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Biomedical subjects

B Lönnerdal

Publications and source records attributed to B Lönnerdal.

At least 91 records · Page 5Linked to original sources
PubMed1994

Iron, zinc, copper and selenium status of breast-fed infants and infants fed trace element fortified milk-based infant formula.

Infants were fed cow's milk-based formulas containing 4 mg of iron/l from 1.5 to 6 months of age and their hematological status was compared to infants receiving the same formula but with 7 mg of iron/l and with breast-fed infants. One formula with 4 mg of iron/l contained iron as ferrous sulfate, in another, part of the iron was provided as bovine lactoferrin. We also studied the effect of selenium (10 micrograms/l) and copper (0.4 mg/l) supplementation on selenium and copper status. There were no significant differences in hematological indices among the groups at 6 months of age; all infants had satisfactory iron status. Serum transferrin receptor levels, a potential novel indicator of iron status, were highest in breast-fed infants, suggesting a cellular need for iron, and lowest in infants receiving formula with 7 mg of iron/l. Selenium status, as assessed by serum glutathione peroxidase activity, was similar at 6 months of age in breast-fed infants and infants fed formula fortified with selenium but lower in infants fed unfortified formula. The lowest levels of glutathione peroxidase activity were found in infants fed the highest concentration of iron (7 mg/l). Serum copper concentrations were similar in all groups, but the lowest levels were found in infants fed the highest concentration of iron. These results suggest that 4 mg of iron/l is adequate for infants up to 6 months of age and that higher levels may have some negative effects.

Blood Urea Nitrogen↗
PubMed1994

Zinc intake, zinc status and growth in a longitudinal study of healthy Danish infants.

Mild, growth-limiting zinc deficiency might be prevalent in otherwise healthy infants according to recent studies. We examined zinc intake and status in 91 healthy term infants from birth to 12 months, as part of the Copenhagen Cohort Study on Infant Nutrition and Growth. Zinc intake was recorded monthly and the amount of zinc absorbed was estimated. These estimates were below recently published FAO/WHO/IAEA values for basal requirements in 68%, 62% and 14% of the infants at 2, 4 and 9 months of age, respectively. Serum zinc decreased significantly (p < 0.01) from 10.6 mumol/l at 6 months to 8.4 mumol/l at 9 months of age (normal range 10-18 mumol/l). Erythrocyte metallothionein values, a tentative indicator of long-term zinc status, decreased significantly from 2 to 6 months (p < 0.001) and from 6 to 9 months (p < 0.01). Serum zinc at 9 months was positively associated with growth velocity during the period from 6 to 9 months (weight: p = 0.05; knee-heel length: p = 0.002). The results provide descriptive data on zinc intake and zinc status in healthy Danish infants. Although some of our data suggest suboptimal zinc status during late infancy, evidence for this can only be obtained through a randomized intervention study.

Deficiency Diseases↗
PubMed1994

Influence of lactoferrin on iron absorption from human milk in infants.

Lactoferrin (Lf) is a major iron (Fe)-binding protein in human milk and has been proposed to facilitate Fe absorption. The potential effect of Lf on Fe absorption was investigated by measuring Fe absorption in infants fed breast milk (with its native content of Lf) and the same milk from which Lf had been removed (> 97%) by treatment with heparin-Sepharose. Eight breast-fed infants (2-10 mo; mean age 5 mo) were fed 700 to 1000 g of each milk in a randomized, cross-over design with each child acting as his/her own control. The milk was labeled with 8.6 mumol (0.5 mg) of 58Fe and Fe absorption was measured by quantifying the incorporation of the isotope into red blood cells 14 d after intake using thermal ionization mass spectrometry. Fractional Fe absorption was significantly lower (p < 0.05) from breast milk than from Lf-free breast milk. The geometric mean (range) was 11.8% (3.4-37.4%) for breast milk and 19.8% (8.4-72.8%) for Lf-free breast milk. These results do not support a direct role for Lf in the enhancement of Fe absorption from human milk at this age. In addition, Fe absorption (11.8%) from human milk fed over several feeds was lower than that previously reported for single feed studies.

