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P D Alexander

Publications and source records attributed to P D Alexander.

6 recordsLinked to original sources
PubMed2006

Genotypic variations in the accumulation of Cd, Cu, Pb and Zn exhibited by six commonly grown vegetables.

Metal contaminants in garden and allotment soils could possibly affect human health through a variety of pathways. This study focused on the potential pathway of consumption of vegetables grown on contaminated soil. Five cultivars each of six common vegetables were grown in a control and in a soil spiked with Cd, Cu, Pb and Zn. Highly significant differences in metal content were evident between cultivars of a number of vegetables for several of the contaminants. Carrot and pea cultivars exhibited significant differences in accumulated concentrations of Cd and Cu with carrot cultivars also exhibiting significant differences in Zn. Distinctive differences were also identified when comparing one vegetable to another, legumes (Leguminosae) tending to be low accumulators, root vegetables (Umbelliferae and Liliaceae) tending to be moderate accumulators and leafy vegetables (Compositae and Chenopodiaceae) being high accumulators.

Apiaceae↗
PubMed1981

An evaluation of the tissue pH electrode for fetal monitoring using the fetal sheep as an experimental model.

The performance of the Roche tissue pH electrode has been assessed by comparison of values recorded by the the electrode with the pH of arterial blood, in fetal sheep. Observations were made under controlled conditions when the fetal pH was steady, during hypoxia, and after hypoxia. The results showed a highly significant correlation of the values recorded by the electrodes with the pH of arterial blood (r = 0.89, p less than 0.001 during control; and r = 0.86, p less than 0.001 during hypoxia and recovery). However, in about 10% of cases the insertion proved to be unsatisfactory, and in one half of the successful insertions there was a rapid initial drift which lasted up to 45 min. After stabilization, tissue pH values were symmetrically distributed about the atrial pH, with a SD of 0.07 unit. Multiple electrodes in the same fetus gave the same scatter. Movements of the electrode caused significant artefacts. During hypoxia (produced by compression of the cord or administration of gas mixtures low in O2), the electrodes lagged behind the changes in arterial pH by up to 10 min. The conclusion is that the inherent variability of the tissue pH electrode makes it unsuitable as an absolute indicator of fetal well-being, and that it cannot be used alone as an indication for operative intervention. Nevertheless, because of the limitations of conventional techniques, it should be valuable as an adjunct and, in particular, it should help in the interpretation of equivocal fetal heart rate tracings, thereby reducing the risk of fetal death.

Animals↗