Iron in sickle cell disease: a review why less is better

Sickle cell anemia (SCA) is an inherited disorder of hemoglobin synthesis that is characterized by life-long severe hemolytic anemia, attacks of pain crisis, and chronic organ system damage. A third of the hemolysis in SCA is intravascular and the resulting urinary losses of iron may lead to iron deficiency. There is no evidence of iron overload in SCA and iron deficiency may be more common than suspected, especially in men. Absence of bone marrow iron remains a gold standard for the diagnosis of iron deficiency in these patients. Although low serum ferritin is highly specific for the diagnosis of iron deficiency, its sensitivity is quite low in SCA because of non-specific elevation due to increased red cell turnover. The kinetics of sickling is strongly concentration dependent such that small decreases in the mean corpuscular deoxyhemoglobin-S concentration (MCHC-S) cause a substantial delay in sickle hemoglobin polymerization. Prolongation of the "delay time of gelation" in excess of the capillary transit time may allow the erythrocyte to traverse the capillary bed to escape to the arterial side before there is rheologic impairment of the erythrocyte from polymerization of sickle hemoglobin. Overt iron deficiency lowers the MCHC-S and thereby decreases the sickling tendency and the severity of hemolysis. The clinical improvement in SCA following the induction of iron deficient erythropoiesis by repeated phlebotomies or by erythrocytapheresis has been reported. Prospective controlled studies are needed to evaluate further, the therapeutic strategy of inducing controlled iron-deficient erythropoiesis in selected patients with SCA.

A micronutrient-fortified beverage prevents iron deficiency, reduces anemia and improves the hemoglobin concentration of pregnant Tanzanian women

Maternal malnutrition continues to be a major contributor to adverse reproductive outcomes in developing countries, despite longstanding efforts to fortify foods or to distribute medicinal supplements to pregnant women. The objective of this study was to test the effect of a micronutrient-fortified beverage containing 11 micronutrients (iron, iodine, zinc, vitamin A, vitamin C, niacin, riboflavin, folate, vitamin B-12, vitamin B-6 and vitamin E) on the hemoglobin, iron and vitamin A status of pregnant women in Tanzania. A group of 259 pregnant women with gestational ages of 8 to 34 wk were enrolled in a randomized double-blind controlled trial in which study women received 8 wk of supplementation. Hemoglobin, ferritin and dried blood spot retinol were measured at baseline and at the end of the supplementation period. The supplement resulted in a 4.16 g/L increase in hemoglobin concentration and a 3 micro g/L increase in ferritin and reduced the risk of anemia and iron deficiency anemia by 51 and 56%, respectively. The risk of iron deficiency was reduced by 70% among those who had iron deficiency at baseline and by 92% among those who had adequate stores. The micronutrient-fortified beverage may be a useful and convenient preventative measure, one that could help improve the nutritional status of women both before and during pregnancy and thereby help avoid some of the potential maternal and fetal consequences of micronutrient deficiencies.

No significant effect of iron deficiency on cadmium body burden or kidney dysfunction among women in the general population in Japan

OBJECTIVE

To examine if iron-deficient conditions modify body burden or health effects of cadmium among women in the general population in Japan.

METHODS

In 2002, 1,482 women aged 20 to 74 years in six prefectures in Japan provided informed consent to participate in this study. They offered peripheral blood and spot urine samples, and answered questionnaires on their social habits and health conditions. Never-smoking, non-pregnant and non-lactating healthy women (1,190 subjects) were selected from the volunteers. Blood samples were analyzed for serum iron, ferritin and total iron-binding capacity (TIBC) in addition to red blood cell (RBC) counts and hemoglobin (Hb) concentration as markers of anemia and iron deficiency. Urine samples were analyzed for cadmium (Cd), alpha(1)-microglobulin (alpha(1)-MG), beta(2)-microglobulin (beta(2)-MG) as markers of Cd burden and Cd-induced tubular dysfunction; the measures were expressed after being corrected for creatinine (cr) as, e.g., Cd-Ucr.

