Separation and detection of phencyclidine in urine by gas chromatography

A rapid, sensitive and selective analytical procedure for phencyclidine and one of its metabolites in urine has bee developed. Three techniques have been studied for extraction of the drug from the biological matrix: (a) reversed-phase XAD resin, (b) charcoal absorption, and (c) solvent extraction using chloroform. Temperature-programmed gas chromatography was used to quantitate the illicit drug. Solvent extraction appears to offer the most efficient separation of the drug and its metabolite, as the recovery was 94% and the technique required only 7-8 min per sample. Reversedphase column extraction is also quite useful; although more time-consuming for an indivisual sample, it would be useful for screening purposes.     

Response times to stimuli of increasing complexity as a function of ageing

Twelve elderly and 12 young subjects were tested on a series of experiments with increasing complexity of perceptual-response mapping. As task complexity increased the differential slowing in performance between young and old increased and an ageXtask complexity interaction was observed. However, with practice this phenomenon disappeared leaving an apparent age lag constant. This slowing was due to increased central processing time rather than peripheral factors. No major differences in strategies were observed between the groups, though the old subjects tended to be less able to extract critical (useful) features from the display. Stimulus repetitions of a new kind were found where all characteristics of the stimulus (relevant and irrelevant) were important. Repetitions of coding rules rather than of particular signals or responses also facilitated RT. It was also found that later in practice old subjects were making fewer errors than the young, reversing earlier observations.     

A post mortem study of equine digital flexor tendons

The results of a survey are presented in which 589 limbs from 206 horses were dissected. In174 of the limbs lesions were found in either the superficial (131) or deep (43) digital flexor tendons. Changes occurring with age were also recorded. The sites of the abnormalities and their macroscopical appearance are described and the value of the results is considered in relation to the diagnosis and the treatment of clinical lesions.