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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 937 records · Page 52
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DOE OSTI2010

Inflammatory effects of inhaled sulfur mustard in rat lung

Inhalation of sulfur mustard (SM), a bifunctional alkylating agent that causes severe lung damage, is a significant threat to both military and civilian populations. The mechanisms mediating its cytotoxic effects are unknown and were investigated in the present studies. Male rats Crl:CD(SD) were anesthetized, and then intratracheally intubated and exposed to 0.7-1.4 mg/kg SM by vapor inhalation. Animals were euthanized 6, 24, 48 h or 7 days post-exposure and bronchoalveolar lavage fluid (BAL) and lung tissue collected. Exposure of rats to SM resulted in rapid pulmonary toxicity, including focal ulceration and detachment of the trachea and bronchial epithelia from underlying mucosa, thickening of alveolar septal walls and increased numbers of inflammatory cells in the tissue. There was also evidence of autophagy and apoptosis in the tissue. This was correlated with increased BAL protein content, a marker of injury to the alveolar epithelial lining. SM exposure also resulted in increased expression of markers of inflammation including cyclooxygenase-2 (COX-2), tumor necrosis factor-{alpha} (TNF{alpha}), inducible nitric oxide synthase (iNOS), and matrix metalloproteinase-9 (MMP-9), each of which has been implicated in pulmonary toxicity. Whereas COX-2, TNF{alpha} and iNOS were mainly localized in alveolar regions, MMP-9 was prominent in bronchial epithelium. In contrast, expression of the anti-oxidant hemeoxygenase, and the anti-inflammatory collectin, surfactant protein-D, decreased in the lung after SM exposure. These data demonstrate that SM-induced oxidative stress and injury are associated with the generation of cytotoxic inflammatory proteins which may contribute to the pathogenic response to this vesicant.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Dose-related gene expression changes in forebrain following acute, low-level chlorpyrifos exposure in neonatal rats

Chlorpyrifos (CPF) is a widely used organophosphorus insecticide (OP) and putative developmental neurotoxicant in humans. The acute toxicity of CPF is elicited by acetylcholinesterase (AChE) inhibition. We characterized dose-related (0.1, 0.5, 1 and 2 mg/kg) gene expression profiles and changes in cell signaling pathways 24 h following acute CPF exposure in 7-day-old rats. Microarray experiments indicated that approximately 9% of the 44,000 genes were differentially expressed following either one of the four CPF dosages studied (546, 505, 522, and 3,066 genes with 0.1, 0.5, 1.0 and 2.0 mg/kg CPF). Genes were grouped according to dose-related expression patterns using K-means clustering while gene networks and canonical pathways were evaluated using Ingenuity Pathway Analysis (registered) . Twenty clusters were identified and differential expression of selected genes was verified by RT-PCR. The four largest clusters (each containing from 276 to 905 genes) constituted over 50% of all differentially expressed genes and exhibited up-regulation following exposure to the highest dosage (2 mg/kg CPF). The total number of gene networks affected by CPF also rose sharply with the highest dosage of CPF (18, 16, 18 and 50 with 0.1, 0.5, 1 and 2 mg/kg CPF). Forebrain cholinesterase (ChE) activity was significantly reduced (26%) only in the highest dosage group. Based on magnitude of dose-related changes in differentially expressed genes, relative numbers of gene clusters and signaling networks affected, and forebrain ChE inhibition only at 2 mg/kg CPF, we focused subsequent analyses on this treatment group. Six canonical pathways were identified that were significantly affected by 2 mg/kg CPF (MAPK, oxidative stress, NF{Kappa}B, mitochondrial dysfunction, arylhydrocarbon receptor and adrenergic receptor signaling). Evaluation of different cellular functions of the differentially expressed genes suggested changes related to olfactory receptors, cell adhesion/migration, synapse/synaptic transmission and transcription/translation. Nine genes were differentially affected in all four CPF dosing groups. We conclude that the most robust, consistent changes in differential gene expression in neonatal forebrain across a range of acute CPF dosages occurred at an exposure level associated with the classical marker of OP toxicity, AChE inhibition. Disruption of multiple cellular pathways, in particular cell adhesion, may contribute to the developmental neurotoxicity potential of this pesticide.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Epigenetic modifications in valproic acid-induced teratogenesis

