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Biomedical subjects

B Lönnerdal

Publications and source records attributed to B Lönnerdal.

At least 217 records · Page 12Linked to original sources
PubMed1984

A longitudinal study of rhesus monkey (Macaca mulatta) milk composition: trace elements, minerals, protein, carbohydrate, and fat.

The concentrations of iron, copper, zinc, calcium, magnesium, sodium, potassium, protein, carbohydrate, and fat were analyzed in milk from rhesus monkeys (Macaca mulatta) during the course of lactation. Concentrations of iron, copper, zinc, magnesium, sodium, potassium, and protein were higher in milk of early lactation (colostrum) than in mature milk, while concentrations of calcium increased with lactation time. Concentrations of zinc in monkey colostrum and mature milk were similar to that of human milk, while iron, copper, calcium, and protein concentrations were higher than in human milk.

Animals↗
PubMed1983

Dependence on cations for the binding activity of lectins as determined by affinity electrophoresis.

The metal ion content of eighteen different lectins was determined. The lectins were demetallized and the binding activity of native and demetallized forms were investigated using non-denaturing polyacrylamide affinity gel electrophoresis. The binding activities of all lectins were dependent on their metal ion content; when the cations were removed the lectins lost their carbohydrate binding activity. There was a marked difference in the strength with which lectins bind divalent cations.

Cations↗
PubMed1983

The effect of copper chelating drugs on liver iron mobilization in the adult rat.

To test the hypothesis that ferroxidase I (ceruloplasmin) activity is essential for iron mobilization, adult rats were fed a copper sufficient diet with or without the chelating drugs D-penicillamine and triethylenetetramine for 120 days. By day 6 of treatment and for the remainder of the experiment the drug-fed rats showed low plasma copper concentration and low ferroxidase I activity. Plasma ferroxidase II activity in the DPA and TETA groups tended to be slightly lower than that of controls. No animals became anemic. Therefore, persistent low plasma ferroxidase I does not necessarily cause anemia in the adult rat.

Animals↗
PubMed1983

Iron, zinc, copper, and manganese in infant formulas.

The concentrations of the trace elements iron, zinc, copper, and manganese were determined in 53 regular infant formulas and 41 special infant formulas used for clinical disorders. Several infant formulas had lower concentrations of trace elements than human milk. The ranges of concentrations found in the formulas were as follows: Iron, 0.0 to 57.5 mg/L; copper, 0.01 to 2.14 mg/L; zinc, 0.10 to 13.5 mg/L; and manganese, 0.0 to 7.8 mg/L. In addition to the wide variation in absolute amounts of the trace elements in the formulas, large variations in the ratios of trace elements were found. While the average ratios of zinc/copper, zinc/iron, and iron/manganese in human milk range from 3.3 to 10, 2.5 to 10, and 25 to 100, respectively, they ranged from 0.4 to 74, 0.02 to 40, and 0.04 to 425 in the formulas. These differences in the ratios may be important, as the ratio can affect the absorption of the individual elements. These findings indicate that more attention should be given to the trace element levels in infant formulas.

Copper↗
PubMed1983

Zinc absorption from human milk, cow's milk, and infant formulas.

Zinc absorption from 450 mL of human milk, cow's milk, humanized cow's milk formula, cereal-cow's milk formula, and soy formula was determined in healthy adults. The milks and formulas were extrinsically labeled with zinc chloride Zn 65 and the absorption was determined from measurement of the whole-body retention of the isotope. The zinc content of the formulas was comparable to or higher than that of human milk. Absorption of zinc was 41% +/- 9% from human milk and 28% +/- 15% from cow's milk. Absorption was 31% +/- 7% from the humanized cow's milk formula, 22% +/- 11% from the cereal-cow's milk formula, and 14% +/- 4% from the soy formula. These results indicate that, with the present levels of zinc supplementation, the amount of zinc absorbed from infant formulas is considerably lower than that absorbed from human milk.

Adult↗
PubMed1983

Dietary superoxide dismutase does not affect tissue levels.

