Pattern classification of renal electrolyte cycles in primary aldosteronism

Application of pattern recognition and feature extraction techniques to volatile constituent metabolic profiles obtained by capillary gas chromatography

The applicability of threshold logic units, a form of nonparametric pattern recognition, to the processing of metabolic profile data obtained by high-efficiency glass capillary column gas chromatography has been investigated. The test data included profiles of the volatile constituents of urine from normal individuals and from individuals with diabetes mellitus. A feature extraction algorithm allowed for dimensionality reduction and indicated the constituents most important in the normal versus pathological distinction. With an optimum number of dimensions, a normal versus pathological prediction rate of 93.75% was achieved. Gas chromatography-mass spectrometry was utilized to identify important profile constituents.

Rhythmic fluctuations in the urine composition of sheep: separation of feed-dependent from other rhythms

The relative contribution of feed-induced and feed-independent changes to the pattern of electrolyte excretion have been determined in sheep maintained for extended schedules providing feeds at intervals of 24, 19, 4 and 1 hr. Power spectral analysis indicated that the pattern of electrolyte excretion was predominantly fixed by the feeding cycle. Frequent small feeds reduced the peak levels of excretion. However, feed-independent periodicities on hourly feeding regimes included a 24 hrs rhythm in urinary total solids, K, Cl and HCO3 and a 32 (or 64) hrs periodicity in a wide range of components. None of these occurred in all animals. It would appear that the sheep studied were not as closely influenced by normal 24 hrs environmental cycles as are human subjects. Furthermore, the sheep electrolyte rhythms were not correlated with the 24 hrs variation in adrenal steroid production.