Indicators of erythrocyte formation and degradation in rats with either vitamin A or iron deficiency

Neurotoxic Anatoxin-a Can Also Exert Immunotoxicity by the Induction of Apoptosis on Carassius auratus Lymphocytes in vitro When Exposed to Environmentally Relevant Concentrations

Hazardous anatoxin-a (ANTX-a) is produced by freshwater algal blooms worldwide, which greatly increases the risk of consumer exposure. Although ANTX-a shows widespread neurotoxicity in aquatic animals, little is known about its mechanism of action and biotransformation in biological systems, especially in immunobiological models. In this study, transmission electron microscopy results showed that ANTX-a can destroy lymphocytes of Carassius auratus in vitro by inducing cytoplasmic concentration, vacuolation, and swollen mitochondria. DNA fragmentations clearly showed a ladder pattern in agarose gel electrophoresis, which demonstrated that the apoptosis of fish lymphocytes was caused by exposure to ANTX-a. Flow cytometry results showed that the apoptotic percentage of fish lymphocytes exposed to 0.01, 0.1, 1, and 10 mg/L of ANTX-a for 12 h reached 18.89, 22.89, 39.23, and 35.58%, respectively. ANTX-a exposure induced a significant increase in reactive oxygen species (ROS) and malonaldehyde (MDA) in lymphocytes. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and the glutathione (GSH) content of the 0.01 mg/L ANTX-a-treated group decreased significantly by about 41, 46, 67, and 54% compared with that of the control group (p < 0.01), respectively. Although these observations were dose-dependent, these results suggested that ANTX-a can induce lymphocyte apoptosis via intracellular oxidative stress and destroy the antioxidant system after a short exposure time of only 12 h. Besides neurotoxicity, ANTX-a may also be toxic to the immune system of fish, even when the fish are exposed to environmentally relevant concentrations, which clearly demonstrated that the potential health risks induced by ANTX-a in aquatic organisms requires attention.

Influence of Dietary Vitamin A and Iron Deficiency on Hematologic Parameters and Body Weight of Young Male Wistar Rats

Micronutrient deficiency is one of the most prominent public health concerns; in particular, vitamin A and iron are determinants of appropriate development, and vitamin A influences iron homeostasis and metabolism. Here we compared the effects of diets that were sufficient and insufficient in vitamin A and iron on the hematologic parameters and body weight of rats. Male Wistar rats were randomly divided into 5 dietary groups (n = 7 per group): adequate in iron and vitamin A (control); adequate in iron but low in vitamin A (FesvAi); adequate in iron but lacking vitamin A (FesvAd); low in iron but adequate in vitamin A (FeivAs); and low in both iron and vitamin A (FeivAi). After 6 wk, rats showed significant differences in serum iron relative to the control diet (control, 256 ± 44 μg/dL; FesvAi, 220± 16 μg/dL; FesvAd, 181 ± 15 μg/dL; FeivAs, 131 ± 44 μg/dL; FeivAi, 75 ± 19 μg/dL). Rats on iron-deficient diets showed reduced Hgb values relative to the control diet (control, 15.9 ± 0.7 g/dL; FeivAs, 13.2 ± 1.6 g/dL; FeivAi, 12.9 ± 1.0 g/dL), MCV (control: 57 ± 10 fL; FeivAs, 48 ± 10 fL; FeivAi, 44 ± 3 fL), and Hct (control, 53% ± 2%; FeivAs, 44% ± 5%; FeivAi, 42% ± 8%). All of the experimental dietary groups showed significant differences in reticulocyte count when compared with the control group (control, 2.7% ± 2.2%; FesvAd, 0.6% ± 0.2%; FesvAi, 0.3% ± 0.1%; FeivAs, 1.2% ± 0.2%; FeivAi, 0.6% ± 0.5%). The mean difference in body weight for the experimental groups, relative to the control group, was 30 ± 10 g. These results suggested that, in young male Wistar rats, both iron and vitamin A are essential to cause increases in body weight and various hematologic parameters.

