Zinc transport in pregnancy

Zimmerman, Andrew W.; Dunham, Barbara; Nochimson, David J.; Kaplan, Bruce M.; Clive, Jonathan; Kunkel, Steven L.

doi:10.1016/0002-9378(84)90029-2

Cited by 53 publications

(25 citation statements)

References 12 publications

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“…Zimmerman et al (1984) suggest that in vivo the feto-maternal zinc gradient is of the order of 5/M. Our mean gradient (30 /uM) compares well with this.…”

Section: Discussionsupporting

confidence: 74%

“…At term in the human, fetal and maternal plasma zinc levels are 15-0+ 4-0 and 10O0 + 1 8 /LM (mean + S.E.M. ), respectively (Zimmerman, Dunham, Nochimson, Kaplan, Clive & Kunkel, 1984). This suggests that transfer of zinc from mother to fetus is an energy-demanding process, although Henkin, Marshall & Meret (1971) have suggested that due to differences in protein binding the level of non-protein-bound zinc in the fetal plasma is less than in the maternal plasma thereby facilitating transfer by simple diffusion.…”

Section: Introductionmentioning

confidence: 99%

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The Transfer of Zinc Across the Term Dually Perfused Human Placental Lobule

et al. 1988

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SUMMARYNet zinc transfer between fetal and maternal circulation has been described in the in vitro perfused lobule of the human term placenta. The transfer results in a 3 ItM differential between fetal and maternal perfusates which is comparable to estimated values in vivo. Tissue zinc concentration is more than 10 times perfusate concentration and is correlated with zinc flux across the fetal borders of the lobule. Open-circuit studies on net transport of zinc, and upon flow of 65Zn relative to tritiated water (3H20), indicate these fluxes depend upon the nonprotein-bound (free) zinc gradient across the fetal-facing membranes. On the other hand movement across the maternal surface is not related to diffusion gradients of free zinc and is either independent of, or inversely related to, the level of tissue zinc. It is concluded that the uptake of zinc from the maternal perfusate may be coupled to metabolism, whereas its transfer to fetal circulation is linked to the level of free zinc in the tissue.

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“…Zimmerman et al (1984) suggest that in vivo the feto-maternal zinc gradient is of the order of 5/M. Our mean gradient (30 /uM) compares well with this.…”

Section: Discussionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

The Transfer of Zinc Across the Term Dually Perfused Human Placental Lobule

et al. 1988

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“…Low plasma zinc concentrations during pregnancy, resulting from low dietary bioavailability (31) or very high amounts of copper or iron in the diet that compete with zinc at absorption sites (45), have been associated with congenital abnormalities, abortions, intrauterine growth retardation, premature birth (46), and preeclampsia (18,19). Zinc deficiency can also affect the immune response because it results in reductions in T cell development, thymic hormone release, and T cell functions (43).…”

Section: Deficiencymentioning

confidence: 99%

Nutrition in pregnancy: mineral and vitamin supplements

Ladipo

2000

The American Journal of Clinical Nutrition

206

129

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Pregnancy is associated with physiologic changes that result in increased plasma volume and red blood cells and decreased concentrations of circulating nutrient-binding proteins and micronutrients. In many developing countries, these physiologic changes can be aggravated by undernutrition, leading to micronutrient deficiency states, such as anemia, that can have disastrous consequences for both mothers and newborn infants. Multiple micronutrients are often taken by pregnant women in developed countries, but their benefits are limited, except for prophylactic folic acid taken during the periconceptional period. Women in developing countries may benefit from multiple-micronutrient prophylaxis in pregnancy, but the underlying basis and rationale for changing from supplementation with iron and folate to supplementation with multiple micronutrients has not been debated in the context of existing program objectives. There is an urgent need for this discussion so that both program effectiveness and program efficacy can be improved. Am J Clin Nutr 2000;72(suppl):280S-90S. KEY WORDSNutrition, vitamins, trace elements, minerals, pregnancy, requirements INTRODUCTIONThe demand for both energy and nutrients is increased during pregnancy (1). For well-nourished women, only a small amount of additional energy is required because the body adapts to the increased energy requirements and becomes more energy efficient through reduced physical activity and a lowered metabolic rate. Although the average-sized, well-nourished woman requires Ϸ10 460 kJ/d (2000 kcal/d) during the last trimester of pregnancy (2), many women in developing countries restrict their food intake during pregnancy to have smaller infants, on the premise that smaller infants will carry a lower risk of delivery complications (3). Recent evidence suggests, however, that infants who are small or disproportionate at birth have increased health risks later in life (4-6). The hypothesis is that such infants have had to adapt to a limited supply of nutrients and that in so doing their physiology and metabolism are permanently changed, although the rationale for this hypothesis has been challenged (7).Requirements for many, but not all, micronutrients increase during pregnancy. Deficiencies can exist because of losses or malabsorption associated with disease or inadequate intakes, lack of knowledge about adequate prenatal nutrition, or dietary taboos associated with pregnancy (8), with potential adverse consequences for both mothers and newborn infants. Rush (9) notes that anemia in pregnancy and pregnancy-induced hypertension are common and thought to contribute significantly to maternal mortality and morbidity in developing countries. Maine (10), however, shows there is little evidence that nutrition plays a role in pregnancy-induced hypertension.This paper discusses minerals and trace elements as well as fat-and water-soluble vitamins in pregnancy-their concentrations, the requirements for them, the consequences of their deficiency, and the functional eff...

