A Human Feeding Trial of Iron-enhanced Rice

A key unknown in the strategy of breeding for micronutrient-dense staple food crops is the bioavailability of the additional trace minerals in nutritionally improved lines. This paper describes a feeding trial to be undertaken in the Philippines during 2001 using human subjects that will examine the effect on iron status of long-term consumption of IR68-144, a high-yielding, aromatic, iron-dense rice that is currently undergoing agronomic testing at the International Rice Research Institute (IRRI). The subjects will be religious sisters-in-training who live year-round in convents in Greater Manila.

This population was selected because they represent a sex and age segment of the population at high risk for iron deficiency. The iron status of the sample of 27 sisters indicates that 74% were anaemic (haemoglobin <120 g/L) and 48% iron deficient (serum ferritin <12 μg/L). These subjects consume large quantities of rice (400 g/day), and all their meals are prepared in common kitchens where different varieties of rice can be easily introduced to the menu. A pilot study found that the introduction of IR68-144 rice was highly tolerated by the kitchen staff who prepared the rice and the sisters who consumed it. There were no perceived differences in taste, texture, colour, or other properties compared with the commercial variety normally consumed.

The high prevalence of iron deficiency, the considerable amount of rice consumed, the high level of cooperation of the subjects, and the structured routine of the convent make this an ideal research setting to investigate the effect of improving iron intakes through a staple food.

Iron regulation in C57BL/6 and DBA/2 mice subjected to iron overload

Many genes are likely involved in the control of iron metabolism in brain and in peripheral tissues, and genetically-defined murine strains present the opportunity to investigate genetic variations in iron metabolism. Weanling C57BL/6 (B6) and DBA/2 (D2) mice were divided into two treatment groups receiving distilled water with or without 5000 ppm ferric chloride ad libitum as their sole fluid source for 100 days. Iron overload increased liver, spleen and plasma iron levels in male and female B6 and female D2 mice. In D2 males, liver iron was increased relative to control, but spleen and plasma iron remained unaffected. Brain iron content was not different between control and iron-treated mice in ventral midbrain, caudate, pons or hippocampus, but D2 iron overloaded mice displayed lower iron levels in nucleus accumbens and prefrontal cortex. We conclude that genetic background influences the accumulation of excess iron in the periphery and iron regulation in the central nervous system.

Iron deficiency: Differential effects on monoamine transporters

In this study, we extend previous work on iron deficiency and dopamine (DA) transporters to include an examination of central serotonin (5-HT) and noradrenergic (NE) transporters. Rats were fed either iron deficient (ID) or iron adequate (CN) diets from weaning until adulthood. In males, an additional group of iron deficient animals (IR) were given iron supplementation. DA, 5-HT, and NE transporter binding was done in situ on thin sections. ID males, but not females, decreased DA transporter binding in the nucleus accumbens, caudate putamen and substantia nigra by 20-40%. ID males also had a 20-30% reduction in 5-HT transporter binding in several areas (nucleus accumbens, olfactory tubercle, colliculus) while in ID females there was 15-25% increased serotonin transporter binding in the olfactory tubercle, zona incerta, anteroventral thalamic nucleus and vestibular nucleus. Iron deficiency reduced 3H-nisoxetine binding to the NE transporter in locus ceruleus and anteroventral thalamic nucleus in males but not females. Only some of the changes observed in DA, serotonin and NE transporter binding were reversible by iron supplementation. These findings show that iron deficiency affects monoamine systems related to homeostasis and in most cases males appear to be more vulnerable than females.

Quantitative Genetic Analysis of Ventral Midbrain and Liver Iron in BXD Recombinant Inbred Mice

Male and female mice from 15 of the BXD/Ty recombinant inbred strain panel were examined for regional brain and liver iron content. Brain regions included medial prefrontal cortex, nucleus accumbens, caudate-putamen and ventral midbrain. Our focal tissue was the ventral midbrain, containing the ventral tegmentum and substantia nigra. This area contains the perikarya of the dopamine neurons that project to nucleus accumbens and caudate-putamen. Genetic correlations between ventral midbrain and liver iron content were not statistically significant, suggesting that peripheral and central iron regulatory systems are largely independent. Correlations between ventral midbrain iron and iron in the caudate-putamen and nucleus accumbens, but not the prefrontal cortex were moderately high and significant. Ventral midbrain and liver iron contents were subjected to quantitative trait loci analysis to identify associated chromosomal locations. This analysis revealed several suggestive loci for iron content in ventral midbrain but fewer loci for liver. Genetic correlations between ventral midbrain iron and published dopamine functional indices were significant, suggesting a link between ventral midbrain iron status and central dopamine neurobiology. This work shows the value of quantitative genetic analysis in the neurobiology of iron and in showing the close association between ventral midbrain iron and nigrostriatal/mesolimbic dopamine function.

New Diversity Arrays Technology (DArT) markers for tetraploid oat (Avena magna Murphy et Terrell) provide the first complete oat linkage map and markers linked to domestication genes from hexaploid A. sativa L

Nutritional benefits of cultivated oat (Avena sativa L., 2n = 6x = 42, AACCDD) are well recognized; however, seed protein levels are modest and resources for genetic improvement are scarce. The wild tetraploid, A. magna Murphy et Terrell (syn A. maroccana Gdgr., 2n = 4x = 28, CCDD), which contains approximately 31% seed protein, was hybridized with cultivated oat to produce a domesticated A. magna. Wild and cultivated accessions were crossed to generate a recombinant inbred line (RIL) population. Although these materials could be used to develop domesticated, high-protein oat, mapping and quantitative trait loci introgression is hindered by a near absence of genetic markers. Objectives of this study were to develop high-throughput, A. magna-specific markers; generate a genetic linkage map based on the A. magna RIL population; and map genes controlling oat domestication. A Diversity Arrays Technology (DArT) array derived from 10 A. magna genotypes was used to generate 2,688 genome-specific probes. These, with 12,672 additional oat clones, produced 2,349 polymorphic markers, including 498 (21.2%) from A. magna arrays and 1,851 (78.8%) from other Avena libraries. Linkage analysis included 974 DArT markers, 26 microsatellites, 13 SNPs, and 4 phenotypic markers, and resulted in a 14-linkage-group map. Marker-to-marker correlation coefficient analysis allowed classification of shared markers as unique or redundant, and putative linkage-group-to-genome anchoring. Results of this study provide for the first time a collection of high-throughput tetraploid oat markers and a comprehensive map of the genome, providing insights to the genome ancestry of oat and affording a resource for study of oat domestication, gene transfer, and comparative genomics.

