Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.31 (beta-glucuronidase)
7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1 Rabbit isolated peritoneal neutrophil polymorphonuclear leucocytes were depleted of calcium by exposure for 1 h to calcium-free bathing fluid at 4 degrees C. 2 Addition of calcium ions to the previously calcium-depleted calls during incubation at 37 degrees C stimulated the release of beta-glucuronidase and of lysozyme but not of lactate dehydrogenase. 3 Low concentrations of indomethacin, flufenamate or salicylate, such as those which occur in the blood plasma after therapeutic doses of these drugs, selectively inhibited the calcium-induced release of beta-glucuronidase. The slight release of this enzyme which occurred in the absence of added calcium ions was not altered by these drugs, neither was the release of lactate dehydrogenase. 4 Release of lysozyme was inhibited by low concentrations of salicylate, amidopyrine or oxyphenbutazone, independent of the presence or absence of calcium ions. 5 Chloroquine, hydrocortisone or colchicine did not alter the release of leucocyte enzymes.
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PMID:Effect of indomethacin and related drugs on the calcium ion-dependent secretion of lysosomal and other enzymes by neutrophil polymorphonuclear leucocytes in vitro. 40 67

In vitro concentrations of chloroquine, amodiaquine, quinine, and mefloquine were assessed with respect to functional responses (chemotaxis, anion superoxide generation, and lysosomal enzyme release) of rat polymorphonuclear leukocytes (PMN) collected after induction of acute pleural inflammation. Chloroquine, amodiaquine, and mefloquine exhibited dose-dependent inhibition of: (1) random migration and oriented migration of PMN; and (2) opsonized zymosan- or phorbol myristate acetate-stimulated PMN O2- release. These effects were not stimulus-specific and were largely reversed by washing the cells before stimulation Mefloquine was the most effective drug. Quinine had no effect on PMN migration. Apart from quinine, the drugs induced similar dose-dependent increases in beta-glucuronidase release from unstimulated PMN. Only quinine inhibited the enzyme release from stimulated PMN. Our data show that the antimalarial derivatives affect PMN functions in various ways and suggest that their effects reflect nonspecific modifications of cellular membrane.
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PMID:Effects of some antimalarial drugs on rat inflammatory polymorphonuclear leukocyte function. 254 68

Chloroquine, when introduced into isolated perfused rat livers, caused a substantial output of cholesterol into bile, occurring after 30 min and peaking at 60 min, whereas the biliary output of acid phosphatase and beta-glucuronidase increased only after 90 min. The origins of this bile-salt-independent cholesterol are discussed.
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PMID:Effect of chloroquine on biliary lipid and lysosomal enzyme output in the isolated perfused rat liver at low bile salt output rates. 368 19

Mouse peritoneal macrophages were cultured for 3 days with or without zymosan and at the same time exposed to various inhibitors of cellular metabolism. The cells were assayed for selective release of a lysosomal enzyme, and for cytotoxic activity against a tumor cell line, L-929-cells. Selective release of beta-glucuronidase was demonstrated in the supernatants from zymosan-stimulated macrophages. The stimulated macrophages were cytotoxic for the tumors cells, evaluated by measuring release of radioactivity during subsequent 4 days' co-culture of macrophages and 14C-thymidine-labelled tumor cells, and by counting cells per culture. Colchicine caused a slight, variable reduction in enzyme release and no change in cytotoxic effect from stimulated macrophages. Monensin decreased extracellular enzyme secretion and reduced the cytotoxicity in stimulated macrophages to control levels. Chloroquine caused a similar reduction in lysosomal enzyme release and cytotoxic activity in zymosan-stimulated cells. This inhibitor increased the enzyme release from control cells and induced a small, variable cytotoxic effect from these cells. The data indicate co-variation between macrophage-mediated cytotoxicity and a secretory process which can be blocked by monensin. The need for intact lysosomal function was also demonstrated.
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PMID:Cytotoxic activity of stimulated mouse macrophages exposed to various inhibitors. 371 7

