of a ferrated siderophore mixture (1 microM) from a culture of Penicillium chrysogenum isolated from soil. The siderophore mixture significantly improved the iron status of these plants as measured by chlorophyll concentration to the same degree as a 100-fold higher FeEDTA supply. Analysis of the siderophore mixture from P. chrysogenum by HPLC and electrospray mass spectrometry revealed that besides the trihydroxamates, coprogen and ferricrocin, large amounts of dimerum acid and fusarinines were present which represent precursor siderophores or breakdown products of coprogen. In order to prove the iron donor properties of dimerum acid and fusarinines for plants, purified coprogen was hydrolyzed with ammonia and the hydrolysis products consisting of dimerum acid and fusarinine were used for iron uptake by cucumber and maize. In short term experiments radioactive iron uptake and translocation rates were determined using ferrioxamine B, coprogen and hydrolysis products of coprogen. While the trihydroxamates revealed negligible or intermediate iron uptake rates by both plant species, the fungal siderophore mixture and the ammoniacal hydrolysis products of coprogen showed high iron uptake, suggesting that dimerum acid and fusarinines are very efficient iron sources for plants. Iron reduction assays using cucumber roots or ascorbic acid also showed that iron bound to hydrolysis products of coprogen was more easily reduced compared to iron bound to trihydroxamates. Ligand exchange studies with epi-hydroxymugineic acid and EDTA showed that iron was easily exchanged between coprogen hydrolysis products and phytosiderophores or EDTA. The results indicate that coprogen hydrolysis products are an excellent source for Fe nutrition of plants.
Biological Transport, Active↗
The regulation of iron release from the perfused rat liver.
Factors affecting iron efflux from the isolated perfused rat liver were studied following the intravenous administration of transferrin-(59)Fe or transferrin-(55)Fe administered to the rat from 1.5 h to 3.5 d before perfusion of the liver. The liver was perfused with rat red cells suspended either in rat plasma or Eagle's Basal Medium (EBM). The mean rate of efflux into a plasma pool containing normal iron and transferrin concentrations was 0.9% of the initial hepatic radioactive iron pool per hour. In EBM the average rate of efflux was 0.1%/h and this could be increased to the rate observed with plasma by the addition of apotransferrin. The rate of iron release from the liver in the presence of apotransferrin or other chelators was inversely proportional to the time of prelabelling. Maximal release rates were observed in livers perfused within 5 h of administering transferrin-(59)Fe to the rat. The effect of apotransferrin on efflux into EBM was concentration dependent. However, the maximum release of liver iron by apotransferrin occurred at physiological apotransferrin concentrations and addition of apotransferrin to plasma produced no increase in the rate of iron efflux. The stimulation of iron release in EBM caused by apotransferrin could be reversed by reducing the unsaturated iron binding capacity of the perfusate, either by addition of iron or removal of apotransferrin. However, increasing the iron concentration in the perfusate by the addition of iron-saturated transferrin without any reduction in the unsaturated iron binding capacity additionally increased iron release into plasma and EBM. This presumably reflects the exchange of plasma transferrin-(56)Fe for liver (59)Fe. Hence iron release measured in these studies represent the sum of two processes-net release of (59)Fe induced by apotransferrin and iron exchange between plasma and liver iron pools. Apotransferrin and desferrioxamine were equally effective, per unit iron binding capacity, in mobilizing liver iron, and may compete for the same parenchymal iron pool. This suggests that mobilization of iron by apotransferrin may depend solely on its ability to chelate ferric iron and not on a more specific ferroxidase activity or interaction with membrane receptors.
Animals↗
Regulation of intestinal iron absorption and mucosal iron kinetics in hereditary hemochromatosis.
