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Biomedical subjects

E G Butler

Publications and source records attributed to E G Butler.

25 records · Page 2Linked to original sources
PubMed1988

Genetic differences in enzymes associated with peroxisome proliferation and hydrogen peroxide metabolism in inbred mouse strains.

Enzyme activities relating to H2O2 production (peroxisomal acyl-CoA oxidase) and degradation (catalase and glutathione peroxidase) were measured in the livers of male mice of the inbred strains C57BL/6J (C57) and C3H/HeJ (C3H) and their F1 hybrid, B6C3F1. Groups of the three genotypes were maintained on either a basal diet or one containing 0.1% of the peroxisome-proliferating agent, nafenopin, for six weeks. In both control and nafenopin-exposed groups, the C57 strain displayed higher acyl-CoA oxidase activity levels than the C3H mice, whereas the activity levels of catalase and glutathione peroxidase were not different for the two inbred strains. The groups of similarly fed B6C3F1 hybrids had intermediate values for acyl-CoA oxidase. Several other parameters relating to peroxisome proliferation did not differ among the three genotypes. Acyl-CoA oxidase levels in cultured hepatocytes from C57 mice were greater than those in hepatocytes obtained from the C3H strain during two days in culture and this difference was maintained for 4 days by nafenopin exposure. Acyl-CoA oxidase is central to the hypothetical H2O2 mechanism of peroxisome proliferator-induced hepatocarcinogenesis and, therefore, the genetic difference documented here may lead to a useful approach in testing this hypothesis.

Acyl-CoA Oxidase↗
PubMed1988

Spinal subdural abscess.

Spinal subdural abscess is a rare condition that is clinically similar to spinal epidural abscess. A case of spinal subdural abscess is reported, and the characteristic clinical findings and specific myelographic features in this patient are noted. Urgent myelography and surgery are necessary to prevent the rapid deterioration that often occurs in this condition.

Abscess↗
PubMed1988

Effect of peroxisome proliferating hypolipidemic agents on serum activity levels of arylesterase and cholinesterase in rats and mice.

The effect of dietary exposures to peroxisome-proliferating, hypolipidemic agents on serum esterases was determined in rats and mice. Four genotypes of mice were fed nafenopin (1000 ppm) for six weeks and clofibrate (5000 ppm) was fed to young and aged rats for three weeks. The exposures significantly increased serum cholinesterase activity levels and decreased serum arylesterase activity levels in all groups of both species.

Animals↗
PubMedDate not supplied

Paraoxon hydrolysis vs. covalent binding in the elimination of paraoxon in the rabbit.

Hydrolysis and covalent binding to nonessential esterases are two biochemical processes which can prevent paraoxon from reacting with the essential enzyme, acetylcholinesterase. Both processes have been proposed as the primary route of paraoxon detoxification in vivo. These experiments were designed to assess the relative contribution of each pathway to the disappearance of paraoxon in the rabbit. In vitro, paraoxon disappeared from whole rabbit blood with a t 1/2 of 17.7 sec. Hydrolysis by paraoxonase (EC 3.1.1.2) accounted entirely for this disappearance and covalent binding contributed essentially nothing. In vivo, following an iv injection of 0.15 mg/kg paraoxon, serum paraoxonase hydrolyzed as much as 41% of the injected dose within the first 30 sec. Pretreatment of rabbits with an ip injection of tri-o-tolyl phosphate eliminated more than 95% of the paraoxon binding sites. However, pretreatment with tri-o-tolyl phosphate had no significant effect on the t 1/2 or volume of distribution of paraoxon, indicating that covalent binding sites did not contribute significantly to the clearance of paraoxon from whole rabbits under these conditions. Hydrolysis of paraoxon by tissue paraoxonases, in addition to that catalyzed by paraoxonase in the blood, could account for its rapid metabolism. These findings demonstrate that paraoxonase has a major role in the disappearance of paraoxon in the rabbit. This suggests that susceptibility of people to chronic paraoxon poisoning may vary, according to their inherited level and type of serum paraoxonase.

Animals↗