Biomedical subjects

G D Haffner

Publications and source records attributed to G D Haffner.

7 recordsLinked to original sources

PubMed2004

Evaluation of chloroform/methanol and dichloromethane/hexane extractable lipids as surrogate measures of sample partition capacity for organochlorines in fish tissues.

Organic contaminant concentration data are often lipid normalized to provide an indication of the chemical fugacity in the sample or to compare the relative equilibrium status of samples from the same environment. This study compared lipid normalized PCB and organochlorine concentration data for tissues of individual fish when lipids were measured using chloroform/methanol (CM) or dichloromethane/hexane (DH) extractions. The CM extraction produced higher lipid yields for dorsal muscle (8-fold difference) and carcass (1.7-fold difference) compared to DH extractions, while both methods yielded comparable lipid contents for liver and adipose tissue. Lipid normalized tissue/carcass PCB and organochlorine concentration ratios were variable across tissue types when lipid contents from the CM technique were used, whereas, tissue/carcass concentration ratios approached the expected value of unity for each tissue when DH-derived lipids were used. These data suggest that the tissue lipid content as derived using the DH extraction provided a better surrogate measure of sample partition capacity than tissue lipids determined using the CM technique.

Adipose Tissue↗

PubMed2004

Genetic and morphological data supporting the hypothesis of adaptive radiation in the endemic fish of Lake Matano.

Adaptive radiation resulting from differential selection acting on functional features is believed to be an important source of biodiversity. In this study, morphometric measures and mitochondrial DNA are used to test for adaptive radiation within four fish genera (Glossogobius, Oryzias, Dermogenys and Telmatherina) endemic to an ancient island lake (Lake Matano, Sulawesi, Indonesia), using the framework proposed by Schluter (The Ecology of Adaptive Radiation, Oxford University Press, 2000). We demonstrate common ancestry and rapid divergence in one genus (Telmatherina) based on 560 bp of 16S sequence data. We found higher levels of variation in feeding-related traits (N = 8) for Telmatherina relative to the other genera, while no differences were found for sexual display traits (N = 8) or neutral morphological traits (N = 8). Telmatherina also had the highest number of distinct colouration patterns among the four genera. These data, combined with the very low productivity of the lake, are indicative of selection driving adaptive radiation. The morphometric divergence in the Telmatherina likely results from selection acting on feeding traits in this low productivity lake, leading to trophic specialization among closely related morphotypes. These results provide indirect but compelling data supporting the adaptive radiation of Telmatherina in this system.

Adaptation, Biological↗

PubMed2002

Quantitative biomonitoring of PAHs using the Barnes mussel (Elliptio complanata).

The elimination rate constants (k(2)) of nine polycyclic aromatic hydrocarbons (PAHs) were examined for the freshwater mussel Elliptio complanata. The concentrations of fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[ a]anthracene, chrysene, benzo[ b]fluoranthene, and indeno[1,2,3-c,d]pyrene revealed a significant inverse relationship with time and their k(2) values ranged from 0.10 to 0.22 day(-1). The k(2) values of these significantly cleared PAHs were similar to k(2) values observed for nonmetabolized organochlorines in mussels previously reported in the literature. The inverse relationship between k(2) and K(ow) provides evidence that the nine PAHs were being passively eliminated from the mussels and that they can be used to calibrate the mussel as a quantitative biomonitor. A general expression relating elimination rate constants and chemical K(ow) is derived for hydrophobic contaminants in E. complanata. The k(2) versus log K(ow) regression equation for mussels developed herein was similar to other studies documenting the elimination of PCBs and PAHs in a number of bivalve species.

Animals↗

PubMed1997

Roles of DT diaphorase in the genotoxicity of nitroaromatic compounds in human and fish cell lines.

