The Toxicologist - Society of Toxicology

84 TCDD-MEDIATED GENE EXPRESSION PROFILING OF
NUCLEAR ENCODED MITOCHONDRIAL GENES
INVOLVED IN OXIDATIVE PHOSPHORYLATION.
A. Forgacs 1, 2 , L. D. Burgoon 1, 2 , S. G. Lynn 1, 2 , J. J. LaPres 1, 2 and T. R.
Zacharewski 1, 2 . 1 Biochemistry & Molecular Biology, Michigan State University, East
Lansing, MI and 2 Center for Integrative Toxicology, Michigan State University, East
Lansing, MI.
Generation of mitochondrial reactive oxygen species (ROS) can be perturbed following
exposure to environmental chemicals such as 2,3,7,8-tetrachlorodibenzo-pdioxin
(TCDD). Reports indicate that the aryl hydrocarbon receptor (AhR) mediates
TCDD induced sustained hepatic oxidative stress by decreasing hepatic ATP
levels, increasing mitochondrial glutathione levels and through hyperpolarization
of the mitochondrial inner membrane. To further elucidate the effects of TCDD on
the mitochondria, high-throughput quantitative real-time PCR (htp-QRTPCR)
was used to evaluate the expression of 103 genes encoding proteins involved in electron
transport, oxidative phosphorylation, uncoupling and associated chaperones.
Htp-QRTPCR analysis of time course (30 μg/kg TCDD at 2, 4, 8, 12, 18, 24, 72
and 168 hrs) liver samples obtained from orally gavaged immature, ovariectomized
C57BL/6 mice identified 60 temporally dysregulated genes (|fold change|>1.5 and
P-value 1 was obtained, were considered to be teratogenic.
The results obtained with this zebrafish assay for compounds listed, allow to classify
compounds as either developmental toxicants or negative compounds, and based
on TI-values compounds can be ranked according to their teratogenic potency.
Through comparison of results with available mammalian and/or human data, an
overall concordance of 81% was obtained, demonstrating the validity of this screening
test for teratogenicity. Hence, we propose that this assay can be integrated into
screening programs for hazard identification of compounds.
88 THE EFFECT OF MEDICAL DEVICE COMPOSITION
ON RESULTS OF CYTOTOXICITY EVALUATED BY THE
DIRECT CONTACT AND ELUTION COLONY ASSAYS.
S. Kostrubsky, K. L. Bullard and J. Wegrzyn. Vistakon, Division of J&J Vision
Care, Jacksonville, FL.
The colony assay using V79 cells, is a sensitive in-vitro test evaluating the potential
for medical devices to cause cytotoxicity either by direct contact with plated cells or
via cells exposed to an extract of a device prepared in culture media. We evaluated
the effect of contact lenses made of silicone and non-silicone materials including
etafilcon A, balafilcon A, lotrafilcon B, comfilcon A, galyficon A and senofilcon A
on cytotoxicity, assessed by number of viable colonies. When cells were seeded on
the top of contact lenses, the average colony formation was 63%, for all lenses with
exception of lotrafilcon B and comfilcon A which showed a 91% and 14%, respectively.
In contrast, when lenses were placed on the top of preplated cells, the colony
formation was 90% for all lenses and 14% for comfilcon A. Only the surface of lotrafilcon
B supported cell attachment whereas positioning of other lenses in a 24-
18 SOT 2010 ANNUAL MEETING