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Biomedical subjects

M Schoemaker

Publications and source records attributed to M Schoemaker.

4 recordsLinked to original sources

A novel method for continuous online glucose monitoring in humans: the comparative microdialysis technique.

The aim of this study was to prove the feasibility of continuous subcutaneous glucose monitoring in humans using the comparative microdialysis technique (CMT). The performance of the CMT was determined by comparing tissue glucose values with venous or capillary blood glucose values in healthy volunteers and type 1 diabetic subjects. The CMT is a microdialysis-based system for continuous online glucose monitoring in humans. This technique does not require calibration by the patient. Physiological saline with glucose (5.5 mM) is pumped in a stop-flow mode through a microdialysis probe inserted into the abdominal s.c. tissue. Tissue glucose concentration is calculated by comparing the dialysate and perfusate glucose concentrations. The time delay due to the measurement process is 9 min. We tested the CMT on six healthy volunteers and six type 1 diabetic patients for 24 h in our clinical setting. Comparisons were made to HemoCue analyzer (Angelholm, Sweden) capillary blood glucose measurements (healthy volunteers) and to venous blood glucose concentration determined with a Hitachi analyzer (diabetic patients). The mean absolute relative error of the CMT glucose values from the blood glucose values was 17.8+/-15.5% (n = 167) for the healthy volunteers and 11.0+/-10.8% (n = 425) for the diabetic patients. The mean difference was 0.42+/-1.06 mM (healthy volunteers) and -0.17+/-1.22 mM (diabetic patients). Error grid analysis for the values obtained in diabetic patients demonstrated that 99% of CMT glucose values were within clinically acceptable regions (regions A and B of the Clarke Error Grid). The study results show that the CMT is an accurate technique for continuous online glucose monitoring.

Adult↗

Motor performance of children during treatment for acute lymphoblastic leukemia.

BACKGROUND: Daily life motor skills of children with acute lymphoblastic leukemia (ALL) were studied during treatment using the Movement Assessment Battery for Children (Movement ABC). In addition, the possible relation with vincristine treatment was investigated. PROCEDURE: Seventeen children treated for ALL, aged 4-12 years, were compared to an age- and sex-matched control group. RESULTS: The leukemia group performed more poorly than the control group on both fine and gross motor skills. In looking at the number of children with ALL who scored in the clinical range of the different subtests, problems in balance skills were found to be most pronounced at the end of induction therapy. Remarkably, half a year after reinduction therapy, problems with balance had decreased, whereas the number of children with fine motor problems had increased. CONCLUSIONS: A relation between the gross motor problems and vincristine neurotoxicity seems plausible based on a descriptive analysis of the data, but this was not supported statistically.

Analysis of Variance↗

The lipoxygenase sensor, a new approach in essential fatty acid determination in foods.

Both an enzyme electrode and enzyme column with immobilized lipoxygenase, respectively, were used for the determination of essential fatty acids. The former was applied in a batch system, the latter was part of a fully automated flow injection analysis (FIA)-system. The oxygen consumption due to the lipoxygenase catalysed oxygenation of essential fatty acids was monitored amperometrically. Both systems were compared with regard to linear ranges of the calibration plots, sensitivities, detection limits, apparent Michaelis-Menten constants and lifetimes. The enzyme electrode showed different sensitivities for linoleic and alpha-linolenic acids, the most common essential fatty acids. The reason for this was not a second oxygenation step by lipoxygenase in case of alpha-linolenic acid, but a different dialytic behaviour of the two substrates. Hence, only the FIA-system was used for the determination of these fatty acids in real matrices such as vegetable oils and margarines. In the presence of detergent the triglycerides of the hydrophobic food samples were converted into water soluble glycerol and free fatty acids by a 15 min incubation with a ready to use lipase/esterase-mix, thus avoiding the use of organic solvents for analysis. Results obtained by the enzymatic FIA-system were in excellent agreement with those obtained by standard gas chromatography.

Biosensing Techniques↗