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Biomedical subjects

B Lönnerdal

Publications and source records attributed to B Lönnerdal.

At least 181 records · Page 10Linked to original sources
PubMed1986

Effects of maternal dietary intake on human milk composition.

The composition of human milk can be affected by the diet consumed by the lactating woman. The influence of the maternal diet on milk composition varies in magnitude between nutrients; for some nutrients no effect at all has yet been documented. Concentrations of fatty acids, fat-soluble and water-soluble vitamins in milk are, in general, significantly affected by the levels of these nutrients in the diet. Protein concentration may be affected under some conditions, although the magnitude of this change appears relatively limited. Lactose, mineral, trace element and electrolyte concentrations seem comparatively resistant to varying maternal intakes. Although there has been significant progress in this research area in the past decade, many early studies are difficult to interpret due to limitations in the study design and analytical methods. This review demonstrates a distinct need for carefully controlled studies on the effects of both nutrient deficiencies and supplements on milk composition. Interactions among nutrients, homeostatic mechanisms and energy balance (weight loss) are factors that need to be studied further. Information from such research will suggest strategies for nutrition intervention in areas of poor nutrition and provide dietary guidelines for lactating women.

Diet↗
PubMed1986

Coffee intake during pregnancy and lactation in rats: maternal and pup hematological parameters and liver iron, zinc and copper concentration.

To study the effects of maternal coffee intake on trace element status of the fetus and newborn, Sprague-Dawley female rats were fed a control purified diet and were provided ad libitum a freeze-dried coffee solution (1.5% wt/vol) (C) or distilled water (W) as their sole source of liquids from d 0 of gestation. On d 21 of gestation, a subsample of dams from each group was killed and litters were removed for examination. At birth, a subsample of litters from each group was cross-fostered to differentiate between pre- and postnatal exposure to coffee (water prenatally, coffee postnatally = WC; coffee prenatally, water postnatally = CW). Food and fluid intake during gestation, maternal weight gain and litter size were similar in the coffee and control groups, but pup birth weight was lower in the coffee group than in the control group (5.82 vs. 6.45 g, P less than 0.05). Compared with that of control pups, hemoglobin (Hb) was significantly lower in C and WC pups, but not in CW pups, at 3 and 14 d of age. Hematological values were not significantly different between C and W dams or C and W fetuses. Livers of C and WC pups had higher concentrations and total content of Fe, Zn and Cu at 3 d of age compared with controls, but the differences were reduced by 14 d of age. The results suggest that maternal coffee intake may impair mobilization of trace elements from liver reserves in early life and that this may result in reduced hemoglobin synthesis.

Animals↗
PubMed1986

Copper deficiency-induced hypercholesterolemia: effects on HDL subfractions and hepatic lipoprotein receptor activity in the rat.

Male Sprague-Dawley rats (10 per group) were fed diets adequate (control) or deficient (CuDef) in copper for 6 wk. In the CuDef group, plasma total cholesterol, high density lipoprotein (HDL) cholesterol and apoA-I levels were significantly higher than in controls. Apolipoprotein analysis of the HDL fractions revealed a relative enrichment of apoE in the CuDef group. Size analysis of 1.21 density lipoproteins by nondenaturing gradient gel electrophoresis demonstrated the presence of more material migrating in the size range of HDL1 in the CuDef group. Separation of HDL into apoE-rich and apoA-I-rich fractions by heparin-affinity chromatography confirmed the presence of increased apoE-rich HDL in the CuDef group. To determine the mechanism responsible for higher apoE-rich HDL in the CuDef group, the lipoprotein receptor binding activity in hepatic membranes from the control and CuDef group was assayed. Kinetic analysis of the binding data revealed that the lipoprotein binding assay was primarily measuring the activity of the HDL receptor, which is not apoE mediated. When corrected for differential enrichment of plasma membrane, hepatic membranes from the CuDef group bound significantly fewer lipoproteins than did controls. Furthermore, the hepatic receptor binding activity was negatively correlated with the proportion of HDL enriched with apoE.

Animals↗
PubMed1986

Zinc-vitamin A interaction in pregnant and fetal rats: supplemental vitamin A does not prevent zinc-deficiency-induced teratogenesis.

