Concentration of copper and zinc in liver of fetuses and infants

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.

Zinc and infant nutrition

Zinc is essential for a wide variety of cellular processes in all cells. It is a critical dietary nutrient, particularly in the early stages of life. In the early neonatal period, adequate sources of zinc can be obtained from breast milk. In rare circumstances, the mammary gland produces zinc deficient milk that is potentially lethal for exclusively breast-fed infants. This can be overcome by zinc supplementation to the infant. Alterations to key zinc transporters provide insights into the mechanisms of cellular zinc homeostasis. The bioavailability of zinc in food depends on the presence of constituents that may complex zinc. In many countries, zinc deficiency is a major health issue due to poor nourishment. Young children are particularly affected. Zinc deficiency can impair immune function and contributes to the global burden of infectious diseases including diarrhoea, pneumonia and malaria. Furthermore, zinc deficiency may extend its influence across generations by inducing epigenetic effects that alter the expression of genes. This review discusses the significance of adequate zinc nutrition in infants, factors that influence zinc nutrition, the consequences of zinc deficiency, including its contribution to the global burden of disease, and addresses some of the knowledge gaps in zinc biology.

Mercury transfer during pregnancy and breastfeeding: hair mercury concentrations as biomarker

Hair mercury (HHg) concentration is a biomarker of exposure that is widely used to assess environmental contamination by fish methylmercury and neurodevelopment in children. In the Rio Madeira basin (Brazilian Amazon), total HHg concentrations in 649 mother-infant pairs were measured at birth (prenatal exposure) and after 6 months of exclusive breastfeeding; these mother-infant pairs were from high fish-eating communities (urban, n = 232; rural, n = 35; and Riverine, n = 262) and low fish-eating tin-miner settlers (n = 120). Differences in kinetics were seen between Hg exposure from fish consumption and environmental exposure to a tin-ore mining environment. Overall maternal HHg concentrations (at childbirth and after 6 months of lactation) were higher than those of infant HHg. However, the relative change in HHg after 6 months of lactation showed that mothers decreased HHg while infants increased HHg. The relative change showed a consistently higher increase for girls than boys with a statistical significance only in high fish-eating mothers. The correlation coefficients between maternal and newborn hair were high and statistically significant for mothers living in urban (r = 0.66, p < 0.001), rural (r = 0.89, p < 0.001), and Riverine (r = 0.89, p < 0.001) communities not for tin miner settlers (r = 0.07, p = 0.427). After 6 months of exclusive breastfeeding, correlation coefficients showed high correlation coefficients and statistical significance for all groups (urban, r = 0.73, p < 0.001; rural, r = 0.88, p < 0.001; Riverine, r = 0.91, p < 0.001) except for Tin miners (r = -0.07, p = 0.428). A linear model analysis was used to assess the longitudinal associations of maternal total HHg and total HHg at birth (0 days) and 6 months of age in exclusively breastfed infants. Regression analysis significantly predicted HHg in newborn from maternal HHg for high fish-eating maternal-infant pairs.

CONCLUSION

The concentration of mercury accumulated in newborn tissues (in utero and during breastfeeding) relevant to both, maternal sources and infant exposure, can be reliably assessed from maternal hair.

Hair mercury in breast-fed infants exposed to thimerosal-preserved vaccines

Because of uncertainties associated with a possible rise in neuro-developmental deficits among vaccinated children, thimerosal-preserved vaccines have not been used since 2004 in the USA (with the exception of thimerosal-containing influenza vaccines which are routinely recommended for administration to pregnant women and children), and the EU but are widely produced and used in other countries. We investigated the impact of thimerosal on the total Hg in hair of 82 breast-fed infants during the first 6 months of life. The infants received three doses of the hepatitis-B vaccine (at birth, 1 and 6 months) and three DTP (diphtheria, tetanus, and pertussis) doses at 2, 4 and 6 months, according to the immunization schedule recommended by the Ministry of Health of Brazil. The thimerosal in vaccines provided an ethylmercury (EtHg) exposure of 25 microgHg at birth, 30, 60 and 120 days, and 50 microgHg at 180 days. The exposure to vaccine-EtHg represents 80% of that expected from total breast milk-Hg in the first month but only 40% of the expected exposure integrated in the 6 months of breastfeeding. However, the Hg exposure corrected for body weight at the day of immunization was much higher from thimerosal- EtHg (5.7 to 11.3 microgHg/kg b.w.) than from breastfeeding (0.266 microgHg/kg b.w.). While mothers showed a relative decrease (-57%) in total hair-Hg during the 6 months lactation there was substantial increase in the infant's hair-Hg (446%). We speculate that dose and parenteral mode of thimerosal-EtHg exposure modulated the relative increase in hair-Hg of breast-fed infants at 6 months of age.

