Transport kinetics of zinc, copper, selenium, and iron in perfused human placental lobule in vitro

Role of zinc in neonatal growth and brain growth: review and scoping review

This manuscript includes (1) a narrative review of Zinc as an essential nutrient for fetal and neonatal growth and brain growth and development and (2) a scoping review of studies assessing the effects of Zinc supplementation on survival, growth, brain growth, and neurodevelopment in neonates. Very preterm infants and small for gestational age infants are at risk for Zinc deficiency. Zinc deficiency can cause several complications including periorificial lesions, delayed wound healing, hair loss, diarrhea, immune deficiency, growth failure with stunting, and brain atrophy and dysfunction. Zinc is considered essential for oligodendrogenesis, neurogenesis, neuronal differentiation, white matter growth, and multiple biological and physiological roles in neurobiology. Data support the possibility that the critical period of Zinc delivery for brain growth in the mouse starts at 18 days of a 20-21-day pregnancy and extends during lactation and in human may start at 26 weeks of gestation and extend until at least 44 weeks of postmenstrual age. Studies are needed to better elucidate Zinc requirement in extremely low gestational age neonates to minimize morbidity, optimize growth, and brain growth, prevent periventricular leukomalacia and optimize neurodevelopment. IMPACT: Zinc is essential for growth and brain growth and development. In the USA, very preterm small for gestational age infants are at risk for Zinc deficiency. Data support the possibility that the critical period of Zinc delivery for brain growth in the mouse starts at 18 days of a 20-21-day pregnancy and extends during lactation and in human may start at 26 weeks' gestation and extend until at least 44 weeks of postmenstrual age. Several randomized trials of Zinc supplementation in neonates have shown improvement in growth when using high enough dose, for long duration in patients likely to or proven to have a Zinc deficiency. Studies are needed to better elucidate Zinc requirement in extremely low gestational age neonates to minimize morbidity, optimize growth and brain growth, prevent periventricular leukomalacia and optimize neurodevelopment.

Determination of trace levels of selenium in natural water, agriculture soil and food samples by vortex assisted liquid-liquid microextraction method: Multivariate techniques

A green vortex assisted based liquid-liquid microextraction (VA-LLME) method was developed for preconcentration of selenium. Ammonium pyrrolidine dithiocarbamate (APDC) was used to form a hydrophobic complex with selenium in natural water, agricultural soil and food samples by GFAAS. Whereas Triton X-114, a nonionic surfactant and 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid were used for Se extraction as a dispersing medium. The conical flasks contents were shack on a vortex mixer to increase the extraction efficiency. Multivariate techniques were used to evaluate extraction parameters; pH, vortex time, APDC amount, volume of ionic liquid and Triton X-114 and centrifugation rate on the recovery of Se. The central composite design (CCD) was used for further optimization of the essential extraction parameters. The enhancement factor and limit of detection were obtained as 98.7 and 0.07 µg L^-1. The certified reference materials was used for accuracy of method and the related standard deviation was found to be 3.51%. The resulted data indicated that concentrations of Se in all types of water samples were below the permissible limit recommended by WHO.

Prenatal selenium status, neonatal cerebellum measures and child neurodevelopment at the age of 18 months

OBJECTIVES

The aim of this study was to evaluate the association of maternal blood selenium (Se) levels and cord blood Se levels with neonatal cerebellum measures and child neurodevelopment at the age of 18 months. Moreover, to investigate whether the neonatal cerebellum measures could be used as a potential biomarker for selenium homeostasis during pregnancy.

STUDY GROUP AND METHODS

The study population consisted of 205 mother-child pairs from Croatian Mother and Child Cohort. Maternal blood and cord blood were obtained at delivery and selenium level was analyzed by Inductively Coupled Plasma Mass Spectrometry. Cranial ultrasonography examination was performed on 49 newborns - cerebellum length and width have been measured. Neurodevelopmental assessment of cognitive, language and motor skills were conducted on 154 children, using The Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III), at the age of 18 months.

