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Find video protocols related to scientific articles indexed in Pubmed.
Image gently campaign back to basics initiative: ten steps to help manage radiation dose in pediatric digital radiography.
AJR Am J Roentgenol
PUBLISHED: 04-27-2013
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The purpose of this review is to summarize 10 steps a practice can take to manage radiation exposure in pediatric digital radiography.
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Characterization of Hepatocellular Carcinoma Related Genes and Metabolites in Human Nonalcoholic Fatty Liver Disease.
Dig. Dis. Sci.
PUBLISHED: 04-18-2013
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The worldwide prevalences of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are estimated to range from 30 to 40 % and 5-17 %, respectively. Hepatocellular carcinoma (HCC) is primarily caused by hepatitis B infection, but retrospective data suggest that 4-29 % of NASH cases will progress to HCC. Currently the connection between NASH and HCC is unclear.
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Organic anion-transporting polypeptide 1a4 (Oatp1a4) is important for secondary bile acid metabolism.
Biochem. Pharmacol.
PUBLISHED: 04-08-2013
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Organic anion transporting polypeptides (human: OATPs; rodent: Oatps) were thought to have important functions in bile acid (BA) transport. Oatp1a1, 1a4, and 1b2 are the three major Oatp1 family members in rodent liver. Our previous studies have characterized the BA homeostasis in Oatp1a1-null and Oatp1b2-null mice. The present study investigated the physiological role of Oatp1a4 in BA homeostasis by using Oatp1a4-null mice. Oatp1a4 expression is female-predominant in livers of mice, and thereby it was expected that female Oatp1a4-null mice will have more prominent changes than males. Interestingly, the present study demonstrated that female Oatp1a4-null mice had no significant alterations in BA concentrations in serum or liver, though they had increased mRNA of hepatic BA efflux transporters (Mrp4 and Ost?/?) and ileal BA transporters (Asbt and Ost?/?). In contrast, male Oatp1a4-null mice showed significantly altered BA homeostasis, including increased concentrations of deoxycholic acid (DCA) in serum, liver and intestinal contents. After feeding a DCA-supplemented diet, male but not female Oatp1a4-null mice had higher concentrations of DCA in serum and livers than their WT controls. This suggested that Oatp1a4 is important for intestinal absorption of secondary BAs in male mice. Furthermore, loss of Oatp1a4 function did not decrease BA accumulation in serum or livers of bile-duct-ligated mice, suggesting that Oatp1a4 is not likely a BA uptake transporter. In summary, the present study for the first time demonstrates that Oatp1a4 does not appear to mediate the hepatic uptake of BAs, but plays an important male-predominant role in secondary BA metabolism in mice.
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The role of retinoic acid in hepatic lipid homeostasis defined by genomic binding and transcriptome profiling.
BMC Genomics
PUBLISHED: 03-22-2013
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The eyes and skin are obvious retinoid target organs. Vitamin A deficiency causes night blindness and retinoids are widely used to treat acne and psoriasis. However, more than 90% of total body retinol is stored in liver stellate cells. In addition, hepatocytes produce the largest amount of retinol binding protein and cellular retinoic acid binding protein to mobilize retinol from the hepatic storage pool and deliver retinol to its receptors, respectively. Furthermore, hepatocytes express the highest amount of retinoid x receptor alpha (RXR?) among all the cell types. Surprisingly, the function of endogenous retinoids in the liver has received very little attention.
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Decreased hepatotoxic bile acid composition and altered synthesis in progressive human nonalcoholic fatty liver disease.
Toxicol. Appl. Pharmacol.
