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R W Wulkan

Publications and source records attributed to R W Wulkan.

12 recordsLinked to original sources
PubMed2004

Procalcitonin as an early marker of infection in neonates and children.

A child or neonate presenting with fever is a common medical problem. To differentiate between those with a severe bacterial infection and those with a localised bacterial or a viral infection can be a challenge. This review provides an overview of neonatal and paediatric studies that assess the use of procalcitonin as an early marker of bacterial infection. Procalcitonin is an excellent marker for severe, invasive bacterial infection in children. However, the use of procalcitonin in the diagnosis of neonatal bacterial infection is complicated, but if correctly used procalcitonin results in a higher specificity than C-reactive protein. In addition, procalcitonin has been shown to correlate with severity of disease (urinary tract infections and sepsis), and can therefore be used as a prognostic marker. Procalcitonin is therefore a useful additional tool for the diagnosis of bacterial disease in neonates and children.

Bacteremia↗
PubMed2001

Measurement of pyruvate in blood by high-performance liquid chromatography with fluorescence detection.

Accurate measurement of pyruvate is particularly important in the detection of mitochondrial enzyme disorders. describe a simple high-performance liquid chromatography assay for pyruvate with derivatization and fluorescence detection. Between-run variation is below 4.5% and the method is linear between I and 1,200 micromol/L. The mean recovery is 101%. After sample pretreatment, the calculated pyruvate concentration proved to be stable for 15 days when samples were kept at -20 degrees C.

Calibration↗
PubMed1991

Multicentre comparison of the Novo Biolabs immunometric CK-MB assay with four established methods.

The analytical performance of a new immunometric CK-MB assay from Novo Biolabs was evaluated in three hospitals. Comparisons were made with another immunometric assay, an immune inhibition/precipitation technique, an immune inhibition method, and a column separation method. The Novo assay exhibited good precision (CV 3-7%) at all concentration levels tested (6-150 micrograms/L) and was found to be linear over the range 0-200 micrograms/L. Comparison of the Novo kit with the other methods using patients' sera showed acceptable correlation between the methods over a wide concentration range (r = 0.96-0.99). We conclude that the assay is a useful adjunct to the specific measurement of CK-MB, particularly in routine laboratories with a high throughput of such determinations.

Creatine Kinase↗
PubMed1991

Graphical non-linear representation of multi-dimensional laboratory measurements in their clinical context.

A polygon-based graphical representation of laboratory test results using nonlinear scaling is described. It is argued that the nonlinearity of the scale and the use of colors in the representation facilitates interpretation of the test result in its relationship to the standard reference range and critical clinical decision levels. Preliminary results suggest that this representation may be fruitfully used to enhance the efficiency of the information transfer from the clinical chemistry laboratory to clinicians. Other applications, inside as well as outside the medical field, may easily be imagined.

Chemistry, Clinical↗
PubMed1990

Detection of aberrant observations in a background of an unknown multidimensional Gaussian distribution.

An exploratory iterative technique for the detection of aberrant observations on a background of a multidimensional Gaussian distribution is described. Its development was motivated by the analysis of a set of three measurements reflecting the acid-base metabolism in the blood of 2,402 intensive care patients. This new, three-dimensional treatment of such data yields a meaningful description. A technical evaluation of the method, using artificially generated data is also presented. It is shown that the model parameters of the underlying Gaussian distributions are determined with good accuracy and that the accuracy with which the contamination is estimated increases with increasing distance of the contaminating observations from the mean.

Acid-Base Equilibrium↗
PubMed1990

Pseudohyperkalaemia in thrombocythaemia.

Pseudohyperkalaemia in thrombocythaemia, in its primary form or associated with polycythaemia vera, can occur with platelet counts in excess of 600 X 10(9)/l, and it is not related to high leukocyte or thrombocyte counts. An increment of 0.15 mmol/l serum potassium was found for every 100 X 10(9)/l rise in platelet count with a correlation coefficient of 0.82. Potassium from platelets is not released during the aggregation phase but during the degranulation phase of the coagulation process.

Electrolytes↗
PubMed1988

Serum water determination by means of microwave evaporation.

A novel method is described for the determination of serum water using a microwave oven. The sources of experimental errors were analysed. Serum samples from two hundred patients were analysed for sodium, water and protein, and the data were used to calculate serum sodium molalities. A possible correlation was investigated between serum water content and protein concentration. The results were compared with those in the literature.

Blood Chemical Analysis↗
PubMed1986

Hydrophobic properties of alkaline phosphatases.

The butanol extraction method of Morton (1950), a routine step in enzyme purification, is discussed with special reference to a hydrophobic form of alkaline phosphatase from human liver tissue. This form slowly precipitates from butanol-extracted liver tissue homogenates stored at 4 degrees C. Furthermore, it is lost when acetone precipitation is applied as a purification procedure. The soluble form in liver tissue is shown to have a higher relative hydrophobicity than the serum liver/bone isoenzyme. The use of sodium cholate in the isolation of the hydrophobic form produces an artefact in isoelectric focusing, which can be abolished by dialysis prior to focusing.

Alkaline Phosphatase↗
PubMed1986

Alkaline phosphatase and cholestasis.

The process of cholestasis in both man and rat leads in the majority of cases to the appearance of a biliary band in the electrophoresis of alkaline phosphatase isoenzymes. In this article, the biochemical nature and mode of formation of the biliary band is discussed, with reference to its appearance in cholestasis and other hepatobiliary diseases.

Alkaline Phosphatase↗
PubMed1985

Isoelectric focusing of alkaline phosphatases in agarose gel.

An isoelectric focusing technique in agarose gel is presented which is suitable for alkaline phosphatases from both serum and tissue sources. An anomaly in the literature about isoelectric focusing of serum alkaline phosphatase from liver origin is discussed and a possible explanation is proposed. The presented technique is used to demonstrate some differences in behaviour of serum liver and bone isoenzymes towards neuraminidase treatment.

Alkaline Phosphatase↗
PubMedDate not supplied

A multi-dimensional analysis of three chemical quantities in the blood.

A three-dimensional model for the analysis of the three quantities pH, pCO2 and base excess (BE), as measured in arterial blood, is presented. Whereas the conventional analysis of these quantities relies on reference regions as established from the univariate distributions, treating the quantities as uncorrelated, the present model estimates the parameters of the three-dimensional reference region from a sample of observations, based on the assumption that the observations inside the reference region follow a multi-dimensional Gaussian distribution. For observations outside the reference region, reference directions are established, corresponding to the conventionally defined specific states of acid-base disturbances. This leads to a new classification model, the results of which are compared to those of the conventional model.

Acid-Base Equilibrium↗