Iron deficiency alters the day-night variation in monoamine levels in mice

Monoamine metabolism in the central nervous system is altered by dietary iron deficiency, with a stronger effect seen during the active than rest span of the circadian cycle. In this report, we examined changes in intracellular and extracellular monoamine levels, synthetic enzymes, transporter and receptor densities, and responses to amphetamine-induced dopamine (DA) efflux in iron-deficient and iron-sufficient mice. Extracellular striatal DA levels were 15-20% higher in all groups during the active dark phase compared to the inactive light phase, with correspondingly lower dopamine transporter (DAT) and higher tyrosine hydroxylase levels. Iron deficiency decreased DAT density by 20% and 28% in the light and dark phases, respectively, and elevated the DOPAC/DA ratio only in the dark, indicating that iron deficiency does interact with the normal diurnal cues for cyclicity. Enhanced DA efflux after amphetamine stimulation indicates no limitation on monoamine synthesis and release and is consistent with altered synaptic efficacy and perhaps recycling of DA in iron deficiency. These experimental findings provide new evidence that brain iron insufficiency does have a differential effect on the DA system at different biological times of the day and night and may be causally related to the phasic motor symptoms observed in Restless Legs Syndrome.

A history of iron deficiency anemia during infancy alters brain monoamine activity later in juvenile monkeys

Both during and after a period of iron deficiency (ID), iron-dependent neural processes are affected, which raises the potential concern that the anemia commonly experienced by many growing infants could have a protracted effect on the developing brain. To further investigate the effects of ID on the immature brain, 49 infant rhesus monkeys were evaluated across the first year of life. The mothers, and subsequently the infants after weaning, were maintained on a standardized diet containing 180 mg/kg of iron and were not provided other iron-rich foods as treats or supplements. As the infants grew, they were all screened with hematological tests, which documented that 16 (33.3%) became markedly ID between 4 and 8 months of age. During this anemic period and subsequently at 1 year of age, cerebrospinal fluid (CSF) specimens were collected to compare monoamine activity in the ID and iron-sufficient infants. Monoamine neurotransmitters and metabolite levels were normal at 4 and 8 months of age, but by 1 year the formerly anemic monkeys had significantly lower dopamine and significantly higher norepinephrine levels. These findings indicate that ID can affect the developmental trajectory of these two important neurotransmitter systems, which are associated with emotionality and behavioral performance, and further that the impact in the young monkey was most evident during the period of recovery.

Altered dopaminergic profile in the putamen and substantia nigra in restless leg syndrome

Restless leg syndrome (RLS) is a sensorimotor disorder. Clinical studies have implicated the dopaminergic system in RLS, while others have suggested that it is associated with insufficient levels of brain iron. To date, alterations in brain iron status have been demonstrated but, despite suggestions from the clinical literature, there have been no consistent findings documenting a dopaminergic abnormality in RLS brain tissue. In this study, the substantia nigra and putamen were obtained at autopsy from individuals with primary RLS and a neurologically normal control group. A quantitative profile of the dopaminergic system was obtained. Additional assays were performed on a catecholaminergic cell line and animal models of iron deficiency. RLS tissue, compared with controls, showed a significant decrease in D2R in the putamen that correlated with severity of the RLS. RLS also showed significant increases in tyrosine hydroxylase (TH) in the substantia nigra, compared with the controls, but not in the putamen. Both TH and phosphorylated (active) TH were significantly increased in both the substantia nigra and putamen. There were no significant differences in either the putamen or nigra for dopamine receptor 1, dopamine transporters or for VMAT. Significant increases in TH and phosphorylated TH were also seen in both the animal and cell models of iron insufficiency similar to that from the RLS autopsy data. For the first time, a clear indication of dopamine pathology in RLS is revealed in this autopsy study. The results suggest cellular regulation of dopamine production that closely matches the data from cellular and animal iron insufficiency models. The results are consistent with the hypothesis that a primary iron insufficiency produces a dopaminergic abnormality characterized as an overly activated dopaminergic system as part of the RLS pathology.

Assessment of iron deficiency in US preschool children and nonpregnant females of childbearing age: National Health and Nutrition Examination Survey 2003-2006

BACKGROUND

A new index to determine body iron promises a simpler approach to monitoring iron deficiency (ID) prevalence.

OBJECTIVE

Our objective was to compare ID defined as body iron <0 mg/kg and calculated from the log ratio of transferrin receptor to ferritin (the body iron model) to ID defined as >/=2 of 3 abnormal concentrations in ferritin, transferrin saturation, or erythrocyte protoporphyrin (the ferritin model).

DESIGN

We used measures of iron status and inflammation from 486 children aged 1-2 y, 848 children aged 3-5 y, and 3742 nonpregnant females aged 12-49 y from the National Health and Nutrition Examination Survey 2003-2006.

RESULTS

ID prevalences (+/-SE) based on the body iron model in children (1-2 and 3-5 y) and in females (12-19 and 20-49 y) were 14.4 +/- 1.9%, 3.7 +/- 0.8%, 9.3 +/- 1.0%, and 9.2 +/- 1.6%, respectively. ID prevalences based on the ferritin model in children (3-5 y) and females (12-19 and 20-49 y) were 4.5 +/- 0.9%, 15.6 +/- 1.2%, and 15.7 +/- 0.8%, respectively. The kappa statistics for agreement between the 2 models were 0.5-0.7. Among females (12-49 y) the positive predictive values of ID based on the body iron model and the ferritin model for identifying anemia were 43 +/- 3% and 30 +/- 2%, respectively, whereas negative predictive values did not differ. C-reactive protein was elevated in 28.8 +/- 3.1% of females with ID by the ferritin model but not by the body iron model and in 0% of persons with ID by the body iron model but not by the ferritin model.