PUBLISHED: 01-13-2013
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Bile acids (BAs) have many physiological roles and exhibit both toxic and protective influences within the liver. Alterations in the BA profile may be the result of disease induced liver injury. Nonalcoholic fatty liver disease (NAFLD) is a prevalent form of chronic liver disease characterized by the pathophysiological progression from simple steatosis to nonalcoholic steatohepatitis (NASH). The hypothesis of this study is that the classical (neutral) and alternative (acidic) BA synthesis pathways are altered together with hepatic BA composition during progression of human NAFLD. This study employed the use of transcriptomic and metabolomic assays to study the hepatic toxicologic BA profile in progressive human NAFLD. Individual human liver samples diagnosed as normal, steatosis, and NASH were utilized in the assays. The transcriptomic analysis of 70 BA genes revealed an enrichment of downregulated BA metabolism and transcription factor/receptor genes in livers diagnosed as NASH. Increased mRNA expression of BAAT and CYP7B1 was observed in contrast to decreased CYP8B1 expression in NASH samples. The BA metabolomic profile of NASH livers exhibited an increase in taurine together with elevated levels of conjugated BA species, taurocholic acid (TCA) and taurodeoxycholic acid (TDCA). Conversely, cholic acid (CA) and glycodeoxycholic acid (GDCA) were decreased in NASH liver. These findings reveal a potential shift toward the alternative pathway of BA synthesis during NASH, mediated by increased mRNA and protein expression of CYP7B1. Overall, the transcriptomic changes of BA synthesis pathway enzymes together with altered hepatic BA composition signify an attempt by the liver to reduce hepatotoxicity during disease progression to NASH.
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Loss of organic anion transporting polypeptide 1a1 increases deoxycholic acid absorption in mice by increasing intestinal permeability.
Toxicol. Sci.
PUBLISHED: 09-13-2011
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Deoxycholic acid (DCA) is a known hepatotoxicant, a tissue tumor promoter, and has been implicated in colorectal cancer. Male mice are more susceptible to DCA toxicity than female mice. Organic anion transporting polypeptide 1a1 (Oatp1a1), which is known to transport bile acids (BAs) in vitro, is predominantly expressed in livers of male mice. In addition, the concentrations of DCA and its taurine conjugate (TDCA) are increased in serum of Oatp1a1-null mice. To investigate whether Oatp1a1 contributes to the gender difference in DCA toxicity in mice, wild-type (WT) and Oatp1a1-null mice were fed a 0.3% DCA diet for 7 days. After feeding DCA, Oatp1a1-null mice had 30-fold higher concentrations of DCA in both serum and livers than WT mice. Feeding DCA caused more hepatotoxcity in Oatp1a1-null mice than WT mice. After feeding DCA, Oatp1a1-null mice expressed higher BA efflux-transporters (bile salt-export pump, organic solute transporter (Ost)?/?, and multidrug resistance-associated protein [Mrp]2) and lower BA-synthetic enzymes (cytochrome P450 [Cyp]7a1, 8b1, 27a1, and 7b1) in livers than WT mice. Intravenous administration of DCA and TDCA showed that lack of Oatp1a1 does not decrease the plasma elimination of DCA or TDCA. After feeding DCA, the concentrations of DCA in ileum and colon tissues are higher in Oatp1a1-null than in WT mice. In addition, Oatp1a1-null mice have enhanced intestinal permeability. Taken together, the current data suggest that Oatp1a1 does not mediate the hepatic uptake of DCA or TDCA, but lack of Oatp1a1 increases intestinal permeability and thus enhances the absorption of DCA in mice.
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Organic anion transporting polypeptides in the hepatic uptake of PBDE congeners in mice.
Toxicol. Appl. Pharmacol.
PUBLISHED: 05-17-2011
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BDE47, BDE99 and BDE153 are the predominant polybrominated diphenyl ether (PBDE) congeners detected in humans and can induce drug metabolizing enzymes in the liver. We have previously demonstrated that several human liver organic anion transporting polypeptides (humans: OATPs; rodents: Oatps) can transport PBDE congeners. Mice are commonly used to study the toxicity of chemicals like the PBDE congeners. However, the mechanism of the hepatic PBDE uptake in mice is not known. Therefore, the purpose of the current study was to test the hypothesis that BDE47, BDE99, and BDE153 are substrates of mouse hepatic Oatps (Oatp1a1, Oatp1a4, Oatp1b2, and Oatp2b1). We used Human Embryonic Kidney 293 (HEK293) cells transiently expressing individual Oatps and quantified the uptake of BDE47, BDE99, and BDE153. Oatp1a4, Oatp1b2, and Oatp2b1 transported all three PBDE congeners, whereas Oatp1a1 did transport none. Kinetic studies demonstrated that Oatp1a4 and Oatp1b2 transported BDE47 with the greatest affinity, followed by BDE99 and BDE153. In contrast, Oatp2b1 transported all three PBDE congeners with similar affinities. The importance of hepatic Oatps for the liver accumulation of BDE47 was confirmed using Oatp1a4-, and Oatp1b2-null mice.
