Serum iron concentration as a tool to measure relative iron absorption from elemental iron powders in man

OBJECTIVE: To present a new method for measuring the relative bioavailability (RBV) of commercial elemental iron powders by investigating induced changes of serum iron concentration (S-Fe) in relation to ferrous sulphate (FeSO4). Earlier studies have shown that in a group of subjects there is good agreement between the increase in S-Fe and the amount of iron absorbed from a simple iron salt as FeSO4. METHODS: The study included two groups of male blood donors (n=2 x 16 subjects) who were served three meals with an interval of approximately nine weeks between each one. In one group the meal was fortified with reduced iron, ferrous sulphate or no iron at all. In the other group the meal was fortified with electrolytic iron, ferrous sulphate or no iron. The S-Fe increase was followed for 6 h. Studying the non-iron meals was necessary so that the basal diurnal variation in the S-Fe during the six hours could be measured and subtracted. RESULTS: The mean S-Fe increase calculated as the area under the curve (AUC) from the reduced iron (RBV=0.43) and the electrolytic iron (RBV=0.73) differed significantly from the AUC following FeSO4 (p=0.002 and p=0.021, respectively). The difference between the reduced and the electrolytic iron was also statistically significant (p=0.036). CONCLUSION: Measuring increases in S-Fe could be a reliable and simple method to determine the RBV in comparative studies of elemental iron powders in relation to FeSO4.     

Bovine ferritin iron bioavailability in man

The bioavailability of ferritin iron was evaluated in human subjects using radiolabelled [⁵⁵Fe]ferritin isolated from bovine spleen and liver. Preliminary studies with bovine spleen ferritin labelled in vitro demonstrated an inappropriately high absorption compared with ferritin labelled in vivo, and the latter was therefore used in all subsequent absorption studies. In 10 subjects, geometric mean absorption from 5 mg of ferritin iron was 3.8% when taken without and 3.2% when taken with food (P >0.05). These values were significantly lower than absorption from the same dose of iron given as ferrous sulphate, which averaged 24.1% without and 8.2% with food. When the iron dose was increased 10-fold, absorption of ferritin iron averaged only 0.6–0.7% with or without food as compared with 7.9% without and 2.6% with food when the iron was given as ferrous sulphate. In a further study, mean absorption from bovine spleen ferritin of 4.0% did not differ significantly from the mean of 2.7% observed with bovine liver ferritin. These findings confirm previous studies indicating that ferritin iron is poorly absorbed. Furthermore, its use as a pharmaceutical iron preparation cannot be advocated.     

Effectiveness of AOS–iron on iron deficiency anemia in rats

Iron deficiency anemia (IDA) is one of the most serious nutritional problems. This study aimed to evaluate the therapeutic effects of a novel agar oligosaccharide–iron complex (AOS–iron) on rats with IDA, such as iron supplementation and recovery of antioxidant ability. Eighty-four weaned male SD rats were randomly divided into a normal control group (n = 12), which was fed with a standard diet, and an anemia model group (n = 72), which was fed with an iron-deficient diet for 4 weeks to establish a model of IDA. After the model was established, the rats with IDA were divided into six groups, namely, an anemia model group, a ferrous gluconate group, a ferrous sulfate (FeSO₄) group, and low-dose (LD), medium-dose (MD) and high-dose (HD) AOS–iron groups, and fed with an iron-deficient diet and different iron supplements for 4 weeks, respectively. The results showed that HD AOS–iron exerted a significant restorative effect by returning blood parameters to normal levels in rats with IDA, including hemoglobin, red blood cells, hematocrit, mean cell volume, mean cell hematocrit, mean cell hemoglobin concentration, serum iron, total iron binding capacity, transferrin saturation, and serum ferritin. A histological analysis suggested that the liver morphology in the MD and HD AOS–iron groups was similar to that in the normal group. Furthermore, MD and HD AOS–iron improved antioxidant activities in the serum and liver. In general, high-dose (the same dose as those of ferrous gluconate and FeSO₄) AOS–iron exhibited the best effects in terms of iron supplementation and antioxidant activities. The present findings showed that AOS–iron might be a potential new iron supplement.