Exposure to the anticonvulsant drug valproic acid (VPA) in utero is associated with a 1-2% increase in neural tube defects (NTDs), however the molecular mechanisms by which VPA induces teratogenesis are unknown. Previous studies demonstrated that VPA, a direct inhibitor of histone deacetylase, can induce histone hyperacetylation and other epigenetic changes such as histone methylation and DNA demethylation. The objective of this study was to determine if maternal exposure to VPA in mice has the ability to cause these epigenetic alterations in the embryo and thus contribute to its mechanism of teratogenesis. Pregnant CD-1 mice (GD 9.0) were administered a teratogenic dose of VPA (400 mg/kg, s.c.) and embryos extracted 1, 3, 6, and 24 h after injection. To assess embryonic histone acetylation and histone methylation, Western blotting was performed on whole embryo homogenates, as well as immunohistochemical staining on embryonic sections. To measure DNA methylation changes, the cytosine extension assay was performed. Results demonstrated that a significant increase in histone acetylation that peaked 3 h after VPA exposure was accompanied by an increase in histone methylation at histone H3 lysine 4 (H3K4) and a decrease in histone methylation at histone H3 lysine 9 (H3K9). Immunohistochemical staining revealed increased histone acetylation in the neuroepithelium, heart, and somites. A decrease in methylated histone H3K9 staining was observed in the neuroepithelium and somites, METHYLATED histone H3K4 staining was observed in the neuroepithelium. No significant differences in global or CpG island DNA methylation were observed in embryo homogenates. These results support the possibility that epigenetic modifications caused by VPA during early mouse organogenesis results in congenital malformations.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Protective effect of N-acetyl-L-cysteine against disulfiram-induced oxidative stress and apoptosis in V79 cells

This work investigated the effect of N-acetyl-L-cysteine (NAC) on disulfiram (DSF) induced oxidative stress in Chinese hamster fibroblast cells (V79). An increase in oxidative stress induced by DSF was observed up to a 200 {mu}M concentration. It was evidenced by a statistically significant increase of both GSH{sub t} and GSSG levels, as well as elevated protein carbonyl (PC) content. There was no increase in lipid peroxidation (measured as TBARS). DSF increased CAT activity, but did not change SOD1 and SOD2 activities. Analysis of GSH related enzymes showed that DSF significantly increased GR activity, did not change Se-dependent GPx, but statistically significantly decreased non-Se-dependent GPx activity. DSF showed also pro-apoptotic activity. NAC alone did not produce any significant changes, besides an increase of GSH{sub t} level, in any of the variables measured. However, pre-treatment of cells with NAC ameliorated DSF-induced changes. NAC pre-treatment restored the viability of DSF-treated cells evaluated by Trypan blue exclusion assay and MTT test, GSSG level, and protein carbonyl content to the control values as well as it reduced pro-apoptotic activity of DSF. The increase of CAT and GR activity was not reversed. Activity of both GPx was significantly increased compared to their values after DSF treatment. In conclusion, oxidative properties are at least partially attributable to the cellular effects of disulfiram and mechanisms induced by NAC pre-treatment may lower or even abolish the observed effects. These observations illustrate the importance of the initial cellular redox state in terms of cell response to disulfiram exposure. -- Research Highlights: {yields}This report explores biological properties of disulfiram under a condition of modulated intra-cellular GSH level. It shows a protective role of N-acetyl-L-cysteine in V79 cells exposed to disulfiram (in GSH metabolism as well as in changes of antioxidant enzyme activity).