RESULTS

The mean levels of selenium in maternal blood and cord blood were 92.6 ng/g and 97.0 ng/g, respectively. Maternal blood selenium levels were moderately and negatively correlated (r = -0.372; p = 0.008) with cerebellum length, while cord blood selenium levels were positively correlated with cerebellum width (r = 0.613; p = 0.007) among female children group. Maternal blood selenium levels were weakly and positively correlated (r = 0.176; p = 0.029) with child's cognitive abilities.

CONCLUSION

To the best of our knowledge, our study is the first one investigating the association between neonatal brain measures and selenium levels in mother-child pairs. Our results indicate that prenatal selenium intake correlated with cerebellum length and width measured by cranial ultrasonography. Hence, cerebellum may be used as a potential biomarker and a target "organ" for early detection of possible adverse effects of prenatal status to various micronutrients.

Changes in total mercury, methylmercury, and selenium blood levels during different life history stages of the Baltic grey seal (Halichoerus grypus grypus)

Using the blood of grey seal pups, the blood and milk of female grey seals inhabiting the Hel Marine Station of Gdansk University's Institute of Oceanography (HMS), we monitored the transfer of total mercury (THg), methylmercury (MeHg), and selenium (Se) with blood during foetal life and nursing. Changes in the concentration of mercury and selenium were characterised in the pups' blood during their first three months of life when they transition from suckling, to a post-weaning fast, to eating fish. In the blood of pregnant females, there was a significant decrease in THg and MeHg concentrations throughout the gestation, indicating the transfer of these toxins through the placenta into the foetus. At no other stage of the pup's development was there such a high level of THg and MeHg as on the day of birth, despite the incorporation of mercury into the lanugo during foetal growth. This suggests that the maternal transfer of mercury during gestation may be the time of greatest mercury exposure for a young seal pup. The consumption of milk caused a rapid increase in weight and a lowering of the mercury level in the blood in the subsequent days of the pups' life. The postweaning fast was the period of the lowest mercury concentration. The switch to a diet consisting of fish caused a systematic increase in the concentration of mercury in the blood of the pups. Milk was the significant source of selenium for pups and the selenium concentration in females' blood was reduced during lactation. The nursing period seemed to have the greatest impact on the mercury and selenium blood levels in examined seals. Natural development of the grey seal pup created an opportunity to decrease the levels of toxic substances obtained through the maternal transfer during foetal growth.

Maternal selenium status and neuropsychological development in Spanish preschool children

BACKGROUND

The relationship between maternal selenium (Se) status and child neurodevelopment has been scarcely assessed. In a previous study we observed an inverse U-shaped association between maternal Se concentrations and infant neurodevelopment at 12 months of age. In this study, this non-linear association was explored at preschool age. The effect modification by breastfeeding, child's sex and cord blood mercury was also evaluated.

METHODS

Study subjects were 490 mother-child pairs from the Spanish Childhood and Environment Project (INMA, 2003-2012). Child neuropsychological development was assessed at around 5 years of age by the McCarthy Scales of Children's Abilities (MSCA). Sociodemographic and dietary characteristics were collected by questionnaire at the first and third trimester of gestation and at 5 years of age. Se was measured in serum samples by ICP-MS at the end of the first trimester of pregnancy (mean ± standard deviation (SD) = 12.4 ± 0.6 weeks of gestation).

RESULTS

The mean ± SD of maternal serum Se concentrations was 79.9 ± 8.1 µg/L. In multivariate analysis, no linear association was found between Se concentrations and the nine MSCA scales. Generalized additive models indicated inverted U-shaped relationships between Se concentrations and the verbal and global memory scales. When assessing the influence of effect modifiers, breastfeeding played a role: the association between Se and neuropsychological development was inverted U-shaped for the quantitative, general cognitive, working memory, fine motor, global motor and executive function scales only for non-breastfed children.

CONCLUSION

Low and high maternal Se concentrations seem to be harmful for child neuropsychological development, however further studies should explore this non-linear relationship.