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Characterization of organic anion-transporting polypeptide (Oatp) 1a1 and 1a4 null mice reveals altered transport function and urinary metabolomic profiles.
Toxicol. Sci.
PUBLISHED: 05-10-2011
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Organic anion-transporting polypeptides (Oatp) 1a1 and 1a4 were deleted by homologous recombination, and mice were characterized for Oatp expression in liver and kidney, transport in isolated hepatocytes, in vivo disposition of substrates, and urinary metabolomic profiles. Oatp1a1 and Oatp1a4 proteins were undetected in liver, and both lines were viable and fertile. Hepatic constitutive messenger RNAs (mRNAs) for Oatp1a4, 1b2, or 2b1 were unchanged in Oatp1a1?/? mice, whereas renal Oatp1a4 mRNA decreased approximately 50% (both sexes). In Oatp1a4?/? mice, no changes in constitutive mRNAs for other Oatps were observed. Uptake of estradiol-17?-D-glucuronide and estrone-3-sulfate in primary hepatocytes decreased 95 and 75%, respectively, in Oatp1a1?/? mice and by 60 and 30%, respectively, in Oatp1a4?/? mice. Taurocholate uptake decreased by 20 and 50% in Oatp1a1?/? and Oatp1a4?/? mice, respectively, whereas digoxin was unaffected. Plasma area under the curve (AUC) for estradiol-17?-D-glucuronide increased 35 and 55% in male and female Oatp1a1?/? mice, respectively, with a concurrent 50% reduction in liver-to-plasma ratios. In contrast, plasma AUC or tissue concentrations of estradiol-17?-D-glucuronide were unchanged in Oatp1a4?/? mice. Plasma AUCs for dibromosulfophthalein increased nearly threefold in male Oatp1a1?/? and Oatp1a4?/? mice, increased by 40% in female Oatp1a4?/? mice, and were unchanged in female Oatp1a1?/? mice. In both lines, no changes in serum ALT, bilirubin, and cholesterol were noted. NMR analyses showed no generalized increase in urinary excretion of organic anions. However, urinary excretion of taurine decreased by 30-40% and was accompanied by increased excretion of isethionic acid, a taurine metabolite generated by intestinal bacteria, suggesting some perturbations in intestinal bacteria distribution.
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Evaluation and validation of multiple cell lines and primary mouse macrophages to predict phospholipidosis potential.
Toxicol In Vitro
PUBLISHED: 03-10-2011
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Phospholipidosis (PLD) in preclinical species can lead to regulatory delays thereby creating incentives to screen for PLD during drug discovery. The objective of this work was to compare, optimize, and validate in vitro PLD assays in primary mouse macrophages and hepatocyte- (HepG2, HuH7) or macrophage-derived cells lines (I.13.35, RAW264.7) and to evaluate whether primary cells were better at predicting PLD. Assay precision, determined by a measure of signal to noise window (Z), within assay variability, and day-to-day variability, using amiodarone, was generally acceptable for all cell types; however, precision limits for HepG2 and HuH7 were slightly below assay acceptance criteria. Up to 66 known PLD inducers and non-inducers were subsequently tested to validate the assays. The concordance for predicting PLD in primary macrophages, I-13.35, RAW264.7, HuH7, and HepG2 cells was 91%, 74%, 73%, 62%, and 62% respectively using a decision limit of EC50?125 ?M as a positive finding. Increasing the number of negative controls tested in RAW264.7 cells and changing the decision limit to ?4-fold increase in PLD, improved the specificity and overall concordance to 88%. RAW264.7 cells were selected as the primary screen for predicting PLD, and together with the primary macrophages, were integrated into an overall testing paradigm proposed for use in PLD risk identification.
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Urinary metabolites of 2-bromoethanamine identified by stable isotope labelling: evidence for carbamoylation and glutathione conjugation.
