Micrograms Of Iron Research Articles

Absorption of Iron from Iron Succinyl-protein Complexes by Mouse Small Intestine

The absorption of iron from iron succinyl-protein complexes was investigated in mice. 59Fe-labelled succinyl-casein and -albumin complexes, [59Fe]ferritin and 59FeSO4, at doses of 20 or 200 micrograms of iron, were administered orally to normal mice or mice with absorption enhanced by chronic hypoxia. 59Fe from iron succinyl-protein was well absorbed in normal mice (greater than 10% of dose) and showed enhanced absorption in hypoxic mice (greater than 40% of dose). Intestinal uptake was predominantly by the duodenum for all compounds studied. In-vivo absorption of 59Fe from an iron succinyl-protein complex was studied using tied-off segments of mouse duodenum, jejunum or ileum of normal or hypoxic mice. Incubation for up to 15 min in duodenum or 60 min in ileum showed very little absorption of 59Fe. No enhancement of absorption was seen in hypoxic mice. It was concluded that absorption of the intact iron succinyl-protein complex cannot explain absorption seen after oral dosing.

Validation of T2* Technique in Ex-Vivo Myocardial Tissue.

BackgroundThe T2* technique has been validated as a non-invasive measurement of myocardial iron load. However, calibration of the technique against myocardial tissue remains to be determined. Since such calibration is easiest to perform using post-mortem tissue, it is useful to know the effects of storage of the tissue in formalin, and in particular whether iron leaks from the heart during storage, and whether fixation alters the myocardial T2* significantly.MethodA heart was donated after death of a patient with sideroblastic anemia who had been poorly compliant with deferoxamine treatment and died in heart failure. The pre-mortem myocardial T2* was 5.2 ms indicating severe myocardial iron loading. The majority of the heart was assigned to a calibration study of myocardial iron, but 2 samples from the heart were available for this study.Sample 1 was an apical short-axis slice of the left ventricle. This was preserved in formalin for 3 days prior to measurement of the initial post-mortem myocardial T2* which was 5.2 ms (Siemens Sonata 1.5T MR scanner). The T2* of the slice was then measured weekly for 4 weeks; then 2 weekly for 8 weeks; and finally 4 weekly.Sample 2 was a 7.35 g piece of apical myocardium which was stored in 280ml formaldehyde. A 1ml sample of formaldehyde solution was taken for iron analysis from sample 2 initially and at 2 days, and then weekly for 4 weeks; two-weekly for 6 weeks; and then 4-weekly for 12 weeks. The iron concentration in the formalin was measured using Inductive Coupled Plasma with Mass Spectometry (ICPMS).ResultsThe results from sample 1 are shown as myocardial T2* against days elapsed. The T2* rose from a pre-mortem and post-mortem (equivalent values) of 5.2ms to a mean of 6ms over the first 20 days, and after this was stable (figure 1).The results from sample 2, show an increase from 16.6 microgram to 74.9 microgram over the initial 3–4 weeks after which little significant additional accumulation occurred (figure 2). Estimation of the total iron content of the myocardial sample (prior to destructive iron measurement at the end of the study) suggested that the total iron leaked into the formalin was 0.44% of the iron in the myocardial sample.ConclusionThere was a small increase in myocardial T2* over the first 20 days of formalin fixation, but little significant change after that. This was associated with a loss of approximately 75 micrograms of iron into the formalin fixation solution, which was estimated as only 0.44% of the iron in the myocardial sample. This suggests that formalin fixation has a small but measurable effect on myocardial T2* over time, and this is not explained by loss of iron into the fixation fluid. [Display omitted] [Display omitted]

Inhibition of iron absorption by omeprazole in rat model

Since gastric acid is an important luminal factor in the absorption of non-heme iron, the effect of omeprazole on the absorption of iron in a rat model was studied. Iron absorption studies were performed on rats on a normal diet (N = 42) and rats fed an iron-deficient diet (N = 43) for three weeks. Rats were orally dosed with 40 mumol/kg of omeprazole or placebo daily for two days prior to iron absorption studies. Rats were orally dosed with 1 mmol of ferrous chloride, ferric chloride or food iron (dietary suspension) containing 11 micrograms of iron and labeled with 1 microCi of 59Fe. Omeprazole-treated rats on the normal diet had no significant reduction in the absorption of ferric, ferrous, or food iron. In the rats on the iron-deficient diet, the absorption of ferrous iron decreased from 76 +/- 7.5% (mean +/- SE) in control rats to 38 +/- 8.5% in the omeprazole-treated rats (P less than 0.003) and the absorption of food iron decreased from 65 +/- 7.5% in control rats to 37 +/- 6.5% in the omeprazole-treated rats (P less than 0.016). There was no significant reduction in the absorption of ferric iron. Omeprazole therapy is unlikely to be associated with significant iron malabsorption in normal patients but may reduce iron absorption in pathological states associated with increased iron absorption such as iron deficiency.

