Gastric Residual Volume Linked to Gastric Fluid pH in Infants with Very Low Birth Weight

He, Lilan

doi:10.11648/j.ajns.20170604.21

Cited by 2 publications

(1 citation statement)

References 16 publications

(24 reference statements)

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“…During ingestion, the environment of milk changes from neutral to acidic when entering the infant’s stomach, and then the pH increases in the intestine (Bourlieu, Menard, Bouzerzour, Mandalari, Macierzanka, Mackie, et al, 2014; Gan, Bornhorst, Henrick, & German, 2018). The typical gastric pH in a newborn infant’s stomach is around 4, but the pH varies from 2 to 6 depending on individual conditions, such as term or preterm birth, developmental stage, and health status (Agunod, Yamaguch, Lopez, Luhby, & Glass, 1969; He, Chen, Li, & Deng, 2017; Maffei & Nobrega, 1975; Mason, 1962; Sondheimer, Clark, & Gervaise, 1985). Fluctuation in pH may affect the ionization state of charged molecules, the structural stability of proteins, the activity of milk enzymes, the microstructure of milk compartments, and the substrate-enzyme molecular interactions within human milk.…”

Section: Introductionmentioning

confidence: 99%

Peptidomic profiling of human milk with LC–MS/MS reveals pH-specific proteolysis of milk proteins

et al. 2019

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Human milk is a dynamic protein-protease system that delivers bioactive peptides to infants. The pH of milk changes from the mother’s mammary gland to the infant’s digestive tract. Although the release of human milk peptides has been studied during in vivo or in vitro digestion, these models did not explicitly vary nor observe the effect of pH. The objective of this research was to determine the effect of pH on the proteolysis of human milk. Using high-resolution accurate-mass Orbitrap mass spectrometry, profiles of endogenous human milk peptides before and after incubation at various pH levels have been mapped. Over 5000 peptides were identified. Comparative analyses classified 74 peptides that were consistently found independent of pH alterations, and 8 peptides that were released only at pH 4 or 5 (typical infant gastric pH). Results documented that the proteolysis of milk proteins, particularly β-casein, polymeric immunoglobulin receptor, and α-lactalbumin, is pH-dependent.

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Section: Introductionmentioning

confidence: 99%

Peptidomic profiling of human milk with LC–MS/MS reveals pH-specific proteolysis of milk proteins

et al. 2019

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Selective Proteolysis of α‐Lactalbumin by Endogenous Enzymes of Human Milk at Acidic pH

Gan

Zheng

Krishnakumar

et al. 2019

Molecular Nutrition Food Res

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Scope: The use of human milk products is increasing for high-risk infants. Human milk contains endogenous enzymes that comprise a dynamic proteolytic system, yet biological properties of these enzymes and their activities in response to variations including pH within infants are unclear. Human milk has a neutral pH around 7, while infant gastric pH varies from 2 to 6 depending on individual conditions. This study is designed to determine the specificity of enzyme-substrate interactions in human milk as a function of pH. Methods and results: Endogenous proteolysis is characterized by incubating freshly expressed human milk at physiologically relevant pH ranging from 2 to 7 without the addition of exogenous enzymes. Results show that the effects of pH on endogenous proteolysis in human milk are protein-specific. Further, specific interactions between cathepsin D and α-lactalbumin are confirmed. The endogenous enzyme cathepsin D in human milk cleaves α-lactalbumin as the milk pH shifts from 7 to 3. Conclusions: This study documents that selective proteolysis activated by pH shift is a mechanism for dynamic interactions between human milk and the infant. Controlled proteolysis can guide the use of human milk products based on individual circumstance.

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Gastric Residual Volume Linked to Gastric Fluid pH in Infants with Very Low Birth Weight

Cited by 2 publications

References 16 publications

Peptidomic profiling of human milk with LC–MS/MS reveals pH-specific proteolysis of milk proteins

Peptidomic profiling of human milk with LC–MS/MS reveals pH-specific proteolysis of milk proteins

Selective Proteolysis of α‐Lactalbumin by Endogenous Enzymes of Human Milk at Acidic pH

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