Iron deficiency anemia (IDA) is one of the most serious nutritional problems.     

Rapid spectrophotometric technique for quantifying iron in cells labeled with superparamagnetic iron oxide nanoparticles: potential translation to the clinic

Labeling cells with superparamagnetic iron oxide (SPIO) nanoparticles provides the ability to track cells by magnetic resonance imaging. Quantifying intracellular iron concentration in SPIO labeled cells would allow for the comparison of agents and techniques used to magnetically label cells. Here we describe a rapid spectrophotometric technique (ST) to quantify iron content of SPIO‐labeled cells, circumventing the previous requirement of an overnight acid digestion. Following lysis with 10% sodium dodecyl sulfate (SDS) of magnetically labeled cells, quantification of SPIO doped or labeled cells was performed using commonly available spectrophotometric instrument(s) by comparing absorptions at 370 and 750 nm with correction for turbidity of cellular products to determine the iron content of each sample. Standard curves demonstrated high linear correlation (R² = 0.998) between absorbance spectra of iron oxide nanoparticles and concentration in known SPIO‐doped cells. Comparisons of the ST with inductively coupled plasma–mass spectroscopy (ICP‐MS) or nuclear magnetic resonance relaxometric (R₂) determinations of intracellular iron contents in SPIO containing samples resulted in significant linear correlation between the techniques (R₂ vs ST, R² > 0.992, p < 0.0001; ST vs ICP‐MS, R² > 0.995, p < 0.0001) with the limit of detection of ST for iron = 0.66 µg ml^?1 for 10⁶ cells ml^?1. We have developed a rapid straightforward protocol that does not require overnight acid digestion for quantifying iron oxide content in magnetically labeled cells using readily available analytic instrumentation that should greatly expedite advances in comparing SPIO agents and protocols for labeling cells. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

Magnetic labeling of non‐phagocytic adherent cells with iron oxide nanoparticles: a comprehensive study

Small particles of iron oxide (SPIO) and ultrasmall particles of iron oxide (USPIO), inducing a strong negative contrast on T₂ and T₂*‐weighted MR images, are the most commonly used systems for the magnetic labeling of cultured cells and their subsequent detection by magnetic resonance imaging (MRI). The purpose of this work is to study the influence of iron incubation concentration, nanoparticle size and nanoparticle coating on the magnetic labeling and the viability of non‐phagocytic adherent cells in culture. The magnetic labeling of 3T6 fibroblasts was studied by T₂‐weighted MRI at 4.7 T and by dosing—or cytochemical revealing—of iron through methods based on Perl's Prussian blue staining. Cells were incubated for 48 h with increasing iron concentrations of SPIO (25–1000 µg Fe/ml Endorem®). Sinerem®, a USPIO (20–40 nm) coated with neutral dextran, and Resovist® (65 nm), a SPIO bearing an anionic carboxydextran coating, were compared with Endorem® (dextran‐coated, 80–150 nm) as magnetic tags. The iron loading of marrow stromal cell primary cultures (MSCs) isolated from rat femurs was compared with that of 3T6 fibroblasts. The SPIO‐labeling of cells with Endorem® was found to be dependent on the iron incubation concentration. MSCs, more sparsely distributed in the culture, exhibited higher iron contents than more densely populated 3T6 fibroblast cultures. A larger iron loading was achieved with Resovist® than with Endorem®, which in turn was more efficient than Sinerem® as a magnetic tag. The magnetic labeling of cultured non‐phagocytic adherent cells with iron oxide nanoparticles was thus found to be dependent on the relative concentration of the magnetic tag and of the cells in culture, on the nanoparticle size, and on the coating type. The viability of cells, estimated by methods assessing cell membrane permeability, was not affected by magnetic labeling in the conditions used in this work. Copyright © 2008 John Wiley & Sons, Ltd.     