Aqueous Ethanol Extraction of Dietary Soy Protein Isolate Improves 59Fe Absorption by the Rat from a Casein-Based Test Meal

A commercial soy protein isolate (SPI) was further processed in an attempt to understand how a diet based on SPI can cause decreased iron retention by the rat from a separately administered casein-based test meal. Groups of eight rats were fed either a casein-based diet or a diet based on SPI. The acid-precipitated SPI was incorporated into diets as such, after neutralization, after 60% (v/v) ethanol extraction and neutralization, or after 60% ethanol exposure and neutralization. All dietary SPI was heat-treated by exposure to steam at 108 degrees C for 30 min. Rats were fed their respective diets, each containing 25 mg Fe/kg, for 13 d, and then all rats were fed a 59Fe-radiolabeled 2.5-g casein test meal containing 64 micrograms of iron. Ingested radioactivity was determined following the meal, and retained radioactivity over the subsequent 10-d period. Absorption was not distinguishable for groups fed the casein-based (78.3 +/- 3.6%) and the ethanol-extracted, SPI-based diet (80.2 +/- 5.4%). Absorption was lower (P less than 0.01) for groups fed each of the other SPI-based diets: SPI as such (68.3 +/- 8.9%), neutralized SPI (69.8 +/- 5.0%) and ethanol-exposed SPI (67.6 +/- 4.8%). An ethanol-extractable component of SPI may be responsible for decreased iron absorption by animals fed SPI prior to a radiolabeled test meal.

Liquefaction of rabbit vitreous by ferrous ions.

Intravitreal injection of 0.7 mumol of ferrous chloride in 0.1 ml into the rabbit eye resulted in liquefaction of the vitreous gel and condensation of vitreous collagen fibrils within two weeks; injection of 0.1 mumol did not cause any obvious vitreous degeneration, although retina damage was noted in the posterior pole. Macrophages migrated at the vitreoretinal interface and local posterior vitreous separation was observed after the injection of ferrous solution. This suggests that the least amount of ferrous ions necessary to cause liquefaction of the rabbit vitreous is in the range of 16.8 to 39.2 micrograms of elemental iron, a concentration of 0.3 to 0.7 mM in the vitreous. Since 0.1 ml of blood contains approximately 50 micrograms of iron, it is possible, at least theoretically, that the iron released by hemoglobin following vitreous hemorrhage could induce liquefaction of the vitreous.

Acute iron overload in mice: pathogenesis of Salmonella typhimurium infection

The bacterial growth in the tissues of C3D2F1 male mice was measured during an experimental infection with two Salmonella typhimurium strains (high virulence, strain 2386/74; low virulence, strain L15403). This experimental model was used for evaluation of the pathogenesis in normal and iron-overloaded animals. Acute iron overload was accomplished by intramuscular injections of chelated iron (with 2,3-dihydroxybenzoic acid and citrate) with a single dose of 100 micrograms of iron per mouse. Bacteria were given intraperitoneally 1 h after the iron injection. Serum iron levels, transferrin levels, and the bacteria counts in blood and liver were measured simultaneously in all animals. There was a significant increase of bacterial growth in all tissues in the iron-treated animals. Iron abolished the normal clearance of the bacteria with low virulence from the blood. This study demonstrates that a general iron overload, as determined by an increased serum iron level, resulting from preinjection of iron, enhances bacterial growth.

Inorganic Precipitation of Carbon in Productivity Experiments Utilizing Carbon-14

In a series of experiments where iron was added to natural waters and photosynthesis was measured by the radiocarbon method, we found that inorganic precipitation of carbon-14, presumably by mechanisms of occlusive coprecipitation, resulted from additions of 100 or more micrograms of iron per liter. Low levels of iron and prefiltered controls are suggested as correction measures.

The analysis of beryllium and beryllium oxide—I: The determination of iron

The importance of beryllium and beryllium oxide to the atomic energy programme has necessitated the development of accurate methods of chemical analysis for the determination of metallic impurities. A method is presented for separating iron by extraction with tri- n-octylphosphine oxide followed by determination with 1:10-phenanthroline. The method is accurate to ±3% or ±3 micrograms of iron, whichever is greater. The accuracy and sensitivity could be increased by appropriate choice of sample weight, volume of extract, and/or cell length. Of the 68 elements investigated, 61 do not interfere in 10-mg amounts. No interference is caused by 5 mg of silicon, 1 mg of antimony, gallium, molybdenum, or tungsten, or 0.1 mg of tellurium or uranium. Only gallium, tellurium and silicon interfere without producing a warning turbidity in the coloured solution.