Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.3 (collagenase)
 18,340 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although the alpha-adrenergic antagonist phentolamine potentiates glucose-stimulated insulin secretion of intact animals, it either does not alter, or it inhibits in vitro insulin secretion. This may be because in the higher concentration used in in vitro studies, phentolamine exerts a second pharmacological effect that counterbalances its primary effect of blocking monoamine action. We recently demonstrated that pancreatic islets contain substantial amounts of monoamine oxidase (MAO), and that MAO inhibitors such as iproniazid and tranylcypromine can alter insulin secretion. In the present study, we determined if other drugs that affect insulin secretion, alter the MAO activity of homogenates of rabbit pancreatic islets (collagenase technique) or liver. Phentolamine, phenoxybenzamine and propranolol (10 muM and 100 muM) inhibit islet and hepatic MAO. Haloperidol (10muM) inhibits hepatic but not islet MAO, while haloperidol (10muM) does not inhibit MAO in either tissue. Ethanol (270 to 2.7mM) inhibits islet MAO. Hepatic MAO is inhibited by high (270 to 180mM) but not by low (27 to 2.7mM) concentrations of ethanol. Collagenase digestion does not increase the sensitivity of islet and liver MAO to inhibition by phentolamine or ethanol. In the absence of added monoamines, phentolamine and phenoxybenzamine do not alter basal or glucose-stimulated insulin secretion from rabbit pancreas. Preincubation of rabbit pancreas with the serotonin precursor 5-hydroxytryptophan (5-HTP) increases the beta cell serotonin content and inhibits glucose-stimulated insulin secretion. Alpha adrenergic antagonists not only fail to block, but actually potentiate the serotonin inhibition of insulin secretion. We conclude that inhibition of islet MAO may cause an increase in islet monoamine content and these monoamines may alter in vitro insulin secretion. One mechanism through which adrenergic antagonists and ethanol modify in vitro insulin secretion may be by inhibiting pancreatic islet MAO.
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PMID:Inhibition of pancreatic islet monoamine oxidase by adrenergic antagonists and ethanol. 0 95

The effect of ethanol feeding for a period of 6 months on parameters of hepatic collagen metabolism was studied in the rat. Ethanol feeding resulted in small increases in the fibrous and ground substance components of hepatic collagen as measured by increases in collagen-bound hydroxyproline and hexosamine, respectively. Liver histology revealagen proline hydroxylase and the incorporation of labeled proline into collagen by liver slices, both of which are associated with collagen synthesis, were not changed. Ethanol feeding resulted in increases in the concentration of protein and deoxyribonucleic acid in the Kupffer cells, but in no changes in collagenase activity. An increase in collagen degradation was suggested, however, by the increase in the urinary excretion of hydroxyproline and glycosaminoglycans found after 2 and 6 months of ethanol feeding, respectively. This study demonstrates that fatty infiltration of the liver in the rat, after prolonged ethanol feeding, is associated with increased deposition of chemically detectable collagen and evidence of increased collagen degradation, although no significant changes in parameters associated with hepatic collagen synthesis were found.
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PMID:Changes in hepatic collagen metabolism in rats produced by chronic ethanol feeding. 55 49

Bacterial endotoxins [lipopolysaccharide (LPS)] are potent immunomodulators, and ethanol is known to depress certain immune defense mechanisms. Thus the combined impact of these two agents on the generation of superoxide anion (O2(-).) by isolated hepatic phagocytic cells was investigated. Ethanol was infused intravenously into rats for 7 h, and Escherichia coli LPS was injected intravenously at 4 h after ethanol administration. Control groups received an equal volume of saline or ethanol alone. Nonparenchymal cells that were composed of endothelial and Kupffer cells and few polymorphonuclear neutrophils (PMN; less than 1%) were obtained after collagenase-pronase digestion. In the LPS-treated rats, the total number of PMN per liver increased significantly. Histological sections of the liver showed PMN infiltration and areas of necrosis after LPS treatment with or without ethanol. In the presence of either phorbol 12-myristate 13-acetate or opsonized zymosan in vitro, Kupffer cells and hepatic PMN from LPS-treated rats generated large amounts of O2(-).. Ethanol intoxication in vitro by these cells to 50%. Ethanol alone (without LPS) had no effect on the production of O2(-).. These studies demonstrate that ethanol intoxication was associated with the downregulation of the LPS-enhanced in vivo priming of hepatic phagocytes to generate O2(-). in vitro and may thus contribute to the enhanced susceptibility of alcoholic subjects to develop an infection.
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PMID:Alcohol-induced downregulation of superoxide anion release by hepatic phagocytes in endotoxemic rats. 185 29