Concentrations of mercury (Hg) and selenium (Se) in afterbirth and their relations with various factors

The aim of the study was to evaluate Hg and Se concentrations and Se:Hg molar ratios in the placenta, umbilical cord and fetal membranes, and to examine the relationship between the concentrations of the elements and selected factors. The study material consisted of the placenta, umbilical cord and fetal membranes obtained from 91 healthy women from northwestern and central Poland. In our study mean Hg and Se concentrations in afterbirth were ~ 0.01 mg/kg dry weight (dw) and ≤ 0.5 mg/kg dw, respectively. Correlation analysis showed negative relationships between placenta weight and Se concentration in the placenta and umbilical cord, as well as between placenta length and Se levels in the umbilical cord. We found negative correlations between THg concentration in the placenta and birth weight and between Se concentration in the placenta and umbilical cord and the morphological parameters of the placenta. Furthermore, we noted new types of interactions in specific parts of the afterbirth. In our study, Se:THg molar ratios ranged from 5 to 626; these values indicate protection against Hg toxicity.

Selenium, selenoproteins and selenometabolites in mothers and babies at the time of birth

The deficiency of Se, an essential micronutrient, has been implicated in adverse pregnancy outcomes. Our study was designed to determine total serum Se, selenoproteins (extracellular glutathione peroxidase (GPx-3), selenoprotein P (SeP)), selenoalbumin (SeAlb) and selenometabolites in healthy women and their newborns at delivery. This cross-sectional study included eighty-three healthy mother-baby couples. Total Se and Se species concentrations were measured in maternal and umbilical cord sera by an in-series coupling of two-dimensional size-exclusion and affinity HPLC. Additional measurements of serum SeP concentration and of serum GPx-3 enzyme activity were carried out using ELISA. Total Se concentration was significantly higher in maternal serum than in cord serum (68·9 (sd 15·2) and 56·1 (sd 14·6) µg/l, respectively; P<0·01). There were significant correlations between selenoprotein and SeAlb concentrations in mothers and newborns, although they also showed significant differences in GPx-3 (11·2 (sd 3·7) v. 10·5 (sd 3·5) µg/l; P<0·01), SeP (42·5 (sd 9·5) v. 28·1 (sd 7·7) µg/l; P<0·01) and SeAlb (11·6 (sd 3·6) v. 14·1 (sd 4·3) µg/l; P<0·01) concentrations in maternal and cord sera, respectively. Serum GPx-3 activity and concentration were positively correlated in mothers (r 0·33; P=0·038) but not in newborns. GPx-3 activity in cord serum was significantly correlated with gestational age (r 0·44; P=0·009). SeAlb concentration was significantly higher in babies, whereas SeP and GPx-3 concentrations were significantly higher in mothers. The differences cannot be explained by simple diffusion; specific transfer mechanisms are probably involved. GPx-3 concentrations in mothers, at delivery, are related to maternal Se status, whereas the GPx-3 activity in cord serum depends on gestational age.

Different levels of prenatal zinc and selenium had different effects on neonatal neurobehavioral development

Either deficient or excessive of essential nutrients had adverse effects. Effects of different levels of prenatal zinc (Zn) and selenium (Se) on fetal neurobehavioral development remain unclear. To determine the effects of different cord serum levels of Zn and Se on neurobehavioral development in neonates and to explore possible threshold level of Zn and Se based on fetal neurodevelopment, we conducted this epidemiological research. In the multi-center study, we investigated these questions in 927 mother-newborn pairs in Shanghai, China, from 2008 through 2009. Umbilical cord serum concentrations of Zn and Se were measured and Neonatal Behavioral Neurological Assessment (NBNA) tests were conducted. The median cord serum Zn and Se concentrations were 794.3 μg/L and 63.1 μg/L, respectively. A nonlinear relationship was observed between cord serum Zn and NBNA after adjusting for potential confounders. NBNA score decreased with increasing Zn levels after 794.3 μg/L (adjusted β=-3.0, 95% CI: -3.6 to -2.4, p<0.001). Additionally, an invert U-shape with a threshold Se of 100 μg/L was observed between cord serum Se and NBNA. The adjusted regression coefficient was 4.4 (95% CI: 3.6-5.2, p<0.001) for Se<100 μg/L while -3.6 (95% CI: -6.1 to -1.1, p<0.01) for Se≥100 μg/L. Of the 927 infants, 50% had a high level Zn (≥794.3 μg/L) and 8.6% had a high level Se (≥100 μg/L). High levels of both Zn and Se mainly had adverse effects on behavior and passive tone (p<0.001). Taken together, our study suggested that a threshold of cord blood Zn and Se was existed for fetal neurodevelopment and the prevalence of excessive Zn was high. Thus, the supplementation of Zn during pregnancy should be considered with caution in Shanghai, China.