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“…A wellknown physiological response of altered zinc utilization in pregnancy is the decrease in cir culating serum zinc, mainly after the second trimester, even in the presence of adequate zinc nutrition. This decrease probably reflects maternal-fetal zinc transfer in response to fe tal growth [3,4]. Elevated serum zinc in mid pregnancy may be a predictor of fetal growth retardation due to poor maternal-fetal trans fer and/or altered zinc utilization [5].…”

Section: Introductionmentioning

confidence: 99%

“…Most studies on maternal-fetal transfer of zinc have related maternal and cord serum zinc, observing either a significant correlation [6,7] or no correlation [8][9][10], A few studies have measured maternal serum zinc in rela tion to other maternal indices of zinc status [11][12][13] and/or to placental zinc [12,14] and cord serum components [4] in normal preg nancies, but the physiological significance of variations in serum zinc in healthy pregnant women is still unclear.…”

Section: Introductionmentioning

confidence: 99%

Maternal, Placental and Cord Zinc Components in Healthy Women with Different Levels of Serum Zinc

Zapata

Melo

Donangelo³

1997

Neonatology

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Serum zinc is known to decrease during pregnancy, but the range of individual values at the end of normal gestation may be considerably large, with uncertain physiological significance in terms of maternal zinc status and maternal-fetal transfer of zinc. In this study we compared several maternal and cord blood indices of zinc status, placental zinc, placental metallothionein and the relationship between maternal, cord and placental components, in 40 healthy pregnant women at delivery with different levels of serum zinc. Subjects were divided into three groups according to serum zinc using as cutoff points the lower and upper quartile values [LZn, < 7.6 µmol/l (n = 10); MZn, 7.6–10.7 µmol/l (n = 20), and HZn, > 10.7 µmol/l (n = 10)]. Habitual zinc intakes were similar in all groups (average 11.5 mg/day). Considering all women, maternal serum and erythrocyte zinc correlated significantly (r = 0.40; p = 0.021). Maternal erythrocyte zinc was higher (p < 0.01) in HZn compared to the other groups. Maternal and cord values of serum zinc correlated significantly (r = 0.43; p = 0.006). Cord serum zinc values were very similar in LZn and MZn but were higher (p < 0.01) in HZn. Cord erythrocyte zinc levels were similar in all groups and about 20–25% of the maternal values. Cord erythrocyte metallothionein levels were also similar in all groups and similar to maternal values. Comparing the percentage distribution of zinc in maternal and cord serum fractions, major differences were observed in HZn, with zinc in albumin fraction being 70% in cord compared to 56% in maternal serum. There was a higher (p < 0.01) percentage of zinc bound to α₂-macroglobulin fraction in maternal serum of HZn compared to maternal serum of the other groups. Maternal and cord zinc in the albumin fractions correlated significantly (r = 0.48; p = 0.002) particularly in HZn (r = 0.71; p < 0.021). Placental zinc correlated negatively (r = ––0.34; p = 0.035) with zinc in the maternal α₂-macroglobulin fraction, but did not relate to placental metallothionein, which had similar levels in all groups (average 0.28 nmol/g wet tissue). Placental zinc levels were lower (p < 0.01) in HZn. Our results indicate that high levels of maternal serum zinc in healthy women at delivery may be related to maternal tissue zinc redistribution that could favor diffusional components of maternal-fetal transfer of zinc.

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Zinc transport in pregnancy

Cited by 53 publications

References 12 publications

The Transfer of Zinc Across the Term Dually Perfused Human Placental Lobule

The Transfer of Zinc Across the Term Dually Perfused Human Placental Lobule

Nutrition in pregnancy: mineral and vitamin supplements

Maternal, Placental and Cord Zinc Components in Healthy Women with Different Levels of Serum Zinc

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