Biomarkers of Nutrition for Development (BOND)-Iron Review

This is the fifth in the series of reviews developed as part of the Biomarkers of Nutrition for Development (BOND) program. The BOND Iron Expert Panel (I-EP) reviewed the extant knowledge regarding iron biology, public health implications, and the relative usefulness of currently available biomarkers of iron status from deficiency to overload. Approaches to assessing intake, including bioavailability, are also covered. The report also covers technical and laboratory considerations for the use of available biomarkers of iron status, and concludes with a description of research priorities along with a brief discussion of new biomarkers with potential for use across the spectrum of activities related to the study of iron in human health.The I-EP concluded that current iron biomarkers are reliable for accurately assessing many aspects of iron nutrition. However, a clear distinction is made between the relative strengths of biomarkers to assess hematological consequences of iron deficiency versus other putative functional outcomes, particularly the relationship between maternal and fetal iron status during pregnancy, birth outcomes, and infant cognitive, motor and emotional development. The I-EP also highlighted the importance of considering the confounding effects of inflammation and infection on the interpretation of iron biomarker results, as well as the impact of life stage. Finally, alternative approaches to the evaluation of the risk for nutritional iron overload at the population level are presented, because the currently designated upper limits for the biomarker generally employed (serum ferritin) may not differentiate between true iron overload and the effects of subclinical inflammation.

Iron Fortification: Its Efficacy and Safety in Relation to Infections

Iron-fortification programs are efficacious and effective provided recent guidelines are followed: the iron compound is carefully chosen and its level in the food is based on target population requirements, the amount lacking in the diet, and the iron bioavailability of the diet and the compound. For monitoring, serum ferritin and transferrin receptor should be included in addition to hemoglobin. Thus, recent studies of provision of iron-fortified salt to children in Morocco, rice to children in India, wheat flour to women in Thailand, and fish sauce in Vietnam have demonstrated efficacy and effectiveness. All were in nonmalarious areas, and intestinal parasites were uncommon except in India, where the children were dewormed. C-reactive protein was used to eliminate high ferritin values due to infection. An efficacy study of iron-fortified salt in dewormed school-aged children in Côte d'Ivoire, where the prevalence of malaria parasitemia was 55%, found no change in hemoglobin after 6 months, but serum ferritin increased and transferrin receptor decreased significantly, and the increase in body iron and estimated iron absorbed compared favorably with the results of a study of similar design in Morocco, where the prevalence of iron-deficiency anemia decreased from 30% to 5% after 10 months. Hence, iron-fortification programs in malarious areas may not decrease anemia prevalence but will improve iron status and, presumably, iron-dependent health outcomes. Eight studies in nonmalarious areas, all but one in infants receiving iron-fortified formula, have found no evidence of increase in infections and some evidence of a decrease in respiratory infection. There have been no studies in malarious areas.

Etiology of anemia among infants, school-aged children, and young non-pregnant women in different settings of South-Central Cote d'Ivoire

Anemia affects one-quarter of the world's population, but its etiology remains poorly understood. We determined the prevalence of anemia and studied underlying risk factors in infants (6-23 months), young school-aged children (6-8 years), and young non-pregnant women (15-25 years) in south-central Côte d'Ivoire. Blood, stool, and urine samples were subjected to standardized, quality-controlled methods. We found high prevalence of anemia, malaria, inflammation, and deficiencies of iron, riboflavin, and vitamin A but low prevalence and intensities of soil-transmitted helminth and schistosome infections. Multivariate regression analysis revealed significant associations between anemia and Plasmodium falciparum for infants, inflammation for school-aged children, and cellular iron deficiency for both school-aged children and non-pregnant women. Women with riboflavin deficiency had significantly lower odds of anemia. Our findings call for interventions to protect infants from malaria, improved intake of dietary iron, better access to health care, and health education.