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Hepatically-metabolized and -excreted artificial oxygen carrier, hemoglobin vesicles, can be safely used under conditions of hepatic impairment

The hemoglobin vesicle (HbV) is an artificial oxygen carrier in which a concentrated Hb solution is encapsulated in lipid vesicles. Our previous studies demonstrated that HbV is metabolized by the mononuclear phagocyte system, and the lipid components are excreted from the liver. It is well-known that many hepatically-metabolized and -excreted drugs show altered pharmaceutics under conditions of liver impairment, which results in adverse effects. The aim of this study was to determine whether the administration of HbV causes toxicity in rats with carbon tetrachloride induced liver cirrhosis. Changes in plasma biochemical parameters, histological staining and the pharmacokinetic distribution of HbV were evaluated after an HbV injection of the above model rats at a putative clinical dose (1400 mgHb/kg). Plasma biochemical parameters were not significantly affected, except for a transient elevation of lipase, lipid components and bilirubin, which recovered within 14 days after an HbV infusion. Negligible morphological changes were observed in the kidney, liver, spleen, lung and heart. Hemosiderin, a marker of iron accumulation in organs, was observed in the liver and spleen up to 14 days after HbV treatment, but no evidence of oxidative stress in the plasma and liver were observed. HbV is mainly distributed in the liver and spleen, and the lipid components are excreted into feces within 7 days. In conclusion, even under conditions of hepatic cirrhosis, HbV and its components exhibit the favorable metabolic and excretion profile at the putative clinical dose. These findings provide further support for the safety and effectiveness of HbV in clinical settings.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Multiple mechanisms underlying troglitazone-induced mitochondrial permeability transition

Troglitazone, a thiazolidinedione class antidiabetic drug, was withdrawn from the market because of its severe idiosyncratic hepatotoxicity. It causes a mitochondrial permeability transition (MPT), which may in part contribute to its hepatotoxicity. In the present study, the mechanism of troglitazone mitochondrial toxicity was investigated in isolated rat liver mitochondria. Mitochondrial swelling induced by 10 {mu}M troglitazone was attenuated by bromoenol lactone (BEL), an inhibitor of Ca{sup 2+}-independent phospholipase A{sub 2} (iPLA{sub 2}). In contrast, that induced by 50 {mu}M troglitazone was exacerbated by BEL. This exacerbation was diminished by addition of 2 mM glutathione, an antioxidant. Oxygen consumption by state 3 respiration in isolated mitochondria was also decreased by troglitazone, but it was not affected by BEL. Mitochondrial swelling induced by 10 {mu}M troglitazone was completely attenuated in the absence of Ca{sup 2+} while that induced by 50 {mu}M troglitazone was not affected. Addition of 1 {mu}M cyclosporin A (CsA), an inhibitor of MPT pores, completely attenuated swelling induced by 10 {mu}M troglitazone while it only partly diminished that induced by 50 {mu}M troglitazone. Thus, the MPT induced by 10 and 50 {mu}M troglitazone are regulated by different mechanism; the MPT induced by 10 {mu}M troglitazone is regulated by the activation of iPLA{sub 2} and caused by the opening of CsA-regulating MPT pores followed by accumulation of Ca{sup 2+} in mitochondria, while that induced by 50 {mu}M troglitazone is partly regulated by reactive oxygen species and mainly caused by the opening of CsA-insensitive MPT pores.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

The role of vitamin D3 upregulated protein 1 in thioacetamide-induced mouse hepatotoxicity

Thioacetamide (TA) is a commonly used drug that can trigger acute hepatic failure (AHF) through generation of oxidative stress. Vitamin D3 upregulated protein 1 (VDUP1) is an endogenous inhibitor of thioredoxin, a ubiquitous thiol oxidoreductase, that regulates cellular redox status. In this study, we investigated the role of VDUP1 in AHF using a TA-induced liver injury model. VDUP1 knockout (KO) and wild-type (WT) mice were subjected to a single intraperitoneal TA injection, and various parameters of hepatic injury were assessed. VDUP1 KO mice displayed a significantly higher survival rate, lower serum alanine aminotransferase and aspartate aminotransferase levels, and less hepatic damage, compared to WT mice. In addition, induction of apoptosis was decreased in VDUP1 KO mice, with the alteration of caspase-3 and -9 activities, Bax-to-Bcl-2 expression ratios, and mitogen activated protein kinase (MAPK) signaling pathway. Importantly, analysis of TA bioactivation revealed lower plasma clearance of TA and covalent binding of [{sup 14}C]TA to liver macromolecules in VDUP1 KO mice. Furthermore, the level of oxidative stress was significantly less in VDUP1 KO mice than in their WT counterparts, as evident from lipid peroxidation assay. These results collectively indicate that VDUP1 deficiency protects against TA-induced acute liver injury via lower bioactivation of TA and antioxidant effects.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Upregulation of contractile endothelin type B receptors by lipid-soluble cigarette smoking particles in rat cerebral arteries via activation of MAPK

