You Are What You Eat: Mass spectrometry in paediatric kinetic studies using stable isotopes

An overview will be presented about applications of stable isotopes in paediatric research. Mass spectrometry has proven to be an essential tool for unravelling kinetic studies in a large range of different research disciplines related to intestinal diseases, obesities, severe cerebral palsy, oxidative stress and foetal metabolism. Due to the diversity and complexity of the different metabolites involved in these studies, there is a high demand on sophisticated mass spectrometric instruments. Several new methods have been developed for measurement of isotopic labelled compounds in body fluids. 13C isotopic glucose enrichment in human plasma is analysed, using liquid chromatography isotope ratio mass spectrometry (LC/IRMS). Also new methods were developed for measuring the glutathione (GSH) fractional synthesis rate (FSR) in neonates after infusion of [1-13C]glycine as a tracer. For measuring energy expenditure and total body water composition in humans the doubly labelled water method is valuable technique. It usually involves blood or urine sampling, which might be difficult in neonates and children with cerebral palsy or other disabilities. We therefore aimed to validate a method making use of saliva samples analyzed by automated thermal conversion elemental analyzer in combination with isotope ratio mass spectrometry (TC/EA/IRMS). The different types of mass spectrometric instruments will be discussed here as well as several applications in paediatric research utilizing these techniques. The applications cover amino acid metabolism and body composition, energy expenditure, and the synthesis of specific proteins such as glutathione and albumin in different groups of children and even in foetuses. Finally, the aims and outline of this dissertation are covered

Does a reduced glucose intake prevent hyperglycemia in children early after cardiac surgery? a randomized controlled crossover study

Introduction: Hyperglycemia in children after cardiac surgery can be treated with intensive insulin therapy, but hypoglycemia is a potential serious side effect. The aim of this study was to investigate the effects of reducing glucose intake below standard intakes to prevent hyperglycemia, on blood glucose concentrations, glucose kinetics and protein catabolism in children after cardiac surgery with cardiopulmonary bypass (CPB).Methods: Subjects received a 4-hour low glucose (LG; 2.5 mg/kg per minute) and a 4-hour standard glucose (SG; 5.0 mg/kg per minute) infusion in a randomized blinded crossover setting. Simultaneously, an 8-hour stable isotope tracer protocol was conducted to determine glucose and leucine kinetics. Data are presented as mean ± SD or median (IQR); comparison was made by paired samples t test.Results: Eleven subjects (age 5.1 (20.2) months) were studied 9.5 ± 1.9 hours post-cardiac surgery. Blood glucose concentrations were lower during LG than SG (LG 7.3 ± 0.7 vs. SG 9.3 ± 1.8 mmol/L; P < 0.01), although the glycemic target (4.0-6.0 mmol/L) was not achieved. No hypoglycemic events occurred. Endogenous glucose production was higher during LG than SG (LG 2.9 ± 0.8 vs. SG 1.5 ± 1.1 mg/kg per minute; P = 0.02), due to increased glycogenolysis (LG 1.0 ± 0.6 vs. SG 0.0 ± 1.0 mg/kg per minute; P < 0.05). Leucine balance, indicating protein balance, was negative but not affected by glucose intake (LG -54.8 ± 14.6 vs. SG -58.8 ± 16.7 μmol/kg per hour; P = 0.57).Conclusions: Currently recommended glucose intakes aggravated hyperglycemia in children early after cardiac surgery with CPB. Reduced glucose intake decreased blood glucose concentrations without causing hypoglycemia or affecting protein catabolism, but increased glycogenolysis.Trial registration: Dutch trial register NTR2079

Load Management - An Industrial Perspective on This Developing Technology

Load Management is a rapidly developing technology which can have a significant impact on all electric users, especially large users. It is mandated by P.U.R.P.A. (Public Utility Regulatory Policy Act) and is akin to energy conservation but its primary focus is to reduce the energy demand component, the magnitude of energy use at any given time. Load Management can reduce a utility's operating and construction cost as well as conserve energy and scarce fuels. It can also significantly reduce the electric energy costs of industrial and commercial users, if applied properly. This presentation will discuss the state-of-the-art of these techniques, the alternative forms they can take, their potential impact on industrial companies, and how industry can use load management to its advantage