Intestinal absorption of zinc: a role for a zinc-binding ligand in milk.

This study examined the proposal that a low molecular weight, zinc-binding ligand (ZBL) in certain milks is important for zinc absorption in the neonatal period. Ten-day-old rats, in which intestinal ZBL is absent, fed (by stomach intubation) 65Zn-labeled ZBL from rat milk, absorbed significantly more 65Zn than those fed free 65ZnCl2 or bovine milk fractions. ZBL from human milk appeared to have an intermediate effect, possibly due to species specificity. 65Zn was found in the ZBL fraction in intestinal mucosa of 10-day-old rats fed rat or human milk fractions, but not in those fed bovine milk or free 65ZnCl2. In contrast, in 18-day-old rats, which have an endogenous intestinal ZBL, there were no differences in zinc absorption, and any of the labeled milk fractions or free 65Zn caused localization of 65Zn in the ZBL fraction of intestinal mucosa. These results support the hypothesis that the intestinal ZBL plays a role in zinc absorption and that in the neonatal period before its development the milk ZBL is valuable for this function. This mechanism may be important in normal human infants as well as in acrodermatitis enteropathica patients.

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Comparative biological availability of manganese from extrinsically labelled milk diets using sucking rats as a model

British Journal Of Nutrition ◽

10.1079/bjn19860009 ◽

1986 ◽

Vol 55 (1) ◽

pp. 49-58 ◽

Cited By ~ 3

Author(s):

M. Hassan Raghib. ◽

Chan Wai-Yee ◽

M. Owen Rennert

Keyword(s):

Human Milk ◽

Digestive Tract ◽

Infant Formula ◽

Bovine Milk ◽

Neonatal Rats ◽

Biological Availability ◽

Gastric Intubation ◽

Old Rats ◽

Mn Concentrations

1. Very little is known about the biological availability of manganese from human milk and other infant milk diets. To determine the relative Mn availability, and to examine whether the age and the duration of previous fasting affect Mn absorption, sucking rats were given human milk, bovine milk and infant formula (regular Similac; Ross Laboratories, Columbus, OH) extrinsically labelled with 54Mn.2. Milk diets were given by gastric intubation and the radioactivity of the carcass, liver and digestive tract was measured 3 h after feeding.3. The concentration of endogenous Mn was lowest in human milk (7–10 μg/l) and highest in rat milk (140–165 μg/l). Increasing the non-radioactive total Mn concentrations of either human milk or bovine milk up to 150 μg/l did not affect the absorption of 54Mn by 10-d-old rats.4. No significant (P> 0.05) difference in 54Mn absorption was found among the three milk diets (human milk, bovine milk, infant formula) in 8- to 11-d-old rats. However, significantly more (P< 0.05) 54Mn was absorbed from human milk and infant formula than from bovine milk when 13-d-old rats were used.5. 54Mn radioactivity detected in carcasses of 8-, 9-, 10- and 11-d-old rats ranged from 25 to 27% of the dose from various milk diets. The activities of 54Mn in the carcasses of 13-d-old rats were 15, 11, and 16% of the dose from human milk, bovine milk and infant formula respectively.6. The trend of 54Mn incorporation into liver was similar to that of the carcass and over 60% of the absorbed 54Mn was incorporated into the liver regardless of the type of milk used.7. Absorption of 54Mn from extrinsically labelled rat milk using 9- or 10-d-old sucking rats was similar to its absorption from infant formula.8. The absorption of 54Mn from the three milk diets decreased with age of the neonatal rats and 54Mn absorption from human milk, bovine milk, infant formula as well as rat milk was affected similarly by duration of previous fasting.

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Is acrodermatitis enteropathica related to the absence of zinc binding ligand in bovine milk?

American Journal of Clinical Nutrition ◽

10.1093/ajcn/32.2.275 ◽

1979 ◽

Vol 32 (2) ◽

pp. 275-277 ◽

Cited By ~ 6

Author(s):

J E Piletz ◽

R E Ganschow

Keyword(s):

Bovine Milk ◽

Zinc Binding ◽

Acrodermatitis Enteropathica

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Zinc binding in bovine milk

Journal of Dairy Research ◽

10.1017/s0022029900026467 ◽

1989 ◽

Vol 56 (2) ◽

pp. 249-263 ◽

Cited By ~ 25

Author(s):

Harjinder Singh ◽

Albert Flynn ◽

Patrick F. Fox

Keyword(s):