Iron pre-load for major joint replacement

Patients undergoing total hip or knee replacement frequently receive blood transfusion. Homologous blood transfusion carries appreciable risks and should therefore be reduced to a minimum. We have investigated the use of preoperative oral iron supplements to optimize haemoglobin concentration and iron stores prior to surgery. All patients attending a preadmission clinic 4 weeks prior to primary hip or knee replacement had a haemoglobin measurement. If the haemoglobin concentration (Hb) was less than 12 g dL^?1 they were given a four week course of ferrous sulphate. If it was greater than or equal to 12 g dL^?1 they were randomized to a control group or given a supplementation course of ferrous sulphate. One hundred patients were seen. Of these 18 (18%) had haemoglobin less than 12 g dL^?1 and 16 were treated with iron. The mean Hb was 10.8 g dL^?1 and mean cell volume (MCV) 86. These patients increased their Hb by a mean 1.1 g dL^?1 prior to admission (P = 0.008). MCV was the best predictor of response (r = ?0.63, P < 0.02). This group dropped their haemoglobin by a mean 1.4 g dL^?1 in the first post-operative week. In the study groups there was no significant preoperative rise in Hb. However, the control group dropped their Hb by a mean 1.3 g dL^?1 in the week following surgery compared with 0.4 g dL^?1 in the group which had received iron supplements (P < 0.001). We conclude that at least 18% of patients attending for hip or knee replacement in this region are frankly anaemic and benefit significantly from preoperative iron supplements over 4 weeks. Iron supplementation in patients without obvious anaemia protects against a fall in Hb during the immediate post-operative period, suggesting a widespread underlying depletion of iron stores in this group despite a normal Hb. Preoperative iron supplements may reduce transfusion requirements as part of a co-ordinated strategy in this group of patients.     

Internalization of annexin A5‐functionalized iron oxide particles by apoptotic Jurkat cells

Apoptosis plays an important role in the etiology of various diseases. Several studies have reported on the use of annexin A5‐functionalized iron oxide particles for the detection of apoptosis with MRI, both in vitro and in vivo. The protein annexin A5 binds with high affinity to the phospholipid phosphatidylserine, which is exposed in the outer leaflet of the apoptotic cell membrane. When co‐exposed to apoptotic stimuli, this protein was shown to internalize into endocytic vesicles. Therefore in the present study we investigated the possible internalization of commercially available annexin A5‐functionalized iron oxide particles (r₁ = 34.0 ± 2.1 and r₂ = 205.0 ± 10.4 mm ^?1 s^?1 at 20 MHz), and the effects of their spatial distribution on relaxation rates R, R₂ and R₁. Two different incubation procedures were performed, where (1) Jurkat cells were either incubated with the contrast agent after induction of apoptosis or (2) Jurkat cells were simultaneously incubated with the apoptotic stimulus and the contrast agent. Transmission electron microscopy images and relaxation rates showed that the first incubation strategy mainly resulted in binding of the annexin A5‐iron oxide particles to the cell membrane, whereas the second procedure allowed extensive membrane‐association as well as a small amount of internalization. Owing to the small extent of internalization, only minor differences were observed between the ΔR/ΔR₂ and ΔR₂/ΔR₁ ratios of cell pellets with membrane‐associated or internalized annexin A5 particles. Only the increase in R₁ (ΔR₁) appeared to be diminished by the internalization. Internalization of annexin A5‐iron oxide particles is also expected to occur in vivo, where the apoptotic stimulus and the contrast agent are simultaneously present. Where the extent of internalization in vivo is similar to that observed in the present study, both T₂‐ and T‐weighted MR sequences are considered suitable for the detection of these particles in vivo. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of enhanced erythropoiesis on iron absorption.

To examine the influence of erythropoiesis on iron absorption, radioiron absorption tests were performed in normal subjects before and after a course of recombinant erythropoietin. The absorption of heme and nonheme iron from a standard meal was measured in nine subjects, and the absorption of a therapeutic dose of ferrous sulfate given with or without food was determined in an additional 11 subjects. The subcutaneous administration of 100 U recombinant human erythropoietin/kg body weight given on 10 successive days over a 2-week period induced a brisk increase in erythropoiesis and a sharp decrease in iron stores. With the standard meal, there was a modest increase in heme iron absorption from 47.0% to 58.6% (p < 0.05) and a dramatic five-fold rise in nonheme iron absorption from 5.9% to 31.8% (p < 0.001). The absorption of 50 mg iron as ferrous sulfate increased from 2.0% to 17.9% when given with food (p < 0.001) and from 7.0% to 24.6% when given with water (p < 0.001). To assess the effect of erythropoiesis independently of the induced changes in iron status, the absorption data were adjusted to a common serum ferritin level. The relative increase in iron absorption was still significant for both dietary nonheme iron (ratio 2.51, p < 0.02) and ferrous sulfate given with food (ratio 2.99, p < 0.01). It is concluded that the striking enhancement of iron absorption following regular erythropoietin administration in normal subjects is related to the combined effect of diminished iron stores and augmented erythropoiesis.     