The influence of a higher-than-normal intake of vitamin A on the detrimental effects of zinc deficiency on vitamin A metabolism was investigated in pregnant Sprague-Dawley rats. At mating, rats were fed diets containing 100 (control), 4.5, or 0.5 micrograms/g zinc combined with 4 (control) or 8 micrograms retinyl acetate/g. Low intake of zinc, but not of vitamin A, caused food intake, total body weight change, fetal weight and placental weight to be low. Incidence of teratogenic effects was more pronounced in low zinc groups than in controls. Concentrations of vitamin A in maternal plasma and liver were affected by the amount of zinc in the diet. Dietary vitamin A, however, did not affect either of these parameters. Maternal plasma zinc concentration was affected only by low dietary zinc, whereas plasma copper and iron were unaffected by the dietary treatments. Maternal liver iron was higher in zinc-deficient rats than in controls; however, maternal liver zinc and copper concentrations were not altered by dietary treatments. No significant differences in vitamin A concentration of fetal liver, fetal plasma, or placenta were seen among the groups. Fetuses from zinc-deficient dams had significantly lower levels of liver vitamin A and liver zinc than did controls. Fetal liver iron was higher in zinc-deficient fetuses than in controls, whereas fetal liver copper was not affected by dietary treatment. These data suggest that supplemental dietary vitamin A does not ameliorate the effect of zinc deficiency on vitamin A metabolism during pregnancy.

Animals↗
PubMed1986

Serum antibodies against native, processed and digested cow's milk proteins in children with cow's milk protein intolerance.

Children with or without cow's milk protein intolerance were investigated for serum antibodies to native cow's milk proteins, processed cow's milk proteins and native- and pepsin-digested beta-lactoglobulin. Antibodies of IgG and IgA isotypes were determined with ELISA and those of IgE isotype with RAST. Children who exhibited slowly appearing untoward reactions to cow's milk feeding had significantly higher titres of IgG antibodies against both native and digested beta-lactoglobulin than children with an immediate type of reaction or no intolerance. The IgG antibodies to pepsin-digested beta-lactoglobulin were efficiently inhibited by native beta-lactoglobulin even at low concentrations, which suggests that there were no antibodies specific for the degraded proteins. The children with slow reactions to cow's milk also tended to have higher antibody levels of the IgG and IgA isotypes to both native and processed cow's milk. Antibodies to this mix of antigens discriminated less well, however, than the antibodies to isolated beta-lactoglobulin between the groups of children with slowly appearing reactions, with immediate reactions and the controls. Seven out of nine children with an immediate type of reaction to cow's milk protein had IgE antibodies against cow's milk protein determined with the RAST, while this type of antibodies could not be demonstrated in any child in the two other groups. Using processed or digested protein as antigen did not increase the sensitivity of the antibody determinations.

Animals↗
PubMed1986

Effects of short-term caloric restriction on lactational performance of well-nourished women.

Milk volume and composition, nutrient intake and plasma prolactin levels of 22 well-nourished lactating women were measured during a 3-week period; an experimental group (E, n = 14) reduced energy intake by 19 to 53% (mean 32%) during week 2 while controls (C, n = 8) maintained normal intake. Mean maternal energy intakes (kcal/day) were: (E) 2316 (wk 1), 1591 (wk 2); (C) 2037, 2121. Mean infant milk intakes (g/day) during these weeks were: (E) 736, 718, 684; (C) 714, 671, 702. Milk intake was not reduced among infants of mothers whose energy intakes were at least 1500 kcal/day during week 2. In group E prolactin levels tended to increase during week 2. Milk composition did not change significantly. Lower energy intakes than those currently recommended appear compatible with successful lactation and gradual maternal weight loss, but longer-term studies are needed to determine a lower limit for safe intakes.

Adult↗
PubMed1986

Infant self-regulation of breast milk intake.

In an experimental study to determine whether augmentation of maternal milk supply affects infant intake, 18 mothers of exclusively breast-fed infants stimulated milk supply by daily expression of extra milk for 2 weeks. Infant milk intake was recorded before, during and after this expression phase. All but 4 mothers increased milk production by greater than 73 g/day over baseline, with an average increase of 124 g/day. On the average, the 14 infants of mothers who increased milk production took in significantly more milk immediately following the expression phase (849 vs. 732 g/day), but about half of them returned to near baseline levels of milk intake after 1-2 weeks. Net change in infant intake at the end of the study was positively correlated with infant weight-for-length (r = 0.59) and age (r = 0.58), and was unrelated to baseline milk intake (r = -0.06). Therefore, the wide range in breast milk volume in well-nourished populations is due more to variation in infant "demand" than to inadequacy of milk production.

Adult↗
PubMed1986

Isolation and characterization of rhesus monkey milk lactoferrin.

