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Biomedical subjects

A R Hardy

Publications and source records attributed to A R Hardy.

6 recordsLinked to original sources
PubMed1991

Species differences in avian serum B esterases revealed by chromatofocusing and possible relationships of esterase activity to pesticide toxicity.

Serum cholinesterase (BChE) and carboxylesterase (CbE) activities were investigated in ten species of birds. Multiple forms of serum BChE and CbE were also separated by chromatofocusing. Higher CbE activity and a wider range of CbE and BChE forms were present in the sera of omnivorous/herbivorous birds than carnivores. Omnivores/herbivores studied were the starling, house sparrow, tree sparrow, pigeon, partridge and magpie. Serum CbE activities of these species ranged from 0.46 to 2.93 mumol/min/mL with 2-6 forms separated by chromatofocusing. 0-6 forms of BChE were separated by the same method. The serum CbE activities of the little owl, tawny owl, barn owl and razorbill ranged from 0.19 to 0.58 mumoles/min/mL with 0-2 forms separated by chromatofocusing. No ChE forms were present within the pH gradient. These results may be significant in contributing to the understanding of the selective toxicity of organophosphorus and carbamate pesticides.

Animals↗
PubMed1987

Distinction between 'A'-esterases and arylesterases. Implications for esterase classification.

'A'-esterase activities (substrates paraoxon and pirimiphos-methyloxon) and arylesterase activities (substrate phenyl acetate) were assayed in the sera of 14 species of birds representing seven different orders and 11 species of mammal representing five different orders. Ten species of birds had no detectable 'A'-esterase, and the remaining four species only low activity, yet all birds showed considerable arylesterase activity (16.8-99.3 mumol/min per ml of serum). Ten species of mammal showed both 'A'- and 'aryl'-esterase activities. In humans, gel filtration of serum completely separated peaks representing paraoxonase and arylesterase activities. Thus, in both birds and humans, serum enzymes exist that express arylesterase activity but not 'A'-esterase activity. These findings suggest that a distinction should be made between these two types of esterase in future classifications.

Animals↗