Cigarette smoke exposure increases the risk of stroke. However, the underlying molecular mechanisms are poorly understood. Endothelin system plays key roles in the pathogenesis of stroke. The present study was designed to examine if lipid-soluble (dimethyl sulfoxide-soluble) cigarette smoke particles (DSP) induces upregulation of contractile endothelin type B (ET{sub B}) receptors in rat cerebral arteries and if activation of mitogen activated protein kinase (MAPK) and nuclear factor-kappaB (NF-{kappa}B) mediate the upregulation of contractile endothelin receptors in the cerebral arteries. Rat middle cerebral arteries were isolated and organ cultured in serum free medium for 24 h in the presence of DSP with or without specific inhibitors: MEK specific (U0126), p38 specific (SB202190), JNK specific (SP600125), NF-{kappa}B specific (BMS-345541) or (IMD-0354), transcription inhibitor (actinomycin D), or translation blocker (cycloheximide). Contractile responses to the ET{sub B} receptor agonist sarafotoxin 6c were investigated by a sensitive myograph. The expression of the ET{sub B} receptors were studied at mRNA and protein levels using quantitative real time PCR and immunohistochemistry, respectively. Results show that organ culture per se induced transcriptional upregulation of contractile ET{sub B} receptors in the cerebral vascular smooth muscle cells. This upregulation was further increased at the translational level by addition of DSP to the organ culture, but this increase was not seen by addition of nicotine or water-soluble cigarette smoke particles to the organ culture. The increased upregulation of contractile ET{sub B} receptors by DSP was abrogated by U0126, SP600125, actinomycin D, and cycloheximide, suggesting that the underlying molecular mechanisms involved in this process include activation of MEK and JNK MAPK-mediated transcription and translation of new contractile ET{sub B} receptors. Thus, the MAPK-mediated upregulation of contractile ET{sub B} receptors in cerebral arteries might be a pharmacological target for the treatment of smoke-associated cerebral vascular disease like stroke.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Evaluation of a bioluminescent mouse model expressing aromatase PII-promoter-controlled luciferase as a tool for the study of endocrine disrupting chemicals

Dysfunction of the enzyme aromatase (CYP19) is associated with endocrine pathologies such as osteoporosis, impaired fertility and development of hormone-dependent cancers. Certain endocrine disrupting chemicals affect aromatase expression and activity in vitro, but little is known about their ability to do so in vivo. We evaluated a bioluminescent mouse model (LPTA (registered)) CD-1-Tg(Cyp19-luc)-Xen) expressing luciferase under control of the gonadal aromatase pII promoter as an in vivo screening tool for chemicals that may affect aromatase expression. We studied the effects of forskolin, pregnant mare serum gonadotropin and atrazine in this model (atrazine was previously shown to induced pII-promoter-driven aromatase expression in H295R human adrenocortical carcinoma cells). About 2-4 out of every group of 10 male or female Cyp19-luc mice injected i.p. with 10 mg/kg forskolin had increased gonadal bioluminescence after 3-5 days compared to controls; the others appeared non-responsive. Similarly, about 4 per group of 9 individual females injected with pregnant mare serum gonadotropin had increased ovarian bioluminescence after 24 h. There was a statistically significant correlation between ovarian bioluminescence and plasma estradiol concentrations (n = 14; p = 0.022). Males exposed to a single dose of 100 mg/kg or males and females exposed to 5 daily injections of 30 mg/kg atrazine showed no change in gonadal bioluminescence over a 7 day period, but a significant interaction was found between atrazine (100 mg/kg) and time in female mice (p < 0.05; two-way ANOVA). Ex vivo luciferase activity in dissected organs was increased by forskolin in testis, epididymis and ovaries. Atrazine (30 mg/kg/day) increased (30%) luciferase activity significantly in epididymis only. In conclusion, certain individual Cyp19-luc mice are highly responsive to aromatase inducers, suggesting this model, with further optimization, may have potential as an in vivo screening tool for environmental contaminants.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Toxicometabolomics approach to urinary biomarkers for mercuric chloride (HgCl{sub 2})-induced nephrotoxicity using proton nuclear magnetic resonance ({sup 1}H NMR) in rats