Rhesus monkey milk lactoferrin was isolated and its characteristics compared with those of human milk lactoferrin in order to assess the feasibility of using the rhesus monkey as an animal model for the study of iron absorption from milk. Monkey lactoferrin was isolated from pooled monkey milk by two chromatographic steps. Concentration of lactoferrin in milk, determined by rocket immunoelectrophoresis, demonstrated similar concentrations in both human and monkey milk, 1-2 mg/ml. Immunodiffusion of lactoferrins from several species using an antibody raised to money lactoferrin resulted in a cross-reaction only with monkey and human lactoferrin. Lactoferrins from cow, sheep, goat, dog, and rat milk were not recognized by the antibody. Amino acid analysis of monkey lactoferrin showed a composition very similar to human lactoferrin, as well as a similarity in the unusual amino acid sequence at the N-terminal of the protein. The carbohydrate moiety of monkey lactoferrin was investigated and shown to contain monosaccharides in similar proportions to those reported for human lactoferrin. In our opinion, the rhesus monkey is a promising model for the study of the role of lactoferrin in iron absorption in the infant, as well as of the other proposed actions of lactoferrin.

Amino Acid Sequence↗
PubMed1985

Effects of high doses of manganese on carbohydrate homeostasis.

The effects of manganese (Mn) toxicity on carbohydrate homeostasis was examined in Sprague-Dawley and Osborne-Mendel rats. Mn injection was followed by increases in Mn concentration in both liver and pancreas. Concentrations of Mn in the pancreas increased more rapidly than in the liver. Plasma insulin levels decreased, plasma glucose levels increased, and a spike in glucagon concentration was observed following Mn injection. Increases in blood glucose in response to Mn injection were also observed in 24- and 48-h fasted rats, although the magnitude of the increase was less than that observed in fed rats. Both strains of rats appeared to respond similarly to Mn injection. The present studies demonstrate that acute Mn injection can affect glucose homeostasis. These effects may be mediated through altered endocrine pancreatic function.

Animals↗
PubMed1985

Casein content of human milk.

Three methods for estimating the casein content of human milk were tested; isoelectric precipitation with washing and correction for co-precipitating proteins, sedimentation by ultracentrifugation, and indirect analysis (ie analyzing for the content of the major whey proteins and subtracting these from the total protein content). Gel electrophoresis and amino acid analysis were used to confirm some of the results. The casein content (mg/ml) of mature human milk (n = 9) was 2.33 +/- 1.69 by isoelectric precipitation, 1.80 +/- 0.48 by sedimentation and 2.96 +/- 1.08 by the indirect approach. A probable partition of nitrogen in breast milk would be casein N: whey protein N: non-protein N of 20:50:30; ie the correct ratio of casein nitrogen: whey nitrogen is approximately 20:80. Analysis of trace elements and minerals demonstrates that of total Ca 10%, Mg 5%, Zn 28%, Cu 17%, and Fe 27% is bound to casein when prepared by ultracentrifugation while isoelectric precipitation causes a redistribution of some of these elements. Since the protein ratio of human milk is considered a guideline when manufacturing infant formulas, these findings should be considered with regard to infant nutrition.

Amino Acids↗
PubMed1985

Manganese binding proteins in human and cow's milk.

Manganese nutrition in the neonatal period is poorly understood, due in part to a lack of information on the amount of manganese in infant foods and its bioavailability. Since the molecular localization of an element in foods is one determinant of its subsequent bioavailability, we have studied the binding of manganese in human and cow's milk. An extrinsic label of 54Mn was shown to equilibrate isotopically with native manganese in milks and formulas. Milk samples were separated into fat, casein and whey by ultracentrifugation. In human milk, the major part (71%) of manganese was found in whey, 11% in casein and 18% in the lipid fraction. In contrast, in cow's milk, 32% of total manganese was in whey, 67% in casein and 1% in lipid. Within the human whey fraction, most of the manganese was bound to lactoferrin, while in cow's whey, manganese was mostly complexed to ligands with molecular weights less than 200. The distribution of manganese in formulas was closer to that of human milk than of cow's milk. The bioavailability of manganese associated with lactoferrin, casein and low molecular weight complexes needs to be assessed.

Animals↗
PubMed1985

Breast milk composition: fat content and fatty acid composition in vegetarians and non-vegetarians.

Milk from vegetarians contained a lower proportion of fatty acids derived from animal fat and a higher proportion of polyunsaturated fatty acids derived from dietary vegetable fat. No significant differences were observed between dietary groups in percent fat in the milk or in proportions of fatty acids synthesized de novo in the mammary gland. Among women consuming less than 35 g animal fat per day, percent milk fat was significantly correlated with animal fat intake. Among women consuming greater than 35 g animal fat, percent fat in milk was positively correlated with percent of C10:0, C12:0, and C18:3 and negatively correlated with percent of C16:0 and C18:0 in the milk fat. These findings suggest that there is a maximum amount of C16:0 and C18:0 that can be taken up from the blood and subsequently secreted into the milk.

