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

The induction of primary DNA damage by the non-carcinogen 4-AAF was reinvestigated in liver cells by comparison with the carcinogen 2-AAF. DNA alkaline elution showed the appearance of single-strand breaks in total liver DNA of rats 4 h after gavage with 200 mg/kg of 4-AAF. The decrease in hepatocyte viability and yield observed in these livers after collagenase perfusion indicated a cytotoxic effect of 4-AAF treatment. Viable hepatocytes isolated from 4-AAF-treated rats as well as hepatocytes from normal rats treated with 4-AAF in vitro did not present DNA single-strand breaks.
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PMID:Lack of DNA single-strand breaks in rat liver cells exposed to 4-acetylaminofluorene, in vivo and in vitro. 236 18

Male F344/DuCrj rats were fed a diet containing 0.02% 2-acetylaminofluorene (2-AAF) for 1 or 3 weeks, and then fed a basal diet for 2 days, 2 weeks, 8 weeks, 22 weeks or 36 weeks. Hepatocytes were isolated from the liver by collagenase perfusion, and their sensitivity to phalloidin, in terms of the formation of multiple cytoplasmic blebs, was examined. The sensitivity of gamma-glutamyltransferase (GGT)-negative hepatocytes decreased on the 22nd and 36th weeks after withdrawal of 2-AAF feeding, and that of GGT-positive cells decreased on the 36th week. Induction of a small number of foci positive for the placental form of glutathione S-transferase (GSTP) was observed in the liver of all rats on the 8th, 22nd and 36th weeks after the withdrawal of the carcinogen. However, the total area of the foci was estimated to account for less than 0.2% of liver tissues even on the 36th week. Therefore, the decrease in phalloidin sensitivity of hepatocytes, particularly of GGT-negative hepatocytes, on the 22nd and 36th weeks after 2-AAF withdrawal is suggested to be a result of a decrease in the sensitivity of otherwise normal-looking hepatocytes, which may be precursors of the cells forming the preneoplastic foci.
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PMID:Decreased sensitivity to phalloidin of normal-looking rat hepatocytes after short-term 2-acetylaminofluorene feeding. 245 96

Sequential carcinogen treatment (diethylnitrosamine/partial hepatectomy followed by 2-acetylaminofluorene (2-AAF] induced multiple hepatocarcinomas in rats with 100% certainty within a year. Enzyme-altered lesions, i.e. gamma-glutamyltranspeptidase (GGT)-positive and/or ATPase-negative cell foci, were numerous already at 8 weeks, and suspensions of purified hepatocytes isolated (by collagenase perfusion) at this time contained 30-40% GGT-positive cells. These hepatocyte suspensions were markedly deficient with respect to autophagic protein degradation (in comparison with cell suspensions from normal rats), and the cells lost less protein and survived much better than normal hepatocytes in culture under conditions of amino acid deprivation (which activates the autophagic mechanism). The anabolic advantage of reduced autophagy may possibly contribute to the selective outgrowth of preneoplastic cells during the earliest stage of liver carcinogenesis. Inclusion of the autophagy inhibitor 3-methyladenine in the culture medium elevated the survival of normal hepatocytes up to the level seen with hepatocytes from carcinogen-treated animals, suggesting that protection of normal cells by autophagy suppression may be a potentially interesting therapeutic principle.
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PMID:Reduced autophagic activity, improved protein balance and enhanced in vitro survival of hepatocytes isolated from carcinogen-treated rats. 285 48

Daily administration of ferric nitrilotriacetate (5 ml/Kg b.w./day i.p.) induces in a few weeks liver siderosis; continuous treatment of the same animals with the carcinogen 2-Acetaminofluorene (300 mg/Kg of diet) results in the appearance of several iron devoid hyperplastic areas or nodules, where enzyme histochemistry reveals gamma-GT activity as well as G-6-Pase disappearance. The perfusion of the liver with calcium-free Hanks solution plus collagenase allows an easy isolation of the hepatocytes, whereas a partial separation of the different kinds of cells can be achieved by isopycnic gradient sedimentation.
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PMID:[Induction, characterization and isolation of preneoplastic hepatocytes following combined treatment with 2-acetaminofluorene and ferric nitrilotriacetate]. 611 69

Male F344 rats were continuously fed 0.05% phenobarbital (PB)- or 0.02% 2-acetylaminofluorene (2-AAF)-containing diet for 3 or 8 weeks. The hepatocytes were isolated by a collagenase-perfusion technique and changes in the phalloidin-sensitivity of the cells were examined. After an 8-week treatment with PB or 2-AAF, the phalloidin-sensitivity, in terms of formation of cytoplasmic blebs over the cell surface, was reduced significantly in both groups. The degree of insensitivity to phalloidin induced by PB was found to be similar to that induced by 2-AAF. Two weeks after cessation of the PB-feeding, the sensitivity had recovered to the control range, while the decreased sensitivity induced by 2-AAF persisted for at least 2 weeks after the cessation of 2-AAF-feeding. Furthermore, cytochemical examinations of normal and 2-AAF-treated hepatocytes revealed that the degree of sensitivity decreased in the order of normal hepatocytes, 2-AAF-treated gamma-glutamyl transpeptidase-negative hepatocytes, and 2-AAF-treated gamma-glutamyl transpeptidase-positive hepatocytes. The decreased sensitivity of the latter two cell types also persisted for 2 weeks after the cessation of carcinogen treatment.
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PMID:Effects of phenobarbital-feeding on the phalloidin-sensitivity of rat hepatocytes. 613 50