The primary objective of this study was to determine and characterize surrogate biomarkers that can predict nephrotoxicity induced by mercuric chloride (HgCl{sub 2}) using urinary proton nuclear magnetic resonance ({sup 1}H NMR) spectral data. A procedure for {sup 1}H NMR urinalysis using pattern recognition was proposed to evaluate nephrotoxicity induced by HgCl{sub 2} in Sprague-Dawley rats. HgCl{sub 2} at 0.1 or 0.75 mg/kg was administered intraperitoneally (i.p.), and urine was collected every 24 h for 6 days. Animals (n = 6 per group) were sacrificed 3 or 6 days post-dosing in order to perform clinical blood chemistry tests and histopathologic examinations. Urinary {sup 1}H NMR spectroscopy revealed apparent differential clustering between the control and HgCl{sub 2} treatment groups as evidenced by principal component analysis (PCA) and partial least square (PLS)-discriminant analysis (DA). Time- and dose-dependent separation of HgCl{sub 2}-treated animals from controls was observed by PCA of {sup 1}H NMR spectral data. In HgCl{sub 2}-treated rats, the concentrations of endogenous urinary metabolites of glucose, acetate, alanine, lactate, succinate, and ethanol were significantly increased, whereas the concentrations of 2-oxoglutarate, allantoin, citrate, formate, taurine, and hippurate were significantly decreased. These endogenous metabolites were selected as putative biomarkers for HgCl{sub 2}-induced nephrotoxicity. A dose response was observed in concentrations of lactate, acetate, succinate, and ethanol, where severe disruption of the concentrations of 2-oxoglutarate, citrate, formate, glucose, and taurine was observed at the higher dose (0.75 mg/kg) of HgCl{sub 2}. Correlation of urinary {sup 1}H NMR PLS-DA data with renal histopathologic changes suggests that {sup 1}H NMR urinalysis can be used to predict or screen for HgCl{sub 2}-induced nephrotoxicity{sub .}

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Beneficial effect of 17{beta}-estradiol on hyperglycemia and islet {beta}-cell functions in a streptozotocin-induced diabetic rat model

The modulating effect of estrogen on glucose homeostasis remains a controversial issue at present. In this study, we sought to determine the beneficial effect of 17{beta}-estradiol (E{sub 2}) on hyperglycemia and islet {beta}-cell functions in streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were injected i.p. with STZ to induce a relatively mild diabetic condition. The rats were then treated with E{sub 2} orally at 500 {mu}g/kg body weight/day for 15 days to evaluate the modulating effect on hyperglycemia, insulin secretion, and islet {beta}-cell proliferation. E{sub 2} administration for 10 days significantly lowered plasma glucose levels, increased plasma insulin levels, and improved glucose tolerance by attenuating insulin response to oral glucose loading. These beneficial effects of E{sub 2} were accompanied by increases in islet number and volume, rate of islet cell proliferation, and the amount of insulin secreted. The growth-stimulatory effect of E{sub 2} on islet cells was linked to the functions of the estrogen receptor {alpha}. Notably, these protective effects of E{sub 2} on diabetic conditions were basically not observed when the STZ-treated rats had a more severe degree of islet damage and hyperglycemia. Taken together, we conclude that E{sub 2} can promote the regeneration of damaged pancreatic islets by stimulating {beta}-cell proliferation in diabetic rats, and this effect is accompanied by improvements in glucose tolerance and a decrease in plasma glucose levels. These findings suggest that oral administration of E{sub 2} may be beneficial in diabetic patients with an accelerated loss of islet {beta}-cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Distribution and responsiveness of rat anti-Muellerian hormone during ovarian development and VCD-induced ovotoxicity