The pattern of activity of certain membrane-associated enzymes was followed in the erythrocytes of Plasmodium berghei-infected Mastomys natalensis. Parasitized erythrocytes were separated from non-parasitized populations by percoll-density gradient centrifugation. The activity of adenylate cyclase was markedly increased while those of ATPase, acid phosphatase, beta-glucuronidase and N-acetyl-beta-D-glucosaminidase were considerably decreased in the membrane preparations of parasitized erythrocytes as compared to normal erythrocytes. There was a decrease in the activity of ATPase and an increase of adenylate cyclase in the membrane preparations of non-parasitized erythrocytes. However, other enzymes did not alter to a significant extent in non-parasitized erythrocytes. Chloroquine (in vitro) stimulated adenylate cyclase, Na+, K+-ATPase and Ca++Mg++-ATPase while acetylcholinesterase was significantly inhibited.
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PMID:Erythrocyte membrane-bound enzymes in Mastomys natalensis during Plasmodium berghei infection. 608 78

Receptor-mediated endocytosis of rat preputial beta-glucuronidase and the glycoconjugate mannose-BSA by rat alveolar macrophages is inhibited by chloroquine and ammonium chloride. We have previously reported that these drugs cause a loss of cell surface binding activity and that they do not inhibit internalization of receptor ligand complexes when incubated with cells at 37 degrees C. In this report we more clearly delineate the intracellular site of weak base inhibition of receptor recycling and the mechanism of that inhibition. From our analysis of the kinetics of ligand transport we conclude that there are two functionally distinct intracellular pools of receptor. One of these, the cycling pool, is not sensitive to the presence of weak bases, and receptor-ligand complexes return from this pool to the cell surface intact. The second pool is responsible for the time-dependent intracellular delivery of ligand to acid vesicles, which is inhibited by weak bases. Chloroquine and ammonium chloride appear to inhibit the dissociation of receptor-ligand complexed in this second pool and thereby the production of free receptors for the continuation of receptor-mediated endocytosis. We examine the internalization and binding of ligand in normal and paraformaldehyde-treated cells and find that these are strongly affected by pH. In particular, the dissociation rate of receptor ligand complexes is enhanced greater than 7.5 fold by lowering the medium pH from 7 to 6. From these results we propose that weak bases raise the pH of acid intracellular compartments, slowing the rate of receptor-ligand dissociation and thereby reducing the cellular pool of free receptors available for further uptake of ligand. In addition, we demonstrate that receptor-ligand complexes cannot return to the cell surface from the amine-sensitive (acid) intracellular pool that led us to call this the nonreleasable pool. This final observation indicates that receptor movements through these two pools are functionally distinct processes.
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PMID:Mannose-specific endocytosis receptor of alveolar macrophages: demonstration of two functionally distinct intracellular pools of receptor and their roles in receptor recycling. 627 62

In these experiments, we tested the hypothesis that chloroquine, a lysosomotropic agent which modifies protein and lipid metabolism by hepatocyte lysosomes, would alter the biliary excretion of lipids and lysosomal enzymes. We treated male rats for 5 days with intraperitoneal chloroquine (50 mg/kg body wt, n = 9) or saline (n = 8) and collected bile for 6 h via bile fistulas; rats were then killed and livers homogenized for biochemical analyses or processed for electron microscopy. Chloroquine markedly increased the biliary excretion of three lysosomal enzymes (mean +/- SEM) expressed as milliunits of activity per gram liver: N-acetyl-beta-glucosaminidase (24.4 +/- 2.7 vs. 12.5 +/- 1.4, p less than 0.01), beta-glucuronidase (26.4 +/- 4.7 vs. 10.9 +/- 1.4, p less than 0.01), and beta-galactosidase (9.8 +/- 1.7 vs. 5.5 +/- 0.8, p less than 0.05). In contrast, biliary outputs of enzymes associated with other organelles (e.g., alkaline phosphodiesterase I and lactic dehydrogenase) were unaffected by chloroquine treatment. Biliary cholesterol secretion was decreased after chloroquine administration (0.28 +/- 0.02 mumol/g liver vs. 0.39 +/- 0.03 mumol/g liver, p less than 0.01), but bile acid and phospholipid secretion were not altered; as a result, cholesterol saturation of bile decreased by 22% (p less than 0.05). Hepatic activities of all three lysosomal enzymes were increased after chloroquine administration (p less than 0.04); activities of enzymes associated with mitochondria, plasma membrane, endoplasmic reticulum, and cell sap were not altered. Morphometric analysis of electron micrographs of rat livers demonstrated a marked increase (p less than 0.001) in the number of lysosomelike vesicles and autophagic vacuoles in the vicinity of bile canaliculi after chloroquine administration; also, the number of canalicular microvilli decreased (p less than 0.003) after chloroquine treatment. We conclude that altered hepatic lysosomal morphology and function after chloroquine is accompanied by marked changes in outputs of lipids and lysosomal enzymes into bile. These findings call attention to a possible role for hepatic lysosomes in modulating biliary protein and lipid secretion.
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PMID:Effect of chloroquine on the form and function of hepatocyte lysosomes. Morphologic modifications and physiologic alterations related to the biliary excretion of lipids and proteins. 641 91