The application of flow cytometry (FCM) to solid human tumors has been hindered by the difficulty in producing high yield, viable, unaltered single cell suspensions. Carcinomas containing a high desmosomal content, such as well-differentiated squamous cell (SCC) cancers of the head and neck (H&N) region, are particularly difficult to prepare. The desire to employ FCM to study cellular DNA parameters of these tumors led to the use of a 3-methylcholanthrene induced murine SCC for the comparative testing of preparative techniques. Dissociation techniques, including mechanical, enucleation, chemical, single and combination enzymes methods, were comparatively tested. Of these, the combination enzyme treatment employing trypsin and collagenase produced the highest cell yields in the shortest time with the highest dye exclusion viability and the least expense. Several fixation systems including glutaraldehyde, paraformaldehyde, acetic acid, and ethanol were comparatively tested using percent of cell loss and quality of the DNA histograms produced as end points. Ethanol-water systems with added fetal calf serum provided minimal cell loss and high quality histograms which were stable for extended periods of time. A murine tumor, closely mimicking the histology of the human tumor of interest, may be used as a model for the determination of optimum techniques of solid tumor preparation for flow cytometric analysis.
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PMID:Solid tumor preparation for flow cytometry using a standard murine model. 244 98

Periportal and perivenous hepatocytes were isolated by the digitonin-collagenase perfusion technique. The activity of the cytosolic glutathione S-transferase was higher in perivenous cells, but the cytosolic glutathione reductase and the microsomal glutathione S-transferase activities were evenly distributed. In contrast, both the Se-dependent and the microsomal Se-independent glutathione peroxidase activity and the glucose-6-phosphate dehydrogenase activity was much lower in perivenous hepatocytes, suggesting that these cells have a lowered detoxification capacity, which may contribute to their greater susceptibility to damage by xenobiotics. The mechanism of the ethanol-induced GSH depletion in vivo was studied by incubating conventionally isolated hepatocytes. In the absence of glutathione precursors, ethanol (80 mM) did not influence the GSH content, despite accumulation of acetaldehyde (10-100 MicroM). L-Methionine or L-cysteine stimulated GSH replenishment to in vivo rates. Ethanol oxidation resulted in acetaldehyde accumulation, but did not inhibit GSH replenishment from L-methionine and even stimulated that from L-cysteine. This seems to exclude conjugation of GSH with acetaldehyde as a mechanism by which ethanol suppresses GSH levels in vivo.
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PMID:Glutathione metabolism in isolated rat hepatocytes: acinar heterogeneity of detoxifying enzymes and effects of ethanol. 342 86

Liver microsomes were isolated by calcium aggregation, and isolated hepatocytes from male Wistar rats were prepared according to a two-step Ca++-free collagenase perfusion method. With the hepatocytes maximal inhibition of glucuronidation (about 40%) was reached at 10 mM ethanol after incubation at 37 degrees C for 60 min. UDP-glucuronic acid concentration and energy charge in the hepatocytes also did decrease maximally (about 90 and 50%, respectively) and the amount of UDP-glucose was tripled in the presence of 10 mM and higher concentrations of ethanol. The alcohol dehydrogenase inhibitor 4-methylpyrazole abolished ethanol-induced inhibition of morphine glucuronidation in the hepatocytes. Acetaldehyde (250-50 microM) and the pH decrease induced by ethanol did not reduce morphine-3-glucuronide formation by the cells. Cellular uptake of morphine and excretion of morphine metabolites were similar in the absence and presence of ethanol. Ethanol (60 mM) did not affect the glucuronidation of morphine (1.7 mM added) during a 30-min incubation at 37 degrees C with the microsomes (UDP-glucuronic acid, 5 mM). When the concentration of UDP-glucuronic acid in the microsomes was lowered from 1 to 0.1 mM, the decrease in morphine-3-glucuronide formation was similar to that observed in cells. The data indicate that the inhibition by ethanol of morphine glucuronidation was due to decreased levels of UDP-glucuronic acid. The mechanism is likely to be inhibition of UDP-glucose dehydrogenase activity by ethanol from increased intracellular NADH/NAD ratio accompanying ethanol oxidation.
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PMID:Mechanisms behind the inhibitory effect of ethanol on the conjugation of morphine in rat hepatocytes. 379 46