Xenobiotica
PUBLISHED: 11-02-2010
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2-Bromoethanamine (BEA) causes renal papillary necrosis (RPN) in rats after a single dose and has been widely used as a model compound for studying the lesion. Although the metabolism of BEA may be an important determinant of toxicity, the metabolic fate of the compound has not been fully elucidated. To date, the only identified BEA metabolites are aziridine, 2-oxazolidone and 5-hydroxy-2-oxazolidone. In this study, stable isotope labelling (SIL) of BEA analogs ((¹³C and ²H) were used to differentiate generated BEA metabolites from endogenous molecules which enabled the accurate liquid chromatography mass spectrometry detection of more than 180 novel metabolites. BEA metabolism was evaluated in rats after acute administration of a non-toxic dose (50 mg/kg) and a toxic dose (250 mg/kg) that caused frank RPN and polyuria. Newly identified metabolites include three carbamoylation products, two mercapturic acids and a group of amino acid conjugates. Overall, the results indicate that BEA metabolism is very complex, suggest the potential formation of reactive intermediates and establish that BEA is subject to conjugation with glutathione. The results also demonstrate the utility and sensitivity of the SIL approach for identification of metabolites from small, reactive compounds.
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Comparison of TNF? to lipopolysaccharide as an inflammagen to characterize the idiosyncratic hepatotoxicity potential of drugs: Trovafloxacin as an example.
Int J Mol Sci
PUBLISHED: 09-12-2010
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Idiosyncratic drug reactions (IDRs) are poorly understood, unpredictable, and not detected in preclinical studies. Although the cause of these reactions is likely multi-factorial, one hypothesis is that an underlying inflammatory state lowers the tolerance to a xenobiotic. Previously used in an inflammation IDR model, bacterial lipopolysaccharide (LPS) is heterogeneous in nature, making development of standardized testing protocols difficult. Here, the use of rat tumor necrosis factor-? (TNF?) to replace LPS as an inflammatory stimulus was investigated. Sprague-Dawley rats were treated with separate preparations of LPS or TNF?, and hepatic transcriptomic effects were compared. TNF? showed enhanced consistency at the transcriptomic level compared to LPS. TNF? and LPS regulated similar biochemical pathways, although LPS was associated with more robust inflammatory signaling than TNF?. Rats were then codosed with TNF? and trovafloxacin (TVX), an IDR-associated drug, and evaluated by liver histopathology, clinical chemistry, and gene expression analysis. TNF?/TVX induced unique gene expression changes that clustered separately from TNF?/levofloxacin, a drug not associated with IDRs. TNF?/TVX cotreatment led to autoinduction of TNF? resulting in potentiation of underlying gene expression stress signals. Comparison of TNF?/TVX and LPS/TVX gene expression profiles revealed similarities in the regulation of biochemical pathways. In conclusion, TNF? could be used in lieu of LPS as an inflammatory stimulus in this model of IDRs.
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Identification of 1- and 3-methylhistidine as biomarkers of skeletal muscle toxicity by nuclear magnetic resonance-based metabolic profiling.
Anal. Biochem.
PUBLISHED: 08-09-2010
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Nuclear magnetic resonance (NMR)-based metabolomic profiling identified urinary 1- and 3-methylhistidine (1- and 3-MH) as potential biomarkers of skeletal muscle toxicity in Sprague-Dawley rats following 7 and 14 daily doses of 0.5 or 1mg/kg cerivastatin. These metabolites were highly correlated to sex-, dose- and time-dependent development of cerivastatin-induced myotoxicity. Subsequently, the distribution and concentration of 1- and 3-MH were quantified in 18 tissues by gas chromatography-mass spectrometry. The methylhistidine isomers were most abundant in skeletal muscle with no fiber or sex differences observed; however, 3-MH was also present in cardiac and smooth muscle. In a second study, rats receiving 14 daily doses of 1mg/kg cerivastatin (a myotoxic dose) had 6- and 2-fold elevations in 1- and 3-MH in urine and had 11- and 3-fold increases in 1- and 3-MH in serum, respectively. Selectivity of these potential biomarkers was tested by dosing rats with the cardiotoxicant isoproterenol (0.5mg/kg), and a 2-fold decrease in urinary 1- and 3-MH was observed and attributed to the anabolic effect on skeletal muscle. These findings indicate that 1- and 3-MH may be useful urine and serum biomarkers of drug-induced skeletal muscle toxicity and hypertrophy in the rat, and further investigation into their use and limitations is warranted.