CONCLUSIONS

The agreement between the 2 indexes was fair to good. Among females, the body iron model produced lower estimates of ID prevalence, better predicted anemia, and appeared to be less affected by inflammation than the ferritin model.

Systems genetics analysis of iron regulation in the brain

Iron imbalances in the brain, including excess accumulation and deficiency, are associated with neurological disease and dysfunction; yet, their origins are poorly understood. Using systems genetics analysis, we have learned that large individual differences exist in brain iron concentrations, even in the absence of neurological disease. Much of the individual differences can be tied to the genetic makeup of the individual. This genetic-based differential regulation can be modeled in genetic reference populations of rodents. The work in our laboratory centers on iron regulation in the brain and our animal model consists of 25 BXD/Ty recombinant inbred mouse strains. By studying naturally occurring variation in iron phenotypes, such as tissue iron concentration, we can tie that variability to one or more genes by way of quantitative trait loci (QTL) analysis. Moreover, we can conduct genetic correlation analyses between our phenotypes and others previously measured in the BXD/Ty strains. We have observed several suggestive QTL related to ventral midbrain iron content, including one on chromosome 17 that contains btbd9, a gene that in humans has been associated with restless legs syndrome and serum ferritin. We have also observed gene expression correlations with ventral midbrain iron, including btbd9 expression and dopamine receptor expression. In addition, we have observed significant correlations between ventral midbrain iron content and dopamine-related phenotypes. The following is a discussion of iron regulation in the brain and the contributions a systems genetics approach can make toward understanding the genetic underpinnings and relation to neurological disease.

Iron deficiency and child and maternal health

BACKGROUND

Iron deficiency is most commonly found in women of reproductive age and infants worldwide, but the influence of maternal iron deficiency on infant development is underexplored.

OBJECTIVE

The objective was to examine the relation between maternal iron status and mother-child interactions in a randomized, double-blind, intervention trial conducted in South Africa.

DESIGN

Women were recruited into the study from a health clinic at 6-8 wk postpartum and were classified as either iron-deficient anemic (IDA) or iron-sufficient after blood analysis. IDA mothers received iron supplements of 125 mg FeSO(4) (IDA-Fe; n = 34) or placebo (IDA-PL; n = 30) daily from 10 wk to 9 mo postpartum. The control group (n = 31) consisted of iron-sufficient mothers. Free-play mother-child interaction sessions were videotaped in the clinic at 10 wk (n = 80) and 9 mo (n = 66) postpartum and coded per the Emotional Availability Scales (4 maternal scales: sensitivity, structuring, nonintrusiveness, and nonhostility; 2 infant scales: responsiveness and involvement).

RESULTS

At 10 wk, scores for maternal sensitivity and child responsiveness were significantly greater in the control group than in the IDA groups (P = 0.028 and 0.009, respectively). At 9 mo, the control and IDA-Fe groups no longer differed. These 2 groups scored significantly better on the maternal sensitivity, structuring, and nonhostility scales and on the child responsiveness scale than did the IDA-PL group (P = 0.007-0.032), whose iron status remained low.

CONCLUSION

These data indicate that maternal iron deficiency negatively affects mother-child interactions and that iron supplementation protects against these negative effects.

A randomized, double-blind, placebo-controlled trial of intravenous iron sucrose in restless legs syndrome

OBJECTIVE

The aim of this study was to ascertain whether high-dose intravenous (IV) iron sucrose could improve symptoms and change brain iron concentrations in idiopathic RLS.

METHODS

The study was a randomized, parallel-group double-blind study of 1000mg iron sucrose given IV versus placebo. Primary measures of the clinical status were global rating scale (GRS) and periodic leg movements of sleep (PLMS). Primary measures of brain iron status were CSF ferritin and MRI-determined iron in the substantia nigra.

RESULTS

At the time of the interim analysis there were 7 placebo and 11 iron-treated subjects. At 2-weeks post-treatment, iron treatment resulted in a small but significant increase in CSF ferritin and a decrease in RLS severity (GRS) but did not change PLMS or MRI iron index. None of the secondary outcomes changed with treatment. There was no single case of clear treatment benefit in any of the patients. This interim analysis revealed an effect size that was too small to allow for adequate power to find significant differences with the planed 36-subject enrollment for either the primary objective outcome of PLMS or any of the secondary outcomes. The study was stopped at this planned break-point given the lack of both adequate power and any indication for clinically significant benefit.

CONCLUSIONS

High-dose IV iron failed to demonstrate the robust changes reported in three prior open-label studies. Differences in iron formulation, dosing regiment, and peripheral iron status may explain some of the discrepancies between this and previous IV iron treatment studies.

Why iron deficiency is important in infant development

Infants who experience iron deficiency during the first 6-12 mo of life are likely to experience persistent effects of the deficiency that alter functioning in adulthood. A lack of sufficient iron intake may significantly delay the development of the central nervous system as a result of alterations in morphology, neurochemistry, and bioenergetics. Depending on the stage of development at the time of iron deficiency, there may be an opportunity to reverse adverse effects, but the success of repletion efforts appear to be time dependent. Publications in the past several years describe the emerging picture of the consequences of iron deficiency in both human and animal studies. The mechanisms for iron accumulation in the brain and perhaps redistribution are being understood. The data in human infants are consistent with altered myelination of white matter, changes in monoamine metabolism in striatum, and functioning of the hippocampus. Rodent studies also show effects of iron deficiency during gestation and lactation that persist into adulthood despite restoration of iron status at weaning. These studies indicate that gestation and early lactation are likely critical periods when iron deficiency will result in long-lasting damage.

