H. Locksley Trenholm
Government of Canada
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Featured researches published by H. Locksley Trenholm.
Toxicological Sciences | 1986
Dan B. Prelusky; Douglas M. Veira; H. Locksley Trenholm; Ken E. Hartin
The excretion profiles of deoxynivalenol (DON) and metabolites (DON glucuronide conjugate, 3 alpha, 7 alpha,15-trihydroxytrichothec-9,12-diene-8-one (DOM-1), and DOM-1 glucuronide conjugate) were defined in male sheep following either intravenous (iv) or oral administration of the toxin at levels of 0.5 and 5.0 mg DON/kg body wt, respectively. After iv dosing, urinary DON levels declined in a biphasic fashion with an average elimination half-life (terminal phase) of 1.2 hr, diminishing to baseline concentrations by 8 hr. Maximum urinary excretion rates for the two major metabolites identified (conjugated DON, conjugated DOM-1) occurred 0.5-1.5 hr after dosing, exhibiting elimination half-lives of 2.2 and 3.1 hr, respectively. Total recovery accounted for only about 66.5% of the dose: 63.0% in the urine (24.1% DON, 21.2% conjugated DON, 0.5% DOM-1, 17.2% conjugated DOM-1) and 3.5% in bile (made up almost completely of conjugated DOM-1). The peak biliary excretion rate for conjugated DOM-1 was found to occur within 1 hr postdosing, which rapidly declined to baseline levels by 5 hr. Following oral administration, urinary excretion rates of the major metabolites (DON, conjugated DON, conjugated DOM-1) reached maximum 6-9 hr post-treatment, and declined exponentially with t 1/2 values of 3.2, 4.0, and 5.0 hr, respectively. Urinary and biliary recovery of administered DON averaged approximately 7.1%: 7.0% in urine (2.1% DON, 3.6% conjugated DON, 0.06% DOM-1, 1.2% conjugated DOM-1) and 0.11% in bile (predominantly conjugated DOM-1).(ABSTRACT TRUNCATED AT 250 WORDS)
Journal of Chromatography B: Biomedical Sciences and Applications | 1989
Dan B. Prelusky; Robert M. Warner; H. Locksley Trenholm
A method is described for the analysis of zearalenone and its metabolites, alpha- and beta-zearalenol, in small volumes (0.5-2.0 ml) of biological fluids including milk, blood, plasma, urine and bile, using high-performance liquid chromatography with fluorescence detection. Isolation of the toxins from biological fluids was achieved using a series of pH-controlled solvent extractions. Detection limits for zearalenone and alpha-zearalenol were 1 ng/ml, and for beta-zearalenol ca. 5 ng/ml, both at a signal-to-noise ratio of 3. In bile, however, the detection was ca. five times less sensitive owing to interfering substances. Recoveries at low ng/ml concentrations were highest from urine (87-94%) and plasma (85-93%), slightly lower from whole blood (78-88%) and milk (75-84%), and lowest from bile (66-77%).
Journal of Environmental Science and Health Part B-pesticides Food Contaminants and Agricultural Wastes | 1992
M. Humayoun Akhtar; Claude Danis; H. Locksley Trenholm; Kenneth E. Hartin
Lactating dairy cows were fed deltamethrin (2 or 10 mg kg-1 feed) for 28 consecutive days and deltamethrin residues measured in milk and tissues. Deltamethrin residues were higher relative to dose administered. The order of relative concentrations of deltamethrin in tissues, measured 1, 4, and 9 days after the last dose was: renal fat greater than subcutaneous fat greater than forequarter muscle greater than hindquarter muscle greater than liver greater than kidney. Depletion of deltamethrin residues in milk was very rapid indicating the half-life of the insectide of about 1 day. Trace amounts of deltamethrin metabolites 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (less than 0.0235 ppm) and 3-phenoxybenzoic acid (less than 0.034 ppm) were also detected in milk and tissues of treated cows.
Natural Toxins | 1994
Dan B. Prelusky; H. Locksley Trenholm; Marc E. Savard
Natural Toxins | 1995
Lynne L. Charmley; H. Locksley Trenholm; Dan B. Prelusky; Alex Rosenberg
Natural Toxins | 1994
Daljit K. Vudathala; Dan B. Prelusky; Mejid Ayroud; H. Locksley Trenholm; J. David Miller
Journal of Agricultural and Food Chemistry | 1994
Stephen M. Croteau; Dan B. Prelusky; H. Locksley Trenholm
Natural Toxins | 1993
Dan B. Prelusky; H. Locksley Trenholm
Journal of Agricultural and Food Chemistry | 1992
H. Locksley Trenholm; Lynne L. Charmley; Dan B. Prelusky; Robert M. Warner
Journal of Agricultural and Food Chemistry | 1991
Dan B. Prelusky; H. Locksley Trenholm