In hereditary hemochromatosis (HH), increased intestinal iron absorption leads to the development of iron overload. To examine the abnormal regulation of iron absorption in this disorder, we analyzed mucosal iron kinetics in six patients with HH and in five normal subjects by using a compartmental model of intestinal iron absorption and systemic ferrokinetics. Subjects were given simultaneous oral and intravenous tracer doses of iron 59-labeled citrate and iron 55-labeled transferrin, respectively. Plasma and whole-body radioactive iron levels were then monitored serially during the next 2 weeks, and mucosal iron transport rate constants were estimated by non-linear least-squares fit of the model to these data. Iron absorption was inversely related to serum ferritin concentration in both normal subjects and patients with HH but was higher in relation to serum ferritin level among the latter (p less than 0.0002). Analysis of mucosal iron kinetics demonstrated a similar inverse relationship between the rate constant for mucosal iron uptake and serum ferritin among all subjects combined, but the mean uptake rate constant in patients with HH did not differ from that of normal subjects (p = 0.71). The mean rate constant for incorporation of iron into the mucosal storage pool in patients with HH also was comparable to that of normal subjects (p = 0.94). In contrast, the rate constant for transfer of mucosal iron to the plasma was higher in patients with HH than in normal subjects for any given serum ferritin level (p less than 0.0001), and the transfer rate constant accounted for 87% of the variability in iron absorption among all subjects. We conclude that the increased iron absorption in HH is mediated primarily by an increase in the rate constant for transfer of mucosal iron to the plasma.
Ferritins↗
Transport of iron and transferrin synthesis by the seminiferous epithelium of the rat in vivo.
The transport of radioactive iron across the seminiferous tubules was analyzed in vivo by light-microscope quantitative radioautography. At 5 min after a single intratesticular injection of 55Fe-transferrin, a strong labeling of the basal aspect of the seminiferous epithelium was observed. Between 30 min and 2 h, the labeling on the basal aspect of the seminiferous epithelium decreased. This decrease was accompanied by a substantial increase of the radioautographic reaction over the cellular elements in the adluminal compartment. These results were consistent with the demonstration of 59Fe associated with meiotic spermatocytes and differentiating spermatids isolated by velocity sedimentation from testes injected with 59Fe-transferrin. Furthermore, after a single intratesticular injection of 59Fe-labeled human transferrin, radiolabeled rat transferrin was immunoprecipitated from homogenates of isolated tubules with a specific antibody and appeared as a single radioactive band on fluorographs of urea/polyacrylamide gels. Similarly, 59Fe-labeled rat transferrin but not 125I-transferrin was immunoprecipitated from rete testis fluids of testes infused with either 59Fe- or 125I-labeled human transferrin. Finally, the synthesis of testicular transferrin in vivo was demonstrated in fluorographs of immunoprecipitated transferrin after an intratesticular injection of 35S-methionine in rats whose livers were excluded from the general circulation by ligation of both the hepatic artery and the portal vein. Thus, our results demonstrated a unidirectional system of iron transport from the basal compartment of the seminiferous epithelium to the germ cells in the adluminal compartment involving two distinct transferrins, i.e., a serum transferrin and a testicular transferrin synthesized by the seminiferous epithelium.
Animals↗
Novel iron uptake system specified by ColV plasmids: an important component in the virulence of invasive strains of Escherichia coli.
The enhanced virulence of invasive strains of Escherichia coli carrying ColV plasmids was shown to be due to a novel plasmid-mediated iron uptake system. Possession of a ColV plasmid conferred strong selective advantage on the host bacterial strain in experimental infections unless excess iron was administered in the inoculum. Moreover, supplementation of defined minimal medium with transferrin to complex available iron caused marked limitation of the growth of plasmid-free strains but had no effect on strains carrying a ColV plasmid. The activity of an efficient iron uptake process was clearly shown by experiments with a mutant of E. coli deficient in enterochelin biosynthesis. Although the mutant was dependent on the presence of citrate in the growth medium to facilitate iron transport, colicinogenic derivatives did not require added citrate for growth. Radioactive iron was shown to be taken up rapidly by nongrowing cells of the plasmid-carrying strain. Furthermore, it was observed that repression of the synthesis of specific outer membrane proteins normally induced by conditions of iron deficit was maintained after a shift of the colicinogenic strains from a rich medium to a medium low in iron. The ColV plasmid-mediated iron uptake system was independent of the active iron transport mechanisms known in E. coli, but like them it required tonB activity as a source of energy.
Animals↗
Quantification of desferrioxamine and its iron chelating metabolites by high-performance liquid chromatography and simultaneous ultraviolet-visible/radioactive detection.
An HPLC-based method for quantification of desferrioxamine (DFO) and its iron chelating metabolites in plasma has been developed. This assay overcomes stability problems associated with DFO by the addition of radioactive iron to convert unbound drug and metabolites to radio-iron-bound species. A dual detection system utilizing uv-vis absorption and radioactive (beta-particle) detector was used to quantify total and radio-iron-bound species. The use of octadecyl silanol solid phase extraction cartridges permits concentration of samples and allows accurate quantification of drug and metabolites down to 0.1 nmol/ml.