Dopamine D2 receptor expression is altered by changes in cellular iron levels in PC12 cells and rat brain tissue

Iron deficiency anemia in early life alters the development and functioning of the dopamine neurotransmitter system, but data regarding the specific effects of brain iron loss on dopamine D(2) receptor regulation are lacking. Cell culture and animal models were employed in this study to determine whether D(2) receptor expression is altered when cellular iron levels are depleted. Endogenous D(2) receptor-expressing PC12 cells exposed to increasing concentrations of the iron chelator desferrioxamine (25-100 micromol/L) exhibited dose-dependent decreases in total D(2) receptor protein concentrations (20-65%), but there were minimal effects on D(2) receptor mRNA levels. When iron-deficient cells were repleted with ferric ammonium citrate for 24 h, D(2) receptor protein densities were similar to control. Dietary iron deficiency for 6 wk in weanling rats also reduced regional iron concentrations by nearly 50% in the ventral midbrain and caudate but did not affect D(2) receptor mRNA levels in the ventral midbrain. Iron deficiency significantly reduced membrane D(2) receptor protein levels by >70% in caudate, whereas cytosolic concentrations showed only 25% losses. D(2) receptor protein densities and regional iron concentrations were restored within 2 wk of dietary iron repletion. These results support the concept that D(2) receptor gene expression is not significantly changed by iron deficiency, whereas dopamine receptor trafficking is affected and is likely related to known dopamine system alterations in iron deficiency.

Diurnal cycle influences peripheral and brain iron levels in mice

Iron movement between organ pools involves a dynamic equilibrium of iron efflux and uptake, and homeostatic mechanisms are likely involved in providing iron to cells and organs when required. Daily iron levels in the plasma pool fluctuate with the diurnal cycle, but clear explanations regarding the objectives and regulation of the flux are lacking. The association between diurnal cycle and iron flux is relevant in the disease of restless legs syndrome (RLS), where individuals display diurnal deficits in motor control, have impaired brain iron metabolism, and perhaps altered iron uptake from the plasma pool. The goal of the present study was to examine diurnal variations in peripheral and regional brain iron to evaluate iron flux between organs in iron-sufficient and iron-deficient mice. In mice fed control diet, liver iron was elevated 30-40%, and plasma iron was reduced 20-30% in the active dark period compared with the inactive light phase. Dietary iron deficiency eliminated this variation in liver iron in male and female mice and in plasma iron in male mice. Reductions in ventral midbrain and nucleus accumbens iron and ferritin were apparent in iron-deficient mice during both diurnal phases, but only during the light phase was an approximately 25% reduction in whole brain iron observed, suggesting different brain iron requirements between phases. These data demonstrate that iron flux between organs is sensitive to diurnal regulatory biology. Importantly, variations in brain iron may have temporal implications regarding neural functioning and may contribute to the diurnal cycle-dependent symptoms of RLS.

Altered iron metabolism in lymphocytes from subjects with restless legs syndrome

OBJECTIVE

Studies using cerebrospinal fluid, magnetic resonance imaging, and autopsy tissue have implicated a primary role for brain iron insufficiency in restless legs syndrome (RLS). If the abnormalities of brain iron regulation reflect a basic disturbance of iron metabolism, then this might be expressed at least partially in some peripheral systems. Thus the study aim was to determine whether patients with RLS and control subjects show differences in lymphocyte iron regulator proteins.

METHODS

Fasting morning blood samples were used to obtain common serum measures of iron status and to determine lymphocyte iron management proteins. Twenty-four women with early-onset RLS and 25 control women without RLS symptoms were studied.

RESULTS

RLS and control subjects were matched for age, hemoglobin, and serum iron profile. However, transferrin receptor (TfR) and DMT1 (divalent metal transporter 1 protein) levels in lymphocytes were significantly higher for RLS patients than for controls. No significant differences in ferritin subtypes or transferrin levels were found. No significant correlations were found between lymphocyte and serum indices of iron status.

INTERPRETATION

RLS lymphocytes showed an increase in ferroportin, implying increased cellular iron excretion, in the face of increased iron need (increased TfR and DMT1). In the absence of changes in H-ferritin, the findings indicate a balance between input and output with no net iron change but probable overall increase in iron turnover. The lack of any significant correlation between serum and lymphocyte iron indices indicates that iron management proteins from lymphocytes are at a minimum an alternative and independent marker of cellular iron metabolism.

What matters most: an investigation of predictors of perceived stress among young mothers in Khayelitsha

Our purpose in the present study was to examine how two different sets of stressors, one representing the physical environment and the other representing the social environment, related to perceived stress among new mothers served by a health clinic in Khayelitsha, South Africa. We found that among the chronic urban poverty-environmental stressors related to water, housing, transportation, toileting, and lack of food, that lack of drinkable water in the home had the strongest correlation with perceived stress. In terms of social stressors we found that 60% of new mothers had no partner, and 43% of those with a partner reported that they currently were not coresiding. In terms of the social stressors, the inability to depend on a partner in times of trouble had the strongest relationship to perceived stress. Other findings relating to partner support are discussed as well as sample and community characteristics. Given the importance of partner support, it is argued that the conditions of poverty itself serve to destabilize relationships, which in turn contributes to the cycle of poverty experienced by many residents of periurban settlements like Khayelitsha.

Nutrient adequacy and food group consumption of Filipino novices and religious sisters over a nine month period

Rice is commonly consumed in the Philippines; however the contribution of other foods to the diet is not well defined. Our aim was to determine the nutrient intake and food group intake of Philippine nuns and compare their intakes to the current estimated average requirements (EAR), and food-based recommendations, respectively, and assess any differences in nutrient adequacy and energy intakes between body mass index (BMI) categories. Body weight was assessed at baseline and at nine months; three-day weighed food intakes were recorded once every fortnight (n=187). At baseline, the mean (SD) age and BMI of the women was: 25.0 (4.6) years and 21.8 (17.3) kg/m2, respectively. Over the nine months, women with an underweight (n=46;<18.5 kg/m2) and acceptable BMI (n=132; 18.5-25 kg/m2) lost 5.0 kg (p=0.005) and 1.5 kg (p=0.047), respectively, whereas overweight women maintained their weight. Irrespective of BMI, 98% of women consumed less than the adequate intake for calcium, and no one met the folate EAR. The intake of all food groups (e.g., rice, vegetables, fruit, meat, dairy) was lower than food-based recommendations. It is evident that the nutrient density of the Philippine diet is poor. In order to meet nutrient requirements, it is recommended that all women increase intake of fruits, vegetables, fish, meat and dairy products, to reduce risk of micronutrient deficiencies. For the overweight women, these nutrient dense foods also are recommended, however it is important that they be substituted for energy dense foods to promote weight loss and prevent weight gain.