Quality control of banked milk in Brasilia, Brazil

The authors studied quality control procedures at human milk banks and nutritional profiles of 909 milk samples (from 195 donors, aged 15 to 45 years) from banked human milk (BHM) in Brasília, Brazil. Number of donations per donor ranged from 1 to > 10 that consisted mostly of mature milk (90.9%) with a mean total energy of 529 +/- 85 kcal/L and a mean total lipid of 22.7 g/L +/- 13.2. Microbiological quality (titrable acidity-Dornic, degrees D) was suitable for infant feeding in 99.2% of samples (< 8 degrees D), ranging from 2 degrees D to 8 degrees D (mean 4.8 +/- 1.4 degrees D). Most BHM (98.1%) samples were dispensed to inpatient infants (1-7 days) diagnosed with respiratory distress (30.1%), prematurity (20.7%), metabolic distress (16.0%), jaundice (14.4%), bacterial infection (6.0%), pneumonia (3.3%), congenital cardiac distress (2.2%), or other conditions (6.2%). Well-motivated mothers and trained staff are serving and sustaining an important life-saving network with long-lasting impact on public health.

Concentrations of copper and zinc in liver and serum samples in biliary atresia patients at different stages of traditional surgeries

Many patients with biliary atresia (BA) have impaired metabolism of copper (Cu) and zinc (Zn) because of the obstruction of bile ducts. An excessive Cu accumulation is cytotoxic and results in fibrosis in hepatic tissues. Since Zn works antagonistically to Cu, lower Zn concentrations may deteriorate liver damage. In the 1980's, we performed a series of surgeries on BA patients for the construction and alteration of the bile flow route, which is the major excretion route for Cu. We obtained liver and serum samples at each surgery, and measured Cu and Zn concentrations by inductively coupled plasma atomic emission spectrometry. Hepatic Cu concentration decreased with the improvement of cholestasis after the establishment of bile excretion. Conversely, when cholestasis persisted or recurred, increases in hepatic and serum Cu concentrations were noted. Hepatic Zn concentration was lower than previously reported normal values. High hepatic and serum Cu concentrations due to persistent or recurrent cholestasis and low hepatic Zn concentration may deteriorate hepatic fibrosis and liver cirrhosis.

Maternal--neonatal serum selenium and copper levels in Greeks and Albanians

AIM

To evaluate selenium (Se) and copper (Cu) concentrations in Greek and Albanian immigrant mothers and in the cord blood of their newborns.

SUBJECTS AND METHODS

From 1118 Greek and 820 Albanian mothers and from the cord blood of their neonates blood was obtained for Se and Cu measurement. Se and Cu concentrations were determined in sera with graphite furnace atomic absorption spectroscopy (GFAAAS) and atomic absorption spectrometry, respectively. In all, 30 days' nutrient intakes were evaluated in both groups.

RESULTS

Animal protein, Se and Cu intakes were poor in the Albanians vs the Greeks (P < 0.001). Se concentrations in the Greek mothers (68.3 +/- 8.5 microg/l) and in their newborns (37.02 +/- 8.9 microg/l) were found higher as compared with those in Albanian mothers (37.4 +/- 9.9 microg/l) and in their newborns (34.3 +/- 9.1 microg/l) (P < 0.001). Cu levels were also found higher (P < 0.001) in the Greek mothers (1687 +/- 353 microg/l) and in their neonates (449 +/- 87 microg/l) compared with those in the Albanian mothers (959 +/- 318 microg/l) and in their newborns (229 +/- 67 microg/l). Additionally, 31.5% of neonates born to Albanian women with Se concentrations less than 28 microg/l had higher Se levels (P < 0.01) than their mothers.

CONCLUSIONS

The low Se and Cu levels evaluated in the Albanian mothers and their newborns could be related to their poor animal protein intake which could be the consequence of their low socioeconomic status. As an effective preventive measure, accurate dietetic strategies to assess the requirements of pregnant immigrant women for trace elements may be planned in Greece.

Zinc deficiency in nursing infants

Zinc deficiency during nursing can occur even in breast-fed infants. Zinc reserves accumulated during fetal development modulate the infant's susceptibility to zinc deficiency. Improvement of maternal zinc nutrition during pregnancy is the key for infant's zinc nutritional support and prevention of low-for-lactation-age zinc concentrations of breast-milk.

Caeruloplasmin isoforms in Wilson's disease in neonates

AIM

To investigate the neonatal diagnosis of Wilson's disease from caeruloplasmin isoforms in cord blood.

METHODS

Serum caeruloplasmin isoforms were measured in 5-10 ml cord blood from 10 fresh umbilical cords using sodium dodecyl polyacrylamide gel electrophoresis (SDS PAGE) and western blotting and analysed by densitometry. Total caeruloplasmin concentrations were determined by nephelometry and caeruloplasmin oxidase by p-nitrophenyldiamine.

RESULTS

Although total caeruloplasmin concentrations are reduced in neonates, the plasma isoform was significantly reduced or absent in patients with Wilson's disease. Sera from healthy neonates and from those with Wilson's disease had reduced biliary isoforms.

