Toxicological sciences : an official journal of the Society of Toxicology, 2013
Hepatocellular carcinoma (HCC) mostly develops in patients with advanced fibrosis; however, the m... more Hepatocellular carcinoma (HCC) mostly develops in patients with advanced fibrosis; however, the mechanisms of interaction between a genotoxic insult and fibrogenesis are not well understood. This study tested a hypothesis that fibrosis promotes HCC via a mechanism that involves activation of liver stem cells. First, B6C3F1 mice were administered diethylnitrosamine (DEN; single ip injection of 1mg/kg at 14 days of age). Second, carbon tetrachloride (CCl(4); 0.2ml/kg, 2/week ip starting at 8 weeks of age) was administered for 9 or 14 weeks to develop advanced liver fibrosis. In animals treated with DEN as neonates, presence of liver fibrosis led to more than doubling (to 100%) of the liver tumor incidence as early as 5 months of age. This effect was associated with activation of cells with progenitor features in noncancerous liver tissue, including markers of replicative senescence (p16), oncofetal transformation (Afp, H19, and Bex1), and increased "stemness" (Prom1 and Epca...
Journal of pharmaceutical and biomedical analysis, 2014
Dietary supplements are a multi-billion dollar business, with yearly profit increases. Allegedly ... more Dietary supplements are a multi-billion dollar business, with yearly profit increases. Allegedly safe, these supplements are marketed to a variety of niches, encompassing claims from immune support to weight loss. Six sports nutrition supplements were acquired that were labeled to contain the furanocoumarin(s) bergamottin and/or 6',7'-dihydroxybergamottin (DHB), both of which are potent irreversible inhibitors of the prominent drug metabolizing enzyme cytochrome P450 3A (CYP3A). Both furanocoumarins are typically present in grapefruit juice, which has been shown to inhibit intestinal CYP3A, perpetrating an increase in the systemic exposure of certain concomitant 'victim' drugs. The acquired supplements were analyzed using ultra-performance liquid chromatography coupled to both a photodiode array (PDA) detector and a triple quadrupole mass spectrometer (MS). Contrary to the product labeling, four of the supplements contained no detectable quantities of either furanoco...
The Journal of pharmacology and experimental therapeutics, 2014
Dietary substances, including herbal products and citrus juices, can perpetrate interactions with... more Dietary substances, including herbal products and citrus juices, can perpetrate interactions with conventional medications. Regulatory guidances for dietary substance-drug interaction assessment are lacking. This deficiency is due in part to challenges unique to dietary substances, a lack of requisite human-derived data, and limited jurisdiction. An in vitro-in vivo extrapolation (IVIVE) approach to help address some of these hurdles was evaluated using the exemplar dietary substance grapefruit juice (GFJ), the candidate marker constituent 6',7'-dihydroxybergamottin (DHB), and the purported victim drug loperamide. First, the GFJ-loperamide interaction was assessed in 16 healthy volunteers. Loperamide (16 mg) was administered with 240 ml of water or GFJ; plasma was collected from 0 to 72 hours. Relative to water, GFJ increased the geometric mean loperamide area under the plasma concentration-time curve (AUC) significantly (1.7-fold). Second, the mechanism-based inhibition kin...
The Journal of pharmacology and experimental therapeutics, 2015
Morphine is metabolized in humans to morphine-3-glucuronide (M3G) and the pharmacologically activ... more Morphine is metabolized in humans to morphine-3-glucuronide (M3G) and the pharmacologically active morphine-6-glucuronide (M6G). The hepatobiliary disposition of both metabolites relies upon multidrug resistance-associated proteins Mrp3 and Mrp2, located on the sinusoidal and canalicular membrane, respectively. Nonalcoholic steatohepatitis (NASH), the severe stage of nonalcoholic fatty liver disease, alters xenobiotic metabolizing enzyme and transporter function. The purpose of this study was to determine whether NASH contributes to the large interindividual variability and postoperative adverse events associated with morphine therapy. Male Sprague-Dawley rats were fed a control diet or a methionine- and choline-deficient diet to induce NASH. Radiolabeled morphine (2.5 mg/kg, 30 µCi/kg) was administered intravenously, and plasma and bile (0-150 or 0-240 minutes), liver and kidney, and cumulative urine were analyzed for morphine and M3G. The antinociceptive response to M6G (5 mg/kg) ...