CSF proteomic analysis reveals persistent iron deficiency-induced alterations in non-human primate infants

Iron deficiency (ID) anemia during infancy results in long-term neurological consequences, yet the mediating mechanisms remain unclear. Infant monkeys often become naturally anemic during the first 6 months of life, presenting an opportunity to determine the effect of developmental iron deficiency. After weaning, animals were chosen randomly for supplementation with oral iron or, fed a standard commercial chow diet. The control group was never iron deficient. ID anemia was corrected by 12 months in both groups, as indicated by hematological parameters. CSF was collected for proteomic analysis at 12 months of age to assess the impact of developmental ID on the brain. The CSF proteome for both formerly iron deficient groups was similar and revealed 12 proteins with expression levels altered at least twofold. These proteins were identified by matrix assisted laser desorption ionization time-of-flight spectrometry and included prostaglandin D synthase, olfactory receptors and glial fibrillary acidic protein. Thus the proteomic analysis reveals a persistent effect of ID and provides insights into reports of disturbed sleep, hypomyelination and other behavioral alterations associated with ID. Furthermore, alterations in the CSF proteome despite normal hematologic parameters indicate that there is a hierarchical system that prioritizes repletion of red cell mass at the expense of the brain.

Systems genetic analysis of peripheral iron parameters in the mouse

Iron homeostasis is one of the most critical functions in living systems. Too little iron can lead to anemia and tissue-specific disorders, such as splenomegaly. Excessive systemic iron is characteristic of hemochromatosis and is implicated in the brain in Parkinson's disease. With the exception of some single gene diseases like hemochromatosis, we know little about genetic-based, individual differences in iron-related parameters and their impact on biology. To model genetic control of iron homeostasis, we measured liver, spleen, and plasma iron concentrations, hematocrit and hemoglobin, transferrin saturation, and total iron-binding capacity in several BXD/Ty recombinant inbred mouse strains derived from C57BL/6 and DBA/2 progenitors. At 120 days of age, the animals were killed for iron analysis. All measures showed genetic-based variability consistent with polygenic influence. Analysis of principal components of the seven measures revealed three factors that we named availability, transport, and storage. Quantitative trait loci (QTL) analysis revealed one suggestive QTL on chromosome 5 for availability, two suggestive QTL (one on chromosome 1 and the other on chromosome 7) for transport, and one weak QTL on chromosome 2 for storage. The results show that iron homeostasis is a complex trait and is influenced by multiple genes.

Iron absorption prediction equations lack agreement and underestimate iron absorption

A number of algorithms have been developed to predict the bioavailability of iron from mixed meals and diets, but their direct validity in predicting change in iron status remains questionable. Throughout the course of conducting a large feeding trial in 10 convents in Manila, we collected weighed food intake data (n = 317) and directly compared the performance of these prediction equations to each other and to the change in serum ferritin (SF). Dietary weighed food intakes were measured on d 3 every 2 wk for each woman and iron status determined at baseline, 4.5 mo, and 9 mo. The Monsen and Balintfy equation predicted higher median absorption efficiency (7.3%) than did the equations of Hallberg and Hulthen (6.1%) and Reddy et al. (5.8%). In contrast, the predictions that used the equations of Bhargava et al. (3.8%), Tseng et al. (2.9%), and Du et al. (2.6%) were significantly lower. The iron absorption efficiencies calculated using the Monsen and Balintfy equation correlated with those using the Hallberg and Hulthen equation (r = 0.91, P < 0.001). This slope did not differ from unity, whereas all other equations underestimated iron absorption efficiency relative to Monsen and Balintfy's equation. The median efficiency of absorption, based on change in SF in 114 subjects, was 17.2%, suggesting that these equations underestimate iron absorption. The inhibitory and enhancing factors in the published prediction equations were quantitatively either too large or perhaps too small to correctly predict apparent iron bioavailability over a 9-mo period. The causes of the lack of agreement between change in iron status estimated by SF change and absorption predicted by algorithms are open to discussion and will need to be resolved.

Variation in the Diets of Filipino Women over 9 Months of Continuous Observation

Background

The variability in habitual intakes of most components in the Philippine diet is unknown.

Objective

To perform a quantitative evaluation of the traditional Philippine diet using data collected over an extended period of time. We sought to identify seasonal variations and within-subject components of variation in nutrient intake.

Methods

A quantitative evaluation of the Philippine diet was conducted in convents in metropolitan Manila as part of an efficacy trial to examine biofortified rice as an approach to improve iron nutritional status. Weighed food intakes were conducted on 54 days in each of more than 300 religious sisters over 9 months in 10 convents. The sisters consumed their habitual diets except for the substitution of one variety of rice for another.

Results

More than 40% of calories were derived from rice, with protein from meat and fish comprising 18% of calories. There were significant variations in macronutri- ent and micronutrient intakes across seasons of the year, with more rice consumed in the wet season and more fruits, eggs, milk, and beverages consumed in the dry season. The day-to-day within-subject variation (CV) in median intake was 23% for energy, 31% for protein, 42% for iron, and 138% for vitamin A.

Conclusions

These novel data show that traditional Filipino dietary patterns have substantial individual variation and are inadequate in certain micronutrients. This quantitative evaluation of diet can provide a reference point for dietary adequacy.