Effect of magnetic field and iron content on NMR proton relaxation of liver,spleen and brain tissues

Iron accumulation is observed in liver and spleen during hemochromatosis and important neurodegenerative diseases involve iron overload in brain. Storage of iron is ensured by ferritin, which contains a magnetic core. It causes a darkening on T₂‐weighted MR images. This work aims at improving the understanding of the NMR relaxation of iron‐loaded human tissues, which is necessary to develop protocols of iron content measurements by MRI. Relaxation times measurements on brain, liver and spleen samples were realized at different magnetic fields. Iron content was determined by atomic emission spectroscopy. For all samples, the longitudinal relaxation rate (1/T₁) of tissue protons decreases with the magnetic field up to 1 T, independently of iron content, while their transverse relaxation rate (1/T₂) strongly increases with the field, either linearly or quadratically, or a combination thereof. The extent of the inter‐echo time dependence of 1/T₂ also varies according to the sample. A combination of theoretical models is necessary to describe the relaxation of iron‐containing tissues. This can be due to the presence, inside tissues, of ferritin clusters of different sizes and densities. When considering all samples, a correlation (r² = 0.6) between 1/T₁ and iron concentration is observed at 7.0 T. In contrast the correlation between 1/T₂ and iron content is poor, even at high field (r² = 0.14 at 7.0 T). Our results show that MRI methods based on T₁ or T₂ measurements will easily detect an iron overloading at high magnetic field, but will not provide an accurate quantification of tissue iron content at low iron concentrations. Copyright © 2014 John Wiley & Sons, Ltd.     

Fe-based metal–organic frameworks as heterogeneous catalysts for highly efficient degradation of wastewater in plasma/Fenton-like systems

Fe-based metal organic frameworks (Fe-MOFs) were successfully synthesized with the dielectric barrier discharge (DBD) plasma method and FeSO₄·7H₂O as the Fe precursor. Fe-MOFs were used as Fenton-like catalysts in DBD plasma/Fenton-like technology to treat wastewater, which addressed the issues with iron solubility. Since the valence state of iron will affect the catalytic performance, the Fe precursor FeSO₄·7H₂O was added to regulate the valence state and adjust the catalytic performance by improving the availability of active sites. The influences of discharge voltage, catalyst addition amount, H₂O₂ addition amount and pH on the degradation efficiency of methyl orange (MO) were systematically examined. Through free radical capture experiments, the reaction mechanism of the plasma/Fenton-like catalytic degradation process was deduced primarily as the coordinated oxidation process of hydroxyl radicals (·OH), photo-generated holes (h⁺) and superoxide radicals (·O₂⁻). The reusability experiments proved that the catalyst was stable and reusable. The possible degradation pathways were proposed based on the identification of intermediate products generated in the degradation process by liquid chromatography-mass spectrometry (LC-MS) analyses.

Fe-based metal organic frameworks (Fe-MOFs) were successfully synthesized with the dielectric barrier discharge (DBD) plasma method and FeSO₄·7H₂O as the Fe precursor.     

