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Biomedical subjects

D T Burton

Publications and source records attributed to D T Burton.

At least 19 recordsLinked to original sources
PubMed1998

Phase III interlaboratory study of FETAX, Part 2: interlaboratory validation of an exogenous metabolic activation system for frog embryo teratogenesis assay--Xenopus (FETAX).

Interlaboratory validation of an exogenous metabolic activation system (MAS) developed for the alternative, short-term developmental toxicity bioassay, Frog Embryo Teratogenesis Assay-Xenopus (FETAX) was performed with cyclophosphamide and caffeine. Seven study groups within six separate laboratories participated in the study in which three definitive concentration-response experiments were performed with and without the MAS in a side-by-side format for each chemical. Since both chemicals had been previously tested in FETAX, the test concentrations were provided to each laboratory prior to testing. Interlaboratory coefficient of variation (CV) values for unactivated cyclophosphamide (no MAS) were 15%, 15%, 29%, and 25% for the 96-hr LC50, 96-hr EC50 (malformation), Minimum Concentration to Inhibit Growth (MCIG), and Teratogenic Index (TI) values, respectively. Addition of the MAS increased the CV values of each endpoint at least 3.9-fold. Interlaboratory CV values for unactivated caffeine were 31%, 18%, 31%, and 46% for the 96-hr LC50, 96-hr EC50 (malformation), MCIG, and TI values, respectively. Addition of the MAS decreased the CV values of each respective endpoint by at least 1.6-fold. Results indicated that bioactivated toxicants may be prone to greater variability in response amongst laboratories than compounds, which are detoxified. Even though more variability was noted with activated cyclophosphamide, results were within interlaboratory variation expected for other aquatic-based bioassays. Thus, results from these studies warrant the continued use and further refinement of FETAX for alternative developmental toxicity assessment.

Abnormalities, Drug-Induced↗
PubMed1984

Behavioral modification of estuarine fish exposed to sulfur dioxide.

This study was designed to determine the avoidance responses of juvenile striped bass (Morone saxatilis) and Atlantic menhaden (Brevoortia tyrannus) exposed to sulfur dioxide (sulfite) at acclimation temperatures of 15, 20, 25, and 30 degrees C. Predictive models were developed and compared for each species at each acclimation temperature. Striped bass avoided 2.2, 2.3, 3.0, and 3.5 mg sulfite/l at 15, 20, 25, and 30 degrees C, respectively. Atlantic menhaden avoided 3.2, 3.6, 2.9, and 3.0 mg sulfite/l at acclimation temperatures of 15, 20, 25, and 30 degrees C, respectively. Acclimation temperature was an important factor influencing the avoidance response of each species exposed to sulfur dioxide. Striped bass avoided lower concentrations of sulfite than Atlantic menhaden at 15 and 20 degrees C. Both species avoided approximately the same concentration of sulfite at 25 degrees C. Atlantic menhaden avoided lower concentrations of sulfur dioxide than striped bass at 30 degrees C.

Acclimatization↗
PubMed1984

Bioconcentration and metabolism of picric acid (2,4,6-trinitrophenol) and picramic acid (2-amino-4,6-dinitrophenol) in rainbow trout Salmo gairdneri.

The bioconcentration and metabolism of picric acid and picramic acid were determined for rainbow trout. The bioconcentration factor (BCF) in the epaxial muscle at 42 d for both of these compounds was less than 1; the skin had a BCF value of 1 and 9, respectively. The half-life (t1/2) elimination for the high and low dose of picric acid was 12.0 and 12.5 d, respectively; and for picramic acid was 9.0 and 9.5 d, respectively. In separate experiments, approximately 34% of the injected [14C]picric acid was metabolized to picramic acid, glucuronide conjugates, and an unidentified group of compounds, and 42% of the [14C]picric acid was metabolized to picric acid, glucuronide conjugates, and an unidentified group of compounds. The low bioconcentration in the trout muscle may be due to the trout's ability to excrete the parent compound and metabolites. The higher radioactivity observed on the skin may be due to the water route of exposure and the binding of the parent compounds to protein.

