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PubMed1982

Prediction of phenytoin dosage in epilepsy using multiple linear regression.

Analysis of plasma phenytoin in a group of patients treated for epilepsy showed that only 36% had values in the therapeutic range. The relationship between plasma phenytoin, body weight, and daily dosage of the drug were explored, and the data were analysed by multiple regression. The resultant equation, relating all three factors, were used to optimise drug dosage, and the importance of using the body weight of the patient before starting a phenytoin regimen is emphasised. An increase in the number of patients with plasma phenytoin in the therapeutic range was achieved, and the clinical value of being in that range is shown.

Body Weight↗
PubMed2000

Four-parametric non-linear regression fit of isovolumic relaxation in isolated ejecting rat and guinea pig hearts.

Left ventricular isovolumic pressure fall is characterized by the time constant tau obtained by fitting the exponential p(t) = p(infinity) + (p(0)-p(infinity))3exp(-t/tau) to pressure fall. It has been shown that tau, calculated from the first half of pressure fall, differs considerably from that found at late relaxation in normal and pathophysiological conditions. The present study aims at testing for such differences statistically and to quantify tau changes during relaxation. Two improvements of the common regression procedure are introduced for that purpose: the use of the four-parametric regression function, p(t) = p(infinity) + (p(0)-p(infinity))3exp[-t/(tau(0)+b(tau)t)], and an optimal data-dependent split of the isovolumic pressure fall interval. The residual regression errors of the methods are statistically compared in one-hundred isolated working rat and one-hundred guinea pig hearts, additionally including a logistic regression method. Regression error is significantly reduced by introducing that b(tau). b(tau) is negative in most cases, indicating accelerated relaxation during isovolumic pressure fall, but zero and positive b(tau) are occasionally seen. Optimal interval tripartition further improves the regression error in most cases. The statistically proved acceleration of the time constant during isovolumic relaxation justifies factor b(t) as a direct and continuous measure of differences between early and late relaxation. This difference between early and late isovolumic relaxation is probably caused by residually contracted myocardium at the beginning of pressure fall, and is therefore important to describe pathophysiological effects on relaxation phases.

Animals↗
PubMed1991

The factors affecting plasma glutathione peroxidase and selenium in rheumatoid arthritis: a multiple linear regression analysis.

The reactive oxygen radicals are trapped by anti-oxidants, such as selenium containing glutathione peroxidase (GSHpx), which also can inhibit the oxygenation of arachidonic acid to pro-inflammatory prostaglandins and leukotrienes. We studied the levels of anti-oxidant glutathione peroxidase and selenium (in plasma) in 48 patients with rheumatoid arthritis (RA). In the multiple regression model, joint score had the highest explanatory value for serum selenium, and sulphasalazine treatment was the most significant variable contributing to GSHpx activity. The plasma GSHpx activity was not increased in RA patients in general, but was high in those taking sulphasalazine as compared with those not doing so (342.4 +/- 48.2 vs. 298.9 +/- 34.7 U/l, 95% confidence interval of difference from 17.9 to 69.1, p less than 0.002). The serum selenium levels correlated with clinical activity of the joint, disease measuring joint score.

Adult↗