Pharmacokinetic and in vivo evaluation of a self‐assembled gadolinium(III)‐iron(II) contrast agent with high relaxivity

A high‐molecular weight tetrametallic supramolecular complex [(Ln‐DTPA‐phen)₃Fe]^? (Ln = Gd, Eu, La) has been obtained upon self‐assembly around one iron(II) ion of three 1,10‐phenantroline‐based molecules substituted in 5′‐position with the polyaminocarboxylate diethylenetriamine‐N,N,N′,N′,N′‐pentaacetate, DTPA‐phen^4?. The ICP‐MS measurements indicated that the lanthanide:iron ratio is 3:1. Photoluminescence spectra of [Eu‐DTPA‐phen]^? and of [(Eu‐DTPA‐phen)₃Fe]^? are nearly identical, implying that the first coordination sphere of the lanthanide(III) ion has not been changed upon coordination of phenantroline unit to iron(II) ion. NMRD measurements revealed that at 20 MHz and 310 K the relaxivity of the [(Gd‐DTPA‐phen)₃Fe]^? is equal to 9.5 ± 0.3 s^?1 mM^?1 of Gd (28.5 s^?1 per millimole per liter of complex) which is significantly higher than that for Gd‐DTPA (3.9 s^?1 mM^?1). The pharmacokinetic parameters of [(Gd‐DTPA‐phen)₃Fe]^? in rats indicate that the elimination of [(Gd‐DTPA‐phen)₃Fe]^? is significantly slower than that of Gd‐DTPA and is correlated with a reduced volume of distribution. The low volume of distribution and the longer elimination time (T_e1/2) suggest that the agent is confined to the blood compartment, so it could have an important potential as a blood pool contrast agent. The biodistribution profile of [(Gd‐DTPA‐phen)₃Fe]^? 2 h after injection indicates significantly higher concentrations of [(Gd‐DTPA‐phen)₃Fe]^? as compared with Gd‐DTPA in kidney, liver, lungs, heart and spleen. The images obtained on rats by MR angiography show the enhancement of the abdominal blood vessels. The signal intensity reaches a maximum of 55% at 7 min post‐contrast and remains around 25% after 90 min. MRI‐histomorphological correlation studies of [Gd‐DTPA‐phen]^? and [(Gd‐DTPA‐phen)₃Fe]^? showed that both agents displayed potent contrast enhancement in organs including the liver. The necrosis avidity tests indicated that, in contrast to the [Gd‐DTPA‐phen]^? precursor complex, the supramolecular complex [(Gd‐DTPA‐phen)₃Fe]^? exhibits necrosis avidity. Copyright © 2006 John Wiley & Sons, Ltd.     

Comparative bioavailability of ferric polymaltose and ferrous sulphate in iron-deficient blood donors

Absolute iron deficiency is treated by correcting the causative lesion and then, traditionally, administering sufficient amounts of ferrous salt to return the haemoglobin level to normal and replenish body stores. The bioavailability of ferric compounds has been questioned and accordingly their therapeutic role remains controversial. A special problem is posed by regular blood donation, where the frequency of phlebotomy is limited by the haemoglobin level, which, in turn, requires maintenance of an adequate supply of iron from dietary sources. Since this latter situation may not always occur, it would be of practical benefit to have a form of supplementation that is effective and can be taken without side effects. These issues were prospectively examined in a consecutive series of otherwise healthy blood donors who developed absolute iron deficiency anaemia and were then randomly allocated to receive 60 mg of this metal as ferrous sulphate twice a day (Group 1: n = 51), 100 mg as chewable ferric polymaltose daily (Group 2: n = 53), or the latter product twice a day (Group 3: n = 55). Serial studies showed that 80% of patients in Groups 1 and 3 had reached normal haemoglobin levels by 12 weeks, but this figure was only 50% in Group 2. Similarly, the proportion of patients improving their percentage saturation of transferrin to within the normal range was significantly better in Groups 1 and 3 than in Group 2 (P < .01). However, body iron stores, reflected in serum ferritin level, was significantly better in Group 1 (P < .01); there was no difference in this respect between Groups 2 and 3. Toxicity was more severe in those receiving ferrous sulphate, with 20% having to discontinue participation owing to nausea and vomiting, whereas this was mild in those receiving ferric polymaltose and none withdrew from the trial for this reason. It can be concluded that the two forms of iron are equally bioavailable for hemoglobin regeneration, but at 12 weeks of study ferrous sulphate was superior in reconstituting stores, as reflected in the serum ferritin level. Since the ferric iron complex is associated with only minimal side effects, it may be useful in selected populations and, in the context of blood donors, valuable as a means of maintaining positive balance, thereby diminishing the number of donors rejected because of their having developed phlebotomy-iron deficiency anaemia. © 1993 Wiley-Liss, Inc.     