Early postnatal iron repletion overcomes lasting effects of gestational iron deficiency in rats

Iron deficiency anemia in early childhood causes developmental delays and, very likely, irreversible alterations in neurological functioning. One primary goal for the present study was to determine whether the effects of late gestational iron deficiency on brain monoamine metabolism, iron content, and behavioral phenotypes could be repaired with iron intervention in early lactation. Young pregnant rats were provided iron-deficient or control diets from mid-gestation (G15). At postnatal d 4 (P4), pups from iron-deficient dams were out-fostered either to other ID dams or control dams while pups of control dams were similarly fostered to other control dams. Dietary treatments continued to adulthood (P65) when brain iron and regional monoamines were evaluated. P4 iron repletion normalized body iron status, brain iron concentrations, monoamine concentrations, and monoamine transporter and receptor densities in most brain regions. Dopamine transporter densities in caudate and substantia nigra were lower in ID rats but were normalized with iron repletion. Serotonin transporter levels in most brain regions and open-field exploration were also normalized with iron repletion. The success of this approach of early postnatal iron intervention following iron deficiency in utero contrasts to a relative lack of success when the intervention is performed at weaning. These data suggest that a window of opportunity exists for reversing the detrimental effects of iron deficiency in utero in rats and provides strong support of intervention approaches in humans with iron deficiency during pregnancy.

Iron treatment normalizes cognitive functioning in young women

BACKGROUND

Evidence suggests that brain iron deficiency at any time in life may disrupt metabolic processes and subsequently change cognitive and behavioral functioning. Women of reproductive age are among those most vulnerable to iron deficiency and may be at high risk for cognitive alterations due to iron deficiency.

OBJECTIVE

We aimed to examine the relation between iron status and cognitive abilities in young women.

DESIGN

A blinded, placebo-controlled, stratified intervention study was conducted in women aged 18-35 y of varied iron status who were randomly assigned to receive iron supplements or a placebo. Cognition was assessed by using 8 cognitive performance tasks (from Detterman's Cognitive Abilities Test) at baseline (n = 149) and after 16 wk of treatment (n = 113).

RESULTS

At baseline, the iron-sufficient women (n = 42) performed better on cognitive tasks (P = 0.011) and completed them faster (P = 0.038) than did the women with iron deficiency anemia (n = 34). Factors representing performance accuracy and the time needed to complete the tasks by the iron-deficient but nonanemic women (n = 73) were intermediate between the 2 extremes of iron status. After treatment, a significant improvement in serum ferritin was associated with a 5-7-fold improvement in cognitive performance, whereas a significant improvement in hemoglobin was related to improved speed in completing the cognitive tasks.

CONCLUSIONS

Iron status is a significant factor in cognitive performance in women of reproductive age. Severity of anemia primarily affects processing speed, and severity of iron deficiency affects accuracy of cognitive function over a broad range of tasks. Thus, the effects of iron deficiency on cognition are not limited to the developing brain.

Iron bioavailability: UK Food Standards Agency workshop report

The UK Food Standards Agency convened a group of expert scientists to review current research investigating factors affecting iron status and the bioavailability of dietary iron. Results presented at the workshop show menstrual blood loss to be the major determinant of body iron stores in premenopausal women. In the presence of abundant and varied food supplies, the health consequences of lower iron bioavailability are unclear and require further investigation.

Early iron deficiency alters sensorimotor development and brain monoamines in rats

Iron deficiency in human infancy reportedly leads to developmental delays and changes in neurobiology that may be irreversible. Using a rodent model, the present study examined whether dietary iron deficiency late in pregnancy and during lactation alters sensorimotor development and brain monoaminergic systems. Rats were assigned to 1 of 4 dietary treatments during gestation and lactation: 1) iron sufficient control; 2) prenatal iron deficiency beginning on gestational d 15 (G15); 3) postnatal iron deficiency beginning on postnatal d 4 (P4); 4) iron deficiency beginning on G15 followed by an iron sufficient diet on P4. Developmental milestones, open field behavior, brain iron and proteins, monoamines, and their transporters were evaluated between P6 and P21. Only G15 iron deficient rats had greater dopaminergic activity than controls as indicated by increased tyrosine hydroxylase levels, phosphorylated tyrosine hydroxylase levels, and cellular dopamine in prefrontal cortex and striatum at P15. These rats also showed delayed eye opening, ear development, and reduced locomotor activity. Iron repletion at P4 returned most measures to control levels by the time of weaning. Postnatal iron deficiency reduced striatal and ventral midbrain iron as well as cellular dopamine levels in prefrontal cortex and striatum at P21. Developmental delays in ear development and achievement in bar holding and surface righting also resulted from postnatal iron deficiency. These results indicate that iron deficiency begun at G15 affects early dopamine neurobiology, the development of specific developmental milestones, and behavior in preweaned rats.

Down-regulation of dopamine transporter by iron chelationin vitrois mediated by altered trafficking, not synthesis

Neurological development and functioning of dopamine (DA) neurotransmission is adversely affected by iron deficiency in early life. Iron-deficient rats demonstrate significant elevations in extracellular DA and a reduction in dopamine transporter (DAT) densities in the caudate putamen and nucleus accumbens. To explore possible mechanisms by which cellular iron concentrations control DAT functioning, endogenous DAT-expressing PC12 cells were used to determine the effect of iron chelation on DAT protein and mRNA expression patterns. In addition, we used human DAT (hDAT)-transfected Neuro2a (N2A) cells to examine DAT degradation and trafficking patterns. A 50 microM treatment for 24 h with the iron chelator, desferrioxamine (DFO), significantly decreased dopamine uptake in a dose-dependent manner, with no apparent change in K(m), in both PC12 and N2A cells. Reduced DA uptake was accompanied by concentration- and time-dependent reductions in total DAT protein levels in both cell lines. Exposure to increasing concentrations of DFO did not significantly alter DAT mRNA in either PC12 or N2A cells. However, DAT degradation rates increased three-fivefold in both cell types exposed to 50 microM DFO for 24 h. Biotinylation studies in N2A cells indicate a more dramatic loss of DAT in the membrane fraction, while OptiPrep fractionation experiments revealed an increase in lysosomal DAT with iron chelation. Inhibition of protein kinase C activation with staurosporin prevented the effect of iron chelation on DAT function, suggesting that in vitro iron chelation affects DAT primarily through the effects on trafficking rather than on synthesis.

