2-Deoxy-d-Glucose (2-DG)-Induced Cardiac Toxicity in Rat: NT-proBNP and BNP as Potential Early Cardiac Safety Biomarkers.

2-Deoxy-d-glucose (2-DG) is being developed as a potential anticonvulsant and disease-modifying agent for patients with epilepsy; however, during preclinical development, cardiac toxicity has been encountered in rats. This study was performed to determine whether cardiac troponin (cTnI and cTnT), atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), N-terminal pro-brain natriuretic peptide (NT-proBNP), and/or creatine kinase (CK) could be useful as indicators of 2-DG cardiac toxicity. In addition, this study also investigated the association of cardiac histopathological changes with these biomarkers. F344 rats (4/sex/group/sacrifice point) were gavaged with either vehicle or 2-DG (50, 125, or 375 mg/kg twice daily; total daily dose of 100, 250, or 750 mg/kg/d) for 7, 14, 21, or 45 days followed by a 15-day recovery. Dose-dependent increases in NT-proBNP and BNP plasma concentrations were observed. Following recovery period, the NT-proBNP and BNP concentrations returned to baseline levels. There were no remarkable increases in CK, ANP, cTnI, or cTnT concentrations. There were no gross cardiac lesions observed at the necropsy. Microscopic findings of vacuolar degeneration and hypertrophy of the endothelial cells of the endocardium were present in the heart at doses of 250 and 750 mg/kg/d. Microscopic findings, in general, were associated with increases in NT-proBNP levels. Cardiac toxicity appeared to be reversible. In conclusion, NT-proBNP and BNP are potential early biomarkers for 2-DG-induced cardiac toxicity that can be useful to monitor 2-DG therapy in clinical trials.

Impacts of aging on in vivo and in vitro measurements of soil-bound polycyclic aromatic hydrocarbon availability.

Ingestion of contaminated soil is an exposure pathway at approximately one-half of the Superfund sites in the United States. This study was designed to evaluate the impacts of aging in soil on the availability of polycyclic aromatic hydrocarbons (PAHs). Two coal tar (CT)-amended soils were prepared. One was aged for 270 days and the other was not aged. Both of these treatments were incorporated into pellets and fed to male Fischer 344 rats. Excretion of 1-hydroxypyrene (1-OHP) in urine and PAH concentrations in the liver were monitored as end points. Additionally, soil:water partitioning and desorption were measured as comparisons to the in vivo results. After 5 days of ingesting their respective treatments, rats in the aged soil group excreted 4.41 +/- 1.67 ppm 1-OHP/mg of pyrene ingested while rats in the unaged soil group excreted 5.27 +/- 1.37 ppm/mg of pyrene ingested. Animals fed aged CT soil had 0.051 +/- 0.011 ppm carcinogenic PAHs in livers/mg ingested while rats fed unaged CT soil had 0.063 +/- 0.037 ppm carcinogenic PAHs in livers/mg ingested. Partitioning and desorption results revealed a similar results. These results indicate that, at high application rates, soil contact time may not play as significant a role in determining availability as simple dispersion and sorption on soil.

Pentachlorophenol potentiates benzo[a]pyrene DNA adduct formation in adult but not infant B6C3F1 male mice.

The objective of this study is to determine whether pentachlorophenol (PCP) alters benzo[a]pyrene (B[a]P)-induced DNA adduct formation in infant and adult B6C3F1 male mice. Mice were exposed intraperitoneally to 55 microg B[a]P/g body weight (BW) alone and in combination with several doses of PCP in DMSO. The 32P-postlabeling assay was used to analyze for (+/-) anti-7,8-diol-9,10-epoxide-B[a]P-N(2)deoxyguanosine (BPDE-N(2)G) adducts formed in liver and lung DNA. Hepatic DNA also was analyzed for 8-hydroxy-2'-deoxyguanosine (8-OHdG) base damage in mice exposed to PCP. 8-OHdG was not detected at any dose of PCP in infant or adult mice. PCP exhibited an antagonistic effect on BPDE-N(2)G accumulation in infant mice exposed to B[a]P in combination with 50 microg PCP/g BW at both 12 and 24 hr. Comparatively, BPDE-N(2)G adducts were increased in adult mice exposed to binary mixtures at 24 hr in both hepatic and lung DNA (P < 0.05). Multiple comparison analysis between infant and adult mice revealed that adduct levels in infants exposed to B[a]P alone or in combination with PCP were not different from those observed in adult mice exposed to B[a]P. However, a significant increase in adducts was observed in adult mice exposed to a combination of B[a]P and PCP compared to that in all other treatment groups (P < 0.05). These results suggest that PCP alters the metabolism of B[a]P in both infant and adult mice through different mechanisms, and that infants are not susceptible to the potentiating effects of PCP observed in adult mice.

Bioavailability of the genotoxic components in coal tar contaminated soils in Fischer 344 rats.

The effect of chemical aging on the bioavailability and subsequent genotoxicity of coal tar (CT)-contaminated soils was evaluated in a 17-day feeding study using Fischer 344 male rats. Rats consumed a control diet or diets amended with soil, 0.35% CT, or soil freshly prepared or aged for 9 months with 0.35% CT. Mild treatment-related microscopic lesions in liver tissue and elevated enzyme levels in serum were detected in all CT treatment groups. The (32)P-postlabeling assay was employed to determine DNA adduct formation in treated animals. All CT treatment groups induced DNA adducts in both the liver and lung. Adduct levels were 3-fold higher in lung DNA compared to hepatic DNA. After correcting adduct levels for total ingested polycyclic aromatic hydrocarbons (PAHs), a significant decrease (p < 0.05) in adduct levels was observed in both CT/soil treatment groups compared to CT control in liver and lung DNA. Adduct profiles of (32)P-postlabeled hepatic and lung DNA displayed several nonpolar DNA adducts that comigrated with PAH-adducted calf thymus DNA standards as determined through both thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC). These results suggest that soil, but not aging of contaminants in soil, decreases the bioavailability of genotoxic components in CT, as evidenced by DNA adduct analysis.