Donald Tillitt, PhD (Former Employee)

Vertebrate embryos are particularly sensitive to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Identification of tissues that are susceptible to the adverse effects of TCDD is requisite for understanding the embryo toxic effects of TCDD. The objective of the present study was to quantitate the temporal appearance of and dose dependence of apoptosis in TCDD-exposed medaka embryos (Oryzias...

An expert meeting was organized by the World Health Organization (WHO) and held in Stockholm on 15-18 June 1997. The objective of this meeting was to derive consensus toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxinlike polychlorinated biphenyls (PCBs) for both human, fish, and wildlife risk assessment. Based on existing...

The triolein-filled semipermeable membrane device (SPMD) is a simple and effective method of assessing the presence of waterborne hydrophobic chemicals. Uptake rate constants for individual chemicals are needed to accurately relate the amounts of chemicals accumulated by the SPMD to dissolved water concentrations. Brown trout and SPMDs were exposed to PCB- contaminated groundwater in a...

The mammalian aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that controls the expression of cytochrome P450 1A (CYP1A) genes in response to halogenated aromatic hydrocarbons such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The natural ligand and normal physiologic function of this protein are as yet unknown. One approach to understanding AHR function and

A porous graphitic carbon column (Hypercarb) was used for the fractionation of polychlorinated biphenyls (PCBs) into classes of 2-4 ortho chlorines, 1 ortho chlorine and 0 ortho chlorine congeners. A method was developed that combined the fractionation of PCBs, polychlorinated dibenzo-p-dioxins and dibenzofurans in a variety of biotic environmental samples. Many of these samples have...

Double-crested cormorant (Phalacrocorax auritus) eggs were injected with either 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126), 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), or an extract derived from field-collected double-crested cormorant eggs. These compounds were injected into the yolks of cormorant eggs from an isolated colony on Lake Winnipegosis, Manitoba, Canada. Upon hatching, chicks...

Semipermeable membrane devices (SPMDs) are sampling and concentrating devices comprised of a thin polyethylene membrane containing a small quantity of triolein. They have previously been used to sample air, water and sediments and have concentrated fish tainting compounds from pulp mill effluents. The ability to induce mixed function oxygenases (MFOs) is a property of a variety of...

Concentrations of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated naphthalenes (PCNs), polychlorinated dibenzothiophenes (PCDTs), and 2,3,7,8-tetrachlo-rodibenzo-p-dioxin (2,3,7,8-TCDD) equivalents were measured in composite samples of forage fishes and several sizes of walleyes (Stizostedion vitreum) and...

White Leghorn chicken (Gallus domesticus) eggs were injected prior to incubation with one of four concentrations (0.001, 0.01, 0.1, and 1.0 egg-equivalent) of an extract derived from 1,000 double-crested cormorant (Phalacrocorax auritus) eggs collected at Spider Island adjacent to Green Bay in Lake Michigan. One egg-equivalent corresponded to the concentration of contaminants present in...

A rat hepatoma cell line, H4IIE serves as a bioassay tool to assess the potential toxicity of dioxin-like chemicals, including polychlorinated biphenyls (PCB) in environmental samples. PCB exposure to these cells induces cytochrome (CYP) P4501A1 activity in a dose-dependent fashion, thus allowing assessment of mixtures. The objective of this study was to determine the effect of different...

The Ah (aryl-hydrocarbon) hydroxylase-receptor active polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) were fractionated by an automated high-performance liquid chromatography (HPLC) system using the Hypercarb™ porous graphitic carbon (PGC) column. This commercially available column was used to fractionate the di-, mono...

The rat hepatoma cell line, H4IIE, serves as a useful tool to assess potential biological effects such as induction of cytochrome P4501A1 expression. The objectives of this study were twofold: to investigate the kinetic time course and dosimetry of PCB77 in rat hepatoma cells dosed with PCB77 and in liver of rats given ip doses of PCB77, and to comparein vitroandin vivoP4501A1 enzyme...