Biological Availability↗
PubMed1994

Infant feeding policies in maternity wards and their effect on breast-feeding success: an analytical overview.

OBJECTIVES: The purpose of this review is to examine the plausibility of a causal relationship between maternity ward practices and lactation success. METHODS: Studies were located with MEDLINE, from our personal files, and by contacting researchers working in this field. Of the 65 studies originally reviewed, 18 met our inclusion criteria (i.e., hospital-based intervention, experimental design with randomization procedures, or quasi-experimental design with adequate documentation). RESULTS: Meta-analysis indicated that commercial discharge packs had an adverse effect on lactation performance. The impact of early mother-infant contact on lactation success was unclear. Rooming-in and breast-feeding guidance in a rooming-in context had a beneficial impact on breast-feeding among primiparae. Breast-feeding on demand was positively associated with lactation success. In-hospital formula supplementation of 48 mL per day was not associated with poor breast-feeding performance. CONCLUSIONS: Hospital-based breast-feeding interventions can have a beneficial effect on lactation success, particularly among primiparous women.

Bottle Feeding↗
PubMed1994

Isolation of mRNA and genomic DNA from epithelial cells in human milk and amplification by PCR.

Studies on the regulation of human milk protein genes and suitable cell culture systems have been limited due to restricted availability of tissue samples from lactating women. Although mammary gland tissue has been available from mammary reduction surgery, studies on tissue-specific expression of milk protein genes require samples obtained during specific stages of expression in the tissue, i.e., lactation. We have therefore developed a technique to isolate mRNA and genomic DNA directly from epithelial cells isolated from human milk and used PCR methodology to specifically amplify the cDNA and genomic DNA for human beta-casein. When comparing fresh human milk with milk that has been stored for five hours at 37 degrees C or frozen and thawed, we found that the amount of mRNA isolated was considerably higher from fresh milk. However, in spite of this, we could still isolate intact mRNA from frozen milk. The described methodology should be useful in studies on milk protein gene expression during lactation and studies on variants of milk protein genes.

Base Sequence↗
PubMed1993

Expression of human milk beta-casein in Escherichia coli: comparison of recombinant protein with native isoforms.

Studies on physiological function and on structure-function relationships of human milk beta-casein have been limited. In this study, we have introduced the human beta-casein cDNA into vectors designed for expression in Escherichia coli. The inducible T7-based expression system resulted in high-level expression of recombinant beta-casein. The recombinant beta-casein, localized intracellularly in E. coli, was purified to homogeneity and compared with purified native beta-casein, in particular with respect to phosphorylation. The E. coli-produced beta-casein was found to comigrate with the full-length, nonphosphorylated native human beta-casein isoform on SDS-PAGE. An N-terminal peptide containing all tentative phosphorylation sites was isolated from the recombinant protein and analyzed by mass spectrometry. The molecular mass as well as the migration of this peptide on reversed-phase chromatography confirmed that it was unphosphorylated.

Amino Acid Sequence↗
PubMed1993

Protein composition of rhesus monkey milk: comparison to human milk.

1. Proteins in human milk and Rhesus monkey milk have been compared by FPLC gel filtration and anion exchange chromatography, SDS-Polyacrylamide gel electrophoresis, nitrogen and protein determination. 2. Mature Rhesus milk is higher in protein concentration (15-20 mg/ml) than human milk (8-9 mg/ml). 3. Non-Protein nitrogen is 6-13% in Rhesus milk but 25-30% in human milk. 4. Secretory IgA, lactoferrin, serum albumin, alpha-lactalbumin and lysozyme are present in Rhesus milk, but at a lower concentration than in human milk. 5. The casein subunit pattern is more complex in Rhesus milk compared to human milk. 6. The ratio of whey proteins to casein is similar in both milks (approximately 60/40). 7. A protein with a M(r) of 21,600 is a major component in monkey whey but is not found in human milk.