The regeneration of Fe-EDTA denitration solutions by nanoscale zero-valent iron

Fe(ii) ethylenediaminetetraacetate (EDTA) chelate solution is generally considered to be an effective nitric oxide (NO) absorbent. However, since the ferrous active site is occupied by nitric oxide and the ferrous chelate is oxidized to ferric chelate by oxygen in air, its absorption capacity will gradually decrease with the NO absorption process. Here, we propose a method for regenerating the NO-attenuated Fe(ii)EDTA solution by adding nanoscale zero-valent iron (NZVI) under three different pH conditions. Furthermore, compared with the commercially available iron powder, NZVI was also found to be effective not only for the regeneration of expired Fe-EDTA solution but also for the reduction of Fe(iii) EDTA solution. According to the results obtained herein, different acidity levels of solution, from weakly acidic to near neutral, are all suitable for the regeneration–absorption process.

NZVI is very effective for the regeneration of the inactive Fe chelate solution in the NO absorption process.     

Effectiveness of oral and intravenous iron therapy in haemodialysis patients

Anaemia is a common and serious complication in patients with end-stage renal disease. Iron therapy is crucial in managing anaemia and maintenance of haemodialysis (HD) patients. This study investigated the efficacy of both oral and intravenous (i.v.) therapies, and the possible factors deleteriously affecting patient response to iron therapy. Forty patients on maintenance HD from a single institution were enrolled in this 6-month retrospective study. Group I (n = 20) received i.v. two ampoules of atofen (ferric chloride hexahydrate 193.6 mg) per week for a total of 6 weeks (total dosage, 960 mg). Group II (n = 20) received oral ferrous sulphate S.C. Tab (ferrous sulphate 324 mg) one pill three times daily (total dosage, 63,000 mg). Patients whose haematocrit (Hct) level increased at minimum 3% within the period were classified as responders. Iron i.v. ferric chloride (960 mg) was more effective than oral ferrous sulphate (63,000 mg) in correcting anaemia in HD patients with iron deficiency. In group I, serum triglyceride (TG) levels were significantly lower in patients responding to i.v. iron therapy than in patients with no response. In group II, serum high-sensitive C-reactive protein (hs-CRP) level was significantly lower in patients responding to oral iron therapy than patients with no response. The i.v. ferric chloride is more effective than oral ferrous sulphate in treating anaemia in HD patients with iron deficiency. Serum hs-CRP and TG levels may be parameters for predicting hyporesponsiveness to oral and i.v. iron therapies, respectively.     

Evaluation of the novel USPIO GEH121333 for MR imaging of cancer immune responses

Tumor‐associated macrophages (TAM) maintain a chronic inflammation in cancers, which is associated with tumor aggressiveness and poor prognosis. The purpose of this study was to: (1) evaluate the pharmacokinetics and tolerability of the novel ultrasmall superparamagnetic iron oxide nanoparticle (USPIO) compound GEH121333; (2) assess whether GEH121333 can serve as a MR imaging biomarker for TAM; and (3) compare tumor MR enhancement profiles between GEH121333 and ferumoxytol. Blood half‐lives of GEH121333 and ferumoxytol were measured by relaxometry (n = 4 each). Tolerance was assessed in healthy rats injected with high dose GEH121333, vehicle or saline (n = 4 each). Animals were monitored for 7 days regarding body weight, complete blood counts and serum chemistry, followed by histological evaluation of visceral organs. MR imaging was performed on mice harboring MMTV‐PyMT‐derived breast adenocarcinomas using a 7 T scanner before and up to 72 h post‐injection (p.i.) of GEH121333 (n = 10) or ferumoxytol (n = 9). Tumor R₁, R₂* relaxation rates were compared between different experimental groups and time points, using a linear mixed effects model with a random effect for each animal. MR data were correlated with histopathology. GEH121333 showed a longer circulation half‐life than ferumoxytol. Intravenous GEH121333 did not produce significant adverse effects in rats. All tumors demonstrated significant enhancement on T₁, T₂ and T₂*‐weighted images at 1, 24, 48 and 72 h p.i. GEH121333 generated stronger tumor T₂* enhancement than ferumoxytol. Histological analysis verified intracellular compartmentalization of GEH121333 by TAM at 24, 48 and 72 h p.i. MR imaging with GEH121333 nanoparticles represents a novel biomarker for TAM assessment. This new USPIO MR contrast agent provides a longer blood half‐life and better TAM enhancement compared with the iron supplement ferumoxytol. Copyright © 2013 John Wiley & Sons, Ltd.     