2,4-Dinitrophenol↗
PubMed1982

A comparison of the avoidance responses of individual and schooling juvenile Atlantic menhaden, Brevoortia tyrannus subjected to simultaneous chlorine and delta T conditions.

The objectives of this study were to determine and compare the avoidance responses of individual and groups of Atlantic menhaden, Brevoortia tyrannus, exposed to simultaneous elevated temperature (0, 2, 4, and 6 degrees C) and total residual chlorine (TRC) (0.00, 0.05, 0.10, and 0.15 mg/l) conditions. An unbalanced three-factor factorial design was used to develop predictive avoidance models with this species at a test temperature of 25 degrees C. Fish tested in groups elicited the following avoidance responses: (1) a high avoidance response occurred at 0.10 and 0.15 mg/l TRC regardless of delta T; (2) avoidance increased with increasing delta T values at 0.00 mg/l TRC; and (3) TRC was the most important factor influencing avoidance. Atlantic menhaden tested individually demonstrated the following responses: (1) avoidance increased with increasing delta T at 0.15 mg/l TRC; (2) minimal increase in avoidance at 0.00, 0.05, and 0.10 mg/l TRC as delta T increased; (3) greatest avoidance occurred at 0.10 mg/l TRC and 6 degrees C delta T; and (4) TRC was the most important factor influencing avoidance. A significant difference was found between avoidance models of the group and individual tests: greater avoidance generally occurred at most test conditions during the group tests. The data collected in this study showed the importance of testing methods when evaluating the avoidance responses of a strongly schooling species exposed to simultaneous chlorine and delta T conditions simulating a power-plant effluent.

Animals↗
PubMed1981

Seasonal temperature and power plant chlorination effects on estuarine invertebrates.

The influence of seasonal temperatures (15-22 degrees C) on chlorine (0.00, 0.15 and 0.30 mg/L total residual chlorine), delta T (2, 6 and 10 degrees C), and exposure duration (0.08, 2.0 and 4.0 hr) interaction studies simulating power plant entrainment and effluent discharge conditions was evaluated for opossum shrimp. Neomysis americana and amphipods, Gammarus Seasonal Temperature was an important factor effecting the toxicity of the three treatment variables with both of these organisms. Mortality responses were greater at the higher acclimation temperatures.

Animals↗
PubMed1981

Acclimation temperature: an important factor in power plant chlorination studies with larval white perch, Morone americana.

Larval white perch were subjected to interacting power plant conditions of total residual chlorine (0.00-0.30 mg/l), elevated temperature (2, 6, and 10 degrees C), and exposure time (0.08, 2.0, and 4.0 h) at acclimation temperatures of 15 and 23 degrees C. Mortality observations were conducted up to 96 h after exposure. Acclimation temperature was a significant factor contributing to the effects of simulated power plant conditions during the low and high thermal conditions. Larvae tested at 23 degrees C generally showed greater mortality at all treatment levels than those tested at 15 degrees C. Mortality of test organisms during a 4-h exposure at the higher acclimation temperature was greater than 85% at elevated temperatures greater than 6 degrees C regardless of other treatment factors. Mortalities as low as 30% were observed at the lower acclimation temperature.

Acclimatization↗
PubMed1981

Toxicity of bromate to striped bass ichthyoplankton (Morone saxatilis) and juvenile spot (Leiostomus xanthurus).

Striped bass (Morone saxatillis) eggs (12 h after fertilization) and larvae (4 d after hatching) and juvenile spot (Leiostomus xanthurus) were exposed to a series of bromate concentrations for 4, 10, and 10 d, respectively, using static replacement bioassay techniques. Three-dimensional mortality response surfaces were constructed by computerized probit regression techniques. Newly hatched striped bass prolarvae were most sensitive to bromate and had a 96-h LC50 of 30.8 mg/l (as BrO3-). Four-day-old striped bass larvae were less sensitive, with 2- to 10-d LC50s ranging from 605.0 to 92.6 mg/l BrO3-, respectively. Juvenile spot were least sensitive, with 1- to 10-d LC50s ranging from 698.0 to 278.6 mg/l BrO3-, respectively.

Animals↗