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At least 19 recordsLinked to original sources
PubMed1992

Determination of absorption and endogenous excretion of iron in man by monitoring fecal excretion of a stable iron isotope (58Fe).

The absorption and endogenous excretion of iron in man was studied by monitoring the fecal excretion of a stable iron isotope (58Fe). The study was carried out for 12 healthy volunteers who were divided into two groups. Group I received 58Fe-labeled ferric ammonium citrate (III) (58FeAC) equivalent to 6 mg of iron as a control, and group II received a combination of 500 mg of vitamin C and 58FeAC. A new formula was used to calculate the 58Fe absorption ratio reflecting the pool of iron in the intestinal cells, and the ratio was compared with that obtained from Janghorbani's formula, which has been used as one of the common methods. As a result, the 58Fe absorption ratio in group II was statistically significantly higher than that of group I (34.4 +/- 6.1% vs. 15.0 +/- 5.5%, M +/- SD) using Janghorbani's formula. The similar absorption ratio (34.1 +/- 6.0% vs. 14.8 +/- 5.5%) was also obtained by our new formula. Our results confirmed the previous findings that the availability of iron is stimulated by the supplementation of vitamin C. Both formulae agreed in the absorption of iron, indicating that the endogenous excretion of iron (caused by the desquamated cells) in the intestine does not disguise the iron absorption.

Absorption↗
PubMed1979

A method for the detection and assay of iron stable isotope tracers in blood serum.

Methodology for use of stable isotopes of iron (54Fe, 57Fe, and 58Fe) as biological tracers was developed. Tracers were quantitated by measurement of ion abundances with a quadrupole mass spectrometer. The volatility of the iron was enhanced by chelation with 2,4-pentanedione prior to analysis. Samples were introduced into the mass spectrometer via a direct inlet probe. Ion abundance ratios were calculated from integrated ion current measurements obtained for selected ions in the two-ligand fragment of the chelate. Stable isotope tracer concentrations were calculated from these ratios. A prodecure was developed for the formation and purification of serum iron chelates. The method was used to analyze iron standards and blood serum samples containing known amounts of added 58Fe. The disappearance from pony serum of injected 58Fe was used as an in vivo test of the method. It was estimated that a minimum of 1.5 mg of either 54Fe, 57Fe, or 58Fe would be required to label 1 g of natural iron at detectable levels. The methods has promise as an alternative to radioisotope tracer techniques for some applications involving human subjects.

Animals↗
PubMed1978

Absorption of stable isotopes of iron, copper, and zinc during oral contraceptives use.

The absorption of iron, copper, and zinc was determined in 22 women 19 to 25 years of age from the difference between intake and fecal output of the stable isotopes 58Fe, 65Cu, and 70Zn, as measured by neutron activation analysis. Of the 22 women, 14 were using oral contraceptive agents, and the other eight were not. Absorption in the group using oral contraceptive agents did not differ significantly from the group not using oral contraceptive agents. The overall iron absorption averaged 14%, copper 57%, and zinc 38%.

Adult↗
PubMed1977

Use of anemic piglet to assess bioavailability of iron from oral iron preparations.

Except for methods using long-lived iron isotopes, there are no reliable means for assessing the bioavilability of iron from oral preparations in human subjects. Use of the anemic piglet as an alternative means was studied. When piglets were made anemic on a commercial milk diet and then dosed with solutions of 1, 2, and 5 mg/kg of ferrous sulfate/day, a dose-related recovery of hematocrit and hemoglobin levels resulted. The most sensitive dose range for use in a bioavailability study of iron was between 1 and 2 mg of iron/kg/day when using these parameters. A study carried out using this method indicated that the iron from a delayed-release capsule and from a ferrous sulfate solution was equally bioavailable. Hemoglobin and hematocrit recovery rates of the anemic piglet were shown to be reliable and sensitive indicators of the bioavailability of iron from various iron dosage forms.

Anemia, Hypochromic↗
PubMed1992

Absorption of non-haem iron in normal women measured by the incorporation of two stable isotopes into erythrocytes.