The effects of dietary supplementation of superoxide dismutase on tissue superoxide dismutase levels were examined in mice. Mice were divided into two groups; the control received a complete purified diet, and the supplemented group received the same diet containing 0.004% superoxide dismutase. There were no differences in the activity of CuZn superoxide dismutase or Mn superoxide dismutase in intestine, liver, kidney, or blood. These data show that oral supplementation of superoxide dismutase does not affect tissue superoxide dismutase activity.

Administration, Oral↗
PubMed1983

An experimental model for studies of zinc bioavailability from milk and infant formulas using extrinsic labeling.

The ability to assess zinc bioavailability from various diets is essential as the zinc content on many foods can be low or marginal. We have investigated the absorption of zinc from human milk, cows' milk, cows' milk formula (whey-adjusted) and soy protein formula as these fluids can comprise the majority of an infant's diet. Radiozinc was added to the diets in tracer amounts. The extrinsic 65Zn was shown by ultracentrifugation, ultrafiltration, and gel filtration to add to milk fractions and individual binding compounds in a manner analogous to the distribution of native zinc, validating the use of extrinsically labeled milk diets. Labeled diets were fed by intubation to 16-day-old suckling rats. Animals were killed after 4 h and tissues removed and counted. Zinc bioavailability was 28% from human milk, 24% from whey-adjusted cows' milk formula, 15% from cows' milk, and 10% from soy formula. Intubation studies using adult rats showed that zinc absorption was lower from all the diets; however, it was still highest from human milk and cows' milk formula. These results show that the rat pup model may provide a rapid, inexpensive, and sensitive method to assay bioavailability of zinc from infant foods.

Age Factors↗
PubMed1983

Superoxide dismutase activity and lipid peroxidation in the rat: developmental correlations affected by manganese deficiency.

The activities of the mitochondrial enzyme manganese-superoxide dismutase (MnSOD), the cytosolic enzyme copper-zinc superoxide dismutase (CuZnSOD), and lipid peroxidation in liver were measured in manganese-sufficient and manganese-deficient rats from birth to 60 days of age. In both groups of rats there was an increase in MnSOD activity during development. In control rats MnSOD activity increased over sixfold between day 1 and day 60. However, in manganese-deficient animals the activity of this enzyme increased only threefold during this time period. In both groups of rats there was approximately a sixfold increase in CuZnSOD activity between day 1 and day 60. After day 10, CuZnSOD activity tended to be higher in Mn-deficient rats, with this difference being significant on day 15 (P greater than 0.01). Measurements of thiobarbituric acid-reacting products (TBA index) under conditions of oxidant stress suggested that there was a higher than normal level of mitochondrial lipid peroxidation in manganese-deficient rats by 60 days of age. Lipid peroxidation increased from day 1 to day 60 in both groups of rats, but a fivefold increase occurred in manganese-deficient rats while in controls the increase was only threefold. These findings suggest that the damage to mitochondrial membranes observed in manganese-deficient animals may be due to depressed MnSOD activity resulting in increased lipid peroxidation from free radicals.

Aging↗
PubMed1983

Zinc deficiency teratogenicity: the protective role of maternal tissue catabolism.

The effect of maternal metabolic state on the response to dietary zinc deficiency was assessed with the pregnant rat as a model. Sprague-Dawley rats were fed from mating to term: 1) a zinc-adequate (100 micrograms/g) control diet ad libitum, or 2) a zinc-deficient diet (0.7 micrograms/g) ad libitum, or 3) a control diet at reduced intake, or 4) a zinc-deficient diet at reduced intake, or 5) a zinc-deficient diet ad libitum plus additional zinc-deficient diet, fed by intubation, to maintain total intake at approximately 14 g/day. Dams receiving the zinc-deficient diet deposited more zinc (240-330%) into the products of conception than was consumed, showing that tissue catabolism is a substantial source of zinc. In rats fed the control diet ad libitum only 3% of the zinc consumed was deposited into the products of conception. Litters from dams fed the deficient diet at restricted levels (resulting in greater tissue catabolism) had fewer malformations and resorptions than litters from dams fed the zinc-deficient diet ad libitum. Maintenance of total intake of the zinc-deficient diet at 14 g/day by intubation resulted in a pronounced drop in voluntary intake. By day 18 of pregnancy voluntary intake had almost ceased, following day 18 the rats became severely distressed if any zinc-deficient diet was force-fed. Rats fed the zinc-deficient diet ad libitum also displayed a dramatic fall in voluntary intake after day 18 of gestation. These data show that the reduction in food intake during zinc deficiency is not due to gustatory influences alone and that metabolic state, defined as the balance between anabolism and catabolism, is a critical factor in determining the availability of zinc to the litter during zinc deficiency.