RESULTS

The subjects were classified into anemic (37 women) and iron-deficient (388 women) groups separately from healthy controls (765 women), taking ferritin (<20 ng/ml) and Hb (<10 g/100 ml) as classification indicators. Strictly matched pairs (with regard to age and prefecture) were established for 36 anemic and 280 iron-deficient cases. Comparison between the cases and the matched controls showed that serum iron was lower and TIBC was higher in accordance with lower levels of ferritin and Hb in the anemic and iron-deficient groups, although the RBC count was only slightly reduced (the anemic group) or stayed essentially unchanged (the iron-deficient group). In contrast, no significant increase in Cd-Ucr, alpha(1)-MG, or beta(2)-MG was observed in either the anemic group or the iron-deficient group compared with the matched controls. Cd-Ucr in one case of clinical anemia, however, tended to be higher than the levels among women of the same age range and from the same prefecture. Her alpha(1)-MG-Ucr and beta(2)-MG-Ucr, however, remained un-elevated.

CONCLUSIONS

The current level of iron deficiency among women in the general population in Japan may not induce significant increase in Cd body burden or Cd-induced tubular dysfunction.

Novel roles for iron regulatory proteins in the adaptive response to iron deficiency

Iron regulatory proteins (IRP) modulate the use of mRNA-encoding proteins that are involved in the transport, storage and use of iron. Several new potential mRNA targets for IRP were recently identified: divalent metal transporter-1 (DMT-1) and ferroportin, which are critical regulators of iron absorption in the gut and of iron cycling between various tissues of the body. Although this may extend the reach of IRP to other processes that are important for maintaining body iron homeostasis, the extent to which IRP modulate other physiological processes that are altered in response to changes in iron availability is not clear. However, in the past several years, targets for IRP and IRP-like proteins were identified in eukaryotes and prokaryotes in the tricarboxylic acid (TCA) cycle and electron-transport chain. In mammals, this includes the mRNA that encodes the TCA-cycle enzyme mitochondrial aconitase (m-acon). Recent work established that m-acon expression is translationally regulated by iron in a manner that is strongly correlated with IRP RNA-binding activity. Interestingly, these studies also demonstrate that IRP regulate their mRNA targets in a hierarchical manner. The changes in m-acon synthesis and abundance in liver during iron deficiency fail to affect TCA-cycle capacity but are associated with a significant upregulation of mitochondrial export of radiolabeled citrate. We conclude that IRP are required for the regulation of physiological pathways that include but are not limited to iron metabolism, and as such, IRP are critical factors in the adaptive response to iron deficiency.

Patients over 45 years with iron deficiency require investigation

BACKGROUND

Iron deficiency anaemia (IDA) that occurs in patients above the age of 45 years is often caused by gastrointestinal blood loss, and guidelines on the appropriate investigation of these patients have been published. There are few data regarding patients with iron deficiency who are not anaemic and it is not clear how these patients should be managed.

OBJECTIVES

We set out to investigate the hypothesis that similar pathologies are likely to underlie iron deficiency and IDA, and to assess whether IDA was being investigated according to the guidelines published by the British Society of Gastroenterology (BSG).

METHODS

The pathology computer identified 153 consecutive patients over the age of 45 years who had serum ferritin levels below 20 microg/dl (normal range 20-200 microg/dl) in a 2 month period (i.e., October and November 2000). Medical records were examined and we recorded all investigations, the diagnoses reached, and the investigating specialty. The results were compared using odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

The study shows that the causes of iron deficiency and IDA are similar, but IDA is investigated more thoroughly than iron deficiency, OR 2.07 (CI 1.08-3.97). Ten patients with iron deficiency without anaemia were found to have coeliac disease, a significant result, OR 6.71 (CI 1.38-32.6). The majority of patients with IDA are not under the care of a gastroenterologist and this group are significantly less likely to be investigated according to the BSG guidelines, OR 0.15 (0.04-0.6).

CONCLUSIONS

The study shows that the yield of investigation of iron deficiency is high and, hence, it should be investigated in all patients over the age of 45 years. Despite guidelines published by the BSG, IDA is investigated sub-optimally and measures other than the issuing of guidelines are needed to change practice.