Animals↗
PubMed1993

Breast-fed infants are leaner than formula-fed infants at 1 y of age: the DARLING study.

Anthropometric indexes from 1 to 24 mo were compared between matched cohorts of infants either breast-fed (BF, n = 46) or formula-fed (FF, n = 41) until > or = 12 mo. Neither group received solid foods before 4 mo. Weight-for-length was significantly greater among FF infants from 7 to 24 mo. In both groups, skinfold thickness (triceps, biceps, subscapular, flank, and quadriceps) and estimated percent body fat (%FAT) increased rapidly during the first 6-8 mo and declined thereafter. At all sites except biceps, FF infants had larger skinfold thicknesses in later infancy (particularly 9-15 mo) than did BF infants; %FAT was significantly higher from 5 to 24 mo. Lower energy intake among BF infants explained the difference between groups. Maternal and infant fatness were positively correlated at 12-24 mo. Breast-milk lipid and energy concentration were unrelated to infant fatness. These results indicate that infants BF for > or = 12 mo are leaner than their FF counterparts.

Adipose Tissue↗
PubMed1993

Magnesium bioavailability from human milk, cow milk, and infant formula in suckling rat pups.

Little is known about the absorption of magnesium from infant diets. Magnesium bioavailability was evaluated from infant diets that varied by protein and carbohydrate source; magnesium, calcium, and phosphorus contents; and the form of magnesium fortification. Diets were separated into soluble, insoluble, and fat fractions to determine magnesium distribution. Most of the magnesium (> 62%) was found in the soluble fraction. Gel filtration of the soluble fraction from all diets studied showed that > 95% of magnesium is free or associated with low-molecular-weight compounds. Distribution of 28Mg and native magnesium in fractions of the diets was similar, thus validating the use of an extrinsic label. In vitro digestion decreased the percent insoluble magnesium from as high as 35% to 2-8%. Whole-body retention of 28Mg-labeled diets in suckling rat pups 4 h after oral intubation ranged from 51% to 92%. No significant differences were found between human milk, cow milk, and infant formula. In conclusion, magnesium from the infant diets studied has high bioavailability, and moderate differences in their composition do not affect bioavailability significantly.

Animals↗
PubMed1993

Potential magnitude of the misclassification of a population's trace element status due to infection: example from a survey of young Peruvian children.

To examine the effects of concurrent infection on population-based assessment of trace element status, we collected data on clinical signs and laboratory indicators of infection when obtaining blood for serum zinc, copper, and ferritin analyses in 153 Peruvian children aged 11-19 mo. Fifty-two (34.7%) of the children had some reported sign of infection and 43 (28.3%) had elevated C-reactive protein concentrations or leukocytosis. Children with any evidence of infection had marginally lower mean (+/- SD) serum zinc concentrations (7.0 +/- 2.3 vs 7.5 +/- 2.0 mumol/L, P = 0.16) and significantly greater serum copper (24.7 +/- 4.7 vs 22.7 +/- 4.2 mumol/L, P = 0.006) and serum ferritin concentrations (10.0 +/- 12.9 vs 3.9 +/- 4.4 micrograms/L, P < 0.001) than did those without infections. Infection caused an underestimation in the rate of low copper status by 1 percentage point and low iron status by 12 percentage points. Thus, the effect of concurrent infections is of variable magnitude and may differ by nutrient, nutritional status of the population, and prevalence and severity of infections.

C-Reactive Protein↗
PubMed1993

Simple and rapid macronutrient analysis of human milk for individualized fortification: basis for improved nutritional management of very-low-birth-weight infants?

