Effects of specific dosages of magnesium and zinc on the teratogenicity of cadmium, nickel, and cobalt in Xenopus embryos, as assessed by the FETAX test

The objective of this study was to determine if exposure to divalent cations, Cd(2+), Ni(2+), and Co(2+) would lead to malformations in Xenopus laevis embryos, and whether addition of Mg(2+) and Zn(2+); separately and in combination, would reduce their toxicity and teratogenicity on the embryos of Xenopus laevis as assessed by 96-h FETAX tests. Results indicate that exposure to Cd(2+), Ni(2+) or Co(2+) lead to an increase in toxicity and teratogenicity in embryos, whereas Mg(2+), Zn(2+), or a combination of them reduced the toxic and teratogenic effects of these divalent cations. Modulation of Cd(2+), Ni(2+) or Co(2+) toxicity and teratogenicity by Mg(2+) and Zn(2+), varied with the metal. Zn(2+) was observed to be a better suppressor of Co(2+) toxicity and teratogenicity than Mg(2+). In contrast, Ni(2+), and Cd(2+) teratogenicity was reduced more prominently by Mg(2+). On the other hand, combination of Mg(2+) and Zn(2+) showed potentialization effect on all divalent cation toxicity and teratogenicity. We concluded that Mg(2+) and Zn(2+) reduced the toxicity and teratogenicity of Cd(2+), Ni(2+), Co(2+).

Modulation of zinc release from bioactive sol–gel derived SiO2-CaO-ZnO glasses and ceramics

Zinc is an essential trace element which may be effective in promoting hard tissue healing. Glasses in the SiO(2)-CaO-ZnO system were synthesized via sol-gel methods. Using a constant silica content (70 mol %), the ratio of Ca to Zn was varied (1.5, 3.5, or 6.5), as was the stabilization temperature (650, 750, or 850 degrees C), to examine such effects on the bioactive response and zinc release in simulated body fluid (SBF). XRD revealed the development of CaSiO(3) and Ca(2)ZnSi(2)O(7) crystalline phases during stabilization at 850 degrees C only. N(2) adsorption analysis determined that the specific surface area (BET) varied between 14 and 179 m(2)/g and was dependent on composition and stabilization temperature, as was the average initial pore size (51-125 A). The formation of hydroxycarbonate (HCA) and amorphous calcium phosphate (ACP) was observed at 14 days for samples stabilized at 650 or 750 degrees C. Only ACP layers were observed on such samples prior to 14 day. Relative to the Ca levels at 14 day (60-485 microg/ml), Zn levels in solution were relatively low (0.06-1.18 microg/ml). EDX and ICP data suggested that released Zn was incorporated into the forming calcium phosphate reaction layer, thereby preventing concentrations of the essential trace element from reaching potentially toxic levels.

Potential for Misclassification of Micronutrient Status in Children Participating in a Head Start Program

OBJECTIVE

To evaluate relations among measures of iron and zinc status, C-reactive protein (CRP), and leukocytes in low-income children participating in the Head Start program.

DESIGN

Cross-sectional correlational study with samples collected at Head Start centers in May 2003.

SUBJECTS/SETTING

Forty-seven children (aged 3 to 5 years) attending Head Start centers in three rural communities.

MEASURES

Zinc, ferritin, CRP, and complete blood count were analyzed in nonfasting blood samples.

STATISTICAL ANALYSES

Correlations were computed among leukocyte levels, CRP levels, and measures of micronutrient status. Children having two abnormal measures (ie, leukocytes and CRP) were compared by univariate analysis of variance with children having zero or one abnormal measure.

RESULTS

Most (72%) of the children had elevated CRP levels. Four percent were anemic (hemoglobin<11.0 g/dL [<110 g/L]); 11% had low iron stores (serum ferritin<or=15 ng/mL [<or=33.7 pmol/L]); and 77% had low iron stores when a reference value that accounts for the presence of infection was used (serum ferritin<or=30 ng/mL [<or=67.4 pmol/L]). Twenty-one percent had low plasma zinc levels. Children with two measures that indicated infection had higher serum ferritin and lower plasma zinc levels than children with zero or one indicator of infection.

CONCLUSIONS

The link between measures of infection and serum ferritin levels suggests low-income preschool children with low iron stores are not identified by the <or=15 ng/mL (<or=33.7 pmol/L) criterion. The link between zinc and infection suggests possible overestimations of zinc deficiency in low-income children. Thus, in this population, the presence of infection (as indicated by CRP levels and leukocyte counts) should be determined to assess micronutrient status.

Comparative analysis of zinc status, food products' frequency intake and food habits of 11-year-old healthy children

Children are particularly vulnerable to zinc (Zn) deficiency during periods of rapid growth and development such as infancy and adolescence. The aim was to find the relationship between food frequency, intake, food habits and zinc status in 11-year-old healthy children from southern Poland. The study group comprised children (n = 157) in the age range 11.0 +/- 0.4 years. The level of Zn in serum, erythrocytes and hair samples was measured using atomic absorption spectrophotometry. The parents of children examined completed a special food frequency questionnaire. The Zn concentration in hair (boys 182.98 +/- 65.63 microg x g(-1), n = 78; girls 203.82 +/- 39.80 microg x g(-1), n = 79; p = 0.0171), erythrocytes (8.60 +/- 2.76 mg x l(-1), n = 50) and blood serum (0.79 +/- 0.15 mg x l(-1)) correlated significantly (p < 0.05) with frequency intake of different products (hair: meat, rolls, fruit juices without additives, brawn, pate, barley, black pudding, fish canned, chips, margarine used for cooking, bacon; erythrocytes: fruits, matured cheese, dishes of meal, white cottage cheese, fruit juices without additives, cakes and cakes with cream, margarine used for bread spread; blood serum: bread, fruits, milk, kefir, yoghurt). The relationship of the Zn amount in food products, food frequency intake and the concentration in different healthy children tissues is influenced by many internal and external factors.