Selenium in reproductive health

Selenium is an essential trace element of importance to human biology and health. Increasing evidence suggests that this mineral plays an important role in normal growth and reproduction in animals and humans, and selenium supplementation is now recommended as part of public health policy in geographical areas with severe selenium deficiency in soil. This review addresses the biological functions of selenium followed by a detailed review of associations between selenium status and reproductive health. In many countries, selenium dietary intake falls below the recommended nutrient intakes and is inadequate to support maximal expression of the selenoenzymes. Numerous reports implicate selenium deficiency in several reproductive and obstetric complications including male and female infertility, miscarriage, preeclampsia, fetal growth restriction, preterm labor, gestational diabetes, and obstetric cholestasis. Currently, there is inadequate information from the available small intervention studies to inform public health strategies. Larger intervention trials are required to reinforce or refute a beneficial role of selenium supplementation in disorders of reproductive health.

Maternal–fetal transport and disposition of copper, iron, molybdenum, selenium and zinc in experimentally induced diabetic rats

OBJECTIVE

To assess maternal-fetal status of essential trace elements such as copper, iron, molybdenum, selenium and zinc, in experimentally induced diabetic and control pregnant rats, and to correlate the findings with those observed in human diabetic pregnancies. Fetal-maternal ratios of the elements and Cu:Zn and Cu:Fe ratios were also computed in control and study groups.

METHODS

Diabetes was experimentally induced in pregnant Sprague Dawley rats by injection of streptozotocin. A cocktail of essential trace elements along with antipyrine as internal reference marker were then injected intra-peritoneally to diabetic and matched control pregnant rats on the 20th day of pregnancy. Maternal and fetal blood and tissue samples were collected after sacrificing the animals at 30- and 60-minutes following cocktail injection. Concentrations of trace elements and antipyrine in various blood and tissue samples were then determined by atomic absorption spectrophotometry and colorimetry, respectively.

RESULTS

Concentrations of Cu, Fe, Mo, Se, Zn, and antipyrine averaged 2907.0 +/- 212.0 microg/L, 3950.0 +/- 766.0 microg/L, 15.8 +/- 1.7 microg/L, 74.8 +/- 6.5 microg/L, 726.4 +/- 67.4 microg/L, and 170.5 +/- 8.2 mg/L, respectively, in maternal blood in control pregnant rats (n = 5) at day 20 in the 30-minute study phase, while in the diabetic group (n = 5) the values of the various trace element concentrations and antipyrine averaged 2875.0 +/- 225.0 microg/L, 5875.0 +/- 688.0 microg/L, 21.2 +/- 2.1 microg/L, 116.0 +/- 3.6 microg/L, 753.0 +/- 71.3 microg/L, and 171.7 +/- 4.2 mg/L, respectively. Unpaired student's t-test showed that Fe and Se levels were significantly higher (p < 0.05) in the diabetic pregnant rats compared to controls. Cu, Mo and Zn values, however, were not significantly different (p > 0.05) between the two groups. Cu:Zn and Cu:Fe ratios showed varying differences between maternal and fetal samples in the control and study groups.

CONCLUSIONS

Considering the disparity of results in pregnant diabetic rats and pregnant diabetic women, we urge exercising caution when comparing data from animal studies to human situations.