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Liver activity, effect

In this study, P-450-related enzyme activities (benzphetamine N-demethylase, 7-ethoxycoumarin O-deethylase) were also measured in liver homogenates (prepared 24 hours after the last treatment) from rats treated orally with MEK for 1-7 days and compared to the activity obtained with phenobarbital treatment (80 mg/kg intraperitoneally for 3 days) (Robertson et al. 1989). Total cytochrome P-450 was also measured. No consistent change was noted in benzphetamine N-demethylase activity as the result of MEK treatment, while 7-ethoxycoumarin O-deethylase was over 3 times higher than controls and comparable to phenobarbital induction. Total P-450 levels were increased to approximately 150-200% of controls with MEK and to 570% of control by phenobarbital. The authors concluded that the potentiating effects of MEK on the neurotoxicity of -hexane appear to arise, at least in part, from the activating effects of MEK on selected microsomal enzymes responsible for -hexane activation. [Pg.105]

Morris, M.E. and Pang, K.S. (1987) Competition between two enzymes for substrate removal in liver modulating effects due to substrate recruitment of hepatocyte activity. Journal of Pharmacokinetics and Biopharmaceutics, 15, 473-496. [Pg.312]

Mueller and Miller (33) and Brodie et al. (34) were the first to show that enzymes in the microsomal fraction of rat liver could effectively oxidize xenobiotics. Comparable enzymes (aryl hydrocarbon monooxygenases) were later reported in the hepatic tissues of fresh water and marine fish by Creaven et al. (35) and Buhler and Rasmusson (36). Reconstituted hepatic microsomal systems require cytochrome P-450 for monooxygenase activity in both mammals (37) and fish (38,39). Bend et al. [Pg.64]

Zang et al [140] reported the liver protective effects of the saponins isolated from A. membranaceus and A. sieversianus against chemical injury induced by CCU, D-galactosamine and acetaminophen in mice. In all cases there were positive activities and the saponins inhibited the rise in SGPT levels, decreased the malondialdehyde (MDA) content and increased the glutathione reduced (GSH) concentration in mouse liver. The same compounds were also evaluated in cultured rat hepatocytes, and the results indicated that the activity may be due to to the antioxidative activity of the saponins, since the content of liver protein in treated mice was more than the control. Moreover, in all treated mice, the level of hepatic microsomal cytochrome P-450 was increased. The liver metabolism and immunoregulating action produced by saponins may be also involved in their hepato-protective effects. Similar results were obtained by Zhang et al [141] when they studied the activity in vitro and... [Pg.219]

Nucleotidases have been studied in liver from various species and activity has been identified in lysosomes, cytoplasmic supernatants and plasma membrane preparations. Arsenis and Touster (31) have purified a 5 -nucleotidase from rat liver lysosomes to apparent homogeneity. The enzyme is unusual in that it hydrolyzes 2 -, 3 -, and 5 -mononucleotides equally well with preference for 5 -dAMP. It also hydrolyzes FMN, p-nitrophenyl phosphate, and /J-glycerol phosphate, but not inorganic pyrophosphate or bis(p-nitrophenyl) phosphate. Unlike the 5 -nucleotidases described thus far, divalent cations such as Co2+, Mn2+, and Mg2+ have no activating effect, but EDTA is inhibitory. In spite of the broad substrate specificity kinetic experiments indicate that a single enzyme is involved. Because of its broad substrate specificity it has been suggested (SI) that it may play a key role in lysosomal catabolism of nucleic acids. [Pg.343]

Controversy has attended both of these claims, but it has been established that wit/o-inositol does have lipotropic activity when it is added to a fat-free diet which is low in other lipotropic agents (for example, choline, or methionine).116 Even here, the inositol does not completely prevent the development of a fatty liver this effect can be produced with choline, with which wq/o-inositol has a supplementary effect. The fatty livers produced (in rats) by the diet mentioned are characteristically high in cholesterol esters. The designation biotin fatty liver for this condition is a misnomer.117... [Pg.162]

Paris BL, Marcum AE, Clarin JR, et al. Effects of common organic solvents on CYP2E1 activity in human liver microsomes effects of order of addition and preincubation with NADPH. Drug Metab Rev 2003 35(suppl 2) 180. [Pg.352]

Fig. 21.2 Major effects of AMPK activation on numerous tissues. AMPK plays a key role in regulating whole body energy storage and expenditure. In hypothalamus, AMPK is involved in regulation of satiety and food intake. Activation of AMPK in the hypothalamus increases food intake, whereas inhibition decreases intake. In peripheral tissues such as skeletal muscle and liver, activation of AMPK increases energy expenditure by stimulating mitochondrial genesis and energy substrate utilization. AMPK also regulates lipolysis in adipose tissue and insulin secretion in pancreas. Fig. 21.2 Major effects of AMPK activation on numerous tissues. AMPK plays a key role in regulating whole body energy storage and expenditure. In hypothalamus, AMPK is involved in regulation of satiety and food intake. Activation of AMPK in the hypothalamus increases food intake, whereas inhibition decreases intake. In peripheral tissues such as skeletal muscle and liver, activation of AMPK increases energy expenditure by stimulating mitochondrial genesis and energy substrate utilization. AMPK also regulates lipolysis in adipose tissue and insulin secretion in pancreas.
In 1926 Minot and Murphy (4) announced that whole liver was effective in the treatment of pernicious anemia. The initial assay methods, which were clinical (5), coupled with what we now know are the exceptionally small amounts of Bi2 (even in a relatively rich source such as liver) required that two more decades pass before Folkers (6) and Smith (7) in 1948 simultaneously isolated crystalline vitamin Bi2 (1, R = CN). A further decade passed before it was realized that the so-called vitamin (cyanocobalamin) was an artifact of the isolation procedure and that the enzymatically active species is the vitamin Bi2 coenzyme (5 -deoxyadenosylcobalamin, 1, R = 5 -deoxyadenosyl). This initial observation arose during Barkers study on the conversion... [Pg.70]

Inoue et al. 1988b). This was due to competitive inhibition of the oxidation mechanisms involved in the metabolism of benzene. Phenobarbital pretreatment of the rats alleviated the suppressive effect of toluene on benzene hydroxylation by the induction of oxidative activities in the liver. This effect has been observed in other studies in rats (Purcell et al. 1990). [Pg.244]

Potentially serious side-effects of azathioprine that are dose- and duration-dependent are haematological (leukopenia and thrombocytopenia) and gastrointestinal. Azathioprine is metabolized to 6-mercaptopurine, and both compounds are rapidly eliminated from blood and oxidized in red cells and liver. Activation of 6-mercaptopurine occurs via hypoxanthine-guanine phosphoribosyl-transferase. 6-Mercaptopurine is inactivated by thiopurine S-methyltransferase and by xanthine oxidase. [Pg.288]

Buzzelll, G., Moscarella, S., Giusti, A., Duchini, A., Marena, C., Lam-pertfco, M. A pilot study on the liver protective effect of silybin-phosphatidylcholine complex (IdB 1016) in chronic active hepatitis. Int. J. Clin. Pharmacol. Ther. Toxicol. 1993 31 456-460... [Pg.888]

Trichloroethane produces mild hepatic effects in animals. The primary effects reported are mild histopathological changes in the liver and effects on liver enzyme activities. Acute exposure to high... [Pg.45]

Effect (Decreases in Increases PPARa Triglycerides or in Liver Activation VLDL-Triglycerides) Weight... [Pg.458]


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See also in sourсe #XX -- [ Pg.104 ]




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