The genotoxicity of nitroaromatic compounds was examined in two cultured cell lines, namely, a human hepatoma cell line, HepG2, and a brown bullhead fibroblast cell line, BB. Furthermore, the role of the quinone-reducing enzyme DT diaphorase [NAD(P)H:(quinone acceptor) oxidoreductase] was examined with respect to its influence on the genotoxic effects of model nitroaromatic pollutants. The nitroreductive characteristics of these two cell lines were examined using an acetylated cytochrome c reduction assay for enzymatic nitroreductase activity. Subsequently, the influence of DT diaphorase on the genotoxicity of two model nitroaromatics, 4-nitroquinoline 1-oxide (4NQ) and nitrofurantoin (NF), revealed that DT diaphorase was the predominant 4NQ reductase in cytosols of both cell lines, but played a lesser role in NF reduction in both species. Despite these interspecific similarities, results revealed marked qualitative differences between the two species in terms of the influence of DT diaphorase on quinone-mediated genotoxicity. When pretreated with the DT diaphorase inhibitor dicoumarol, HepG2 cells exhibited an exacerbation of genotoxicity in the presence of 4NQ, indicating a protective influence of the enzyme. In contrast, 4NQ genotoxicity in BB cells was reduced in the presence of dicoumarol, indicating a deleterious effect of DT diaphorase activity. Conversely, dicoumarol pretreatment was moderately protective against NF-mediated genotoxicity in HepG2 cells but exacerbated NF toxicity in BB cells. This study illustrates the manner in which functionally analogous enzymes may have markedly distinct influences on xenobiotic toxicity in different cellular systems.

4-Nitroquinoline-1-oxide↗

PubMed1996

Influence of DT diaphorase on quinone-mediated genotoxicity in human and fish cell lines.

The influence of the quinone-reducing enzyme, DT diaphorase [NAD(P)H: (quinone acceptor) oxidoreductase], on the genotoxicity of quinones was examined in two cell lines, namely a human hepatoma cell line, HepG2 and a brown bullhead fibroblast cell line, BB. The quinone-reductive characteristics of these two cell lines were examined using an acetylated cytochrome c reduction assay for enzymatic reductase activity. Subsequently, the influence of DT diaphorase on the genotoxicity of two model quinones, menadione (MND) and 9,10-phenanthrenequinone (PQ) was examined in an alkaline unwinding assay for DNA single-strand breaks. Results revealed that DT diaphorase was the predominant quinone reductase in cytosols of both cell lines, and that levels of specific DT diaphorase activity were generally equivalent in the two species. Despite these similarities, results revealed marked qualitative differences between the two species in terms of the influence of DT diaphorase on quinone-mediated genotoxicity. When pretreated with the DT diaphorase inhibitor, dicoumarol, HepG2 cells exhibited a marked exacerbation of genotoxicity in the presence of either MND or PQ, indicating protective influence of the enzyme. In contrast, quinone genotoxicity in BB cells was not affected by DT diaphorase inhibition, indicating the lack of a protective effect of DT diaphorase. This study illustrates the manner in which functionally analogous enzymes may have markedly distinct influences on xenobiotic toxicity in different cellular systems.

Animals↗

PubMed1995

Human bioassays to assess environmental genotoxicity: development of a DNA break bioassay in HepG2 cells.

OBJECTIVES: Increasing interest in environmental health issues has created a demand for improved methods for the assessment of pollutant effects on humans. Our laboratory has developed an in vitro assay for the quantification of genotoxicity, monitored as DNA single strand breaks (SSB), in the HepG2 human hepatoma cell line. DESIGN AND METHODS: This assay procedure, which is based upon alkaline unwinding and hydroxylapatite DNA chromatography, is both rapid and simple to perform. RESULTS: HepG2 cells responded to the standard mutagen, 4-nitroquinoline N-oxide, demonstrating SSB formation at concentrations above 0.1 mumol/L. Phenanthrene-9,10-quinone, a component of diesel exhaust, mediated SSB formation at concentrations above 250 nmol/L. Finally, an extract of contaminated sediment from the Great Lakes Basin mediated SSB formation in a dose-dependent manner. CONCLUSIONS: These results illustrate the utility of this human genotoxicity assay for future use in screening of environmental pollutants.

4-Nitroquinoline-1-oxide↗

PubMedDate not supplied

In vitro toxicological methods for environmental health testing.

Increasing public interest in environmental health issues has created a demand for alternatives to using animals for assessing the toxic effects of chemical mixtures on humans. This review focuses on applications of in vitro toxicological screening methods developed for human health biomonitoring using cultured clonal cell lines, which have the which have the following advantages: genetic variation between samples and experiments is minimal; the cultivation of cell lines is rapid and consistent conditions for culture are easily maintained; most of the phenotypic variation that is encountered with use of cell donors is eliminated; and radiolabeled precursors can be used for labeling and quantifying protein and DNA. We describe the current state of development of in vitro toxicity testing methods, present detailed procedures for the test methods optimized in our laboratory, and compare these techniques with other approaches. Toxicity testing using cell lines provides a mechanism to quantify the risks associated with environmental exposure to chemical mixtures.

Animal Testing Alternatives↗