Anti-Muellerian hormone (AMH) is produced by granulosa cells in primary to small antral follicles of the adult ovary and helps maintain primordial follicles in a dormant state. The industrial chemical, 4-vinylcyclohexene diepoxide (VCD) causes specific ovotoxicity in primordial and small primary follicles of mice and rats. Previous studies suggest that this ovotoxicity involves acceleration of primordial to primary follicle recruitment via interactions with the Kit/Kit ligand signaling pathway. Because of its accepted role in inhibiting primordial follicle recruitment, the present study was designed to investigate a possible interaction between AMH and VCD-induced ovotoxicity. Protein distribution of AMH was compared in neonatal and adult F344 rat ovaries. AMH protein was visualized by immunofluorescence microscopy in large primary and secondary follicles of the adult ovary, but in small primary follicles in neonatal rat ovaries. In cultured postnatal day (PND) 4 F344 rat ovaries, VCD exposure (30 {mu}M, 2-8 days) decreased (P < 0.05) AMH mRNA (d4-8) and protein (d6-8). Recombinant AMH (100-400 mg/ml) in PND4 ovaries cultured 8 days {+-} VCD (30 {mu}M) caused an increase (P < 0.05) in primordial, and a decrease (P < 0.05) in small primary follicles, supporting that AMH retarded primordial follicle recruitment. However, no concentration of AMH had an effect on VCD-induced ovotoxicity. Whereas, VCD caused a reduction in expression of AMH (d4-d8), it followed previously reported initial disruptions in Kit signaling induced by VCD (d2). Thus, collectively, these results do not support a mechanism whereby VCD causes ovotoxicity via generalized activation of primordial follicle recruitment, but instead provide further support for the specificity of other intracellular mechanisms involved in VCD-induced ovotoxicity.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Xanthine oxidase-derived reactive oxygen species mediate 4-oxo-2-nonenal-induced hepatocyte cell death

Among the aldehydes derived from lipid peroxidation, there have been several reports concerning the toxicity of 4-hydroxy-2-nonenal (4-HNE), whereas little information is available about 4-oxo-2-nonenal (4-ONE). In the present study, we examined the effects of 4-HNE and 4-ONE on the cell viability of primary rat hepatocyte cultures. At concentrations of 5, 10, and 20 {mu}M, 4-HNE had no significant effect on the cell viability of primary rat hepatocytes cultures, whereas 4-ONE potently decreased the cell viability in a dose-dependent manner (5-20 {mu}M, 23-69% inhibition). The TUNEL assay showed that 4-ONE causes apoptosis in the cells. 4-ONE also increased 2',7'-dichlorofluorescein-fluorescence intensity from 2',7'-dichlorodihydrofluorescein, an indicator of reactive oxygen species (ROS) generation. Allopurinol, a xanthine oxidase (XO) inhibitor, diminished the 4-ONE-induced increase in the 2',7'-dichlorofluorescein-fluorescence intensity and the decrease in viability, indicating the role of XO in mediating 4-ONE-induced cell death. These observations suggest that 4-ONE has the potential to induce liver cell death via XO-derived ROS generation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

The lack of target specificity of small molecule anticancer kinase inhibitors is correlated with their ability to damage myocytes in vitro

Many new targeted small molecule anticancer kinase inhibitors are actively being developed. However, the clinical use of some kinase inhibitors has been shown to result in cardiotoxicity. In most cases the mechanisms by which they exert their cardiotoxicity are not well understood. We have used large scale profiling data on 8 FDA-approved tyrosine kinase inhibitors and 10 other kinase inhibitors to a panel of 317 kinases in order to correlate binding constants and kinase inhibitor binding selectivity scores with kinase inhibitor-induced damage to neonatal rat cardiac myocytes. The 18 kinase inhibitors that were the subject of this study were: canertinib, dasatinib, dovitinib, erlotinib, flavopiridol, gefitinib, imatinib, lapatinib, midostaurin, motesanib, pazopanib, sorafenib, staurosporine, sunitinib, tandutinib, tozasertib, vandetanib and vatalanib. The combined tyrosine kinase and serine-threonine kinase selectivity scores were highly correlated with the myocyte-damaging effects of the kinase inhibitors. This result suggests that myocyte damage was due to a lack of target selectivity to binding of both tyrosine kinases and serine-threonine kinases, and was not due to binding to either group specifically. Finally, the strength of kinase inhibitor binding for 290 kinases was examined for correlations with myocyte damage. Kinase inhibitor binding was significantly correlated with myocyte damage for 12 kinases. Thus, myocyte damage may be multifactorial in nature with the inhibition of a number of kinases involved in producing kinase inhibitor-induced myocyte damage.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Preferential induction of the AhR gene battery in HepaRG cells after a single or repeated exposure to heterocyclic aromatic amines