The pancreas is a key target tissue in human and animal carcinogenesis, yet few short-term test systems measure genotoxicity in pancreatic cells. A method has been developed for the measurement of DNA repair as unscheduled DNA synthesis (UDS) in primary cultures of rat pancreatic cells (PRP) following in vitro or in vivo exposures to chemicals. PRP were isolated from female Sprague-Dawley (SD) or male Fischer-344 rats by mincing the pancreas in a collagenase solution followed by digestion in dispase. For in vitro exposures, PRP were incubated with 3H-thymidine (3H-TdR) in the presence of genotoxic agents for 18-22 hr. For in vivo exposures, male Fischer-344 rats were treated with genotoxic agents 2 hr prior to sacrifice of the animals, and cells were incubated with 3H-TdR. UDS was measured by quantitative autoradiography as net grains/nucleus (NG). Solvent controls ranged from -1.0 to -2.8 NG. Cells isolated from female SD rats and treated in vitro with methylmethane sulfonate (MMS), ethylmethane sulfonate (EMS), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), and the pancreatic carcinogen azaserine all yielded over 4.0 NG. Cells treated in vitro with the hepatocarcinogens 2-acetylaminofluorene (2-AAF) and dimethylnitrosamine (DMN) and with the multisite carcinogen benzo[a] pyrene (B[a]P) yielded between -1.0 and -3.3 NG. These results are consistent with the lack of carcinogenic activity of 2-AAF, DMN, and B[a]P in the pancreas and indicate that pancreatic cells are incapable of metabolizing these compounds to genotoxic forms. In vivo treatment with MMS at 100 mg/kg yielded 1.9 NG and with azaserine at 100 mg/kg yielded 8.2 NG. This method should be useful in detecting agents that are genotoxic to the pancreas.
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PMID:Induction of unscheduled DNA synthesis in primary cultures of rat pancreatic cells following in vivo and in vitro treatment with genotoxic agents. 637 85

The bone marrow (BM) micronucleus (MN) test is a sensitive assay for identifying clastogens. However, some clastogenic compounds and metabolites may never reach the BM. The liver has been suggested as an alternative tissue to BM but adult rat liver has a low mitotic index that increases the difficulty of evaluating hepatocytes (HEP) for MN induction. Chemical mitogens and partial hepatectomy have been used to increase HEP proliferation to improve the sensitivity for detection of clastogenic compounds, but these practices raise concerns for the evaluation of drug candidates. The use of 4-wk-old rats provides an alternative to mitogenic stimulation because livers from these animals have approximately 5.4% of their HEP in S-phase. HEP were isolated by collagenase perfusion, or from formalin-fixed tissue, from 4-wk-old treated rats. Six compounds were evaluated for the incidence of MN in HEP that were isolated by both methods. The results for MN induction by these compounds were similar for the two methods and confirmed that formalin-fixed tissue is an acceptable source of cells for evaluating MN induction in HEP. BM polychromatic erythrocytes (PCE) also were harvested at the end of the live phase for each study and then evaluated for the incidence of MN. Diethylnitrosamine and 2-nitrofluorene induced MN in HEP but had no effect in PCE. 2-Acetylaminofluorene, cyclophosphamide and 7,12-dimethylbenz[a]anthracene did not induce MN in HEP but were positive in PCE. The direct-acting clastogen, mitomycin C, was positive in both HEP and PCE. These results indicate that this modified liver micronucleus test, using 4-wk-old rats, offers an alternative to existing methods that use mitogens or partial hepatectomy to stimulate cell replication. Analysis of MN from formalin-fixed tissue provides additional flexibility by allowing the investigator to assess MN induction at a later time.
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PMID:An evaluation of micronucleus induction in bone marrow and in hepatocytes isolated from collagenase perfused liver or from formalin-fixed liver using four-week-old rats treated with known clastogens. 921 89

The oval cell is regarded as a compensatory cell in liver injury, and is thought to be equivalent to liver stem/progenitor cells. Oval cells were induced by the 2-AAF/CCl(4) dietary method in Fischer 344 rats, and were isolated from excised liver by the collagenase perfusion, enzyme treatment, and cell cloning method. Transmission electron microscopy observation and double immunofluorescence methods were used to characterize the cells. We have developed an in vitro system consisting of three-dimensional collagen and hormonal and cytokine factors. Over 3 weeks, albumin secretion and urea detoxification rate were estimated to assess the biological function of the oval cells cultured in a scaffold. Oval cells cultured in the scaffold demonstrated higher biological functions than did those in a two-dimensional tissue culture plate. The pore structure and collagen in a scaffold may play an important role in fostering the biochemical functions of oval cells. The three-dimensional culture of oval cells could be considered in designing a cell-delivering tool for hepatic disease.
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PMID:Behavior of isolated rat oval cells in porous collagen scaffold. 1285 9