1. Iron absorption has been quantitatively measured as the incorporation of physiological doses of stable iron isotopes into erythrocytes. Five milligrams of 57Fe (orally) and 250 micrograms of 58Fe (intravenously) were given to five healthy women on 2 consecutive days. Fourteen days later the changes in the 57Fe/56Fe and 58Fe/56Fe ratios in the erythrocytes of each subject were measured using an inductively coupled plasma mass spectrometer. Isotope ratios were also measured in two subjects who were not given any enriched isotope. Concomitant measurements of plasma volume using a dye-dilution technique enabled the estimation of body iron mass and the calculation of iron absorption. 2. The mean coefficients of variation for the 57Fe/56Fe ratio and the 58Fe/56Fe ratio were 0.22% and 0.47%, respectively. This precision allowed enrichments of basal ratios to be reliably detected in all cases. The mean change in the 57Fe/56Fe ratio was 0.00116 (SD 0.00052, P < 0.001) and the mean change in the 58Fe/56Fe ratio was 0.00035 (SD 0.00004, P < 0.001). Control subjects showed no enrichment. 3. The calculated iron absorption ranged from 10% to 34%, and the amount of absorption was related to the iron stores of the subjects. Percentage iron absorption was identical when estimates of the plasma volume (derived from a body mass equation) were used instead of the plasma volume determined by dye-dilution measurements. Incorporation of intravenous iron into erythrocytes was on average 81% (range 68-93%). 4. The method is especially applicable to the study of iron absorption during pregnancy when incorporation into erythrocytes cannot be predicted.

Absorption↗
PubMedDate not supplied

[Bone marrow scanning (author's transl)].

Personal experience of Technetium-99m-sulfur colloid in the scintiscanning of bone marrow is reported. The method offers technical advantages over other methods and superior protection, while its only limitation is that it does not permit a dynamic study of hematopoiesis. Four pathologic scans typical of four groups of diseases may be distinguished. Further, metastatic bone marrow localisations can be diagnosed much earlier and more precisely than by radiography.

Bone Marrow↗
PubMed1975

Mossbauer effect studies in the fungus Phycomyces.

Mossbauer spectra of 57- Fe have been observed from different parts (mycelia, spores, sporangiophores) of the fungus Phycomyces blakesleeanus grown in an agar medium isotopically enriched with 57- Fe. The spectra indicate that the iron within Phycomyces exists primarily in two chemical states: one which is the same as that of the iron in the growth medium and the other in the form of ferritin, an iron-storage protein. The amount of iron in the former state is observed to decrease relative to the amount of iron in the latter state in going from mycelia to the sporangiophores to the sporangia themselves. Thus, the conversion of iron from the chemical state of the nutrient to ferritin has been monitored for different parts of the phycomyces. In addition, our spectra indicate that at low temperatures the iron atoms clustered within a ferritin molecule are antiferromagnetically coupled. The size of these clusters is inferred from their superparamagnetic behavior at low tempertures and comparison with horse ferritin indicates that the phycomyces ferritin iron clusters are smaller by a factor of two.

Agar↗
PubMed1992

Iron absorption and incorporation into red blood cells by very low birth weight infants: studies with the stable isotope 58Fe.

Measurements of iron absorption and incorporation into RBCs were obtained with the stable isotope 58Fe, administered as a reference dose, in 11 premature infants with birth weights between 780 and 1,520 g and gestational ages between 24 and 33 weeks. Each study included a timed stool and urine collection, nasogastric tube administration of a single dose of about 228 micrograms of 58Fe/kg of body weight (as FeSO4, with 10 mg/kg of vitamin C) between feedings, and blood samples before 58Fe (day 1) and then 2 weeks (day 15) later. Gastrointestinal absorption of the 58Fe dose as measured by fecal isotope balance was 41.6 +/- 17.6% (mean +/- SD). However, only 12.0 +/- 9.6% of the 58Fe dose (28.7 +/- 22.3% of the absorbed 58Fe dose) was incorporated into RBCs on day 15. 58Fe absorption and 58Fe incorporation into RBCs on day 15 were significantly correlated with the hemoglobin concentration and reticulocyte count on day 1. Transfusion history did not affect 58Fe absorption or 58Fe incorporation into RBCs. We conclude that concurrent measurement of 58Fe absorption with fecal monitoring and of 58Fe incorporation into RBCs permits a better understanding of the fate of iron ingested by premature infants than either measurement alone.