Chloroquine-resistant (CQr) clones (CQ-21 and CQ-22) have been isolated from mutagenized hamster lung V79 cells by exposing the cells to a high dose of chloroquine. CQ-21 and CQ-22 showed about 3-fold higher resistance to chloroquine than the parental V79 cells, and they showed specific cross-resistance to another amine, NH4Cl, which is also concentrated in lysosomes. CQr clone showed no cross-resistance to other unrelated agents. Chloroquine-induced inhibition of [125I]ricin internalization was observed in both cell lines at neutral pH, but the inhibition of uptake was less in the variant. Also, the degradation of endogenous protein was slowed in the mutant; further, treatment of cells with 30 micrograms/ml of chloroquine inhibited the degradation of endogenous proteins in the parental V79, but not in CQ-22 cells. Similar levels of acid phosphatase, beta-glucuronidase and cathepsin D were observed in V79 and CQ-22 cells, but the level of cathepsin B was lower in the mutant. Electron microscopy showed an increased number of electron-dense bodies, possibly autophagosomes/lysosomes, in the mutant cells grown for 4 days with 5 micrograms/ml of chloroquine. Similar aberrant structures were observed in the parental V79 cells treated for only 3 h with 5 micrograms/ml of chloroquine.
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PMID:Isolation of chloroquine-resistant Chinese hamster V79 cell variants that are also resistant to ammonium chloride. 665 68

Chloroquine is widely used as a lysosomal enzyme inhibitor, and while effects on DNA repair and membrane recycling have also been reported, there has been no investigation of effects on the processing of secretory products. To determine whether chloroquine had any effect on secretion and secretory organelles, we monitored the effects of low concentrations (10(-6) M) of chloroquine on a cell population which normally secretes copious amounts of a simple polypeptide (PRL) in vitro and in which there exists a subpopulation of cells which releases PRL very rapidly after synthesis. Cultured anterior pituitary cells were exposed to 10(-6) M chloroquine for 6, 12, 24, or 48 h. At these times, the culture medium was used for determination of PRL content and beta-glucuronidase activity, and the cells were used for determination of DNA content and level of beta-glucuronidase activity or for electron microscopy. Treatment with 10(-6) M chloroquine resulted in 20-40% inhibition of PRL release (maximum inhibition at any dose), no change in the total amount of beta-glucuronidase activity, and a number of ultrastructural changes in the Golgi region consistent with an accumulation of chloroquine within the cisternae and immature granules. The effects of chloroquine on Golgi morphology were unaltered by cotreatment with 50 micrograms/ml cycloheximide, and chloroquine had no affect on PRL synthesis. These results are consistent with an adverse effect of chloroquine on packaging of PRL into immature granules in the Golgi apparatus, without any effect on the release of mature secretory granules.
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PMID:Chloroquine affects prolactin secretion and Golgi morphology in the mammotroph. 669 60

Cultured smooth muscle cells from pig aortas were incubated with low density lipoproteins (LDL) and chloroquine for up to 5 days, as an in vitro model for lipid accumulation in atherosclerosis. Cells incubated with LDL alone had a normal morphology, except that some cells contained large lipid droplets. The activities of acid phosphatase, catalase and malate dehydrogenase were increased in homogenates prepared from these cells. Cells incubated with chloroquine alone developed large autophagic vacuoles. The activities of the three acid hydrolases, acid phosphatase, N-acetyl-beta-glucosaminidase and beta-glucuronidase, were decreased, as was the proteolytic activity of the cell homogenates at acid pH toward 125I-labelled LDL. There was, however, a transient increase in the activity of malate dehydrogenase. Chloroquine by itself was toxic to the cells, but LDL protected against this toxic effect. Cells incubated with LDL and chloroquine together developed both autophagic vacuoles and large lipid droplets. The cholesteryl ester content of the cells was increased many-fold and the non-esterified cholesterol content was increased to a lesser extent. The above four acid hydrolase activities were decreased, as was the activity of catalase, whereas the activities of lactate dehydrogenase and malate dehydrogenase were increased.
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PMID:Lipid accumulation in arterial smooth muscle cells in culture. Morphological and biochemical changes caused by low density lipoproteins and chloroquine. 715 Mar 93


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