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) are two of the most common heterocyclic aromatic amines (HAA) produced during cooking of meat, fish and poultry. Both HAA produce different tumor profiles in rodents and are suspected to be carcinogenic in humans. In order to better understand the molecular basis of HAA toxicity, we have analyzed gene expression profiles in the metabolically competent human HepaRG cells using pangenomic oligonucleotide microarrays, after either a single (24-h) or a repeated (28-day) exposure to 10 {mu}M PhIP or MeIQx. The most responsive genes to both HAA were downstream targets of the arylhydrocarbon receptor (AhR): CYP1A1 and CYP1A2 after both time points and CYP1B1 and ALDH3A1 after 28 days. Accordingly, CYP1A1/1A2 induction in HAA-treated HepaRG cells was prevented by chemical inhibition or small interference RNA-mediated down-regulation of the AhR. Consistently, HAA induced activity of the CYP1A1 promoter, which contains a consensus AhR-related xenobiotic-responsive element (XRE). In addition, several other genes exhibited both time-dependent and compound-specific expression changes with, however, a smaller magnitude than previously reported for the prototypical AhR target genes. These changes concerned genes mainly related to cell growth and proliferation, apoptosis, and cancer. In conclusion, these results identify the AhR gene battery as the preferential target of PhIP and MeIQx in HepaRG cells and further support the hypothesis that intake of HAA in diet might increase human cancer risk.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

Mono-hydroxy methoxychlor alters levels of key sex steroids and steroidogenic enzymes in cultured mouse antral follicles

Methoxychlor (MXC) is an organochlorine pesticide that reduces fertility in female rodents by decreasing antral follicle numbers and increasing follicular death. MXC is metabolized in the body to mono-hydroxy MXC (mono-OH). Little is known about the effects of mono-OH on the ovary. Thus, this work tested the hypothesis that mono-OH exposure decreases production of 17{beta}-estradiol (E{sub 2}) by cultured mouse antral follicles. Antral follicles were isolated from CD-1 mice (age 35-39 days) and exposed to dimethylsulfoxide (DMSO), or mono-OH (0.1-10 {mu}g/mL) for 96 h. Media and follicles were collected for analysis of sex steroid levels and mRNA expression, respectively. Mono-OH treatment (10 {mu}g/mL) decreased E{sub 2} (DMSO: 3009.72 {+-} 744.99 ng/mL; mono-OH 0.1 {mu}g/mL: 1679.66 {+-} 461.99 ng/mL; 1 {mu}g/mL: 1752.72 {+-} 532.41 ng/mL; 10 {mu}g/mL: 45.89 {+-} 33.83 ng/mL), testosterone (DMSO: 15.43 {+-} 2.86 ng/mL; mono-OH 0.1 {mu}g/mL: 17.17 {+-} 4.71 ng/mL; 1 {mu}g/mL: 13.64 {+-} 3.53 ng/mL; 10 {mu}g/mL: 1.29 {+-} 0.23 ng/mL), androstenedione (DMSO: 1.92 {+-} 0.34 ng/mL; mono-OH 0.1 {mu}g/mL: 1.49 {+-} 0.43 ng/mL; 1 {mu}g/mL: 0.64 {+-} 0.31 ng/mL; 10 {mu}g/mL: 0.12 {+-} 0.06 ng/mL) and progesterone (DMSO: 24.11 {+-} 4.21 ng/mL; mono-OH 0.1 {mu}g/mL: 26.77 {+-} 4.41 ng/mL; 1 {mu}g/mL: 20.90 {+-} 3.75 ng/mL; 10 {mu}g/mL: 9.44 {+-} 2.97 ng/mL) levels. Mono-OH did not alter expression of Star, Hsd3b1, Hsd17b1 and Cyp1b1, but it did reduce levels of Cyp11a1, Cyp17a1 and Cyp19a1 mRNA. Collectively, these data suggest that mono-OH significantly decreases levels of key sex steroid hormones and the expression of enzymes required for steroidogenesis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2010

