Greetings and Happy World Breastfeeding Week!

Some new studies on human milk: 


Title:  Structural basis for broad substrate specificity of UDP-glucose 4-epimerase in the human milk oligosaccharide catabolic pathway of Bifidobacterium longum.
In:  Scientific Reports 2019 Jul 31;9(1):11081. doi: 10.1038/s41598-019-47591-w.
Authors:  Nam YW, Nishimoto M, Arakawa T, Kitaoka M, Fushinobu S.

Abstract:  "Infant gut-associated bifidobacteria has a metabolic pathway that specifically utilizes lacto-N-biose I (Gal-β1,3-GlcNAc) and galacto-N-biose (Gal-β1,3-GalNAc) from human milk and mucin glycans. UDP-glucose 4-epimerase (GalE) from Bifidobacterium longum (bGalE) catalyzes epimerization reactions of UDP-Gal into UDP-Glc and UDP-GalNAc into UDP-GlcNAc with the same level of activity that is required to send galacto-hexoses into glycolysis. Here, we determined the crystal structures of bGalE in three ternary complex forms: NAD+/UDP, NAD+/UDP-GlcNAc, and NAD+/UDP-Glc. The broad specificity of bGalE was explained by structural features of the binding pocket for the N-acetyl or C2 hydroxy group of the substrate. Asn200 is located in a pocket of the C2 group, and its side chain adopts different conformations in the complex structures with UDP-Glc and UDP-GlcNAc. On the other side, Cys299 forms a large pocket for the C5 sugar ring atom. The flexible C2 pocket and the large C5 pocket of bGalE are suitable for accommodating both the hydroxy and N-acetyl groups of the substrate during sugar ring rotation in the catalytic cycle. The substrate specificity and active site structure of bGalE were distinct from those of Esherichia coli GalE but similar to those of human GalE."

Open access:  https://www.nature.com/articles/s41598-019-47591-w


Title:  Macronutrient analysis of preterm human milk using mid-infrared spectrophotometry.
In:  Journal of Perinatal Medicine 2019 Jul 31. pii: /j/jpme.ahead-of-print/jpm-2019-0105/jpm-2019-0105.xml. doi: 10.1515/jpm-2019-0105. [Epub ahead of print]
Authors:  Bulut Ö, Çoban A, İnce Z.

Abstract:  
Background:  "Human milk is the optimal source of nutrition for preterm infants. However, breast milk alone is often not sufficient to satisfy the high nutritional needs for growth and development in preterm infants. Fortified human breast milk is the best way to meet the nutritional needs of preterm infants. Human breast milk is fortified according to the estimated nutrient content of mature breast milk; however, because the content of breast milk is highly variable, the macronutrient support may be more or less than needed. The goal of this study was to analyze the macronutrient content of preterm human milk during the first 6 weeks of lactation."

Methods: "The study included 32 mothers of preterm infants with a gestational age of ≤32 weeks. Breast milk was collected in 24-h cycles and analyzed daily using mid-infrared (MIR) spectroscopy. We measured protein, fat and lactose concentrations in the breast milk, and the energy content was calculated."

Results: "The protein content was high during the first weeks of lactation, but decreased as lactation progressed. The fat, energy and lactose contents of the breast milk were low during the first 2 weeks of lactation, increased as lactation progressed and remained constant thereafter. In women with high body mass index (BMI), higher protein levels were found in transitional milk. In women who had high income level, higher fat and energy levels were found in transitional milk."

Conclusion: "Our findings indicate that the macronutrient content of preterm breast milk changes throughout the course of lactation, with BMI and income level. Knowledge of the macronutrient composition of breast milk is necessary to ensure that preterm infants receive the appropriate types and quantities of nutrients to promote optimal growth, and to ensure that breast milk is fortified according to individual needs. Our findings may be useful for the provision of optimal nutritional support for preterm infants."

Abstract only: https://www.degruyter.com/view/j/jpme.ahead-of-print/jpm-2019-0105/jpm-2019-0105.xml


Title:  Validation and Application of Biocrates AbsoluteIDQ® p180 Targeted Metabolomics Kit Using Human Milk.
In:  Nutrients 2019 Jul 26;11(8). pii: E1733. doi: 10.3390/nu11081733.
Authors:  Hampel D, Shahab-Ferdows S, Hossain M, Islam MM, Ahmed T, Allen LH.

Abstract:  "Human-milk-targeted metabolomics analysis offers novel insights into milk composition and relationships with maternal and infant phenotypes and nutritional status. The Biocrates AbsoluteIDQ® p180 kit, targeting 40 acylcarnitines, 42 amino acids/biogenic amines, 91 phospholipids, 15 sphingolipids, and sum of hexoses, was evaluated for human milk using the AB Sciex 5500 QTRAP mass-spectrometer in liquid chromatography-tandem mass-spectrometry (LC-MS/MS) and flow-injection analysis (FIA) mode. Milk (<6 months lactation) from (A) Bangladeshi apparently healthy mothers (body mass index (BMI) > 18.5; n = 12) and (B) Bangladeshi mothers of stunted infants (height-for-age Z (HAZ)-score <-2; n = 13) was analyzed. Overall, 123 of the possible 188 metabolites were detected in milk. New internal standards and adjusted calibrator levels were used for improved precision and concentration ranges for milk metabolites. Recoveries ranged between 43% and 120% (coefficient of variation (CV): 2.4%-24.1%, 6 replicates). Milk consumed by stunted infants vs. that from mothers with BMI > 18.5 was lower in 6 amino acids/biogenic amines but higher in isovalerylcarnitine, two phospholipids, and one sphingomyelin (p < 0.05 for all). Associations between milk metabolites differed between groups. The AbsoluteIDQ® p180 kit is a rapid analysis tool suitable for human milk analysis and reduces analytical bias by allowing the same technique for different specimens. More research is needed to examine milk metabolite relationships with maternal and infant phenotypes."

