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Biomedical subjects

M M Giles

Publications and source records attributed to M M Giles.

6 recordsLinked to original sources
PubMed1990

Magnesium metabolism in preterm infants: effects of calcium, magnesium, and phosphorus, and of postnatal and gestational age.

This study tests the hypothesis that increasing the calcium and phosphorus content of formulas for very low birth weight (VLBW) infants to the level required to decrease the incidence of rickets has a negative impact on magnesium balance. Using formulas variously supplemented with these minerals, we measured absorption and retention in two groups of preterm infants: (1) VLBW infants, less than 1500 gm and at less than 32 weeks of gestational age, with 3-day mineral balances begun at days 10, 20, 30, and 40; and (2) low birth weight infants appropriately grown and at 32 to 34 weeks of gestational age, with a single 3-day balance begun at day 10. Magnesium did not affect calcium balance in VLBW or low birth weight infants but promoted phosphorus retention in VLBW infants from day 20 onward. Absorption and retention of magnesium increased with postnatal age in VLBW infants, but this effect was obvious only when calcium or phosphorus intakes were low or when magnesium intake was high. Calcium and phosphorus supplementation further reduced magnesium absorption and retention in VLBW infants to the extent that they were in negative balance throughout the study; however, magnesium supplementation improved absorption and retention in VLBW infants. The low birth weight infants absorbed and retained more magnesium than VLBW infants at the same postnatal age whether or not magnesium was supplemented. We conclude that magnesium deficits occur at currently recommended intakes of 10 mg/kg/day for VLBW infants with calcium and phosphorus intakes that allow retentions equivalent to in utero accretions; however, with magnesium intakes approaching 20 mg/kg/day, appropriate retention can be achieved.

Absorption↗
PubMed1987

Sequential calcium and phosphorus balance studies in preterm infants.

Forty-six infant boys less than 1500 g at birth and less than 32 weeks gestation were fed enterally from birth until day 47. Cohorts were given milk formula varying in calcium and phosphorus content: group A, calcium 45 mg/dL, phosphorus 33 mg/dL; group B, calcium 85 mg/dL, phosphorus 33 mg/dL; group C, calcium 125 mg/dL, phosphorus 33 mg/dL; group D, calcium 125 mg/dL, phosphorus 50 mg/dL; and group E, calcium 125 mg/dL, phosphorus 64 mg/dL. Three-day balance studies were begun at days 10, 20, 30, and 40. Calcium net absorption and retention were influenced by postnatal age and calcium intake. Calcium retention best approached intrauterine accretion rates in group C. Phosphorus was well absorbed irrespective of the calcium content of the milk. Phosphorus retention increased with increments in the calcium content of the milk. Increasing the phosphorus content of the milk (groups D and E) resulted in no overall change in calcium absorption and retention but some increments in phosphorus retention.

Birth Weight↗
PubMed1980

Maternal vitamin D intake and mineral metabolism in mothers and their newborn infants.

Pregnant women receiving daily supplements of 400 IU (10 microgram) of vitamin D2 from the 12th week of pregnancy had plasma calcium concentrations higher at 24 weeks but similar at delivery to those in control pregnant women who did not receive the supplements. Infants of the women receiving the supplements had higher calcium, lower phosphorus, and similar magnesium concentrations on the sixth day of life and a lower incidence of hypocalcaemia than infants of the control women. Plasma concentrations of 25-hydroxycholecalciferol, which showed a seasonal variation, were higher in mothers and infants in the treated group. Cord-blood calcium, magnesium, phosphorus, and 25-hydroxycholecalciferol concentrations correlated with maternal values at delivery. Breast-fed infants had higher calcium and magnesium and lower phosphorus and 25-hydroxycholecalciferol concentrations than artificially fed infants. A defect of dental enamel was found in a high proportion of infants (many of whom had suffered from hypocalcaemia) born to the control women. These results suggest that vitamin D supplementation during pregnancy would be beneficial for mothers, whose intake from diet and skin synthesis is appreciably less than 500 IU of vitamin D daily.

Blood Proteins↗
PubMed1977

Clinical and biochemical assessment of a modified evaporated milk for infant feeding.

A clinical and biochemical evaluation has been made of a new milk formula, Modified Carnation milk (MCM), based on cows' milk but with the mineral content and concentration of caloric nutrients altered to make it correspond more closely to human milk. MCM produced higher plasma calcium and magnesium concentrations in 6-day-old infants than those produced by unmodified evaporated and dried milks, achieving concentrations closer to those of breast milk. Plasma free amino acid concentrations in MCM-fed infants are nearer breast-fed values than those in unmodified milk-fed infants where higher individual plasma amino acid concentrations persist during the first 3 months. MCM-fed infants had low plasma urea concentrations and lower urine osmolalities at 6 days, 3 weeks, 6 weeks, 3 months, and 6 months than infants fed on the evaporated and dried milks, and similar plasma urea and urine osmolalities to those of breast-fed infants. MCM is likely to be superior to unmodified evaporated and dried milks in preventing convulsions of the hypocalcaemic/hypomagnesaemic/hyperphosphataemic type, and seems less likely to cause hypertonic dehydration. MCM is easily prepared, readily accepted by babies, and appears to be nutritionally adequate for the feeding of term infants.

Amino Acids↗