Toxicological sciences : an official journal of the Society of Toxicology, 2013
Hepatocellular carcinoma (HCC) mostly develops in patients with advanced fibrosis; however, the m... more Hepatocellular carcinoma (HCC) mostly develops in patients with advanced fibrosis; however, the mechanisms of interaction between a genotoxic insult and fibrogenesis are not well understood. This study tested a hypothesis that fibrosis promotes HCC via a mechanism that involves activation of liver stem cells. First, B6C3F1 mice were administered diethylnitrosamine (DEN; single ip injection of 1mg/kg at 14 days of age). Second, carbon tetrachloride (CCl(4); 0.2ml/kg, 2/week ip starting at 8 weeks of age) was administered for 9 or 14 weeks to develop advanced liver fibrosis. In animals treated with DEN as neonates, presence of liver fibrosis led to more than doubling (to 100%) of the liver tumor incidence as early as 5 months of age. This effect was associated with activation of cells with progenitor features in noncancerous liver tissue, including markers of replicative senescence (p16), oncofetal transformation (Afp, H19, and Bex1), and increased "stemness" (Prom1 and Epca...
Journal of pharmaceutical and biomedical analysis, 2014
Dietary supplements are a multi-billion dollar business, with yearly profit increases. Allegedly ... more Dietary supplements are a multi-billion dollar business, with yearly profit increases. Allegedly safe, these supplements are marketed to a variety of niches, encompassing claims from immune support to weight loss. Six sports nutrition supplements were acquired that were labeled to contain the furanocoumarin(s) bergamottin and/or 6',7'-dihydroxybergamottin (DHB), both of which are potent irreversible inhibitors of the prominent drug metabolizing enzyme cytochrome P450 3A (CYP3A). Both furanocoumarins are typically present in grapefruit juice, which has been shown to inhibit intestinal CYP3A, perpetrating an increase in the systemic exposure of certain concomitant 'victim' drugs. The acquired supplements were analyzed using ultra-performance liquid chromatography coupled to both a photodiode array (PDA) detector and a triple quadrupole mass spectrometer (MS). Contrary to the product labeling, four of the supplements contained no detectable quantities of either furanoco...
The Journal of pharmacology and experimental therapeutics, 2014
Dietary substances, including herbal products and citrus juices, can perpetrate interactions with... more Dietary substances, including herbal products and citrus juices, can perpetrate interactions with conventional medications. Regulatory guidances for dietary substance-drug interaction assessment are lacking. This deficiency is due in part to challenges unique to dietary substances, a lack of requisite human-derived data, and limited jurisdiction. An in vitro-in vivo extrapolation (IVIVE) approach to help address some of these hurdles was evaluated using the exemplar dietary substance grapefruit juice (GFJ), the candidate marker constituent 6',7'-dihydroxybergamottin (DHB), and the purported victim drug loperamide. First, the GFJ-loperamide interaction was assessed in 16 healthy volunteers. Loperamide (16 mg) was administered with 240 ml of water or GFJ; plasma was collected from 0 to 72 hours. Relative to water, GFJ increased the geometric mean loperamide area under the plasma concentration-time curve (AUC) significantly (1.7-fold). Second, the mechanism-based inhibition kin...
The Journal of pharmacology and experimental therapeutics, 2015
Morphine is metabolized in humans to morphine-3-glucuronide (M3G) and the pharmacologically activ... more Morphine is metabolized in humans to morphine-3-glucuronide (M3G) and the pharmacologically active morphine-6-glucuronide (M6G). The hepatobiliary disposition of both metabolites relies upon multidrug resistance-associated proteins Mrp3 and Mrp2, located on the sinusoidal and canalicular membrane, respectively. Nonalcoholic steatohepatitis (NASH), the severe stage of nonalcoholic fatty liver disease, alters xenobiotic metabolizing enzyme and transporter function. The purpose of this study was to determine whether NASH contributes to the large interindividual variability and postoperative adverse events associated with morphine therapy. Male Sprague-Dawley rats were fed a control diet or a methionine- and choline-deficient diet to induce NASH. Radiolabeled morphine (2.5 mg/kg, 30 µCi/kg) was administered intravenously, and plasma and bile (0-150 or 0-240 minutes), liver and kidney, and cumulative urine were analyzed for morphine and M3G. The antinociceptive response to M6G (5 mg/kg) ...
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