Open access:  https://www.mdpi.com/2072-6643/11/8/1733


Title:  Polyamines in Food.
In:  Frontiers in Nutrition 2019 Jul 11;6:108. doi: 10.3389/fnut.2019.00108. eCollection 2019.
Authors:  Muñoz-Esparza NC1,2,3, Latorre-Moratalla ML1,2,3, Comas-Basté O1,2,3, Toro-Funes N4, Veciana-Nogués MT1,2,3, Vidal-Carou MC1,2,3.

Abstract:  "The polyamines spermine, spermidine, and putrescine are involved in various biological processes, notably in cell proliferation and differentiation, and also have antioxidant properties. Dietary polyamines have important implications in human health, mainly in the intestinal maturation and in the differentiation and development of immune system. The antioxidant and anti-inflammatory effect of polyamine can also play an important role in the prevention of chronic diseases such as cardiovascular diseases. In addition to endogenous synthesis, food is an important source of polyamines. Although there are no recommendations for polyamine daily intake, it is known that in stages of rapid cell growth (i.e., in the neonatal period), polyamine requirements are high. Additionally, de novo synthesis of polyamines tends to decrease with age, which is why their dietary sources acquire a greater importance in an aging population. Polyamine daily intake differs among to the available estimations, probably due to different dietary patterns and methodologies of data collection. Polyamines can be found in all types of foods in a wide range of concentrations. Spermidine and spermine are naturally present in food whereas putrescine could also have a microbial origin. The main polyamine in plant-based products is spermidine, whereas spermine content is generally higher in animal-derived foods. This article reviews the main implications of polyamines for human health, as well as their content in food and breast milk and infant formula. In addition, the estimated levels of polyamines intake in different populations are provided."

Open access:  https://www.frontiersin.org/articles/10.3389/fnut.2019.00108/full


Title:  Tetrabromobisphenol A: Disposition, kinetics and toxicity in animals and humans. [Review article]
In:  Environmental Pollution 2019 Jul 13;253:909-917. doi: 10.1016/j.envpol.2019.07.067. [Epub ahead of print]
Authors:  Yu Y, Yu Z, Chen H, Han Y, Xiang M, Chen X, Ma R, Wang Z.

Abstract:  "Tetrabromobisphenol A (TBBPA) is a nonregulated brominated flame retardant with a high production volume, and it is applied in a wide variety of consumer products. TBBPA is ubiquitous in abiotic matrices, wildlife and humans around the world. This paper critically reviews the published scientific data concerning the disposition, metabolism or kinetics and toxicity of TBBPA in animals and humans. TBBPA is rapidly absorbed and widely distributed among tissues, and is excreted primarily in the feces. In rats, TBBPA and its metabolites have limited systemic bioavailability. TBBPA has been detected in human milk in the general population. It is available to both the developing fetus and the nursing pups following maternal exposure. It has been suggested that TBBPA causes acute toxicity, endocrine disruptor activity, immunotoxicity, neurotoxicity, nephrotoxicity, and hepatotoxicity in animals. Cell-based assays have shown that TBBPA can induce reactive oxygen species in a concentration-dependent manner, and it promotes the production of inflammatory factors such as TNF α, IL-6, and IL-8. Cells exposed to high levels of TBBPA exhibit seriously injured mitochondria and a dilated smooth endoplasmic reticulum. This review will enhance the understanding of the potential risks of TBBPA exposure to ecological and human health."

Abstract only:  https://www.sciencedirect.com/science/article/pii/S0269749119310188?via%3Dihub


Title:  Antitumor effects of seleno-β-lactoglobulin on human breast cancer MCF-7 and MDA-MB-231 cells in vitro.
In:  Toxicology In Vitro 2019 Jul 23:104607. doi: 10.1016/j.tiv.2019.104607. [Epub ahead of print]
Authors:  Xu X, Feng Y, Chen X, Wang Q, Meng T, Liu A.

Abstract:  "Seleno-β-lactoglobulin (Se-β-Lg) was synthesized using seleninic acid, an organoselenium compound, and β-lactoglobulin (β-Lg), an important component of milk. Previously, we have studied the effects of Se-β-Lg on hepatocellular carcinoma and gastric cancer cells. In this study, we investigated the antitumor effects of Se-β-Lg and its potential mechanisms of action against human breast cancer cells (MCF-7 and MDA-MB-231). The results showed that the half-maximal inhibitory concentrations (IC50) of Se-β-Lg were 40.84 μg/mL for MCF-7 cells and 46.04 μg/mL for MDA-MB-231 cells at 24 h, while the compound showed no cytotoxicity to normal breast cells. The involvement of reactive oxygen species (ROS) in the activation of the apoptotic signaling pathway by Se-β-Lg was demonstrated by the incubation of cells with 80 μg/mL Se-β-Lg and determination of the rates of apoptosis and intracellular ROS levels after the addition of 10 mM N-acetyl-l-cysteine, a ROS inhibitor. Our findings revealed highly potent anticancer activities of Se-β-Lg against breast cancer cells and suggested that the compound may be used as a chemopreventive agent for breast cancer. Furthermore, we thoroughly elucidated the antitumor mechanism of Se-β-Lg."

Abstract only:  https://www.sciencedirect.com/science/article/pii/S0887233319301055?via%3Dihub


With best regards,

Debbie

Debra Swank, RN BSN IBCLC
Program Director
More Than Reflexes Education
Elkins, West Virginia USA
http://www.MoreThanReflexes.org

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