Interpretation of serum ferritin concentrations as indicators of total-body iron stores in survey populations: the role of biomarkers for the acute phase response

BACKGROUND

Nutritional surveys use acute phase protein (APP) biomarkers such as C-reactive protein (CRP) and alpha1-acid glycoprotein (AGP) to identify the influence of inflammation on the distribution of iron status biomarkers. Few, however, have examined which biomarker better identifies persons with spurious elevations in iron status markers.

OBJECTIVE

We explored the relations of APP biomarkers to iron-status biomarkers in infants and school-age children.

DESIGN

In screening surveys, we identified a sample of African American infants (n = 351) and Guatemalan school-age children (n = 375). We used a common set of APP and iron-status biomarkers to examine the association between the 2 sets of markers (laboratory variables).

RESULTS

The overall prevalence of either inflammation or iron deficiency was <10% in both samples. The log AGP and CRP values were significantly correlated (r = 0.70), but the unexplained variance still was >50%. Serum ferritin-but not transferrin receptor, transferrin receptor index, or serum iron-was related to APP concentrations, but poor positive predictive value (<72%) and low kappa scores were found. Ferritin concentrations >1 geometric SD above the geometric mean were poorly predicted by either elevated AGP or CRP. Qualitative CRP analysis was not effective in identifying persons who had other indications of mild inflammation.

CONCLUSIONS

These analyses show that a low prevalence of inflammation has little influence on the distribution of ferritin, and 2 common indicators of inflammation do not perform equally well in identifying persons who may have elevations in ferritin due to inflammation.

Quantitative genetic analysis of brain copper and zinc in BXD recombinant inbred mice

Copper and zinc are trace nutrients essential for normal brain function, yet an excess of these elements can be toxic. It is important therefore that these metals be closely regulated. We recently conducted a quantitative trait loci (QTL) analysis to identify chromosomal regions in the mouse containing possible regulatory genes. The animals came from 15 strains of the BXD/Ty recombinant inbred (RI) strain panel and the brain regions analyzed were frontal cortex, caudate-putamen, nucleus accumbens and ventral midbrain. Several QTL were identified for copper and/or zinc, most notably on chromosomes 1, 8, 16 and 17. Genetic correlational analysis also revealed associations between these metals and dopamine, cocaine responses, saccharine preference, immune response and seizure susceptibility. Notably, the QTL on chromosome 17 is also associated with seizure susceptibility and contains the histocompatibility H2 complex. This work shows that regulation of zinc and copper is under polygenic influence and is intimately related to CNS function. Future work will reveal genes underlying the QTL and how they interact with other genes and the environment. More importantly, revelation of the genetic underpinnings of copper and zinc brain homeostasis will aid our understanding of neurological diseases that are related to copper and zinc imbalance.

Persistent neurochemical and behavioral abnormalities in adulthood despite early iron supplementation for perinatal iron deficiency anemia in rats

BACKGROUND

Iron deficiency anemia (IDA) has been associated with altered cognitive, motor, and social-emotional outcomes in human infants. We recently reported that rats with chronic perinatal IDA, had altered regional brain iron, monoamines, and sensorimotor skill emergence during early development.

OBJECTIVE

To examine the long-term consequences of chronic perinatal IDA on behavior, brain iron and monoamine systems after dietary iron treatment in rats.

METHODS

Sixty dams were randomly assigned to iron-sufficient (CN) or low-iron (EID) diets during gestation and lactation. Thereafter, all offspring were fed the iron-sufficient diet, assessed for hematology and behavior after weaning and into adulthood and for brain measures as adults (regional brain iron, monoamines, dopamine and serotonin transporters, and dopamine receptor). Behavioral assessments included sensorimotor function, general activity, response to novelty, spatial alternation, and spatial water maze performance.

RESULTS

Hematology and growth were similar for EID and CN rats by postnatal day 35. In adulthood, EID thalamic iron content was lower. Monoamines, dopamine transporter, and dopamine receptor concentrations did not differ from CN. EID serotonin transporter concentration was reduced in striatum and related regions. EID rats had persisting sensorimotor deficits (delayed vibrissae-evoked forelimb placing, longer sticker removal time, and more imperfect grooming chains), were more hesitant in novel settings, and had poorer spatial water maze performance than CN. General activity and spatial alternation were similar for EID and CN.

CONCLUSION

Rats that had chronic perinatal IDA showed behavioral impairments that suggest persistent striatal dopamine and hippocampal dysfunction despite normalization of hematology, growth and most brain measures.

Moderate iron deficiency in infancy: Biology and behavior in young rats

Iron deficiency anemia in early childhood is associated with developmental delays and perhaps, irreversible alterations in neurological functioning. The goals were to determine if dietary induced gestational and lactational iron deficiency alters brain monoamine metabolism and behaviors dependent on that neurotransmitter system. Young pregnant rats were provided iron deficient or control diets from early in gestation through to weaning of pups and brain iron concentration, regional monoamine variables and achievement of specific developmental milestones were determined throughout lactation. Despite anemia during lactation, most brain iron concentrations did not fall significantly until P25, and well after significant changes in monoamine levels, transporter levels, and D2R density changed in terminal fields. The changes in D2R density were far smaller than previously observed models that utilized severe dietary restriction during lactation or after weaning. Iron deficient pups had normal birth weight, but were delayed in the attainment of a number of milestones (bar holding, vibrissae-evoked forelimb placing). This approach of iron deficiency in utero and during lactation sufficient to cause moderate anemia but not stunt growth demonstrates that monaminergic metabolism changes occur prior to profound declines in brain iron concentration and is associated with developmental delays. Similar developmental delays in iron deficient human infants suggest to us that alterations in iron status during this developmental period likely affects developing brain monaminergic systems in these infants.