Iron deficiency alters brain development and functioning

Iron deficiency anemia in early life is related to altered behavioral and neural development. Studies in human infants suggest that this is an irreversible effect that may be related to changes in chemistry of neurotransmitters, organization and morphology of neuronal networks, and neurobiology of myelination. The acquisition of iron by the brain is an age-related and brain-region-dependent process with tightly controlled rates of movement of iron across the blood-brain barrier. Dopamine receptors and transporters are altered as are behaviors related to this neurotransmitter. The growing body of evidence suggests that brain iron deficiency in early life has multiple consequences in neurochemistry and neurobiology.

Approaches to improve iron bioavailability from complementary foods

The importance of trace element bioavailability in the etiology of nutritional deficiencies, for example in the etiology of iron deficiency and iron deficiency anemia, can be expected to be most pronounced in individuals with high requirements. Of special concern is the situation in poor communities where infants and young children are consuming monotonous, cereal-based diets. Traditionally, cereal-based gruels are often one of the first semisolid foods to be introduced into the infant's diet. These foods can be expected to have low energy and nutrient density as well as low bioavailability of iron due to the presence of phytic acid. Ascorbic acid is a potent enhancer of non-heme iron absorption that can overcome the inhibiting effect of phytic acid when present in high enough quantities. However, home prepared complementary foods based on cereals and legumes contain negligible amounts of ascorbic acid unless ascorbic acid-rich foods are mixed with the cereal or consumed at the same time. Different approaches to improve iron bioavailability from plant-based complementary foods, e.g., by enzymatic degradation of phytic acid and/or by increased consumption of ascorbic acid-rich foods, should be explored and adapted to local conditions. In addition, there is a need to evaluate efficacy and effectiveness of strategies to increase the dietary intake of bioavailable iron by dietary diversification and food fortification under realistic conditions.

The quantitative assessment of body iron

Current initiatives to reduce the high prevalence of nutritional iron deficiency have highlighted the need for reliable epidemiologic methods to assess iron status. The present report describes a method for estimating body iron based on the ratio of the serum transferrin receptor to serum ferritin. Analysis showed a single normal distribution of body iron stores in US men aged 20 to 65 years (mean +/- 1 SD, 9.82 +/- 2.82 mg/kg). A single normal distribution was also observed in pregnant Jamaican women (mean +/- 1 SD, 0.09 +/- 4.48 mg/kg). Distribution analysis in US women aged 20 to 45 years indicated 2 populations; 93% of women had body iron stores averaging 5.5 +/- 3.35 mg/kg (mean +/- 1 SD), whereas the remaining 7% of women had a mean tissue iron deficit of 3.87 +/- 3.23 mg/kg. Calculations of body iron in trials of iron supplementation in Jamaica and iron fortification in Vietnam demonstrated that the method can be used to calculate absorption of the added iron. Quantitative estimates of body iron greatly enhance the evaluation of iron status and the sensitivity of iron intervention trials in populations in which inflammation is uncommon or has been excluded by laboratory screening. The method is useful clinically for monitoring iron status in those who are highly susceptible to iron deficiency.

Nutrient intake and iron status of urban poor and rural poor without access to rice fields are affected by the emerging economic crisis: the case of pregnant Indonesian women

OBJECTIVE

We evaluated the adequacy of nutrient intake in comparison with the Indonesian Estimated Average Requirement (EARs) among pregnant Indonesian women and explain the short-term effect of economic crisis on nutrient intake and iron status.

DESIGN

Cross-sectional study.

SETTING

Purworejo District, Central Java, located 60 km west of Yogyakarta Province, Indonesia.

SUBJECTS

During the period from 1996 to 1998, up to six 24 h recalls were performed during the second trimester of pregnancy among 450 women. Nutrient intake and iron status was evaluated in relation to date of data collection relative to the economic crisis that emerged in August 1997. A computer program (Inafood) was developed to calculate nutrient intake.

RESULTS

: Forty percent of the pregnant women were at risk of inadequate intake of energy and protein, and 70% were at risk of inadequate intake of vitamin A, calcium and iron even before the crisis. Our results also demonstrate an effect of short-term economic crisis on nutrient intake and iron status. When the crisis emerged, urban poor experienced a decrease in intake of most nutrients. During the crisis, rich women experienced a significant decrease in fat (P<0.05). Negative changes in fat density during crisis were experienced by the rich and the rural, poor, and access to rice field subgroups (P<0.01). A significant increase in carbohydrate densities was seen for the rich and rural, poor, and access to rice fields groups (P<0.05). Urban poor experienced decreased serum ferritin concentration (P<0.05), whereas rich women experienced a significant increase (P<0.05).

