The iron absorption from ferritin and hemosiderin biosynthetically labeled with radioiron was studied in 108 subjects. The geometric mean absorption of ferritin iron in both normal and iron-deficient subjects was 1.9 percent. Its mean absorption ranged from 0.9 percent in normal subjects to 2.5 percent in subjects with moderate iron deficiency and 5.7 percent in subjects with marked iron deficiency. The administration of this iron compound with vegetals in a meal showed distinctly lower absorption values than the absorption from either maize, wheat, or soybean. Ferritin iron absorption was also different from that of ferric chloride when they were administered together as a drink or mixed with maize or liver. The iron absorption from ferritin was markedly increased when it was administered with either meat or liver, but it did not reach the absorption level of these foods. It is still to be elucidated whether the difference in iron absorption between ferritin and vegetable foods administered together reflect that this iron is incompletely miscible with a nonheme iron pool or that it really forms a third iron pool. (+info)
Marrow erythroid and neutrophil cellularity in the dog.
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This paper describes a method for determining the number of marrow erythroid and neutrophil cells in which the cellularity of marrow sections was related to that of the total marrow by radioiron dilution. Tissue sections were prepared from methacrylate-embedded dog marrow biopsies, and neutrophils were identified by staining of their primary granules. After correction of direct section counts for multiple counting error, accurate neutrophil-erythroid ratios were established with a coefficient of variation of less than 10 percent when 10-4 cells were examined. An average neutrophil-erythroid ratio of 1.2 was found in six normal dogs. The total number of nucleated red cells in the dog was 5.48 plus or minus 0.78 times 10-9/kg (plus or minus 1 SD), and the corresponding erythron iron turnover was 0.90 plus or minus 0.11 mg Fe/100 ml whole blood/day. The total number of marrow neutrophils, derived from the neutrophil-erythroid ratio, was 6.6 plus or minus 0.59 times 10-9 cells/kg, of which 1.4 were promyelocytes and myelocytes, 2.3 were metamyelocytes and bands, and 3.0 were segmented neutrophils. Leukopheresis studies were carried out in six dogs to confirm the accuracy of these cellular measurements. Marrow counts showed a mean decrease of 22.7 times 10-9 cells or 35 percent of the postmitotic neutrophil pool, and it was calculated that 10.2 times 10-9 additional cells had been taken from already circulating blood. This estimated deficit of 32.9 times 10-9 was almost identical to the 33 times 10-9 cells actually counted in the removed blood. (+info)
Oxymetholone treatment for sickle cell anemia.
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Seven patients with sickle cell anemia were treated with oxymetholone for at least 2 mo. Markedly increased basal rates of hemolysis and erythropoiesis were confirmed. The urinary erythropoietin excretion was either normal or lower than expected for the red cell mass, and an expanded blood volume was due primarily to an increased plasma volume. After androgen therapy, six patients demonstrated more than a fivefold increase in urinary erythropoietin, with an increase in red cell mass ranging from 17%-75% above the control value. All showed a decline in serum iron level to the 25-75 mug/100 ml range within 4 wk after the start of therapy. Less marked changes followed lower oxymetholone doses. Reversible hepatic toxicity, with a serum bilirubin concentration exceeding 50 mg/100 ml, occurred in one patient. Androgenic hormone therapy may be useful for selected adult patients with sickle cell disease when severe anemia contributes to disease morbidity. (+info)
Selective damage to erythroblasts by 55-Fe.
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The low energy and short range of 55-Fe Auger electrons were utilized in mice to deliver lethal intracellular radiation to iron-incorporating erythropoietic precursors with minimal radiation damage to other bone marrow cells. The ensuing intramedullary, selective erythropoietic death was demonstrated by absolute and differential bone marrow cell counts and by decreased blood uptake of 59-Fe. The decreased number of colony-forming units in spleen colony assay and the decreased ability of tranplanted bone marrow to protect fatally irradiated mice shows that the bone marrow was partially depleted of pluripotent stem cells. These data are interpreted to indicate an increased pluripotent stem cell utilization in response to increased demand for differentiation of stem cells along the erythropoietic pathway. (+info)
The measurement of iron-binding capacity in serum and purified transferrin with the aid of chemical affinity chromatography.
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In a mew method for the estimation of transferrin by iron-binding capacity iron is added as the tartrate in NaCl with about 10 mM bicarbonate. The excess iron is removed by passage through DEAE-Sephadex A-50 previously treated with the iron chelator disodium catechol-3,5-disulphonate. The iron remaining bound to transferrin is measured without protein precipitation by the use of ferrozine. The method is applicable to fresh, frozen, or lyophilized serum, purified transferrin, and some quality control preparations. Validation experiments confirm that transferrin in serum and in pure solution is saturated with iron and give some evidence of specificity. The possible use of commercially available transferrin preparations as analytical reference standards is discussed. (+info)
Accumulation of 55Fe-labeled precursors of the iron-molybdenum cofactor of nitrogenase on NifH and NifX of Azotobacter vinelandii.
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Iron-molybdenum cofactor (FeMo-co) biosynthesis involves the participation of several proteins. We have used (55)Fe-labeled NifB-co, the specific iron and sulfur donor to FeMo-co, to investigate the accumulation of protein-bound precursors of FeMo-co. The (55)Fe label from radiolabeled NifB-co became associated with two major protein bands when the in vitro FeMo-co synthesis reaction was carried out with the extract of an Azotobacter vinelandii mutant lacking apodinitrogenase. One of the bands, termed (55)Fe-labeled upper band, was purified and shown to be NifH by immunoblot analysis. The (55)Fe-labeled lower band was identified as NifX by N-terminal sequencing. NifX purified from an A. vinelandii nifB strain showed a different electrophoretic mobility on anoxic native gels than did NifX with the FeMo-co precursor bound. (+info)
Iron overload following manganese exposure in cultured neuronal, but not neuroglial cells.
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Our previous studies show that manganese (Mn) exposure inhibits aconitase, an enzyme regulating the proteins responsible for cellular iron (Fe) equilibrium. This study was performed to investigate whether Mn intoxication leads to an altered cellular Fe homeostasis in cultured neuronal or neuroglial cells as a result of disrupted Fe regulation. Our results reveal a significant increase in the expression of transferrin receptor (TfR) mRNAs and a corresponding increase in cellular 59Fe net uptake by PC12 cells, but not astrocytes, following Mn exposure. These findings suggest that alteration by Mn of cellular Fe homeostasis may contribute to Mn-induced neuronal cytotoxicity. (+info)
Iron.
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The most useful and appropriate methods for assessing the bioavailability of (nonheme) iron supplements are described. When the supplement can be labeled isotopically, the best method for measuring bioavailability is hemoglobin incorporation, followed by fecal monitoring. Caco-2 cell in vitro systems can be used for rapid screening to predict potential availability for absorption. If the compound cannot be labeled, then the plasma appearance/disappearance of oral iron given together with an intravenous dose of iron isotope can be used to quantify absorption. With oral doses in excess of 25 mg, the 4- to 6-h plasma concentration can provide a qualitative assessment of bioavailability. Approaches for normalizing results to minimize intraindividual and interindividual variability in efficiency of iron absorption are discussed. (+info)