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Macrophages and Their Potential Role in Hyperreactive Airways Disease
Published in Devendra K. Agrawal, Robert G. Townley, Inflammatory Cells and Mediators in Bronchial Asthma, 2020
β-glucuronidase is an enzyme located in lysosomes that will catalyze the hydrolysis of conjugated glucuronides. At this time there are no data suggesting that this enzyme is, by itself, either directly or indirectly toxic to epithelia. However, it is a marker for macrophage activation, and release of this enzyme closely parallels release of superoxide.102
Nonessential Dietary Components: Bioflavonoids and Curcumin
Published in Luke R. Bucci, Nutrition Applied to Injury Rehabilitation and Sports Medicine, 2020
In 1985, Srivastava and Srimal, from the Division of Pharmacology at the Central Drug Research Institute, Lucknow, India, attempted to further elucidate the mechanism for antiinflammatory effects of curcumin by comparison with ibuprofen, an NSAID with known antiinflammatory activity and known mechanisms.1353 The effects of oral doses of curcumin on uncoupling of oxidative phosphorylation, stabilization of lysosomal membranes, release of adrenal steroid hormones, and inhibition of prostaglandin biosynthesis (known mechanisms of NSAIDs) were measured in rats. Ibuprofen was 10 times more effective by weight than curcumin at reduction of granuloma formation in the granuloma pouch and sponge pellet models (200 mg/kg of curcumin was equipotent to 20 mg/kg of ibuprofen). Acid phosphatase and cathepsin-D enzyme activities in livers and granuloma tissues of these rats were both reduced by curcumin and ibuprofen. Lysosomal integrity was maintained to a greater degree by curcumin than ibuprofen at doses up to 1 mM. Likewise, inhibition of lysosomal β-glucuronidase activity was inhibited by curcumin at high doses, but not by ibuprofen. Both curcumin and ibuprofen elevated ATPase activity in liver and granuloma tissues, with ibuprofen being 10 times more effective than curcumin.
Molecular Radiation Biology
Published in Kedar N. Prasad, Handbook of RADIOBIOLOGY, 2020
The β-glucuronidase activity is higher in the tubule than in the interstitial cells. This enzyme activity is nearly absent from the periphery of the tubules, perhaps due to the regeneration of cells at the periphery 15 days after exposure. Surprisingly, at 30 days, the interstitial tissue has considerable enzyme activity, whereas the periphery of tubules has very little enzyme activity. It is interesting to note that the site of β-glucuronidase activity moves from the tubules to the Leydig cells after regeneration. This perhaps confirms the importance of Leydig cell secretions for spermatogenesis.
Melatonin and alcohol-related disorders
Published in Chronobiology International, 2020
Natalia Kurhaluk, Halyna Tkachenko
Acetyl-N-β-glucosaminidase (NAG) represents lysosomal enzymes that are sensitive indicators of the degree of damage to kidney tubular epithelial cells in the course of occupational xenobiotic exposure (Marchewka et al. 2005; Voss et al. 2005). The high level of NAG activity observed in mice following ethanol administration represents its effects on lysosomal membrane permeability. β-GR (β-glucuronidase) activity may include impaired glycosylation and trafficking of the enzyme to the organelles, leakage from damaged cells and activated Kupffer cells or from blood due to the reduced clearance of lysosomal enzymes. LPS mediated by the CD14 receptor activates Kupffer cells to produce prostaglandin D2 and E2, reactive nitrogen and oxygen species, endothelin-1, tumor necrosis factor-α and interleukin 1 and 6, resulting in the hypermetabolic liver state (Waszkiewicz et al. 2009, 2012). As shown by Yao et al. (2018), LPS induces expression of endogenous β-galactosidase (β-GD) via a signaling cascade of c-myc in hepatocytes and intrahepatic biliary epithelial cells in a dose- and time-dependent manner. Wilson (1990) demonstrated an increase in β-GD activity in the blood of ethanol-treated rats with protein deficiency. An increase in β-GD activity was also noted in a group of patients with alcohol-related pancreatitis.
Identification of UGTs and BCRP as potential pharmacokinetic determinants of the natural flavonoid alpinetin
Published in Xenobiotica, 2019
Chunli Qi, Jiangnan Fu, Huinan Zhao, Huijie Xing, Dong Dong, Baojian Wu
Our finding that the BCRP pump mediated efflux transport of alpinetin glucuronide is consistent with previous studies in which BCRP was involved in the excretion of many flavonoid glucuronides (Liu et al., 2006; Xu et al., 2009; Zhou et al., 2011). Another finding that inhibition of BCRP led to down-regulation of cellular glucuronidation (Figure 6) lend a strong support to the kinetic interplay between UGTs and efflux transporters as noted previously (Zhang et al., 2015). The possible mechanism for the occurrence of this kinetic interplay was proposed. Inhibition of BCRP results in reduced glucuronide excretion, leading to marked accumulation of glucuronide within the cells. Intracellular glucuronide accumulation activates the deglucuronidation pathway (mediated by β-glucuronidase (Sun et al., 2015), thereby facilitating conversion of glucuronide back to the parent compound and reducing the total cellular glucuronidation. It was noteworthy that we performed experiments to confirm that the transporter inhibitor Ko143 did not influence the enzyme activity and to ensure the inhibitor was appropriately used (Figure 5). This is necessary because in a previous study the transporter inhibitor has the potential to alter UGT activity as well (Quan et al., 2015).
Effect of Saccharomyces Boulardii Cell Wall Extracts on Colon Cancer Prevention in Male F344 Rats Treated with 1,2-Dimethylhydrazine
Published in Nutrition and Cancer, 2018
Olivier Fortin, Blanca R. Aguilar-Uscanga, Khanh D. Vu, Stephane Salmieri, Monique Lacroix
β-glucosidase (EC 3.2.1.21) and β-glucuronidase (EC 3.2.1.31) assays were based on Park, Bae, Han, Choi and Kim (32) with some modifications. Enzymatic activities of β-glucosidase and β-glucuronidase were determined using, respectively, p-nitrophenyl β-D-glucopyranoside and p-nitrophenyl β-D-glucuronide as substrates. Briefly, 30 µl of samples from faecal supernatants were added into a 96-well microplate. A volume of 20 µl of 2 mmol/l respective substrate was added into each well and the microplate was incubated at 37°C for 15 min. Then, the reaction was stopped by adding 250 µl of 10 mmol/l NaOH. Absorbance values were measured at 405 nm using a microplate reader (Biotek). Blank consisted of 30 µl of heat-inactivated caecum supernatants. Based on the fact that one activity unit is defined as the quantity of enzyme required to hydrolyze substrate into one µmol/l of p-nitrophenol per minute, a standard curve of p-nitrophenol ranging from 0 to 300 µmol/l was used to calculate the specific activities of both enzymes which were expressed as units of p-nitrophenol formed per min per mg protein of caecum supernatant.