Feeding human milk exclusively to the very-low-birth-weight infant may lead to insufficient intakes of protein and energy. Although the milk is therefore often supplemented with protein and additional calories, there is usually no prior information on its macronutrient composition. If such data were available, it would be possible to individualize the fortification of the milk. To find simple, rapid, and inexpensive methods of enriching it, we evaluated existing macronutrient assays of human milk. Thirty frozen samples of early human milk (3-20 days of lactation) were analyzed for contents of protein (Kjeldahl, Lowry, and Bio-Rad protein assays), fat (Folch, total lipids assay, and creamatocrit), and carbohydrates (lactose and orcinol assays). The methods were modified to minimize cost and time. From these data, we find it appropriate to recommend the use of the Lowry (or, alternatively, the Bio-Rad) protein assay, the total lipids assay, and the orcinol carbohydrate assay for reasonably accurate determinations of the protein and energy contents of human milk. Because the variation in the carbohydrate content of human milk is very small, a more simple alternative approach would be to include only an average carbohydrate value for an estimate of energy content. These low-cost methods can be used in all laboratories affiliated to neonatal units taking care of preterm infants. Such individualized fortification should serve to further improve the nutritional management of very-low-birth-weight infants.

Carbohydrates↗
PubMed1993

Zinc supplementation impairs monocyte function.

Zinc has been shown to be involved in many functions of the immune system. This study was conducted to examine the effect of zinc supplementation on phagocytic, fungicidal and metabolic activity of blood monocytes of marasmic infants during nutritional rehabilitation. A controlled, double-blind design was used in which 19 infants fed a zinc-fortified formula were compared with 20 infants fed the same, unfortified formula. Evaluation of phagocytic-fungicidal capacity, growth, zinc, copper and iron status was performed in both groups on admission and after 60 and 105 days of nutritional rehabilitation. Although energy, copper and iron intakes were similar in the two groups, a decrease in the number of infants able to phagocytose one or more Candida buds was observed after 60 days of zinc supplementation compared to admission (p < 0.03). No change in phagocytic ability was detected between admission and 60 days in the control group. The number of infants with depressed fungicidal activity increased significantly after 105 days of nutritional rehabilitation in the zinc-fortified group as compared to controls (p < 0.04). The number and duration of impetigo episodes was significantly greater in the group fed the zinc-fortified formula. These results suggest that zinc supplements at the RDA level may impair monocyte function.

Candida albicans↗
PubMed1993

Use of growth models to describe patterns of length, weight, and head circumference among breast-fed and formula-fed infants: the DARLING Study.

Nine mathematical models were applied to 24-month length, weight, and head circumference growth curves of 39 breast-fed and 31 formula-fed infants from the DARLING study. For both breast-fed and formula-fed infants, the Karlberg infancy-childhood-puberty (ICP) model best describes the relationship between recumbent length and age and the Jenss model best describes the relationship between head circumference and age. For formula-fed infants several models appropriately describe the relationship between weight and age, and we recommend the Jenss model. However, none of the models suitably describes the shape of the weight curve for breast-fed infants.

Analysis of Variance↗
PubMed1992

Calcium and zinc retention from protein hydrolysate formulas in suckling rhesus monkeys.

OBJECTIVE: To determine calcium and zinc retention from infant formulas based on protein hydrolysates. DESIGN: Randomized, crossover. SETTING: Newborn nursery at the California Primate Research Center, Davis. PARTICIPANTS: Suckling infant rhesus monkeys (N = 7), aged 6 weeks at the beginning of the study. Each infant received seven different formulas. INTERVENTIONS: Fasted infant monkeys were fed diets radiolabeled with calcium 47 and zinc 65. Retention was determined by counting whole body radioactivity immediately after dosing and 7 days after dosing. MEASUREMENTS AND RESULTS: Retention of 47Ca was a mean (+/- SEM) of 79% +/- 4% from casein hydrolysate and 72% +/- 6% from the whey protein hydrolysate formula. Calcium 47 retention from hydrolysates based on whey protein/casein mixtures (a ratio of 60:40 or 50:50) was similar despite differences in protein sources and calcium content. Calcium 47 retention from two types of soy/collagen hydrolysate formula was found to be 68% +/- 6% and 59% +/- 4%, respectively, which is significantly lower than retention from casein hydrolysate. Considering the different calcium content of these formulas, total calcium retention from milk protein hydrolysates was higher than from soy/collagen products. Retention of 65Zn from milk protein hydrolysates ranged from 18% +/- 3% to 29% +/- 4% and was higher than that from soy/collagen formulas with a mean retention of 7% +/- 3% and 10% +/- 4%, respectively. Despite these differences in 65Zn retention, total zinc retention from all soy/collagen formulas was similar due to their higher zinc content. CONCLUSIONS: Calcium and zinc bioavailability was high from formulas based on milk protein hydrolysate, but was considerably lower from soy hydrolysates. Higher levels of calcium and zinc provided in soy hydrolysate formula compensated for the lower bioavailability and resulted in similar amounts of calcium and zinc retained.