Algorithms↗
PubMed1978

Indium and iron as tracers for erythroid precursors.

External visualization and delineation of functional bone marrow is important for diagnostic, prognostic and therapeutic purposes. Because of difficulties in using the isotopes of iron for bone-marrow imaging, indium-111 chloride has been used extensively for this purpose. In this investigation we attempted to solve the problem of cellular localization of indium chloride by employing a rat model with erythropoietic precursors selectively damaged by lethal intracellular radiation from the Auger electrons of Fe-55. In the rat, we have shown that the absolute marrow uptakes of indium and iron are different, whereas the absolute uptakes of indium and sulfur colloid are the same. However, in animals whose erythroid activity was partially destroyed with Fe-55, the fractional depressions of iron and indium uptakes were the same and corresponded to the extent of the remaining erythroid activity. In addition, following an in vitro separation of the cellular elements of marrow with iron carbonyl, both iron and indium were found in the erythroid-rich supernatant, whereas sulfur colloid was in the precipitate. These results indicate that, in the rat, In-111 chloride is an effective in vivo marker for the early phases of iron uptake by the bone marrow.

Animals↗
PubMed1977

Functional equivalence of iron bound to human transferrin at low pH or high pH.

Human transferrin was labeled with 59Fe at one of its two metal-binding sites (designated A) at pH 6.0. 55Fe was then added to site B at pH 7.5. Both isotopes of iron were taken up in equal proportions by human reticulocytes. These experiments do not support the hypothesis that each binding site of transferrin has a different physiologic function.

Binding Sites↗
PubMed1979

Uptake and conversion of the antibiotic albomycin by Escherichia coli K-12.

The antibiotic albomycin is transported into cells of Escherichia coli K-12 by the same uptake system as the iron-supplying ferrichrome complex. The iron-complexing hydroxamate moieties of albomycin and ferrichrome are structurally similar. During the phase of rapid iron uptake the chelators were not found in the cells. In order to understand the antibiotic activity of albomycin, it was labeled in the hydroxamate with tritium and in the presumed antibiotically active area with radioactive sulfur. While the tritium label was not retained by the cells, part of the sulfur label was taken up and concentrated 500-fold within the cell. The sulfur was not incorporated into proteins or nucleic acids since it was recovered as a low molecular weight component. Gel filtration on Bio-Gel P-2 revealed one tritium-labeled and two sulfur-labeled cleavage products in the incubation medium. We conclude that albomycin is actively transported via its ferrichrome-like portion into the cells and that the growth-inhibitory moiety is released by hydrolysis intracellularly and remains there.

Anti-Bacterial Agents↗
PubMedDate not supplied

Post-transfusion survival of 50Cr-labeled erythrocytes in neonatal foals.

Erythrocytes transfused allogeneically into mature horses have a short survival (less than 4 days) compared with an expected erythrocyte life span of 140-150 days. Yet, foals undergo transfusions for neonatal isoerythrolysis successfully. The authors have determined the survival of transfused erythrocytes in neonatal foals, using the stable isotope, 50Cr, to label the erythrocytes. Normal foals underwent transfusions with labeled erythrocytes from three sources: their own erythrocytes (autologous), the erythrocytes of their dam, and the erythrocytes of an unrelated castrated male. After transfusion, samples were taken at 15 minutes and then daily for a week and every 2 or 3 days for 20 days. A stable isotope of iron (57Fe) and 50Cr were determined on diluted-packed erythrocytes by inductively coupled argon-coupled mass spectrometry techniques. 57Fe was used as measure of the sample hemoglobin concentration. The ratio of 50Cr to 57Fe decreased exponentially in all foals. Half-time (T1/2) was 11.7 days (standard error = 2.2) for four foals that underwent autologous transfusions, 5.5 +/- 1.0 days for five foals that underwent transfusions with the erythrocytes of their dams, and 5.2 +/- 1.1 days for five foals that had transfusions with erythrocytes from an unrelated gelding. The authors conclude that erythrocytes that are transfused allogenically into neonatal foals will survive longer than those transfused into mature horses and that 50Cr labeling can be used to measure survival of transfused erythrocytes.

Animals↗