323 research outputs found
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
Een beschouwing over de waarde van verschillende onderzoekingsmethoden der booggangen
In dit proefschrift wordt gepoogd een inzicht te krijgen in de waarde van de vestibulaire onderzoekingsmethoden door middel van rotatoire en calorische prikkels. In een overzicht van de historische ontwikkeling van het rotatoire onderzoek wordt uitvoerig ingegaan op het onderzoek door middel van kleine gedoseerde draaiprikkels volgens Van Egmond, Jongkees en Groen, de cupulometrie. De grote betekenis van de onderzoekingen van de Utrechtse school wordt besproken
Analyse van tekstverwerker-eigenschappen in verband met de eisen van wetenschappelijke instellingen
Milk protein oxidation in healthy subjects:A preliminary study
The role of protein oxidation in the regulation of whole body protein metabolism is unknown. Previously, it was observed that vigorous exercise led to increased protein oxidation. To further characterise 13C-milk protein oxidation in healthy subjects, the oxidation of ingested 13C-protein after an overnight fast was measured using a non-invasive 13C-protein breath test. This approach enables the analysis of 13C-protein oxidation kinetics and the effect of interfering factors. It was found that the estimated maximal 13C-milk protein oxidation was 0.07 g min−1, corresponding to a theoretical maximal oxidation capacity of ≈1.4 g kg body weight−1 d−1. No indications were found for preferential oxidation of non-essential amino acids. Combined ingestion of 30 g 13C-whey protein with 30 g glucose resulted in a 19% decrease of 13C-whey protein oxidation. It was concluded that exogenous 13C-whey protein oxidation can be affected by other co-ingested nutrients like glucose
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