Functionalized single‐walled carbon nanotubes containing traces of iron as new negative MRI contrast agents for in vivo imaging

Single‐walled carbon nanotubes (SWCNTs) containing traces of iron oxide were functionalized by noncovalent lipid‐PEG or covalent carboxylic acid function to supply new efficient MRI contrast agents for in vitro and in vivo applications. Longitudinal (r₁) and transversal (r₂) water proton relaxivities were measured at 300 MHz, showing a stronger T₂ feature as an MRI contrast agent (r₂/r₁ = 190 for CO₂H functionalisation). The r₂ relaxivity was demonstrated to be correlated to the presence of iron oxide in the SWNT‐carboxylic function COOH, in comparison to iron‐free ones. Biodistribution studies on mice after a systemic injection showed a negative MRI contrast in liver, suggesting the presence of the nanotubes in this organ until 48 h after i.v. injection. The presence of carbon nanotubes in liver was confirmed after ex vivo carbon extraction. Finally, cytotoxicity studies showed no apparent effect owing to the presence of the carbon nanotubes. The functionalized carbon nanotubes were well tolerated by the animals at the dose of 10 µg g^?1 body weight. Copyright © 2012 John Wiley & Sons, Ltd.     

Bovine ferritin iron bioavailability in man

The bioavailability of ferritin iron was evaluated in human subjects using radiolabelled [⁵⁵Fe]ferritin isolated from bovine spleen and liver. Preliminary studies with bovine spleen ferritin labelled in vitro demonstrated an inappropriately high absorption compared with ferritin labelled in vivo , and the latter was therefore used in all subsequent absorption studies. In 10 subjects, geometric mean absorption from 5 mg of ferritin iron was 3.8% when taken without and 3.2% when taken with food ( P  >0.05). These values were significantly lower than absorption from the same dose of iron given as ferrous sulphate, which averaged 24.1% without and 8.2% with food. When the iron dose was increased 10-fold, absorption of ferritin iron averaged only 0.6–0.7% with or without food as compared with 7.9% without and 2.6% with food when the iron was given as ferrous sulphate. In a further study, mean absorption from bovine spleen ferritin of 4.0% did not differ significantly from the mean of 2.7% observed with bovine liver ferritin. These findings confirm previous studies indicating that ferritin iron is poorly absorbed. Furthermore, its use as a pharmaceutical iron preparation cannot be advocated.     

Labile iron,ROS, and cell death are prominently induced by haemin,but not by non-transferrin-bound iron

BackgroundIn transfusion-related iron overload, haem-derived iron accumulation in monocytes/macrophages is the initial event. When iron loading exceeds the ferritin storage capacity, iron is released into the plasma. When iron loading exceeds transferrin binding capacity, labile, non-transferrin-bound iron (NTBI) appears and causes organ injury. Haemin-induced cell death has already been investigated; however, whether NTBI induces cell death in monocytes/macrophages remains unclear.Material and MethodsHuman monocytic THP-1 cells were treated with haemin or NTBI, particularly ferric ammonium citrate (FAC) or ferrous ammonium sulfate (FAS). The intracellular labile iron pool (LIP) was measured using an iron-sensitive fluorescent probe. Ferritin expression was measured by western blotting.ResultsLIP was elevated after haemin treatment but not after FAC or FAS treatment. Reactive oxygen species (ROS) generation and cell death induction were remarkable after haemin treatment but not after FAC or FAS treatment. Ferritin expression was not different between the FAC and haemin treatments. The combination of an iron chelator and a ferroptosis inhibitor significantly augmented the suppression of haemin cytotoxicity (p = 0.011).DiscussionThe difference in LIP suggests the different iron traffic mechanisms for haem-derived iron and NTBI. The Combination of iron chelators and antioxidants is beneficial for iron overload therapy.     

