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To study the potential of multivariate classification methods in order to obtain more insight into abnormal laboratory data from patients with sickle cell disease, we investigated standard haematological and clinical chemical variables of 18 controls and 37 apparently healthy persons with heterozygous sickle cell disease (Hb AS), all women, using both univariate and multivariate classification methods. In the univariate method, those with Hb AS showed decreased serum log aspartate aminotransferase (log AST) activity, mean corpuscular volume and mean corpuscular haemoglobin (MCH) and increased sodium concentration. The multivariate method identified sodium, potassium, urea, uric acid, log AST, alanine aminotransferase and MCH as the variables that produced maximal separation between persons with Hb As and controls. It increased the 'non-error rate' for classification of persons with Hb AS by 16.4% compared with classification based on the variable, MCH, that produced maximal separation by the univariate method. The frequency distribution of percentage Hb S in the Hb AS group proved bimodal with maximal separation at 37.0% Hb S. The subgroup with 37.0% or less (n = 16) was considered to have concomitant heterozygous alpha-thalassaemia-2. In the univariate method the subgroup characterized by greater than 37.0% Hb S (n = 21) had increased serum sodium and uric acid concentrations, perhaps related to sickle cell nephropathy, whereas the subgroup with less than or equal to 37% Hb S did not. The multivariate method added information to the univariate method by additionally identifying abnormalities in serum potassium and urea concentrations in the former subgroup.(ABSTRACT TRUNCATED AT 250 WORDS)

This paper deals with a new method for the determination of serum nucleotidase (EC 3.1.3.5). The assay is performed with cytidine-5'-monophosphate as substrate, followed by deamination of the generated cytidine. The principle of the method and the determination of the liberated ammonia by the Berthelot indophenol-reaction are comparable to the Persijn--van der Slik method in which adenosine-5'-monophosphate is used as substrate. The correlation between the results obtained with these two methods was found to be good; the new method has the advantage of higher sensitivity.

In preparation for multivariate analysis, an exploratory study has been undertaken to investigate the relative position, separability, homogeneity and shape of three major disease groups, using data from a clinical chemical routine package.The data set consists of 46 hepatology patients, 50 nephrology patients and 46 cardiology patients, and the measured blood levels include 20 common clinical chemical routine assays. Missing value problems were avoided by deleting some of the variables and objects.A univariate analysis was used as the basis ofa rescaling of the data.Bivariate (pairwise) plots of some major assays each show limited separation. The set of three such plots of the three major principal components reveals more distinction between the groups than was offered by univariate analysis. Three-dimensional extensions of these techniques allow better insight than any of the two-dimensional plots, but these three-dimensional versions require more plots for complete interpretation.Non-linear mapping of the data is the best way of retaining the distances and a fairly good separation is achieved in the plot. The plot is less informative about shape and relative position of the classes.Representation of the data as pictures of faces does not offer additional information and visual clustering is worse than in any of the techniques mentioned.During the analysis many assumed properties of the data are confirmed and a good starting pointfor multivariate classification is attained. Easy visual detection of outliers is offered by all techniques. Unfortunately, valuable information is lost in this data set by deleting some incomplete variables.

The manual method of Persijn & Van der Slik (J. Clin. Chem. Clin. Biochem. 6, 441-446 (1968): 7, 493-497 (1969); 8, 398-402 (1970) for the determination of serum 5'-nucleotidase has been adapted to the Auto-Analyzer II System. In the Auto-Analyzer II, the incubation temperature for the enzyme reactions is 37 degrees C, and the effective sample speed is 30/h, at a sample/wash ratio of 2:1. There is good agreement and correlation between the manual method and the Auto-Analyzer II method (equation of regression line: y = x + 0.6, correlation coefficient = 0.988; the normal range is 2.9-10.5 U/l for both methods). In routine use, within-run and between-day reproducibility are considerably smaller for the Auto-Analyzer II than for the manual method, especially when large numbers of samples are assayed.

Serum mucleotidase activity (EC 3.1.3.5) is measured by the amount of ammonia liberated from cytidine after incubation with cytidine deaminase (EC 3.5 4.5). Purification of the cytidine deaminase results in the abolition of interfering reactions, so that routine application is possible.

A capillary gas chromatographic method for the profiling of trimethylsilylated mono- and disaccharides and polyols in urine, plasma and unwashed and washed erythrocytes is described. The prepurification method is based on the moderate inhibition of the derivatization experienced in the presence of physiological amounts of inorganic salts and the relative stability of the formed trimethylsilylethers towards treatment with water and dilute hydrochloric acid. Series to series quality control data for 31 sugars/polyols in a pooled urine are given. The method was used to establish age-dependent concentrations of 18 sugars/polyols in urines of 72 control persons on a free diet. Gas chromatographic profiles and quantitative data obtained from urines of pediatric patients with galactosemia treated with a diet low in lactose and galactose, type 1 hereditary tyrosinemia treated with a diet low in phenylalanine and tyrosine, and a neurological disorder with a high calorie gastric drip feeding, are presented and discussed. Examples of the profiling of sugars/polyols in the plasma, unwashed and washed erythrocytes of a healthy adult, and the plasma of a newborn with galactosemia prior to treatment, are given.

The determination of N tau-methylhistamine in urine, using gas chromatography with nitrogen-phosphorus detection and the homologue N tau-ethylhistamine as internal standard, is described. A comparison between the present method and a previously described stable isotope dilution mass fragmentographic method resulted in a regression line of Y = 0.023 + 0.944X mumol/l with a correlation coefficient of 0.996. The 24-h excretions of 35 normal adults on a free diet ranged from 0.4 to 1.8 mumol. Patients with mastocytosis, chronic myelocytic leukemia, anaphylactic reactions and a patient after bronchial provocation showed above normal values.

A new, simple and sensitive method is described for assay of serum gamma-glutamyltransferase activity based on the hydrolysis of the substrate L-gamma-glutamyl-3-carboxy-4-nitranilide which offers the advantage of producing directly its own chromogen. The substrate is highly soluble and the method can therefore easily be adapted to any equipment for the automated assay of gamma-glutamyltransferase. The activities at measured optimum substrate concentration are slightly higher than with the Szasz ((1969), Clin. Chem. 15, 124-136) method in which L-glutamyl-p-nitroanilide is used as substrate.

The profiling of total long-chain fatty acids and cholesterol in a variety of biological materials, using capillary gas chromatography with flame ionization detection, is described. The within-run precision and day-to-day precision for fifteen fatty acids and cholesterol in erythrocyte samples were investigated. Quantitative data on the analysis of amniotic fluid samples collected from women in the 30th to 38th week are given together with a correlation study on their lecithin/sphingomyelin and their palmitic acid/stearic acid ratios. In addition, the method was applied to lumbar cerebrospinal fluid, plasma, isolated leukemic blood cells and neuroblastoma tissue.