Vitamin A deficiency increases hepcidin expression and oxidative stress in rat

OBJECTIVE

The interaction between vitamin A and iron status has been widely reported; however, the exact mechanism involved in this interaction has not been well characterized. The present study investigated the mechanism involved in tissue iron accumulation and changes in the oxidative status in vitamin A-deficient rats.

METHODS

Rats were treated with a control diet, a vitamin A-deficient diet, or a vitamin A/iron-deficient diet for 57 d. The animals were sacrificed; the blood, liver, and spleen were collected for biochemical analysis. Analysis of variance or Mann-Whitney tests were used to compare groups and Pearson's or Spearman's tests to investigate the bivariate correlation.

RESULTS

Vitamin A deficiency increased liver hepcidin mRNA and iron spleen concentrations; however, iron deficiency in vitamin A-deficient rats deeply inhibits liver hepcidin mRNA expression and significantly increases divalent metal transporter-1 mRNA levels. Liver ferroportin and hereditary hemochromatosis gene mRNA levels did not change in either treatment. In the vitamin A-deficient groups, liver carbonyl protein increased, whereas catalase and glutathione S-transferase activities decreased, suggesting that vitamin A protects the liver against protein oxidation. A significant positive correlation was found between lipid oxidative damage and iron concentration in the liver and spleen (r = 0.611, P = 0.007; r = 0.558, P = 0.025, respectively).

CONCLUSION

These results suggest that vitamin A maintains iron homeostasis by the modulation of liver hepcidin expression. The increase of lipid peroxidation in vitamin A deficiency seems to be iron dependent, whereas protein oxidation is not.

Retinoic acid modulates hepatic iron homeostasis in rats by attenuating the RNA-binding activity of iron regulatory proteins

Vitamin A deficiency has been widely associated with perturbations of iron homeostasis, a consequence that can be reversed by retinoid supplementation. Despite the numerous studies that demonstrate an interaction between these 2 nutrients, the mechanistic basis for this relation has not been well characterized. Because iron regulatory proteins (IRP) have been established as central regulators of iron homeostasis, we investigated the potential role of IRP in the regulation of iron homeostasis under conditions of vitamin A deficiency and supplementation with all-trans-retinoic acid (atRA). Rats were fed a control diet or a diet deficient in either vitamin A or iron or both micronutrients. Four parallel groups of rats were supplemented with atRA daily (30 micromol/kg body weight) during the final week of this study. As expected, iron-deficient (-Fe) rats exhibited a decrease in hepatic nonheme iron levels and a subsequent increase in IRP RNA-binding activity, resulting in diminished ferritin abundance. Interestingly, atRA supplementation inhibited the increase in IRP RNA-binding activity in -Fe rats to a level that was not significantly (P = 0.139) different from control values, and it partially restored ferritin abundance. This inhibition of IRP RNA-binding activity by atRA supplementation was also associated with a 40% reduction in transferrin receptor abundance. Taken together, these results indicate that IRP represent a mechanistic link between vitamin A and the regulation of iron homeostasis, a key finding toward further understanding this important nutrient-nutrient interaction.

Only a small proportion of anemia in northeast Thai schoolchildren is associated with iron deficiency

BACKGROUND

Iron deficiency is assumed to be the major cause of anemia in northeast Thailand, but other factors may be involved.

OBJECTIVE

We determined the prevalence of anemia among schoolchildren in northeast Thailand and the role of hemoglobinopathies, selected micronutrient deficiencies, and other factors in hemoglobin status.

DESIGN

Blood samples were collected from 567 children aged 6-12.9 y attending 10 primary schools for the determination of a complete blood count and hemoglobin type [Hb AA (normal hemoglobin), Hb AE (heterozygous for Hb type E), and Hb EE (homozygous for Hb type E)] and the measurement of serum ferritin, transferrin receptor, retinol, vitamin B-12, and plasma and erythrocyte folate concentrations. Children with a C-reactive protein concentration > or = 10 mg/L (n = 12), which indicated infection, were excluded.