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Gamma-glutamyl transpeptidase null mice fail to develop tolerance to coumarin-induced Clara cell toxicity.
Food Chem. Toxicol.
PUBLISHED: 03-15-2010
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Coumarin was used as a model Clara cell toxicant to test the hypothesis that tolerance to injury requires increased gamma-glutamyl transpeptidase (GGT) activity. Wildtype (GGT(+/+)) and GGT-deficient (GGT(-/-)) mice on a C57BL/6/129SvEv hybrid background were dosed orally with corn oil (vehicle) or coumarin (200 mg/kg). In vehicle-treated mice, Clara cell secretory protein (CC10) expression was distributed throughout the bronchiolar epithelium. After one dose of coumarin, CC10 expression was dramatically reduced and the bronchiolar epithelium was devoid of Clara cells in GGT(+/+) and GGT(-/-) mice. In wildtype mice, 9 doses of coumarin produced tolerance, characterized as a renewed bronchiolar epithelium with Clara cells expressing CC10 along with a 40% increase in total glutathione (GSH) and a 7-fold increase in GGT activity in the lung. In contrast, tolerance was not observed in GGT(-/-) mice. To assess whether changes in whole lung levels of GSH and GGT activity reflect Clara cell specific changes an enriched population of cells was isolated from female wildtype B6C3F1 mice made tolerant to coumarin. Compared to Clara cells from control mice, GSH and GGT activity increased 3- and 13-fold, respectively. Collectively, these data suggest Clara cell tolerance to coumarin toxicity requires increased GGT activity favoring enhanced GSH synthesis.
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Modulation of ascorbic acid metabolism by cytochrome P450 induction revealed by metabonomics and transcriptional profiling.
Magn Reson Chem
PUBLISHED: 09-22-2009
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In the present study, NMR-based urinary metabonomic profiles resulting from dosing with widely recognized microsomal enzyme inducers were evaluated in male rats. Wistar or Sprague-Dawley rats were dosed daily by oral gavage with phenobarbital (PB; 100 mg/kg), diallyl sulfide (DAS; 500 mg/kg), the investigational compound DMP-904 (150 mg/kg), or beta-naphthoflavone (BNF; 100 mg/kg) for 4 days, and urine was collected daily for analysis. Compounds known to increase cytochrome P450 2B enzymes, including PB, DAS and DMP-904, increased the urinary excretion of gulonic and ascorbic acid in a time-dependent manner, reaching a maximum following 3-4 days of dosing. In contrast, BNF, an agent that induces primarily Cyp1A enzymes, did not increase gulonic or ascorbic acid excretion, despite inducing Cyp1A1 more than 200-fold. Given the metabonomic results, hepatic transcriptional changes in the regulation of ascorbic acid biosynthesis were determined by RT-PCR. All Cyp2B inducers increased hepatic mRNA levels of aldo-keto reductase 1A1, an enzyme that catalyzes the formation of gulonic acid from glucuronate with concurrent decreased expression of both regucalcin (Rgn), the enzyme responsible for conversion of gulonic acid to gulono-1, 4-lactone and gulonolactone oxidase (Gulo), the rate-limiting enzyme in ascorbate biosynthesis. These effects would be expected to increase levels of gulonic acid. In addition, Cyp2B inducers also increased hepatic expression of enzymes regulating ascorbic acid reutilization including glutaredoxin reductase (Glrx2) and thioredoxin reductase (Txnrd1). In contrast, BNF did not effect hepatic expression of any enzyme regulating gulonic or ascorbic acid biosynthesis. Thus, some microsomal enzyme inducers alter transcriptional regulation of ascorbic acid biosynthesis, and these changes are detected by noninvasive metabonomic profiling. However, not all microsomal enzyme inducers appear to alter ascorbic acid metabolism. Finally, the work illustrates how metabonomic results can direct additional studies to determine the biochemical mechanisms underlying changes in urinary metabolite excretion.
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Biomarkers of drug-induced skeletal muscle injury in the rat: troponin I and myoglobin.