Adult↗
PubMed1985

Changes in hepatic superoxide dismutase activity in alcoholic monkeys.

The hepatic concentrations of copper, zinc and manganese, the activity of the mitochondrial enzyme manganese-superoxide dismutase (MnSOD), and the activity of the cytosolic enzyme copper-zinc SOD (CuZnSOD) were measured in control and ethanol-fed monkeys. In the ethanol-fed group, liver Zn levels were decreased while the Mn concentration was increased. The activity of MnSOD was higher in the ethanol-fed group while the activity of CuZnSOD tended to be lower. The finding of increased activity of MnSOD is consistent with the finding of enlarged mitochondria and increased liver Mn in the ethanol-fed group. Increased MnSOD may reflect substrate induction, since superoxide anions are generated by ethanol metabolism. On the other hand, insufficient CuZnSOD activity may contribute to increased ethanol-induced lipid peroxidation with resultant mitochondrial damage. Thus, the chronic consumption of ethanol results in altered levels of trace minerals and SOD activities in the liver which in turn may contribute to hepatic injury.

Alcoholism↗
PubMed1985

Does iron supplementation compromise zinc nutrition in healthy infants?

Iron supplements are commonly administered to infants in order to prevent iron deficiency. We wished to determine whether iron administration could compromise zinc nutrition as might be suspected from previous studies. Measures of iron nutrition, serum zinc, and serum copper were measured before and after randomization of 291 healthy 1-yr-old infants to a 3 mo course of placebo or iron treatment (30 mg iron as ferrous sulfate given before a meal). There was no significant difference in serum zinc or copper in the two groups before or after treatment; thus iron administration did not result in any evidence of zinc deficiency in a healthy, well-nourished group of T-yr-old infants.

Age Factors↗
PubMed1985

Copper absorption from human milk, cow's milk, and infant formulas using a suckling rat model.

Since copper deficiency is known to occur during infancy, it becomes important to assess copper uptake from various infant diets. We have investigated the uptake of copper from human milk, cow's milk, cow's milk formulas, cereal/milk formula and soy formula, compensating for the decay of 64Cu and using the suckling rat as a model. Radiocopper was added to the diet in trace amounts. Ultracentrifugation, ultrafiltration, and gel filtration were used to show that the added 64Cu bound to milk fractions and individual binding compounds in a manner analogous to the distribution of native copper, thus validating the use of extrinsically labeled diets. Labeled diets were intubated into 14-day-old suckling rats. Animals were killed after 6 h and tissues removed and counted. Liver copper uptake was 25% from human milk, 23% from cow's milk formula, 18% from cow's milk, 17% from premature (cow's milk based) infant formula, 17% from cereal/milk formula and 10% from soy formula. These results show that the rat pup model may provide a rapid, inexpensive, and sensitive method to assay bioavailability of copper from infant foods.

Animals↗
PubMed1985

Biochemistry and physiological function of human milk proteins.

Human milk has many unique properties that benefit the breast-fed infant. Several of these properties reside in the protein fraction of human milk; eg, host defense factors (such as immunoglobulins, lysozyme, and lactoferrin), digestive enzymes (lipases, proteases, amylase), specific binding proteins, and growth factors. Increased knowledge of human milk proteins and their biochemistry will aid our understanding of their physiological significance in the infant.

Carrier Proteins↗
PubMed1985

Different effects of zinc and copper deficiency on composition of plasma high density lipoproteins in rats.

Male Sprague-Dawley rats (six per group) were fed an egg white-based diet containing 0 or 5 micrograms/g Cu with 1, 10, 100 or 1000 micrograms/g Zn. After 6 wk of feeding, the rats were killed, and the tissues were processed for trace element, lipid and lipoprotein analysis. Copper deficiency was associated with a higher concentration of plasma free cholesterol, high density lipoprotein (HDL) cholesterol and HDL apolipoproteins. Plasma total cholesterol was not significantly affected. No significant differences were noted in HDL lipid composition. However, HDL apo E and apo A-I concentrations were higher with copper deficiency. Lecithin:cholesterol acyltransferase (LCAT) was not affected in a consistent manner by copper status. Varying the amount of zinc in the diet did not produce significant changes in plasma total cholesterol, plasma free cholesterol, HDL cholesterol, or HDL apolipoprotein concentrations. However, HDL from zinc-deficient rats were enriched in free cholesterol and depleted in triglycerides. Furthermore, the concentration of HDL apo C increased as the level of dietary zinc increased.

Animals↗