RESULTS

The prevalence of anemia was 31%. Age, hemoglobin type, and serum retinol were the major predictors of hemoglobin concentration. Hb AA and Hb AE children with anemia had lower (P < 0.01) hematocrit, mean cell volume, and serum retinol values than did their nonanemic counterparts; no significant differences in serum ferritin were found by hemoglobin type. Only 16% (n = 22) of the anemic Hb AA and Hb AE children were iron deficient. Hb AA and Hb AE children with a serum retinol concentration <0.70 micromol/L (n = 14) had a significantly higher geometric mean serum ferritin concentration than did those with a retinol concentration > or = 0.70 micromol/L (P = 0.009); no significant difference in transferrin receptor concentrations was found between these 2 groups.

CONCLUSIONS

Hemoglobinopathies, suboptimal vitamin A status, and age were the major predictors of hemoglobin concentration. The contribution of iron deficiency to anemia was low, and its detection was complicated by coexisting suboptimal vitamin A status.

Iron deficiency and marginal vitamin A deficiency affect growth, hematological indices and the regulation of iron metabolism genes in rats

Iron deficiency and marginal vitamin A (VA) deficiency frequently coexist and affect billions of people, mostly children and women, worldwide. The effects of these micronutrient deficiencies alone and in combination on hematologic, biochemical and molecular indices of iron and VA status were investigated in a 2 x 2 randomized blocked study conducted in growing male Sprague-Dawley rats. From 3-8 wk of age, rats were fed one of four purified diets that were either adequate or restricted in iron (Fe) and adequate or marginal in VA: (+)Fe(+)VA, 20.3 and 0.367 micro g/g, respectively, denoted control diet; (-)Fe(+)VA, 3.34 and 0.405 micro g/g; (+)FeVA(m), 22.2 and 0.051 micro g/g; or (-)FeVA(m), 3.03 and 0.055 micro g/g. Weight-matched rats fed adequate micronutrients were included to control for possible confounding effects of Fe deficiency on growth and feed efficiency. Iron restriction reduced (P < 0.05) weight gain, feed efficiency, blood hemoglobin and hematocrit. Plasma and liver iron and plasma transferrin saturation were reduced by approximately 50%, whereas liver transferrin mRNA and protein and transferrin receptor mRNA were elevated, as was liver ferritin light-chain protein and light-chain mRNA. Liver heavy-chain ferritin mRNA, hemopexin, ceruloplasmin and cellular retinol-binding protein mRNA were not affected by iron or VA restriction. Although marginal VA deficiency did not exacerbate indices of poor iron status during iron deficiency, iron deficiency was associated with lower plasma retinol and elevated liver VA concentrations. These results are consistent with an impaired mobilization of liver retinol during iron deficiency as well as multiple alterations in iron metabolism.

The anemia of vitamin A deficiency: epidemiology and pathogenesis

OBJECTIVE

To gain insight into vitamin A deficiency as a cause of anemia.

METHODS

Comprehensive review of the scientific literature.

RESULTS

Although vitamin A deficiency is recognized to cause anemia, 'vitamin A deficiency anemia' lacks complete characterization as a distinct clinical entity. Vitamin A appears to be involved in the pathogenesis of anemia through diverse biological mechanisms, such as the enhancement of growth and differentiation of erythrocyte progenitor cells, potentiation of immunity to infection and reduction of the anemia of infection, and mobilization of iron stores from tissues. Epidemiological surveys show that the prevalence of anemia is high in populations affected by vitamin A deficiency in developing countries. Improvement of vitamin A status has generally been shown to reduce anemia, but the actual public health impact on anemia is unclear.

CONCLUSIONS

Further work is needed to elucidate the biological mechanisms by which vitamin A causes anemia. The inclusion of anemia as an outcome measure in future micronutrient intervention studies should help provide further insight into the anemia of vitamin A deficiency.