CONCLUSIONS

Urban poor and rural poor landless women were most directly affected by the emerging economic crisis.

Iron status at 12 months of age -- effects of body size, growth and diet in a population with high birth weight

OBJECTIVE

To investigate effects of growth and food intake in infancy on iron status at the age of 12 months in a population with high birth weight and high frequency of breast-feeding.

DESIGN

In a longitudinal observational study infants' consumption and growth were recorded. Weighed 2 day food records at the ages of 6, 9 and 12 months were used to analyse food and nutrient intake.

SETTING

Healthy-born participants were recruited from four maternity wards. Blood samples and growth data were collected from healthcare centres and food consumption data at home.

SUBJECTS

Newborn infants (n=180) were selected randomly according to the mother's domicile and 77% (n=138) participated, of them, 83% (n=114), or 63% of original sample, came in for blood sampling.

RESULTS

Every fifth child was iron-deficient (serum ferritin <12 microg/l and mean corpuscular volume<74 fl) and 2.7% were also anaemic (Hb<105 g/l). Higher weight gain from 0 to 12 months was seen in infants who were iron-deficient at 12 months (6.7+/-0.9 kg) than in non-iron-deficient infants (6.2+/-0.9 kg) (P=0.050). Serum transferrin receptors at 12 months were positively associated with length gain from 0 to 12 months (adjusted r(2)=0.14; P=0.045) and mean corpuscular volume negatively to ponderal index at birth (adjusted r(2)=0.14; P=0.019) and 12 months (adjusted r(2)=0.17; P=0.006). Iron-deficient infants had shorter breast-feeding duration (5.3+/-2.2 months) than non-iron-deficient (7.9+/-3.2 months; P=0.001). Iron status indices were negatively associated with cow's milk consumption at 9-12 months, significant above 460 g/day, but were positively associated with iron-fortified breakfast cereals, fish and meat consumption.

CONCLUSIONS

: In a population of high birth weight, iron deficiency at 12 months is associated with faster growth and shorter breast-feeding duration from 0 to 12 months of age. The results suggest that a diet of 9-12-month-olds should avoid cow's milk above 500 g/day and include fish, meat and iron-fortified breakfast cereals to improve iron status.

Neonatal iron deficiency results in irreversible changes in dopamine function in rats

Iron deficiency in human infants and in young animal models produces changes in neural functioning that may be related to monoamine metabolism. This study employed both behavioral and biochemical approaches in a design using cross-fostering to examine alterations in dopamine (DA) function when iron deficiency occurs during the neonatal period. We measured brain Fe, dopamine transporters (DAT) and dopamine receptor density in rats made iron deficient, or not, from postnatal day (PND) 4 to PND 14 or 21. Some pups were then weaned to an iron-deficient diet and others to the control diet to examine the reversibility of these effects. Behaviors related to dopamine function were measured. Dopamine D(2) receptor (D(2)R), D(1)R and iron concentrations were approximately 70, 80 and 30% of control values, respectively, in the nucleus accumbens and striatum in iron-deficient rats at PND 14. The DAT density was also reduced to 50% of control density in the nucleus accumbens but was unchanged in the striatum. By PND 21, there was also a significant 50% lowering of DAT, D(1)R and D(2)R densities in the prefrontal cortex (PFC). Iron repletion at PND 21-49 normalized D(1)R, D(2)R, and DAT levels in the nucleus accumbens, PFC and ventral midbrain but not in the striatum. In summary, neonatal iron deficiency is associated with changes in DA biology that vary with duration of iron deficiency, and are not completely normalized despite replenishment of iron status. Changes in DA-related behaviors that were persistent after postweaning iron repletion suggest the existence of a critical neonatal developmental period that is expressed by alterations in DA functioning.