Calcium Phosphate ◽

Human Milk ◽

Equilibrium Dialysis ◽

Bovine Milk ◽

Skim Milk ◽

Zinc Binding ◽

Casein Micelles ◽

Infant Formulae ◽

Colloidal Calcium Phosphate ◽

Acid Whey

SummaryAbout 90% of the Zn in bovine skim milk was sedimented by ultracentrifugation at 100000 g for 1 h. About half of the non-sedimentable Zn was non-dialysable, indicating that it was associated with protein, probably non-sedimented casein micelles. Casein micelles incorporated considerable amounts of Zn added to skim milk as ZnCl2, and at Zn concentrations ≥ 16 mM coagulation of casein micelles occurred. Ca was displaced from casein micelles by increasing ZnCl2 concentration and ˜ 40% of micellar Ca was displaced by 16 mM-ZnCl2. Micellar Zn, Ca and P1 were gradually rendered soluble as the pH of milk was lowered and at pH 4·6 > 95% of the Zn, Ca and P1 were non-sedimentable. These changes were largely reversible by readjustment of the pH to 6·7. About 40% of the total Zn in skim milk was non-sedimentable at 0·2 mM-EDTA and most of the remainder was gradually rendered soluble by EDTA over the concentration range 1–50 mM. This indicates that there are two distinct micellar Zn fractions. No micellar Ca or P1 was solubilized at EDTA concentrations up to 1·0 mM, indicating that both colloidal calcium phosphate (CCP) and casein micelles remained intact under conditions where the more loosely bound micellar Zn fraction dissolved. Depletion of casein micelles of colloidal Ca and P1 by acidification and equilibrium dialysis resulted in removal of Zn, and in colloidal Pi-free milk non-dialysable Zn was reduced to ·-2 mg/1 (˜ 32% of the original Zn). Thus, ˜ 32% of the Zn in skim milk is directly bound to caseins, while ˜ 63% is associated with CCP. Over 80% of the Zn in colloidal Pi-free milk was rendered soluble by 0·2 mM-EDTA, indicating that the casein-bound Zn is the loosely bound Zn fraction in casein micelles. A considerable fraction of the Zn in acid whey (pH 4·6) co-precipitated with Ca and Pi on raising the pH to 6·7 and heating for 2 h at 40 °C, indicating that insoluble Zn phosphate complexes form readily under these conditions. Studies on dialysis of milk against water, or dilution of milk or casein micelles with water, showed that CCP and its associated Zn is very stable and dissolves only very slowly at pH 6·6. The nature of Zn binding in casein micelles may help to explain the lower nutritional bioavailability of Zn in bovine milk and infant formulae compared with human milk.

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A Retrospective Analysis of the Effects of an Exclusively Human Milk Protein Diet on Neonatal Feeding Tolerance

American Journal of Perinatology ◽

10.1055/s-0040-1721374 ◽

2020 ◽

Author(s):

Jessica Wickland ◽

Christine Wade ◽

Becky Micetic ◽

Keith Meredith ◽

Gregory Martin

Keyword(s):

Birth Weight ◽

Human Milk ◽

Milk Protein ◽

Very Low Birth Weight ◽

Bovine Milk ◽

Milk Diet ◽

Vlbw Infants ◽

Key Points ◽

Human Milk Protein ◽

Feeding Tolerance

Objective This study was aimed to evaluate the effect of human milk protein fortifier (HMPF) versus bovine milk protein fortifier (BMPF) on feeding tolerance defined as the time to reach full feeds and necrotizing enterocolitis (NEC) in premature very low birth weight (VLBW) infants. Study Design A retrospective review using the BabySteps Database included 493 infants born ≤33 weeks of gestational age and ≤1,250 g (g) birth weight. A total of 218 infants fed a human milk diet (HMD) with BMPF were compared with 275 infants fed an HMD with HMPF. Results Full feeds were reached significantly sooner in the HMPF group (median: 14 vs. 16 days, p = 0.04). Weight at full feeds was significantly lower in the HMPF group (1,060 vs. 1110 g, p = 0.03). Conclusion Using HMPF to provide an exclusively HMD allowed VLBW infants to achieve full feeds sooner, but did not affect rate of NEC compared with using a BMPF with an HMD. Key Points

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The Abundance of Human Milk Oligosaccharide (HMO)-Metabolizing Genes in Fecal Samples from Six-Month-Old Human Infants

Microorganisms ◽

10.3390/microorganisms9071352 ◽

2021 ◽

Vol 9 (7) ◽

pp. 1352

Author(s):

Lynn E. Ferro ◽

Kameron Y. Sugino ◽

Vanja Klepac-Ceraj ◽

Sarah S. Comstock

Keyword(s):