Serum hepcidin concentration in chronic haemodialysis patients: associations and effects of dialysis, iron and erythropoietin therapy

Background Hepcidin, a liver‐derived peptide induced by iron overload and inflammation, is a major regulator of iron homeostasis. As hepcidin decreases gastrointestinal iron absorption and recirculation from monocytes, over‐expression is associated with the development of anaemia. Methods We studied the associations between circulating hepcidin levels and various laboratory parameters related to anaemia and/or inflammation in 20 patients on chronic haemodialysis. Furthermore, we determined the impact of dialysis and iron and/or erythropoietin (rhEpo) supplementation therapy on hepcidin serum concentrations. The patients were withheld from iron and rhEpo for 2 weeks before study entry. Hepcidin was measured by liquid chromatography‐mass spectrometry (LC‐MS/MS); serum iron and haematological parameters, cytokines and pro‐hepcidin by commercially available enzyme‐linked immunosorbent assays (ELISA) or standard automated methods. Results While hepcidin levels at baseline were not correlated to pro‐hepcidin, interleukin‐6 or transforming growth factor‐beta concentrations, we found significant associations with reticulocyte count (r = ?0·55; P = 0·015), serum iron (r = 0·7; P = 0·004) and ferritin levels (r = 0·63; P = 0·004) and transferrin saturation (r = 0·69, P = 0·001). Dialysis using either a high or a low flux biocompatible dialyser resulted in a significant decrease of hepcidin concentrations, which returned to pre‐dialysis values before the next dialysis session. When studying the effects of anaemia treatment, we observed a significant reduction of hepcidin levels following administration of rhEpo but not iron. Conclusions Hepcidin levels in stable haemodialysis patients appear to reflect systemic iron load, but not inflammation. Due to the negative association between reticulocyte counts and hepcidin, the reduction of circulating hepcidin concentrations by dialysis and/or rhEpo treatment may positively affect erythropoiesis.     

Effectiveness of inulin-type on the iron bioavailability in anemic female rats fed bio-yogurt

It is well-documented that iron deficiency leads to anemia, which is the utmost critical problem of nutrition worldwide. Inulin, indigestible polysaccharides, or prebiotic agents may act as vehicles to enhance the iron bioavailability through the formation of the polysaccharide–iron complex. The present study was undertaken to evaluate the therapeutic effects of yogurt fortified with iron and supplemented by long- or short-chain inulin on the growth status, blood parameters, antioxidant capacity, and liver function enzymes in anemic rats. Five animal groups were assigned as the control (G1), which were fed a standard diet and there were four anemic groups, in which haemolytic anemia was induced by phenylhydrazine. The anemic rats were divided into 4 groups according to the regime of feeding as G2: control anemic group fed low-iron diet while the remaining anemic groups were fed yogurt fortified with Fe₂(SO₄)₃ without inulin (G3) or with either long- (G4) or short-chain (G5) inulin. The results showed that the animals subjected to treatment G4 had the highest (P ≤ 0.05) weight gain and organ coefficient compared with other anemic groups (G2, G3, and G5). Among the anemic groups, the animals that belonged to G4 showed a significant restorative effect by returning the hemoglobin and hematocrit levels and the red blood cell count to the normal control liver. Also, the liver iron content, enzymatic activities, and antioxidant capacities improved in the animals subjected to G4 and G5 treatment groups. The histological structures of the liver tissues of the animals that belonged to G4 and G5 were extremely close to that of the normal control liver. Long-chain inulin-containing yogurt exhibited the best effects in terms of iron supplementation, bioavailability, and antioxidant activities. This formula might be a potential new iron supplement and a good functional food candidate.

It is well-documented that iron deficiency leads to anemia, which is the utmost critical problem of nutrition worldwide.