A randomized trial investigating an iron-rich natural mineral water as a prophylaxis against iron deficiency in pregnancy

Spatone Iron-Plus is a naturally occurring mineral water from Trefriw Wells Spa in Conwy County, North Wales, UK. It contains approximately 0.20 mg of iron per millilitre as ferrous sulphate and has been shown to provide iron in a highly bio-available form. A 24 ml sachet contains approximately 5 mg of iron. Iron deficiency is common in the obstetric population. However, compliance with traditional iron supplements is poor because of gastrointestinal side-effects. We designed a randomized, double-blind, placebo-controlled trial. A total of 102 low-risk antenatal patients, who were noncompliant with routinely prescribed ferrous sulphate tablets, were randomized to receive 48 ml of Spatone water or placebo. The study was conducted between 22 and 28 weeks gestation. Primary outcome measures were compliance, gastrointestinal side-effects and changes in ferritin levels during the trial period. Compliance in the intervention group was 57% compared with 67% in the control group, P = 0.22. Dyspepsia scores, as determined by a recognized and well-validated questionnaire, did not differ between the two groups. During the trial period, mean ferritin levels fell by 24% in the Spatone Iron-Plus group compared with a mean fall of 51% in ferritin levels among the control group, P = 0.016.

Iron solutions: acquisition strategies and signaling pathways in plants

Iron is an essential nutrient for plants and crucial for a variety of cellular functions. In most soils, iron is present in large quantities, but mainly in forms that are not available to plants. Mobilization of iron by plants is achieved by different strategies, either by secretion of plant-borne chelators or by reductive and proton-promoted processes. These reactions, and subsequent uptake of Fe via specific transporters, are increased when the Fe requirements of the plant are not being met. When iron is taken up in excess of cellular needs, toxic oxygen radicals can form. Therefore, plants must tightly regulate iron levels within the cell. This article presents recent progress towards an integrative picture of how iron is sensed and acquired.

[Developmental expression and regulation of divalent metal transporter 1 in rat heart]

OBJECTIVE

To investigate the expression of divalent metal transporter 1 (DMT1) mRNA in male Sprague-Dawley rat heart of different ages and the expression of DMT1 regulated by dietary iron.

METHODS

Reverse transcriptase (RT)-PCR and Western blot were used in this study.

RESULTS

(1)Two isoforms of DMT1 mRNA [with and without iron-responsive element (IRE)] were both detected in rat heart, which were correlated with heart iron content. During development, both of two isoforms of DMT1 mRNA expression were the lowest at the age of PND 7, and increased at PND 21, 63 to 196. (2) After fed with a high iron diet or low iron diet for 6 weeks, the rats developed iron overload or iron deficiency respectively. No significant differences in DMT1 mRNA expression were detected among iron overload, iron deficiency and control rats. By using Western blot analysis, a 21% and 40% reduction in DMT1 protein non IRE form and IRE form respectively were found in iron overload rat (P<0.01, compared with control). Increases (26% approximate, equals 28%) in the levels of two isoforms of DMT1 protein were also observed in iron deficient rat (P<0.01, compared with control).

CONCLUSION

The level of DMT1 mRNA expression in heart is age dependent;the two isoforms of DMT1 protein may be both regulated by iron on the posttranscriptional mechanism.

Duodenal mucosal reductase in wild-type and Hfe knockout mice on iron adequate, iron deficient, and iron rich feeding

BACKGROUND

Genetic haemochromatosis is a common hereditary iron loading disorder in humans. The disease is associated with loss of function mutations in the HFE gene. This is thought to change iron stores via increased iron absorption.

AIMS

In this study we investigated how adaptation of mucosal reductase activity is engaged in this process and how the changes compare with adaptation seen when an iron deficient diet is fed.

METHODS

Duodenal mucosal surface reductase was measured with nitroblue tetrazolium in age matched groups of male Hfe knockout mice (Hfe) and wild- type mice fed a purified diet containing normal (iron adequate), high (iron rich), or low (iron deficient) iron concentrations.

RESULTS

Reductase activity increased when mice were fed an iron deficient diet and decreased when they were fed an iron rich diet. Total villus activity, as measured by the average area under the activity curve along the crypt-villus axis, was increased 2.8-2.9-fold by iron deficiency in both genotypes. Approximately half of this difference was attributable to the significantly increased length of the villi in mice on an iron deficient diet (p<0.05). Hfe knockout did not affect villus length but increased mucosal reductase activity near the villus tips. Similar increases (1.3-1.6-fold) were seen on all diets but the increase was significant for iron deficient and iron loaded diets only (p<0.05).