A unified algorithm for predicting partition coefficients for PBPK modeling of drugs and environmental chemicals

The algorithms in the literature focusing to predict tissue:blood PC (P{sub tb}) for environmental chemicals and tissue:plasma PC based on total (K{sub p}) or unbound concentration (K{sub pu}) for drugs differ in their consideration of binding to hemoglobin, plasma proteins and charged phospholipids. The objective of the present study was to develop a unified algorithm such that P{sub tb}, K{sub p} and K{sub pu} for both drugs and environmental chemicals could be predicted. The development of the unified algorithm was accomplished by integrating all mechanistic algorithms previously published to compute the PCs. Furthermore, the algorithm was structured in such a way as to facilitate predictions of the distribution of organic compounds at the macro (i.e. whole tissue) and micro (i.e. cells and fluids) levels. The resulting unified algorithm was applied to compute the rat P{sub tb}, K{sub p} or K{sub pu} of muscle (n = 174), liver (n = 139) and adipose tissue (n = 141) for acidic, neutral, zwitterionic and basic drugs as well as ketones, acetate esters, alcohols, aliphatic hydrocarbons, aromatic hydrocarbons and ethers. The unified algorithm reproduced adequately the values predicted previously by the published algorithms for a total of 142 drugs and chemicals. The sensitivity analysis demonstrated the relative importance of the various compound properties reflective of specific mechanistic determinants relevant to prediction of PC values of drugs and environmental chemicals. Overall, the present unified algorithm uniquely facilitates the computation of macro and micro level PCs for developing organ and cellular-level PBPK models for both chemicals and drugs.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2011

Inhibition of the Rho/ROCK pathway prevents neuronal degeneration in vitro and in vivo following methylmercury exposure

Methylmercury (MeHg) is an environmental neurotoxicant which induces neuropathological changes in both the central nervous and peripheral sensory nervous systems. Our recent study demonstrated that down-regulation of Ras-related C3 botulinum toxin substrate 1 (Rac1), which is known to promote neuritic extension, preceded MeHg-induced damage in cultured cortical neurons, suggesting that MeHg-mediated axonal degeneration is due to the disturbance of neuritic extension. Therefore we hypothesized that MeHg-induced axonal degeneration might be caused by neuritic extension/retraction incoordination. This idea brought our attention to the Ras homolog gene (Rho)/Rho-associated coiled coil-forming protein kinase (ROCK) pathway because it has been known to be associated with the development of axon and apoptotic neuronal cell death. Here we show that inhibition of the Rho/ROCK pathway prevents MeHg-intoxication both in vitro and in vivo. A Rho inhibitor, C3 toxin, and 2 ROCK inhibitors, Fasudil and Y-27632, significantly protected against MeHg-induced axonal degeneration and apoptotic neuronal cell death in cultured cortical neuronal cells exposed to 100 nM MeHg for 3 days. Furthermore, Fasudil partially prevented the loss of large pale neurons in dorsal root ganglia, axonal degeneration in dorsal spinal root nerves, and vacuolar degeneration in the dorsal columns of the spinal cord in MeHg-intoxicated model rats (20 ppm MeHg in drinking water for 28 days). Hind limb crossing sign, a characteristic MeHg-intoxicated sign, was significantly suppressed in this model. The results suggest that inhibition of the Rho/ROCK pathway rescues MeHg-mediated neuritic extension/retraction incoordination and is effective for the prevention of MeHg-induced axonal degeneration and apoptotic neuronal cell death.

60 APPLIED LIFE SCIENCES↗