Toxicol. Sci.
PUBLISHED: 07-23-2009
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The purpose of this investigation was to determine the utility of fast-twitch skeletal muscle troponin I (fsTnI) and urinary myoglobin (uMB) as biomarkers of skeletal muscle injury in 8-week-old Sprague-Dawley rats. fsTnI and uMB were quantified by enzyme-linked immunosorbent assay and compared with standard clinical assays including creatine kinase, aldolase, aspartate aminotransferase, and histopathological assessments. Detectable levels of uMB were normalized to urinary creatinine to control for differences in renal function. Seven compounds, including those with toxic effects on skeletal muscle, cardiac muscle, or liver, were evaluated. fsTnI was typically nondetectable (< 5.9 ng/ml serum) in vehicle-treated female and male rats but increased in a dose-dependent manner to at least 300 ng/ml in cerivastatin-induced severe fast-twitch specific myotoxicity. Minimal myopathy induced by investigational compounds BMS-600149 and BMS-687453 increased serum fsTnI to about 30-50 ng/ml, suggesting a reasonable dynamic range for detecting mild to severe skeletal muscle toxicity. In direct contrast, fsTnI was only marginally increased relative to population control values in rats treated with triamcinolone acetonide, which produces muscle atrophy or the cardiotoxins isoproterenol and CoCl2. uMB was typically nondetectable (< 1.6 ng/ml urine) in vehicle-treated female and male rats but increased to approximately 140, 300, and 30 ng/mg creatinine in rats treated with cerivastatin, BMS-687453, and triamcinolone acetonide, respectively. Cardiotoxicity also increased uMB in rats treated with isoproterenol and CoCl2 with urine concentrations ranging from 20 to 30 ng/mg creatinine. Severe hepatotoxicity (coumarin) did not significantly affect serum fsTnI or uMB levels. Collectively, these data suggest that fsTnI is specific for skeletal muscle toxicity, whereas uMB is nonspecific, increasing with skeletal muscle and cardiac toxicity. Accordingly, the complement of fsTnI and uMB, in conjunction with standard clinical assays may comprise a useful diagnostic panel for assessing drug-induced myopathy in rats.
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Hepatobiliary disposition of thyroid hormone in Mrp2-deficient TR- rats: reduced biliary excretion of thyroxine glucuronide does not prevent xenobiotic-induced hypothyroidism.
Toxicol. Sci.
PUBLISHED: 02-11-2009
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The hepatobiliary disposition of thyroxine (T4) was evaluated in Groningen Yellow transport deficient (TR(-)) rats lacking functional multidrug resistance-associated protein 2 (Mrp2; Abcc2). Male Wistar and TR(-) rats were dosed orally (4 days) with phenobarbital (PB; 100 mg/kg) or DMP 904 (200 mg/kg), after which T4 homeostasis and hepatic cytochromes P450, UDP-glucuronosyltransferase, xenobiotic transporters, and T4 glucuronidation were determined. Serum concentrations of T4 were approximately 50% higher in control TR(-) rats than Wistars. PB and DMP 904 increased hepatic levels of P450s and T4-glucuronidation (T4-G), and these changes were associated with decreased serum T4 levels in both strains. In Wistar but not TR(-) rats, DMP 904 increased thyroid stimulating hormone levels twofold. Hepatobiliary clearance of T4 was determined after intravenous infusion of [(125)I]T4 to rats dosed with PB and DMP 904 (4 days). PB and DMP 904 increased plasma clearance and hepatic uptake of [(125)I]T4 equivalents in Wistar but not TR(-) rats. Total biliary clearance (Cl(bile)) was approximately 0.85 and 0.2 ml/h in Wistar and TR(-) rats, respectively, with virtually no T4-G excreted in bile in TR(-) rats. Biliary clearance of unconjugated T4 was also lower in control TR(-) rats than in Wistars, although DMP 904 increased its biliary clearance in both strains. These results suggest that Mrp2 is likely to be responsible for biliary excretion of T4-G and contributes in part to excretion of T4. Decreased biliary clearance of T4 and metabolites in TR(-) rats mitigated but did not prevent drug-induced changes in serum T4, suggesting that other factors contribute to changes in T4 homeostasis in these rats.
