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Title: Interrelationships of zinc, copper, vitamin A and various proteins in pregnancies complicated by neural-tube defects
Author: Tan, Jenny Chiew Yeong
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1987
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Zinc and copper, as components of metalloenzymes, are important for normal fetal development and vitamin-A is essential for differentiation of epithelial tissues. However, deficiency of either zinc, copper, vitamin-A or vitamin-A excess during the crucial stages of gestation, areteratogenic causing congenital malformations including neural-tube-defects (NTD) in animals. This is the first study which has analysed all three essential nutrients in human normal and NTD-pregnancies, in order to gain further insight into their metabolism and interrelationships in association with fetal-NTD. Total vitamin-A, zinc and copper concentrations were determined in 128 second trimester, serum and amniotic fluid samples. 18 pregnancies were associated with fetal-NTD and terminated. The elevated amniotic fluid zinc concentrations (p<0.001 ) found in 83$ of the NTD-pregnancies, were correlated to the AFP levels (p<0.00l) and has potential as a diagnostic marker. This finding prompted further studies to elucidate zinc’s increased presence, especially in relation to proteins. A novel ultrafiltration method was developed to measure non-protein-bound zinc concentrations in plasma and amniotic fluid. The proportion found was 0.2$ of the total zinc in normal plasma and 16$ of total in amniotic fluid. A value of 22$ in NTD-amniotic fluid was significantly higher compared with normals (p<0.0 5)» probably due to the presence of low-molecular-weight zinc ligand(s), addition to the amino acids. in 86$ of the total zinc in normal and 77$ in NTD-amniotic fluid were bound to albumin and alpha-1-antitrypsin. The vitamin-A concentrations were higher in NTD-amniotic fluid (p<0.00l) and were correlated to zinc levels (p<0.0l), but the retinol-binding-protein concentrations were normal. Copper concentrations in NTD-amniotic fluid were normal, therefore only fetal plasma-constituents associated with the abnormality were mobilised. The study has shown more of how these three nutrients interrelate with each other and with proteins; the zinc and vitamin-A metabolism indicated association with human fetal-NTD, either as cause or result.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available