LC-MS/MS-based reference intervals for hair cortisol in healthy children.

Background: Human scalp hair is a valuable matrix for determining long-term cortisol concentrations, with wide-spread applicability in clinical care as well as research. However, pediatric reference intervals are lacking. The aim of this cross-sectional study is to establish age-adjusted reference intervals for hair cortisol in children and to gain insight into hair growth velocity in children up to 2 years old.

Variation in Coronary Atherosclerosis Severity Related to a Distinct LDL (Low-Density Lipoprotein) Profile: Findings From a Familial Hypercholesterolemia Pig Model.

Objective: In an adult porcine model of familial hypercholesterolemia (FH), coronary plaque development was characterized. To elucidate the underlying mechanisms of the observed inter-individual variation in disease severity, detailed lipoprotein profiles were determined. Approach and Results: FH pigs (3 years old, homozygous R84C mutation) received an atherogenic diet for 12 months.

Hair Glucocorticoids as a Biomarker for Endogenous Cushing's Syndrome: Validation in Two Independent Cohorts.

Background/aims: The current diagnostic workup of Cushing's syndrome (CS) requires various tests which only capture short-term cortisol exposure, whereas patients with endogenous CS generally have elevated cortisol levels over longer periods of time. Scalp hair assessment has emerged as a convenient test in capturing glucocorticoid concentrations over long periods of time. The aim of this multicenter, multinational, prospective, case-control study was to evaluate the diagnostic efficacy of scalp hair glucocorticoids in screening of endogenous CS.

Albumin synthesis in very low birth weight infants is enhanced by early parenteral lipid and high-dose amino acid administration.

Background & Aims: Albumin is one of the most important plasma proteins and plays a key role in many physiologic processes, such as preserving colloid osmotic pressure, scavenging radicals, and binding and transporting bilirubin, hormones, and drugs. However, albumin concentrations are often low in preterm infants during the first days of life. We hypothesized that early parenteral lipid and high-dose amino acid (AA) administration to very low birth weight (VLBW) infants from birth onwards increases hepatic albumin synthesis rates.

LC-MS/MS-based method for long-term steroid profiling in human scalp hair.

Background: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the method of choice for quantification of steroids. Human scalp hair provides the possibility to measure long-term retrospective steroid concentrations, which is especially useful for steroids with large time-dependent fluctuations in concentration, such as the glucocorticoid cortisol.

Aim: We set up and validated a LC-MS/MS-based method for long-term steroid profiling, quantifying cortisol, cortisone, testosterone, androstenedione, dehydroepiandrosterone sulphate (DHEAS) and 17-α-hydroxyprogesterone (17OHP).

Adaptive regulation of amino acid metabolism on early parenteral lipid and high-dose amino acid administration in VLBW infants - a randomized, controlled trial.

Background & Aims: An anabolic state can be achieved upon intravenous amino acid administration during the immediate postnatal phase despite a low energy intake. The optimal dosing of amino acid and energy intake has yet to be established. The aim was to quantify the efficacy of early initiation of parenteral lipids and increased amounts of amino acids on metabolism and protein accretion in very low birth weight infants.

Safety and efficacy of early parenteral lipid and high-dose amino acid administration to very low birth weight infants.

Objective: To assess the efficacy and safety of early parenteral lipid and high-dose amino acid (AA) administration from birth onwards in very low birth weight (VLBW, birth weight <1500 g) infants.

Study Design: VLBW infants (n = 144; birth weight 862 ± 218 g; gestational age 27.4 ± 2.

Continuous enteral administration can enable normal amino acid absorption in rats with methotrexate-induced gastrointestinal mucositis.

It is unknown what feeding strategy to use during chemotherapy-induced gastrointestinal mucositis, which causes weight loss and possibly malabsorption. To study the absorptive capacity of amino acids during mucositis, we determined the plasma availability of enterally administered amino acids (AA), their utilization for protein synthesis, and the preferential side of the intestine for AA uptake in rats with and without methotrexate (MTX)-induced mucositis. Four days after injection with MTX (60 mg/kg) or saline (controls), rats received a primed, continuous dual-isotope infusion (intraduodenal and intravenous) of labeled L-leucine, L-lysine, L-phenylalanine, L-threonine, and L-methionine.

Lysine requirement of the enterally fed term infant in the first month of life.

Background: Infant nutrition has a major impact on child growth and functional development. Low and high intakes of protein or amino acids could have a detrimental effect.

Objective: The objective of the study was to determine the lysine requirement of enterally fed term neonates by using the indicator amino acid oxidation (IAAO) method.

Intestinal threonine utilization for protein and mucin synthesis is decreased in formula-fed preterm pigs.

Threonine is an essential amino acid necessary for synthesis of intestinal (glyco)proteins such as mucin MUC2 to maintain adequate gut barrier function. In premature infants, reduced barrier function may contribute to the development of necrotizing enterocolitis (NEC). Human milk protects against NEC compared with infant formula.

Simultaneous analysis of (13)C-glutathione as its dimeric form GSSG and its precursor [1-(13)C]glycine using liquid chromatography/isotope ratio mass spectrometry.

Determination of glutathione kinetics using stable isotopes requires accurate measurement of the tracers and tracees. Previously, the precursor and synthesized product were measured with two separate techniques, liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). In order to reduce sample volume and minimize analytical effort we developed a method to simultaneously determine (13)C-glutathione as its dimeric form (GSSG) and its precursor [1-(13)C]glycine in a small volume of erythrocytes in one single analysis.

Human fetal amino acid metabolism at term gestation.

Background: Knowledge on human fetal amino acid (AA) metabolism, largely lacking thus far, is pivotal in improving nutritional strategies for prematurely born infants. Phenylalanine kinetics is of special interest as is debate as to whether neonates will adequately hydroxylate phenylalanine to the semiessential AA tyrosine.

Objective: Our aim was to quantify human fetal phenylalanine and tyrosine metabolism.