CONCLUSION

Hfe gene product and dietary iron downregulate villus reductase activity in mice.

Comparing nutrient intake from food to the estimated average requirements shows middle- to upper-income pregnant women lack iron and possibly magnesium

OBJECTIVE

To determine whether nutrient intake from food alone was adequate across trimesters for middle- to upper-income pregnant women when compared with estimated average requirements (EAR), and to determine whether food intake exceeded the tolerable upper intake level (UL) for any nutrient.

DESIGN

Observational study in which pregnant women completed 3-day diet records each month during their pregnancy. Records were analyzed for nutrient content, and usual intake distributions were determined.

SUBJECTS/SETTING

Subjects were low-risk women in their first trimester of pregnancy (living in middle- to upper-income households). Ninety-four women were recruited, and sixty-three participated.

STATISTICAL ANALYSIS PERFORMED

Nutrient intake data were adjusted to achieve normality by using a power transformation. A mixed model method was used to assess trends in intake over time, and to estimate mean intake and within-subjects and between-subjects variance. The usual intake distribution for each nutrient was determined and compared with the EAR and UL.

RESULTS

The probabilities of usual nutrient intake from food being less than the EAR were highest for iron (.91), magnesium (.53), zinc (.31), vitamin B6 (.21), selenium (.20), and vitamin C (.12). Women were not at risk of exceeding the UL from food intake for any nutrient studied.

APPLICATIONS/CONCLUSIONS

Study participants did not consume adequate amounts of iron from food to meet the needs of pregnancy, and therefore iron supplementation is warranted in this population. Intake of magnesium was suboptimal using the EAR as a cut-point for adequacy.

Effects of haemoglobin and serum ferritin on cognitive function in school children

The association between iron deficiency anaemia and cognitive function impairment has been widely reported in young children, but whether the impairment is a result of iron deficiency per se or a combination of iron deficiency and anaemia, and how these conditions interact, is still questionable. Four hundred and twenty-seven school children from two schools in socioeconomically deprived communities were selected in southern Thailand. Iron status was determined by haemoglobin and serum ferritin concentrations. Cognitive function in this study was measured by IQ test and school performance, including Thai language and mathematics scores, using z-scores based on distributions within the same grade and school. Data on demography and socioeconomic status were collected by questionnaire answered by the parents. Linear regression models were used to investigate the effect of anaemia and iron deficiency, reflected by haemoglobin and serum ferritin concentration, on cognitive function and school performance. We found that cognitive function increased with increased haemoglobin concentration in children with iron deficiency, but did not change with haemoglobin concentration in children with normal serum ferritin level. Children with iron deficiency anaemia had consistently the poorest cognitive function (IQ, 74.6 points; Thai language score, 0.3 SD below average; and mathematics score, 0.5 SD below average). Children with non-anaemic iron deficiency but with high haemoglobin levels had significantly high cognitive function (IQ, 86.5 points; Thai language score, 0.8 SD above average; and mathematics score, 1.1 SD above average). This study found a dose-response relationship between haemoglobin and cognitive function in children with iron deficiency, whereas no similar evidence was found in iron sufficient children.

Zinc and iron status during pregnancy of Filipino women

Low birthweight is associated with maternal anaemia and, in some circumstances, with low iron and zinc status, but this relationship has not been investigated in the Philippines. In this study, we assessed the prevalence of anaemia and suboptimal iron and zinc status in pregnant women from three geographical regions (mountain, coast, city) of Zamboanga del Sur province at 24 weeks (n = 305). and again at 36 weeks (n = 127), gestation. At 24 weeks, 34% were anaemic (i.e., haemoglobin < 105 g/L) from all causes, of whom only 14% had concomitant low serum ferritin values (i.e., < 12 microg/L). The presence of infection was low, based on both elevated white blood cell count (> 11 x 10(9)/L; 19%) and serum C-reactive protein (> 15 mg/L; 3%). Of the women surveyed, 20% were iron depleted but not anaemic, and 15% were zinc deficient (i.e., serum zinc < 7.1 Micromol/L). The mean (+/- SD) birthweight of the infants (n = 250) was 3074 g +/- 408 g, of whom 5% were of low birthweight (< 2500 g). No differences existed for biochemical indices or birthweight among the three regions, or between women consuming maize or rice-based diets. Women with low haemoglobin (P = 0.05) and low serum zinc (P = 0.14) values at 24 weeks gestation had infants with lower birthweights than those with values > or = 105 g/L and > or = 7.1 micromol/L, respectively. However, in the multivariate model, the contribution of maternal haemoglobin to the variance in birthweight at 24 weeks gestation was non-significant, although modest for serum zinc. Anaemia and/or suboptimal zinc status during pregnancy may be related to low birthweight in the Philippines, and their aetiology deserves further study.