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Evidence for the involvement of xenobiotic-responsive nuclear receptors in transcriptional effects upon perfluoroalkyl acid exposure in diverse species.
Reprod. Toxicol.
PUBLISHED: 01-03-2009
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Humans and ecological species have been found to have detectable body burdens of a number of perfluorinated alkyl acids (PFAA) including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). In mouse and rat liver these compounds elicit transcriptional and phenotypic effects similar to peroxisome proliferator chemicals (PPC) that work through the nuclear receptor peroxisome proliferator-activated receptor alpha (PPAR alpha). Recent studies indicate that along with PPAR alpha other nuclear receptors are required for transcriptional changes in the mouse liver after PFOA exposure including the constitutive activated receptor (CAR) and pregnane X receptor (PXR) that regulate xenobiotic metabolizing enzymes (XME). To determine the potential role of CAR/PXR in mediating effects of PFAAs in rat liver, we performed a meta-analysis of transcript profiles from published studies in which rats were exposed to PFOA or PFOS. We compared the profiles to those produced by exposure to prototypical activators of CAR, (phenobarbital (PB)), PXR (pregnenolone 16 alpha-carbonitrile (PCN)), or PPAR alpha (WY-14,643 (WY)). As expected, PFOA and PFOS elicited transcript profile signatures that included many known PPAR alpha target genes. Numerous XME genes were also altered by PFOA and PFOS but not WY. These genes exhibited expression changes shared with PB or PCN. Reexamination of the transcript profiles from the livers of chicken or fish exposed to PFAAs indicated that PPAR alpha, CAR, and PXR orthologs were not activated. Our results indicate that PFAAs under these experimental conditions activate PPAR alpha, CAR, and PXR in rats but not chicken and fish. Lastly, we discuss evidence that human populations with greater CAR expression have lower body burdens of PFAAs.
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Establishment of a molecular embryonic stem cell developmental toxicity assay.
Toxicol. Sci.
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The mouse embryonic stem cell test (EST) is a 10-day screen for teratogenic potential developed to reduce animal use for embryotoxicity testing of chemicals (Spielmann, 2005; Spielmann et al., 1997). In this study, we used the cytotoxicity IC(50) values and transcriptional expression changes as primary endpoints in a shorter 4-day version of the EST, the molecular embryonic stem cell assay. Mouse D3 embryonic stem cells were used for cytotoxicity assessment (monolayers) or grown as embryoid bodies in low attachment plates for transcriptional profiling. Sixty-five compounds with known in vivo teratogenicity (33 teratogens and 32 nonteratogens) were evaluated to develop a model for classifying compounds with teratogenic potential. The expression of 12 developmentally regulated gene targets (nanog, fgf5, gsc, cd34, axin2, apln, chst7, lhx1, fgf8, sox17, foxa2, and cxcr4) was measured following exposure of embryoid bodies to a single compound concentration (0.1 × the cytotoxicity IC(20)) for 4 days. In the decision-tree model, compounds with IC(50) values < 22 µM were categorized as teratogens, whereas compounds in the two groups with IC(50) values between 22-200 µM and > 200 µM were categorized as teratogens if ? 8 and 12 genes, respectively, were deregulated by at least 10%. Forty-seven of 65 compounds of the training set were correctly identified (72% total concordance). In a test set of 12 additional compounds (5 teratogens, 7 nonteratogens), 10 were correctly classified by this approach (83% concordance). The false positive rate in the training and test sets was 24 and 0%, respectively, indicating that this assay has potential to identify teratogens.
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Dysfunction of organic anion transporting polypeptide 1a1 alters intestinal bacteria and bile acid metabolism in mice.