Animals↗
PubMed1983

Zinc and copper in rat bile and pancreatic fluid: effects of surgery.

The control of Zn and Cu homeostasis in the gut is not well understood; a role for bile and pancreatic secretions has been suggested. In the present study, the changes in biliary and pancreatic Zn and Cu after surgery were followed. Rats were prepared surgically with pancreatic, biliary, and intestinal cannulae, placed in restraint cages, and allowed to recover from anesthesia. Fluids were collected for up to 120 hours. Aliquots of the collected samples were analyzed for Zn and Cu. Zn in pancreatic juice did not follow a consistent pattern; however, the concentration of Zn was well correlated with pancreatic protein concentration. Cu in pancreatic juice was very low and was apparently not affected by surgery. In bile, Zn concentration increased markedly at about 40 hours postsurgery but declined to its initial level by days 4-5. Cu concentration in bile was similar to that of Zn initially, then increased 10-fold after 20-30 hours postsurgery, and returned to the initial level by days 4-5. These results demonstrate that the surgical procedure of cannulating bile and pancreatic ducts has a pronounced effect on the concentrations of Zn and Cu in bile and pancreatic fluid. This effect must be considered when designing and evaluating experiments concerned with the role of these secretions in trace element homeostasis.

Animals↗
PubMed1983

Comparative aspects of dietary copper and zinc deficiencies in pregnant rats.

The utilization and distribution of copper during dietary copper deficiency was studied in the pregnant rat, and the effects of maternal copper deficiency on fetal development were compared with those of maternal zinc deficiency. Sprague-Dawley rats were fed from mating to term (per gram diet): 1) a control diet (10 micrograms copper, 100 micrograms zinc) or 2) a copper-deficient diet (0.7 micrograms copper, 100 micrograms zinc) or 3) a zinc-deficient diet (10 micrograms copper; 0.7 micrograms zinc). Dams fed the copper-deficient diet deposited only 15.5% of the dietary copper consumed during pregnancy into the products of conception (fetuses, uterus and placentas); in comparison dams fed the zinc-deficient diet deposited more zinc into their litters than was consumed (240%). Copper concentration in the fetuses of copper-deficient dams was 30% of that of controls, but the size and number of live fetuses was unaffected. The zinc concentration of the zinc-deficient fetuses was 78% of that of the controls, and both the size and number of live fetuses were considerably lower than normal. Accumulation of copper in the products of conception may be accounted for by dietary copper intake, whereas accumulation of zinc in fetuses of zinc-deficient females is dependent in part on catabolism of maternal tissues.

Animals↗
PubMed1983

The effects of vitamin E on zinc deficiency teratogenesis in rats.

It has been suggested that zinc deficiency may interfere with fatty acid metabolism, possibly by increasing the rate of lipid peroxidation. The hypothesis was investigated that the teratogenicity of zinc deficiency might be alleviated by vitamin E supplementation. Sprague-Dawley rats were fed during pregnancy a complete purified diet containing either 100 micrograms zinc/gram diet (control) or less than 0.4 microgram zinc/gram diet (deficient). Half of the animals in each diet group received supplemental vitamin E (200 X control). At term, fetuses were removed, examined for malformations, resorption sites were counted, and maternal and fetal tissues were analyzed for zinc concentration. Vitamin E supplementation of the control diet did not produce teratogenic effects. The number of total sites affected (resorptions + malformed fetuses) in the zinc-deficient groups was not influenced by vitamin E supplementation. Tissue zinc was significantly lower in the zinc-deficient groups, but vitamin E supplementation had no effect. These results show that vitamin E supplementation does not ameliorate the teratogenicity of zinc deficiency.