Chromatography, High Pressure Liquid↗
Hallervorden-Spatz syndrome.
Two siblings with Hallervorden-Spatz syndrome showed striking homotypism and homochronism. Neuropathologic examination and electron microscopic studies were done; neutron activation analysis showed an increase in the uptake of iron in the basal ganglia. Of particular relevance is the application of radioactive iron studies in the clinical course of this syndrome. These studies disclosed an increase in the uptake of iron in the area of the basal ganglia in one sibling and in another isolated patient. This procedure will be helpful toward the clinical diagnosis.
Axons↗
[Recent advances in the area of iron metabolism using radioactive isotopes].
Explore the source record for details and available documents.
Humans↗
Staphylococcus aureus but not Staphylococcus epidermidis can acquire iron from transferrin.
Staphylococci grow and cause infection under the iron-restricted conditions found in vivo. They therefore must possess mechanisms to obtain iron for metabolism from this environment. To determine if staphylococci can extract iron bound to human transferrin, we labelled transferrin with 55Fe and performed uptake assays on cells grown in iron-restricted and iron-plentiful conditions. Growing cultures of Staphylococcus aureus NCTC 8532 could take up radioactive iron during mid- to late-exponential phase of growth. This process was iron-regulated and did not require direct contact between the cell and the labelled transferrin. Siderophore production was detected during this phase, but reductase or protease activity was not. S. epidermidis ATCC 14990 could not access 55Fe bound to transferrin, nor did this isolate produce siderophore, reductase or protease. This difference in the ability to acquire iron bound to transferrin may contribute to the increased virulence of S. aureus when compared to S. epidermidis.
Biological Transport↗
Iron release from isolated hepatocytes.
The isolated hepatocyte suspension was evaluated as an experimental procedure for investigating liver iron metabolism. Following prelabelling in vivo with transferrin-59Fe, isolated hepatocytes released radioactive iron in vitro by a temperature dependent process, without change in cell viability. Iron mobilization was increased by serum, apotransferrin and a range of iron chelators, of which the most effective were citrate, desferrioxamine and the ionophore A 23187. The rate of iron release was inversely related to oxygen levels, indicating that a ferric-ferrous reduction was involved in iron mobilization. The uncoupler TTFB, DTPA, and hypercapnia caused a reduction in iron release, but the metabolites cysteine, NADH and ascorbic acid had no effect. It was concluded that isolated hepatocytes are a useful experimental model for studying iron metabolism and for further evaluation of iron chelators.
Animals↗
59Fe is retained from an elemental 59Fe powder supplement without effects on 65Zinc, 47Calcium and 67Copper in young pigs.
In vivo counting with the use of a germanium detector evaluated the retention of an elemental 59Fe powder supplement while measuring potential interactions with zinc, calcium and copper. Effects of dietary iron and zinc on in vivo retentions of 59Fe, 65Zn, 67Cu and 47Ca were studied in young pigs. In Experiment 1, 4-d-old piglets fed a cereal-based diet were randomly assigned to one of four treatment groups (2 x 2 factorial arrangement, n = 5 per group). Variables were dietary iron source (either elemental iron or FeSO4, each at 100 mg iron/kg diet) and the dosage form of radioactive iron (either elemental 59Fe powder or 59FeSO4). Experiment 2 (2 x 3 factorial arrangement) was performed using two levels of iron (100 and 200 mg/kg, as elemental iron) and three levels of zinc (25, 50 and 100 mg/kg). Piglets were also dosed with 47Ca, 65Zn and 67Cu; all radioisotopes were measured for 8 d. Apparent absorption of elemental 59Fe powder was 13 +/- 1%, whereas 59Fe sulfate was significantly (P < 0.05) higher at 26 +/- 1%. The FeSO4 diet decreased 65Zn retention in Experiment 1, in contrast to the elemental iron diet, which did not have this effect in either experiment. Apparent 65Zn absorption averaged 44 +/- 2, 35 +/- 1 and 27 +/- 2% for the three levels of zinc (25, 50 and 100 mg/kg), respectively. Retention of 47Ca was not affected by dietary iron or zinc; retention of 67Cu was not affected by dietary iron. The data demonstrate good bioavailability of elemental iron without effects on zinc, copper and calcium.