Different behaviour of 63Ni and 59Fe during absorption in iron-deficient and iron-adequate jejunal rat segments ex vivo

Nickel exhibits low oral toxicity. It shares the absorptive pathways for iron, though there are substantial quantitative differences in handling of both metals. To analyse these differences more closely, jejunal segments from iron-deficient and iron-adequate rats were luminally perfused ex vivo with 59Fe and 63Ni at six different concentrations (1-500 micromo1/l) under steady state conditions. 59Fe over-all absorption increased 2.0-4.6-fold in iron-deficiency at luminal concentrations between 1 and 100 micromol/l, while 63Ni absorption increased to a much lower extent (2.6-fold at 1 micromol/l and 1.5-fold at higher luminal concentrations). Moreover, there was a 5-7-fold higher concentration for 63Ni in the jejunal tissue than in the absorbate at luminal concentrations above 50 micromol/l which was not observed at 1 micromol 63Ni/l and not for 59Fe. 63Ni tissue load showed a linear and a saturable fraction. In iron-deficiency the saturable 63Ni fraction increased 4-fold as compared to only 1.5-fold increments for 59Fe. Moreover, a substantially higher share of 63Ni was retained in the jejunal tissue at high as compare to low luminal concentrations after perfusion had been continued without luminal radioactivity. This was not found for 59Fe and suggests a concentration-dependent block of 63Ni export across the enterocytes' basolateral membrane. To explain these results one may speculate that 63Ni may bind more tightly to tissue ligands than 59Fe due to the higher thermodynamic and kinetic stability of nickel complexes. In particular, nickel may bind to a basolateral population of metal carriers and block its own basolateral transfer in a concentration-dependent manner. Tight 63Ni binding to non-specific jejunal ligands is responsible for the unaltered high linear fraction of jejunal 63Ni load in iron-deficient and iron-adequate segments. Binding of 63Ni to food and tissue ligands in the small intestine may, thus, be a likely explanation for the low oral nickel toxicity.

Differential effects of iron deficiency on the expression of CD80 and CD86 co-stimulatory receptors in mitogen-treated and untreated murine spleen cells

The interaction of CD28 and its ligands (CD80, CD86) on antigen presenting cells and that of TCR/CD3-MHC are required for T lymphocyte activation. To determine whether impaired lymphocyte proliferation associated with iron deficiency is due to reduced expression of these ligands, spleen cells obtained from eight to nine C57BL/6 mice/group of iron deficient (ID), iron replete (R), control (C), pair-fed (PF), and high iron (HI) mice were labeled with anti-CD80-fluorescein isothiocyante (FITC) and anti-CD86-FITC. Diets differed only in iron concentration: 5, 50, and 125 mg/kg for the ID, C, and HI, respectively. Mean levels of hemoglobin and liver iron stores of ID and R mice were less than 50% those of C mice (P < 0.005). In non-activated and concanavalin A-treated cultures, significant differences were observed among groups in the percentage of CD80 + cells: ID>R > C = PF = HI (P < 0.05). The same trend was observed for CD86 + cells (P > 0.05). Fluorescence intensity (FI) of either marker did not significantly change by iron status. In vitro iron chelation by deferoxamine (20, 200 microg/ml) for 1, 2, and 24 h increased FI of both markers on unactivated B and T cells (P < 0.05). However, it had no effect on FI of either marker of mitogen-treated cells presumably because the maximum levels are achieved by the mitogen. Lymphocyte proliferative responses to mitogens positively and significantly correlated with CD80 and CD86 FI (r = 0.41-0.59) but negatively correlated with the percentages of CD80 + cells (r = -0.48) (P < 0.05). Data suggest that impaired lymphocyte proliferation associated with iron deficiency is not due to reduced CD80 and CD86 expression.