Abnormalities, Drug-Induced↗
PubMed1983

Milk and nutrient intake of breast-fed infants from 1 to 6 months: relation to growth and fatness.

Dietary intake, milk composition, growth, and activity were monitored monthly for 20 breast-fed infants from 1 to 6 months. Breast milk intake (of infants receiving no more than 50 kcal from other foods) ranged from 341 to 1,096 ml/day, with mean intake increasing from 673 to 896 ml/day from 1 to 6 months. Energy intake per kilogram body weight averaged 113 kcal/kg/day at 1 month, decreasing to 85-89 kcal/kg/day at 5-6 months--considerably lower than the recommended 115 kcal/kg/day. At 6 months, all infants except one were above the 10th percentile of weight-for-age. Nutrient content of milk samples was similar to previously reported values. Protein, iron, zinc, copper, sodium, and potassium levels declined during the first 6 months. Intakes of iron, zinc, calcium, and magnesium were lower than recommended allowances for infants. Weight-for-length and weight gain were significantly correlated with total energy intake, but not with activity level, during the first 6 months.

Body Weight↗
PubMed1983

Supplementation of milk with iron bound to lactoferrin using weanling mice: L. Effects on hematology and tissue iron.

Lactoferrin is an iron-binding protein present in high concentrations in human milk. The efficacy of supplementing iron bound to lactoferrin to iron-deficient and iron-sufficient young mice was evaluated in comparison with supplementation of iron as iron chloride. Mice fed a nonsupplemented milk diet (approximately 1 mg Fe/L) for 4 weeks had a microcytic, hypochromic anemia and low tissue iron concentrations. Iron supplementation of the diet with lactoferrin-iron, or iron chloride at a level of 5 mg Fe/L prevented the anemia and resulted in tissue iron levels similar to levels found for mice fed a stock commercial diet. There was no significant difference in any of the parameters analyzed between the groups of mice receiving the two iron supplements following a diet deficient in iron. Apolactoferrin when supplemented to the diet had no negative effect on the iron status of the mice. These results show that lactoferrin may be a useful vehicle for supplementation of iron.

Anemia, Hypochromic↗
PubMed1983

Distribution of trace elements and minerals in human and cow's milk.

The concentration of iron in cow's milk, 0.40-0.59 microgram/ml, was found to be very similar to that of human milk, 0.20-0.69 microgram/ml. The copper concentration of cow's milk (0.06-0.09 microgram/ml) is lower than in human milk (0.24-0.50 microgram/ml) whereas the concentration of zinc is higher in cow's milk (3.23-5.15 micrograms/ml) than in human milk (1.16-3.83 micrograms/ml). Cow's milk contains about 4-5 times more calcium and magnesium, 854-1430 micrograms/ml and 87-131 micrograms/ml, respectively, than human milk (220-252 micrograms/ml and 26-35 micrograms/ml). Cow's milk was fractionated and the trace element and mineral contents of the different fractions were compared to results from human milk. The casein fraction in cow's milk contains a large proportion of the total amounts of the elements cited above (Fe 24%, Cu 44%, Zn 84%, Ca 41%, Mg 25%) whereas human casein only binds minor amounts (Fe 9%, Cu 7%, Zn 8%, Ca 6%, Mg 6%). Whey proteins bind a major part of these elements in human milk, but not in cow's milk. Significant amounts of iron are bound to the lipid fraction in both cow's and human milk (14 and 33%, respectively), predominantly bound to the outer fat globule membrane. Low molecular weight compounds (ligands) bind significant proportions of all the elements investigated in both cow's and human milk, with the exception of zinc in cow's milk, of which only 2% is associated with this fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