Plasma betaine concentrations correlate with plasma cortisol but not with C-reactive protein in an elderly population.

Background: Low plasma betaine concentrations are a feature of seriously ill patients. Increased dietary betaine intake has been associated with lowered systemic inflammation. We aimed to compare plasma cortisol (a stress marker) and C-reactive protein (an inflammation marker) as statistical predictors of plasma betaine concentrations.

Detection of volatile compounds produced by microbial growth in urine by selected ion flow tube mass spectrometry (SIFT-MS).

Selected ion flow tube-mass spectrometry has been used to measure the volatile compounds occurring in the headspace of urine samples inoculated with common urinary tract infection (UTI)-causing microbes Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, Klebsiella pneumoniae, Enterococcus faecalis, or Candida albicans. This technique has the potential to offer rapid and simple diagnosis of the causative agent of UTIs.

Increased concentrations of breath haloamines are not detectable in airways inflammation using SIFT-MS.

The haloamines, including the chloramines (H(2)NCl, HNCl(2)) and bromamine (H(2)NBr), are diffusible gases that are likely to be produced during inflammation and so may be present as markers of lung inflammation on breath. Although haloamines are quite reactive, it is possible to measure these compounds in humid samples using SIFT-MS. Until recently the quantification of haloamines in breath suffered from interference from other common breath compounds.

Accurate, reproducible measurement of acetone concentration in breath using selected ion flow tube-mass spectrometry.

Using selected ion flow tube-mass spectrometry (SIFT-MS) for on-line analysis, we aimed to define the optimal single-exhalation breathing manoeuvre from which a measure of expired acetone concentration could be obtained. Using known acetone concentrations in vitro, we determined the instrument's accuracy, inter-measurement variability and dynamic response time. Further, we determined the effects of expiratory flow and volume on acetone concentration in the breath of 12 volunteers and calculated intra-individual coefficients of variation (CVs).

Modelling acute renal failure using blood and breath biomarkers in rats.

This paper compares three methods for estimating renal function, as tested in rats. Acute renal failure (ARF) was induced via a 60-min bilateral renal artery clamp in 8 Sprague-Dawley rats and renal function was monitored for 1 week post-surgery. A two-compartment model was developed for estimating glomerular filtration via a bolus injection of a radio-labelled inulin tracer, and was compared with an estimated creatinine clearance method, modified using the Cockcroft-Gault equation for rats.

Monitoring chloramines and bromamines in a humid environment using selected ion flow tube mass spectrometry.

The selectivity and sensitivity of selected ion flow tube mass spectrometry (SIFT-MS) for individual breath analysis of haloamines has been improved by heating the flow tube in a commercial instrument to around 106 degrees C. Data is presented showing the marked reduction in the number density of water clusters of product ions of common breath metabolites that are isobaric with the product ions from monochloramine and monobromamine that are used to monitor the haloamine concentrations. These results have direct relevance to the real-time monitoring of chloramines in drinking water, swimming pools and food processing plants.

In vitro SIFT-MS validation of a breath fractionating device using a model VOC and ventilation system.

The measurement of volatile organic compounds in exhaled breath is becoming recognized as a method of disease diagnosis and therapeutic monitoring. The aim of this study was to validate the collection of breath from intubated patients in the intensive care setting. This was done by assembling a system of ventilators and humidification to emulate the human respiratory system.

Separation of cationic aracyl derivatives of betaines and related compounds.

Cationic aracyl esters of betaines can be formed by alkylation with aracyl halides or trifluoromethanesulfonates. HPLC on a non-endcapped strong cation exchange (SCX) column gave high retention of these derivatives. Cation exchange HPLC may be carried out on a normal-phase (silica or alumina) column using a polar organic solvent (acetonitrile, propan-2-ol) containing an aqueous buffer with an organic cation and a hydrophilic anion.

Validation of (1)H NMR spectroscopy as an analytical tool for methylamine metabolites in urine.

Background: Methylamines have many metabolic roles and there is an increasing demand for their measurement. Glycine betaine is an important osmolyte, and a reservoir for methyl groups. Proline betaine and trigonelline are important dietary betaines.

A simple binding assay for the direct determination of biotin in urine.

Background: We have devised a simple assay to detect adequate biotin intake, which uses an alternative configuration from most existing assays.

Methods: The assay depends on the competition of streptavidin peroxidase for immobilized biotin or soluble biotin in standards or samples. Immobilized streptavidin peroxidase is detected using tetramethylbenzidine, and the plates are read at 450 nm.

A high performance liquid chromatographic method for the measurement of total carnitine in human plasma and urine.

Total carnitine in plasma and urine can be measured by high performance liquid chromatography (HPLC) using the novel fluorescent derivatisation reagents 6'-methoxynaphthacyl trifluoromethanesulfonate and 2'-phenanthrenacyl trifluoromethanesulfonate. Sample preparation for total carnitine analysis involves: extraction of plasma and urine in methanol, the optional addition of serine betaine as an internal standard, saponification of acyl carnitines with calcium hydroxide, followed by derivatisation with 6'-methoxynaphthacyl trifluoromethanesulfonate or 2'-phenanthrenacyl trifluoromethanesulfonate. The derivatives were separated using an alumina column and measured by fluorescence detection.