Acoustic startle response is disrupted in iron-deficient rats

Diurnal effects on motor control are evident in the human disease of Restless Leg Syndrome (RLS), which is purported to be linked to brain iron deficiency as well as alterations in dopaminergic systems. Thus, we explored the relationship between daily rhythms, the onset of motor dysregulation and brain iron deficiency in an animal model of iron deficiency. Male and female weanling Sprague-Dawley rats consuming control (CN) or iron-deficient (ID) diets were examined weekly for acoustic startle response (ASR) and prepulse inhibition (PPI) for a 5-week period. Iron deficiency reduced the magnitude, but not timing, of the ASR at specific time points. ASR was elevated 60% at the onset of the dark cycle relative to the median of the light cycle in male CN and ID rats. The respective elevation was 400% and 150% in female CN and ID rats during the first 2 weeks of testing. The diurnal cycle of ASR response was attenuated by 3 weeks of testing in both dietary treatment groups. PPI was not affected by iron deficiency, sex, diurnal cycle or the interaction between these factors. These results thus demonstrate that iron deficiency moderately alters ASR signaling although the inhibitory pathways of ASR do not appear to be affected.

Ferritin subunits in CSF are decreased in restless legs syndrome

Restless legs syndrome (RLS) is a neurological disorder that may be related to iron misregulation at the level of the central nervous system. Evidence that iron is involved in RLS comes from magnetic resonance imaging data, autopsy studies, analyses of cerebrospinal fluid (CSF), and correlations of symptoms with serum ferritin. To further examine the possibility that brain iron status is insufficient in RLS, we determined ferritin levels in the CSF. Specifically, we differentiated between the H- and L-subunits of ferritin, because these peptides are expressed from different chromosomes and have different functions. We measured H- and L-ferritin subunit levels in control and RLS human CSF using immunoblot analysis and found that both H- and L-ferritin are significantly decreased in early but not late-onset RLS. Additionally, we quantified total protein in each CSF sample to establish that the decrease in ferritin subunits in RLS did not reflect a decrease in total protein in CSF. Furthermore, we used equal amounts of total CSF protein in the immunoblot analyses, in contrast to previously published studies that provided only volumetric data, to determine which approach was more accurate for quantifying the amount of ferritin relative to other proteins in CSF. Our results establish a protein standard in RLS, provide a comparative analysis of protein-controlled versus volumetric immunoblot techniques, and argue for a profound loss of iron storage capacity in the brain in RLS, specifically in the early onset RLS phenotype. These data suggest that CSF ferritin levels may provide a biomarker for assisting in the diagnosis of RLS.

Cellular iron concentrations directly affect the expression levels of norepinephrine transporter in PC12 cells and rat brain tissue

Neurological development and functioning are adversely affected by iron deficiency in early life. Iron-deficient rats are known to have elevations in extracellular DA and NE, suggesting alterations in reuptake of these monoamines. To explore possible mechanisms by which cellular iron concentrations may alter NE transporter functioning, we utilized NET expressing PC12 cells and iron-deficient rats to explore the relationship between NET protein and mRNA expression patterns and iron concentrations. Treatment of PC12 with the iron chelator, desferrioxamine mesylate (DFO, 50 microM for 24 h), significantly decreased [3H] NE uptake by more than 35% with no apparent change in Km. PC12 cells exposed to increasing concentrations of DFO (25-100 microM) exhibited a dose response decrease in [3H] NE uptake within 24 h (38-73% of control) that paralleled a decrease in cellular NET protein content. Inhibition of protein synthesis with cycloheximide resulted in NET disappearance rates from DFO-treated cells greatly exceeding the rate of loss from control cells. RT-PCR analysis revealed only a modest decrease in NET mRNA levels. Rat brain locus ceruleus and thalamus NET mRNA levels were also only modestly decreased (10-15%) despite a 40% reduction in regional brain iron. In contrast, NET proteins levels in thalamus and locus ceruleus were strongly affected by regional iron deficiency with high correlations with iron concentrations (r > 0.94 and r > 0.80 respectively). The present findings demonstrate that NET protein concentrations and functioning are dramatically reduced with iron deficiency; the modest effect on mRNA levels suggests a stronger influence on NET trafficking and degradation than on protein synthesis.

Iron deficiency affects acoustic startle response and latency, but not prepulse inhibition in young adult rats

Iron deficiency is associated with alterations in dopamine and serotonin transporters as well as changes in dopamine receptor (DR) density, monoamine concentrations, and in vivo extracellular contents of monoamines in terminal fields. Human infants with iron deficiency have both delayed maturation as well as lengthened central conduction times in auditory evoked potential studies. The current study utilizes the magnitude of the acoustic startle response (ASR), prepulse inhibition (PPI), and mean latency to maximum startle response (T(max)), to examine the functional integrity of response to environmental cues. Male and female rats consumed iron deficient (ID) or iron adequate (CN) diets from weaning until adulthood. ID rats of both sexes had 20-60% reductions in ASR when compared to CN rats but there was no effect on PPI. T(max) was significantly longer by 10-20% in females, but not males. Dopamine transporter density was significantly lower in putamen, nucleus accumbens, and olfactory tubercle in males, but not female rats while the serotonin transporter was significantly different from control animal density in five of 14 brain regions. Norepinephrine transporter density was lower in the locus ceruleus of ID male rats but was unaffected in ID female rats. Regression modeling of ASR with brain monoamine transporters and receptors showed hematocrit, norepinephrine transporter (NET) in dentate gyrus, and D1R in the nucleus accumbens account for nearly 49% of the variance in ASR. T(max) was not significantly associated with any of the independent variables. We conclude that iron deficiency affects the startle response, but not the inhibitory circuits involved in prepulse inhibition. Importantly, sex also strongly influenced these behavioral responses. Future studies, perhaps pharmacologic in nature, are necessary to ascertain whether iron deficiency modifies the contribution of monoaminergic systems to responses to environmental stimuli.