Human Milk ◽

Mode Of Delivery ◽

Dietary Exposure ◽

Quantitative Real Time Pcr ◽

Human Infants ◽

Fecal Samples ◽

Gene Abundance ◽

Development And Validation ◽

Biology Laboratory ◽

Further Development

Herein, we report the abundance and prevalence of HMO-metabolizing genes, specifically those of Bifidobacterium infantis, in fecal samples from human infants. Forty dyads were enrolled, and each mother collected a fecal sample from her infant at six months of age. Genomic DNA was extracted, and quantitative real-time PCR was used to determine gene abundance. The mode of delivery was not associated with gene abundance. Several gene regions, Sia (a sialidase), B. inf (16S), and GH750 (a glycoside hydrolase), were more abundant in the feces of human milk-fed infants (p < 0.05). Others, Sia and HC bin (16S), tended to be less abundant when a larger percentage of an infant’s diet consisted of solids (p < 0.10). When accounting for solid food intake, human milk exposure was positively associated with Sia and B. inf (p < 0.05) and tended to be related to the abundance of the GH750 and HC bin (p < 0.10) gene regions. With further development and validation in additional populations of infants, these assays could be used to group samples by dietary exposure even where no record of dietary intake exists. Thus, these assays would provide a method by which infant human milk intake can be assessed quickly in any well-equipped molecular biology laboratory.

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ZINC CITRATE, HUMAN MILK, AND ACRODERMATITIS ENTEROPATHICA

The Lancet ◽

10.1016/s0140-6736(79)91132-2 ◽

1979 ◽

Vol 313 (8117) ◽

pp. 677-678 ◽

Cited By ~ 33

Author(s):

LucilleS Hurley ◽

Bo Lönnerdal ◽

AnnaG Stanislowski

Keyword(s):

Human Milk ◽

Acrodermatitis Enteropathica

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Comparison of methods for milk pre-processing, exosome isolation, and RNA extraction in bovine and human milk

10.1101/2020.08.14.251629 ◽

2020 ◽

Author(s):

Sanoji Wijenayake ◽

Shafinaz Eisha ◽

Zoya Tawhidi ◽

Michael A. Pitino ◽

Michael A. Steele ◽

...

Keyword(s):

Human Milk ◽

Biological Fluid ◽

Rna Extraction ◽

Bovine Milk ◽

Total Soluble Protein ◽

Long Term Storage ◽

Transmission Electron ◽

Whole Milk ◽

Membrane Bound

AbstractMilk is a highly complex, heterogeneous biological fluid that contains bioactive, membrane-bound extracellular vesicles called exosomes. Characterization of milk-derived exosomes (MDEs) is challenging due to the lack of standardized methods that are currently being used for milk pre-processing, exosome isolation, and RNA extraction. In this study, we tested: 1) three pre-processing methods to remove cream, fat, and casein proteins from bovine milk to determine whether pre-processing of whole milk, prior to long-term storage, improves MDE isolations, 2) two commonly-used exosome isolation methods, and 3) four extraction protocols for obtaining high quality MDE RNA from bovine and human milk. MDEs were characterized via Transmission Electron Microscopy (TEM) and Nanoparticle Tracking Analysis (NTA). We also present an optimized method of TEM sample preparation and isolation of total soluble protein from MDEs. Our results indicated that: 1) pre-processing of bovine milk prior to storage does not affect the final exosome yield or the purity, 2) ExoQuick precipitation is better suited for MDE isolation than ultracentrifugation for bovine and human milk, and 3) TRIzol LS produced the highest RNA yield in bovine milk, whereas TRIzol LS, TRIzol+RNA Clean and Concentrator, and TRIzol LS+RNA Clean and Concentrator methods can be used for human milk.

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Glucose-6-phosphatase in normal adult human intestinal mucosa

Clinical Science ◽

10.1042/cs0830683 ◽

1992 ◽

Vol 83 (6) ◽

pp. 683-687 ◽

Cited By ~ 6

Author(s):

John Pears ◽

Roland T. Jung ◽

John Jankowski ◽

Ian D. Waddell ◽

Ann Burchell

Keyword(s):

Phosphatase Activity ◽

Intestinal Mucosa ◽

Storage Disease ◽

Immunoblot Analysis ◽

Glycogen Storage ◽

Enzyme Protein ◽

Normal Human ◽

Low Levels ◽

Phosphatase Enzyme

1. The existence of specific glucose-6-phosphatase activity in human intestinal mucosa has been somewhat controversial. 2. We have demonstrated the presence of low levels of specific glucose-6-phosphatase activity in normal human adult intestinal mucosa. Activity was found in oesophagus, stomach, duodenum and colon. 3. Immunoblot analysis using antibodies monospecific for the 36.5 kDa liver glucose-6-phosphatase catalytic subunit demonstrated that intestinal mucosa contains low levels of the glucose-6-phosphatase enzyme protein. 4. The low levels of activity together with problems of proteolysis make human intestinal biopsies unsuitable for use in the diagnosis of type 1 glycogen-storage disease.

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