High Doses of Exogenous Glucagon Stimulate Insulin Secretion and Reduce Insulin Clearance in Healthy Humans.

Glucagon is generally defined as a counterregulatory hormone with a primary role to raise blood glucose concentrations by increasing endogenous glucose production (EGP) in response to hypoglycemia. However, glucagon has long been known to stimulate insulin release, and recent preclinical findings have supported a paracrine action of glucagon directly on islet β-cells that augments their secretion. In mice, the insulinotropic effect of glucagon is glucose dependent and not present during basal euglycemia.

Multiplexed quantification of insulin and C-peptide by LC-MS/MS without the use of antibodies.

Introduction: The measurement of insulin and C-peptide provides a valuable tool for the clinical evaluation of hypoglycemia. In research, these biomarkers are used together to better understand hyperinsulinemia, hepatic insulin clearance, and beta cell function. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is an attractive approach for the analysis of insulin and C-peptide because the platform is specific, can avoid certain limitations of immunoassays, and can be multiplexed.

Fucosylated Human Milk Oligosaccharide Foraging within the Species Bifidobacterium pseudocatenulatum Is Driven by Glycosyl Hydrolase Content and Specificity.

Human milk enriches members of the genus in the infant gut. One species, Bifidobacterium pseudocatenulatum, is found in the gastrointestinal tracts of adults and breastfed infants. In this study, B.

Associations of Human Milk Oligosaccharides and Bioactive Proteins with Infant Morbidity and Inflammation in Malawian Mother-Infant Dyads.

Background: Human milk oligosaccharides (HMOs) and bioactive proteins likely benefit infant health, but information on these relations is sparse.

Objectives: We aimed to examine associations of milk content of HMOs and bioactive proteins with incidence and longitudinal prevalence of infant morbidity (any illness, fever, diarrhea, acute respiratory infection, and loss of appetite) and markers of inflammation [C-reactive protein (CRP) and α-1-acid glycoprotein (AGP)]. These are secondary analyses of a randomized controlled trial.

High-throughput glycomic analyses reveal unique oligosaccharide profiles of canine and feline milk samples.

Oligosaccharides are important components of milk, serving as substrates for the intestinal microbiota, acting as antimicrobials that prevent pathogen colonization, and supporting the developing gastrointestinal immune system of neonates. Nutrient composition of canine and feline milk samples has been described previously, but little is known about the oligosaccharide content. Therefore, the objective of this study was to characterize canine and feline milk samples using a high-throughput glycomics approach.

Associations of human milk oligosaccharides and bioactive proteins with infant growth and development among Malawian mother-infant dyads.

Background: Human milk oligosaccharides (HMOs) and bioactive breast milk proteins have many beneficial properties. Information is sparse regarding associations between these milk constituents and infant growth and development in lower-income countries.

Objectives: We aimed to examine associations of milk content of HMOs and bioactive proteins at 6 mo postpartum with infant growth and motor and cognitive development.

The proteomics of roadside hawk (Rupornis magnirostris), broad-snouted caiman (Caiman latirostris) and loggerhead sea turtle (Caretta caretta) tears.

Background: Tears play an important role in ocular surface protection, and help wild animals maintain visual acuity in the face of air and water friction. The proteomics of tears has only been described for mammals. The knowledge of the proteomics of wild animal tears can aid not only in the setting of normal standards for ocular disease studies in these animals, but also to base the search for new molecules to be used in ophthalmology therapeutics.

Deep Structural Analysis and Quantitation of O-Linked Glycans on Cell Membrane Reveal High Abundances and Distinct Glycomic Profiles Associated with Cell Type and Stages of Differentiation.

Proteins on cell membrane are modified by N- and O-glycans. N-Glycans have been extensively characterized using advanced separation and mass spectrometry techniques. However, O-glycans remain a challenge, because of the lack of universal enzymes to release them and the large background abundances of N-glycans.

Immunoglobulin A N-glycosylation Presents Important Body Fluid-specific Variations in Lactating Mothers.