Tumour necrosis factor-alpha transcription in transferrin-stimulated human blood mononuclear cells: is transferrin receptor involved in the signalling mechanism?

Transferrin (Tf) and tumour necrosis factor-alpha (TNF-alpha) participate in immune response regulation. We studied the capacity of Tf to modulate 'in vitro' TNF-alpha secretion, membrane expression and transcription by human blood mononuclear cells (BMNC). Women 25-45 years of age with normal iron status (n = 20) or with iron deficiency (ID, n = 20) due to gynaecological bleeding were studied. BMNC were incubated with different proportions of Fe-exempt and Fe-saturated Tf (apo-Tf:holo-Tf). Apo-Tf or holo-Tf uniformly induced TNF-alpha secretion in the cell supernatants from both groups. Nevertheless, cytokine levels were significantly lower in ID subjects. For all Tf-Fe saturations assayed, mean TNF-alpha levels varied between 1.4-1.6 ng/ml and 0.4-0.7 ng/ml for normal and ID women respectively (P < 0.001). The addition of apo-Tf enhanced TNF-alpha secretion in a dose-dependent manner, but the cytokine levels were lower in ID group. Tf did not induce pro-TNF-alpha expression in monocytes and lymphocytes from either group. Tf-treated cells from normal individuals expressed approximately two to three times more TNF-alpha mRNA than cells from ID subjects. Mean values ranged 96-110 atmol/ml in normal women and 24-31 atmol/ml in ID women for all Tf-Fe saturation levels tested (P < 0.001). These results show that Tf-induced TNF-alpha secretion is transcriptionally regulated. The impaired TNF-alpha transcription in cells from ID subjects indicates that the quality of the immune response is linked to the Fe status of mononuclear cells.

The role of the placenta in iron transfer from mother to fetus and the relationship between iron status and fetal outcome

During pregnancy, iron is transferred from the mother to the fetus across the placenta. The mechanism has been extensively studied. Altered iron metabolism changes transfer, but also has other consequences. In this review, we examine how the placenta adapts to altered iron supply, both in terms of changing cytokine expression and in relation to the proteins of iron transfer. Changing iron levels alters the levels of other metals, especially copper, and we review how this is related to changing function. There are also consequences to the placenta itself, to vascularisation and other aspects of the physiology. In turn, this has effects on the fetus and we review how growth and development are modified. Finally, we examine in more detail the efflux process, how it is regulated and, especially, the putative role of the placental Cu oxidase in the efflux process. As appropriate, we draw on data from humans, from animal models and from cell culture systems to illustrate the information.

[Iron and vitamin A deficiencies and prevalence of anemia in boys and girls between 6 to 24 months of age in Chaco, Argentina]

To determine the prevalence of anemia, and iron (ID) and vitamin A deficiencies aiming at their prevention, 414 children between 6 and 24 months of age, were randomly selected from the whole province of Chaco. A sociodemographic survey was implemented, and hemoglobin (Hb), plasma ferritin and retinol were measured. Anemia prevalence (Hb < 110 g/L) was 66.4%, without differences between age groups, and included 18% with Hb < 90 g/L. These cases were significantly less in children 6-8 month of age (5.1%) than in the others (approximately equal to 20%) (P: 0.007). Mean Hb was also higher in 6-8 months old children and was associated with lower prevalence of ID (ferritin < 12 micrograms/L) (p < 0.000) but not with age (p = 0.8865). ID already present, however, in 36.6% of children in this age group, reached a prevalence of 72.9% in children older than 18 months. Anemia prevalence was significantly higher in males, in children whose birth weight was < 3000 g, in those who had never taken iron supplements and among the poor, both structural and by income. Retinol values < 20 micrograms/dl occurred only in 5.1% of children. Iron nutrition prior to, during pregnancy and in children during the first 2 years of life must be improved by joining strategies based on community empowerment aimed at improving dietary iron, assuring effective preventive supplementation and promoting the opportune umbilical cord ligation.