Animals↗
Effect of chronic ethanol administration on iron metabolism in the rat.
This study shows that the ingestion of ethanol provokes alterations in iron metabolism which may lead to iron overload. Impaired release of reticuloendothelial iron was shown by a decrease of the maximum red blood cell utilization when radioactive iron was supplied as colloidal iron. An impairment in the erythropoietic activity of ethanol-treated animals was also observed, as can be seen from the reduced plasma iron turnover and red blood cell utilization within 24 h of iron administration. A rise in marrow transit time was also observed. In ethanol-treated rats there was an increase in the amount of iron retained both in the liver and the spleen. This was observed in both sexes and also in the offspring from ethanol-treated mothers.
Animals↗
The significance of folic acid, tissue iron stores, and tissue viability in determining iron uptake from serum by thyroid tissue slices.
This paper describes an attempt to measure in vitro iron uptake from serum by human thyroid slices and to relate the uptake to tissue iron stores, folic acid status, and tissue viability. It is an extension of work previously reported (Buchanan, 1969). Thyroids were obtained from patients undergoing partial thyroidectomy for colloid goitre and serum from clinically normal healthy adults. The haemoglobin, serum iron, and folic acid levels of both thyroid and serum donors were measured and thyroids examined histologically for the presence of stainable iron. Viable and non-viable tissue slices were incubated in sera treated with radioactive iron so as to produce high and normal levels of transferrin saturation. Iron was taken up both from sera with normal and high transferrin saturation but the amount was, in almost all cases, greater from the more highly saturated. The uptake by non-viable tissue was appreciable but did not vary to any great extent from one serum to the next, and was attributed to simple diffusion of ionic iron into the tissue. There was, however, marked variation in uptake from different sera by viable tissue. It was concluded therefore that viability is a factor affecting the uptake. As the variation in uptake by viable tissue incubated in a single serum was significantly less than tissue incubated in a number of different sera it was further concluded that there was also a factor in the serum itself affecting iron uptake. The nature of the factor was not elucidated but neither folic acid nor levels of iron stores appeared to influence uptake because no correlation was found between iron uptake and iron stores or folic acid.
Adult↗
Failure to label baboon milk intrinsically with iron.
The widely held belief that 50% of the iron in human milk is absorbed is based on studies that have used an extrinsic radioactive iron tag. To determine the validity of an extrinsic tag, it is necessary to label the milk intrinsically with one isotope and to compare absorption of this isotope with absorption of another isotope added as the extrinsic tag. We chose the baboon as a model and infused 59Fe intravenously. In each of three attempts we failed to label the milk intrinsically.
Absorption↗
Mitochondrial iron loss from leukemia cells injured by macrophages. A possible mechanism for electron transport chain defects.
Activated macrophages inhibit replication of murine lymphoblastic leukemia L1210 cells without lysis. This inhibition of replication is associated with abnormalities of mitochondrial electron transport at the level of NADH dehydrogenase (NADH-DH) and succinate dehydrogenase (SDH). The mechanism of inhibition is unknown, although it has been demonstrated that as NADH-DH and SDH activity is lost, iron is released from cells. Because both NADH-DH and SDH contain numerous iron-sulfur clusters, damage to these structures may be one result of injury by activated macrophages. L1210 cells were labeled with 55Fe and co-cultivated with activated murine peritoneal macrophages (injured L1210 cells). At 48 h, injured L1210 cells had released 83 +/- 8% (mean +/- SEM of 55Fe activity into the media, compared with 25 +/- 4% release from control and 37 +/- 7% from nondividing mitomycin C-treated control cells. All cells were greater than 90% viable. These differences were also reflected in the iron content of the cells. Mitochondria were then separated by centrifugation after cell disruption and 55Fe activity was found to be similarly decreased in both mitochondrial and nonmitochondrial fractions of injured L1210 cells. To further characterize the changes in mitochondrial iron content, mitochondrial proteins from injured and control L1210 cells were separated by IEF and 55Fe activity of gel slices was determined. There was selective loss of 55Fe activity in the area of the gel corresponding to SDH and NADH-DH, suggesting that iron loss from iron-sulfur clusters may occur in L1210 cells injured by activated macrophages. Iron uptake into L1210 cells after removal from macrophages showed a rapid large influx of radioactive iron. L1210 cells in contact with macrophages appear to develop an iron-depleted state, which is dependent on the continued presence of macrophages.
Animals↗