In vitro studies were carried out on isolated rat hepatocytes to examine further the proposed cytoprotective actions of prostaglandins (PG) using carbon tetrachloride (CCl4) as the toxic agent. Isolated hepatocytes, prepared by collagenase, were cultured in Leibowitz-15 medium. Following preincubation, CCl4 (300 or 150 micrograms/ml) was added to the hepatocytes. Treatment with Indomethacin (INDO), 16, 16-dimethyl-PGE2(PGE2) and prostacyclin (PGI2) was assayed in the cultures. Cell damage was measured by lactic dehydrogenase (LDH) release. 6-keto-PGF1 alpha was measured in the supernatant by direct radioimmunoassay. The results showed PGI2 (30.0 ng/ml) treatment 30 min after CCl4 (300 micrograms/ml) addition to be highly protective (p less than 0.001 versus CCl4 control). PGE2 (3 ng/ml) showed similar protection (p less than 0.001). INDO (2 micrograms/ml) following CCl4 (150 micrograms/ml) demonstrated increased cell death (p less than 0.001). INDO (0.5 micrograms/ml) reduced 6-keto-PGF1 alpha production (p less than 0.05). Low dose ethanol (1.5 micrograms/ml) increased 6-keto-PGF1 alpha production (p less than 0.05). Ethanol (1.5 micrograms/ml), added to stimulate endogenous PG production, was cytoprotective when added prior to CCl4 (p less than 0.01). This protection was suppressed by INDO. Ethanol added after CCl4 was not protective. We conclude that exogenously added PGI2 and PGE2 are cytoprotective in this in vitro model and that endogenous PG production may play a protective role in the initial stages of cellular damage.
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PMID:Cytoprotective effect of prostaglandins on isolated rat liver cells. 388 50

Ethanol metabolism in rat hepatocytes isolated either from the periportal (pp) or the perivenous (pv) area by collagenase gradient perfusion was compared to reveal metabolic factors that could be associated with the development of perivenous alcoholic liver damage. Cells were also isolated from rats given ethanol (E) chronically by addition to the drinking fluid. One group (EM) received in addition the alcohol dehydrogenase inhibitor 4-methylpyrazole, which potentiated the ethanol treatment by causing sustained elevated diurnal blood ethanol levels. Fatty degeneration ensued in only one-third of the E rats but in all of the EM rats. The periportal/perivenous activity distributions of alanine aminotransferase (ALAT) and glutamate dehydrogenase (GLDH) were 2.2 and 0.75, respectively. Both ethanol treatments significantly decreased the ALAT and increased the GLDH activities, but did not change their pp/pv distributions. Ethanol treatment also increased ethanol and acetaldehyde oxidation, but to the same extent in pp and pv cells. The increase was more marked in cells from EM rats despite their more severe liver fatty degeneration. Ethanol incubation also increased the lactate/pyruvate ratio to the same extent in pp and pv cells both from control or ethanol-treated rats. Our results indicate that periportal and perivenous hepatocytes convert ethanol via acetaldehyde to acetate equally well and with similar effects even after chronic ethanol treatment. Consequently, preferential damage of the perivenous area after chronic ethanol intake is not caused by inherent or acquired differences in ethanol metabolism between perivenous and periportal hepatocytes. Rather, sinusoidal gradients only established in the intact liver may exaggerate the metabolic imbalance by ethanol in the perivenous area, thus explaining its greater vulnerability to damage by alcohol abuse.
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PMID:Comparison of ethanol metabolism in isolated periportal or perivenous hepatocytes: effects of chronic ethanol treatment. 390

Ethanol-fixed Onchocerca nodules and skin snips were successfully digested with collagenase to assess the parasite load. The importance of this technique for investigations in the field is discussed.
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PMID:Quantitative assessment of microfilariae and adults of Onchocerca volvulus in ethanol-fixed biopsies and nodules. 608 6

Cells with electron-microscopic characteristics of myofibroblasts were isolated from baboon liver biopsy specimens by collagenase digestion and Percoll density gradient centrifugation and then cultured. The cultures consisted of only one cell type. By immunofluorescence, these cells synthesized collagen types I, III, and IV and laminin. Typical features of myofibroblasts were maintained throughout many passages in the culture. To study the effects of ethanol (and its oxidation product acetaldehyde and associated metabolite lactate) on myofibroblast collagen synthesis, the cell cultures were incubated for 24 h in a medium containing either 50 mM ethanol, 200 microM acetaldehyde, or 5 mM lactate. The cells did not contain significant alcohol dehydrogenase activity. Acetaldehyde stimulated significantly (p less than 0.05) myofibroblast collagen synthesis without changing noncollagen protein synthesis or proline pools. Lactate caused a significant (p less than 0.02) increase in intracellular proline pool and collagen synthesis. Ethanol itself did not have any effect on collagen synthesis of myofibroblasts. The stimulation of collagen synthesis of hepatic myofibroblasts by acetaldehyde and lactate may contribute to the development of alcoholic liver fibrosis, as alcohol intake is known to elevate acetaldehyde and lactate in tissues and blood.
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PMID:Acetaldehyde and lactate stimulate collagen synthesis of cultured baboon liver myofibroblasts. 638 Dec 14


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