Secretory Immunoglobulin A (SIgA) is central to mucosal immunity: represents one of the main immunological mechanisms of defense against the potential attack of pathogens. During lactation SIgA is produced by plasmablasts in the mammary gland and is present in breast milk, playing a vital role in the passive immunity of the newborn. Interestingly, the different components of SIgA are highly N-glycosylated, and these N-Glycans have an essential role in health maintenance.

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

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.

Human Milk Proteins and Their Glycosylation Exhibit Quantitative Dynamic Variations during Lactation.

Background: Proteins in human milk are essential and known to support the growth, development, protection, and health of the newborn. These proteins are highly modified by glycans that are currently being recognized as vital to protein structure, stability, function, and health of the intestinal mucosa. Although milk proteins have been studied, the quantitative changes in milk proteins and their respective site-specific glycosylation are unknown.

Mass Spectrometry Approaches to Glycomic and Glycoproteomic Analyses.

Glycomic and glycoproteomic analyses involve the characterization of oligosaccharides (glycans) conjugated to proteins. Glycans are produced through a complicated nontemplate driven process involving the competition of enzymes that extend the nascent chain. The large diversity of structures, the variations in polarity of the individual saccharide residues, and the poor ionization efficiencies of glycans all conspire to make the analysis arguably much more difficult than any other biopolymer.

Lipid-Based Nutrient Supplements During Pregnancy and Lactation Did Not Affect Human Milk Oligosaccharides and Bioactive Proteins in a Randomized Trial.

Background: Human milk oligosaccharides (HMOs) and bioactive proteins are beneficial to infant health. Recent evidence suggests that maternal nutrition may affect the amount of HMOs and proteins in breast milk; however, the effect of nutrient supplementation on HMOs and bioactive proteins has not yet been well studied.

Objective: We aimed to determine whether lipid-based nutrient supplements (LNSs) affect milk bioactive protein and HMO concentrations at 6 mo postpartum in women in rural Malawi.

Composition and Variation of Macronutrients, Immune Proteins, and Human Milk Oligosaccharides in Human Milk From Nonprofit and Commercial Milk Banks.

Background: When human milk is unavailable, banked milk is recommended for feeding premature infants. Milk banks use processes to eliminate pathogens; however, variability among methods exists. Research aim: The aim of this study was to compare the macronutrient (protein, carbohydrate, fat, energy), immune-protective protein, and human milk oligosaccharide (HMO) content of human milk from three independent milk banks that use pasteurization (Holder vs.

Absolute Quantitation of Human Milk Oligosaccharides Reveals Phenotypic Variations during Lactation.

Background: The quantitation of human milk oligosaccharides (HMOs) is challenging because of the structural complexity and lack of standards.

Objective: The objective of our study was to rapidly measure the absolute concentrations of HMOs in milk using LC-mass spectrometry (MS) and to determine the phenotypic secretor status of the mothers.

Methods: This quantitative method for measuring HMO concentration was developed by using ultraperformance LC multiple reaction monitoring MS.

Quantitation of human milk proteins and their glycoforms using multiple reaction monitoring (MRM).

Human milk plays a substantial role in the child growth, development and determines their nutritional and health status. Despite the importance of the proteins and glycoproteins in human milk, very little quantitative information especially on their site-specific glycosylation is known. As more functions of milk proteins and other components continue to emerge, their fine-detailed quantitative information is becoming a key factor in milk research efforts.

Quantitation of Site-Specific Glycosylation in Manufactured Recombinant Monoclonal Antibody Drugs.

During the development of recombinant monoclonal antibody (rMAb) drugs, glycosylation receives particular focus because changes in the attached glycans can have a significant impact on the antibody effector functions. The vast heterogeneity of structures that exist across glycosylation sites hinders the in-depth analysis of glycan changes specific to an individual protein within a complex mixture. In this study, we established a sensitive and specific method for monitoring site-specific glycosylation in rMAbs using multiple reaction monitoring (MRM) on an ultrahigh-performance liquid chromatography-triple quadrupole MS (UHPLC-QqQ-MS).