Absorption↗
PubMed1992

Effect of a zinc-fortified formula on immunocompetence and growth of malnourished infants.

This study attempted to define the possible contribution of zinc nutrition to immunocompetence and growth in severely malnourished infants. The effect of zinc supplementation was evaluated in marasmic infants during nutritional rehabilitation by using a controlled double-blind design in which 19 infants fed a zinc-fortified formula were compared with 20 infants fed the same non-supplemented formula. Evaluation of immunocompetence, growth, and zinc, copper, and iron status was performed on admission and at 30, 60, and 105 d of nutritional rehabilitation. Although energy intake was similar in both groups, the zinc-supplemented infants had significantly higher linear growth gain, and their immune function improved as demonstrated by conversion of their delayed hypersensitivity skin reactions, enhanced lymphoproliferative response to PHA, and increased salivary IgA concentrations. Thus, the use of a zinc-fortified formula during nutritional rehabilitation can prevent the development of zinc deficiency and improve growth and immune function.

Copper↗
PubMed1992

Growth patterns of breast-fed infants in affluent (United States) and poor (Peru) communities: implications for timing of complementary feeding.

We compared growth, dietary intake, and morbidity of infants breast-fed for > or = 12 mo from two populations: Davis, CA (n = 46) and Huascar, Peru (n = 52). When compared against WHO reference data (based primarily on formula-fed infants), Huascar infants appeared to falter as early as 3-4 mo, but when compared with Davis breast-fed infants, the curves for weight and length were very similar in girls until 10-12 mo and in boys until 6-9 mo. Thereafter, Huascar infants grew less rapidly than did Davis infants. Breast milk intake was very similar between groups, but in Huascar the amount and nutrient density of complementary foods consumed after 6 mo were lower and morbidity rates were much higher than in Davis. These results indicate that growth faltering of Huascar infants, when judged against breast-fed infants in the United States, occurs primarily after the first 6 mo of life and is not due to poor lactation performance.

Animals↗
PubMed1992

Iron absorption differs in piglets fed extrinsically and intrinsically 59Fe-labeled sow's milk.

Iron bioavailability from species-specific milk is assumed to be high for the offspring, possibly due to species-specific iron-binding proteins in the milk. To assess this bioavailability using radioisotopes, the validity of extrinsic labeling technique needs to be proven. Using the suckling piglet as an animal model, we have compared iron bioavailability from sow's milk labeled extrinsically and intrinsically. During intrinsic labeling transfer into milk of 59Fe given intramuscularly was slow and was found to be at maximum 14 h post-injection. Recovery of isotope in the milk was only 0.00014%. Extrinsic and intrinsic labels were distributed differently among milk fractions; intrinsic iron bound primarily to the fat fraction but the extrinsic iron bound primarily to the casein fraction. Iron retention from intrinsically labeled milk was considerably higher than from extrinsically labeled milk. These results show that the extrinsic tag method is not valid for studies on iron absorption from sow's milk and suggest that the situation may be the same for human milk.

Absorption↗