PLoS ONE
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Organic anion transporting polypeptide 1a1 (Oatp1a1) is predominantly expressed in liver and is able to transport bile acids (BAs) in vitro. Male Oatp1a1-null mice have increased concentrations of taurodeoxycholic acid (TDCA), a secondary BA generated by intestinal bacteria, in both serum and livers. Therefore, in the present study, BA concentrations and intestinal bacteria in wild-type (WT) and Oatp1a1-null mice were quantified to investigate whether the increase of secondary BAs in Oatp1a1-null mice is due to alterations in intestinal bacteria. The data demonstrate that Oatp1a1-null mice : (1) have similar bile flow and BA concentrations in bile as WT mice; (2) have a markedly different BA composition in the intestinal contents, with a decrease in conjugated BAs and an increase in unconjugated BAs; (3) have BAs in the feces that are more deconjugated, desulfated, 7-dehydroxylated, 3-epimerized, and oxidized, but less 7-epimerized; (4) have 10-fold more bacteria in the small intestine, and 2-fold more bacteria in the large intestine which is majorly due to a 200% increase in Bacteroides and a 30% reduction in Firmicutes; and (5) have a different urinary excretion of bacteria-related metabolites than WT mice. In conclusion, the present study for the first time established that lack of a liver transporter (Oatp1a1) markedly alters the intestinal environment in mice, namely the bacteria composition.
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Organic anion transporting polypeptide 1a1 null mice are sensitive to cholestatic liver injury.
Toxicol. Sci.
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Organic anion transporting polypeptide 1a1 (Oatp1a1) is predominantly expressed in livers of mice and is thought to transport bile acids (BAs) from blood into liver. Because Oatp1a1 expression is markedly decreased in mice after bile duct ligation (BDL). We hypothesized that Oatp1a1-null mice would be protected against liver injury during BDL-induced cholestasis due largely to reduced hepatic uptake of BAs. To evaluate this hypothesis, BDL surgeries were performed in both male wild-type (WT) and Oatp1a1-null mice. At 24 h after BDL, Oatp1a1-null mice showed higher serum alanine aminotransferase levels and more severe liver injury than WT mice, and all Oatp1a1-null mice died within 4 days after BDL, whereas all WT mice survived. At 24 h after BDL, surprisingly Oatp1a1-null mice had higher total BA concentrations in livers than WT mice, suggesting that loss of Oatp1a1 did not prevent BA accumulation in the liver. In addition, secondary BAs dramatically increased in serum of Oatp1a1-null BDL mice but not in WT BDL mice. Oatp1a1-null BDL mice had similar basolateral BA uptake (Na(+)-taurocholate cotransporting polypeptide and Oatp1b2) and BA-efflux (multidrug resistance-associated protein [Mrp]-3, Mrp4, and organic solute transporter ?/?) transporters, as well as BA-synthetic enzyme (Cyp7a1) in livers as WT BDL mice. Hepatic expression of small heterodimer partner Cyp3a11, Cyp4a14, and Nqo1, which are target genes of farnesoid X receptor, pregnane X receptor, peroxisome proliferator-activated receptor alpha, and NF-E2-related factor 2, respectively, were increased in WT BDL mice but not in Oatp1a1-null BDL mice. These results demonstrate that loss of Oatp1a1 function exacerbates cholestatic liver injury in mice and suggest that Oatp1a1 plays a unique role in liver adaptive responses to obstructive cholestasis.
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The Toxicology Education Summit: building the future of toxicology through education.
Toxicol. Sci.
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Toxicology and careers in toxicology, as well as many other scientific disciplines, are undergoing rapid and dramatic changes as new discoveries, technologies, and hazards advance at a blinding rate. There are new and ever increasing demands on toxicologists to keep pace with expanding global economies, highly fluid policy debates, and increasingly complex global threats to public health. These demands must be met with new paradigms for multidisciplinary, technologically complex, and collaborative approaches that require advanced and continuing education in toxicology and associated disciplines. This requires paradigm shifts in educational programs that support recruitment, development, and training of the modern toxicologist, as well as continued education and retraining of the midcareer professional to keep pace and sustain careers in industry, government, and academia. The Society of Toxicology convened the Toxicology Educational Summit to discuss the state of toxicology education and to strategically address educational needs and the sustained advancement of toxicology as a profession. The Summit focused on core issues of: building for the future of toxicology through educational programs; defining education and training needs; developing the "Total Toxicologist"; continued training and retraining toxicologists to sustain their careers; and, finally, supporting toxicology education and professional development. This report summarizes the outcomes of the Summit, presents examples of successful programs that advance toxicology education, and concludes with strategies that will insure the future of toxicology through advanced educational initiatives.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.