CONCLUSION

Identification of caeruloplasmin isoforms may be a marker for Wilson's disease in neonates.

Multielemental analysis of human fetal tissues using inductively coupled plasma-mass spectrometry

Inductively coupled plasma-mass spectrometry (ICP-MS) was used to study the distribution of 26 major and trace elements in six tissues from 21 human fetuses aged 16-22 wk. Brain, lung, spleen, kidney, heart, and liver were analyzed following a microwave oven digestion step carried out according to clean techniques designed for ultratrace metal analyses. Precision and accuracy controls were conducted using standard reference material #1577b Bovine Liver. Significant differences among tissues were found for most of the elements. Essential trace elements seem to be increasingly retained as fetal tissues mature and become physiologically functional. The ranges of concentrations measured in fetal tissues at this stage of development are generally lower and much narrower than in adult tissues. The age of the fetus, which is not given in most studies, as well as the different techniques and levels of quality assurance could be responsible for the discrepancies in the trace metal concentrations reported here and in the literature. Intratissue homogeneity was also assessed in five human fetal brains. Frontal, occipital, parietal and temporal lobes, striatum, hippocampus, and thalamus were isolated and analyzed separately. No significant differences were found in the distribution of any of the elements at this stage of development. Because of the relatively narrow ranges of concentrations found for most elements, we believe that the results presented in this study represent the inorganic fingerprint of the main tissues of normal fetuses at midpregnancy for the Greater Montreal area.

Hepatic concentrations of zinc, copper and manganese in infants with extrahepatic biliary atresia

The objective of this study was to determine the concentration of Zinc (Zn), Copper (Cu) and Manganese (Mn) in hepatic tissue from extrahepatic biliary atresia (EHBA). Liver biopsy samples were obtained at time of portoenterostomy from 49 infants ages 1.1 to 20.7 months (median 2.1) with EHBA. Samples were dry ashed and analyzed by flame (Zn) or flameless (Cu and Mn) atomic absorption spectrophotometry. Hepatic Cu concentrations are physiologically elevated at birth and decline rapidly during the first 2 month of life, therefore only samples from 29 infants, ages greater than 8 weeks were considered for Cu. Concentrations (mg/kg dry weight, mean and range) were: Zn 142 (70-507), Cu 204 (19-570), Mn 9.1 (2.8-21.8) vs. literature controls in the same age range: Zn 262 (82-543), Cu 92, Mn 4.3 (3.3-11.5). No correlations were found between serum alkaline phosphatase, AST or total bilirubin and hepatic trace element concentrations, between trace element concentrations and age, or between Cu and Mn. Decreased bile flow with intrahepatic cholestasis may result in hepatic accumulation of Mn as well as Cu. The low hepatic Zn concentrations indicate the need for further study of Zn metabolism in this population.

Hormonal effects of zinc on growth in children

Zinc deficiency impairs the metabolism of thyroid hormones, androgens, and above all growth hormones. In view of their important role in growth, it is not surprising to find growth disorders associated with zinc deficiency. Stunted growth linked to zinc deficiency is found during gestation, and also in the newborn and children up to adolescence. Depending on the country, 5-30% of children suffer from moderate zinc deficiency, responsible for small-for-age height. Zinc supplementation has proven effective in many studies, mainly in children where zinc deficiency has first been found. Finally, zinc supplementation makes it possible in certain cases to overcome resistance to growth hormone treatment.

Zinc and copper of fetal organs during the second trimester of pregnancy

In fetus with a mean gestational age of 18 weeks (range 15-25, n = 14), zinc and copper concentrations in liver, femur, rib, and skeletal muscle were measured. Zinc and copper concentrations are highest in liver. A trend of decreasing liver zinc concentrations during gestational age is suggested. Zinc concentrations are significantly correlated with copper concentrations in liver and in femur, suggesting steady growth in both organs. Femur zinc values rank ca. 30% of those in liver, femur copper, ca. 2%. Zinc or copper concentrations in rib are of the same levels as in skeletal muscle. Their concentration for zinc ranks ca. 20%, for copper, ca. 5% of the values in liver. All zinc and copper values are lower than reported in third trimester fetal organs. Calculated zinc/copper molar ratios are distinctive for the various organs: in liver, 6 +/- 1, in femur, 73 +/- 8, and in soft tissues, 26 +/- 3. Calculated ratios from published values obtained from the third trimester of pregnancy show that the ratios in liver and skeletal muscle maintain these levels. The zinc/copper molar ratio can serve as an internal reference in zinc and/or copper measurements.

Zinc and vitamin A in liver of foetuses and infants

The association of zinc and vitamin A levels was studied in liver of foetuses and infants which were stillborn or died of various causes between the age of 26 weeks of gestation up to 16 weeks post-partum. No correlation between zinc and vitamin A was observed (r = 0.07). Although smaller infants had more hepatic vitamin A than larger infants no significant difference was observed between these groups for liver zinc values.