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)

A method is described for obtaining and culturing large numbers of lung cells from normal adult male rats. The lungs were perfused in situ to remove blood cells and then perfused via the trachea with a trypsin-collagenase solution to initiate tissue digestion. The tissue was further digested in the enzyme solution and approximately 2 X 10(8) viable lung cells were obtained per animal. Primary cultures contained a mixed cell population. Through eight subcultures about 70% of the cell population possessed an epithelial-like morphology, whereas the remaining 30% was fibroblast-like. Three clones of epithelial-like cells were isolated at the fourth subculture. The mass culture lung cells and the epithelial-like clone that was studied retained a normal karyotype and did not grow in soft agar. Both the mass culture cells and the epithelial clone metabolized the lung carcinogen benzo(a)pyrene (BP) to water-soluble products. Furthermore, the mass culture lung cells metabolized BP to intermediate(s) which mutated Chinese hamster V79 cells from ouabain sensitivity to ouabain resistance. These lung cell cultures have potential use in cell transformation, mutation and carcinogen metabolism studies.
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PMID:Culture of adult rat lung cells: benzo(a)pyrene metabolism and mutagenesis. 51 Dec 5

1. Metabolites and DNA adducts of 3H-benzo(a)pyrene (BaP) formed by isolated hepatocytes from English sole (Parophrys vetulus) in vitro were compared to those in bile and liver of sole exposed i.m. to 3H-BaP. 2. English sole liver was perfused with a collagenase solution and hepatocytes were isolated with greater than 95% viability. Determination of kinetic parameters for metabolism of 3H-BaP showed a Km of 29 +/- 10 microM and an apparent Vmax of 1300 pmol BaP metabolized/10(6) cells per h. 3. Analysis of medium from hepatocyte cultures and bile by ion-pair h.p.l.c. showed significant amounts of radioactivity in regions where glucuronide and glutathione conjugates of BaP metabolites elute. No sulphate conjugates of BaP metabolites were detected. The major unconjugated metabolite formed by hepatocytes was the BaP-9,10-dihydrodiol. 4. Hydrolysis of glucuronide conjugates by beta-glucuronidase and reversed-phase h.p.l.c. analysis of chloroform-soluble metabolites showed the presence of BaP-7,8-dihydrodiol, 1-hydroxyBaP and 3-hydroxyBaP. The identities of these metabolites were confirmed by comparing their fluorescence spectra with those of standard BaP metabolites. 5. Analysis by 32P-postlabelling of the BaP-DNA adducts formed in isolated hepatocytes and liver revealed that major adducts detected are derived from the anti-7,8-dihydrodiol-9,10-epoxideBaP (anti-BaPDE) and syn-BaPDE. 6. Results show that the types of conjugated metabolites and BaP-DNA adducts formed in primary hepatocyte culture were similar to those in bile and liver of English sole exposed to BaP. Thus, isolated hepatocytes from English sole afford a reliable alternative to live fish for studies of the mechanisms of hepatic xenobiotic metabolism and DNA adduct formation in a species shown to be susceptible to induction of hepatocarcinogenesis by PAHs.
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PMID:The metabolism of benzo(a)pyrene by English sole (Parophrys vetulus): comparison between isolated hepatocytes in vitro and liver in vivo. 141 84

Primary culture of lung cells from CD rats was established for pulmonary genotoxicity studies using two genetic endpoints, sister-chromatid exchange (SCE) and micronucleus formation (MN). In the cell isolation study, a combined enzyme separation of rat lungs with trypsin (1.3 mg/ml) plus collagenase (50 U/ml) gave the highest yield of viable and colony-forming cells. For the MN assay, the cytokinesis block induced by cytochalasin B (CYB) was employed to enumerate MN in binucleated (BN) cells. Treatment of primary lung cells with 2 micrograms CYB/ml for two days appeared to be optimal for scoring micronuclei in CYB-induced BN cells. By this procedure, mitomycin C (MMC), triethylenemelamine, and benzo[a]pyrene caused a dose-related increase in micronucleated BN cells in vitro without metabolic activation. In the SCE assay, maximum second-division metaphases were obtained after cells were incubated with bromodeoxyuridine for 48-54 h. After this incubation time, high frequencies of SCE induced by MMC and 3-methylcholanthrene after in vitro exposure (without S9 activation) or in vivo exposure were observed. The results indicate that rat primary lung cells can metabolize polycyclic aromatic hydrocarbons and that this lung cell system is potentially useful for the detection of pulmonary genotoxicants.
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PMID:Use of rat primary lung cells for studying genotoxicity with the sister-chromatid exchange and micronucleus assays. 233 86

A simple yet effective method (iso-density percoll centrifugation) has been developed for consistently preparing isolated rat liver parenchymal cells with over 98% initial viability. The method has been applied to cells isolated by a variety of collagenase digestion techniques. This procedure involves the low-speed centrifugation (50 X g) of the initial cell suspension through a percoll medium having a density of 1.06 g/ml and results in the separation of single and viable parenchymal cells from cell aggregates, debris, and nonparenchymal cells. The enriched parenchymal cells have been shown to be superior to untreated cells by a number of criteria including: preparation homogeneity, cell morphology, maintenance of cytochrome P-450, hormonal responsiveness (measured by the induction of tyrosine aminotransferase after treatment with glucagon or dexamethasone, or both), plasma membrane integrity (determined by both trypan blue exclusion and leakage of glutamic-oxaloacetic transaminase), and the DNA repair capability after treatment with benzo[a]pyrene or 2-acetylaminofluorene.
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PMID:Use of a low-speed, iso-density percoll centrifugation method to increase the viability of isolated rat hepatocyte preparations. 287 Oct 8

Often results from toxicological studies using rodent models cannot be directly extrapolated to probable effects in human beings. In order to examine the genotoxic potential of chemicals in human liver cells, a human hepatocyte DNA repair assay has been defined. Procedures were optimized to prepare primary cultures of human hepatocytes from discarded surgical material. On eight different occasions human hepatocyte cultures of sufficient viability to measure DNA repair were successfully prepared by collagenase perfusion techniques. The cells were allowed to attach to plastic or collagen substrata for periods of 1.5 to 24 h and subsequently incubated with [3H]thymidine and test chemicals for periods of 18 to 24 h. Chemically induced DNA repair, measured as unscheduled DNA synthesis, was quantitated autoradiographically. The following compounds were tested: 2-acetylaminofluorene, aflatoxin B1, 2-aminobenzyl alcohol, aniline, benzo(a)pyrene, carbon tetrachloride, chloroform, 2,4-diaminotoluene, 2,6-diaminotoluene, di(2-ethylhexyl)phthalate, dimethylnitrosamine, 1,6-dinitropyrene, 2,4-dinitrotoluene, 2,6-dinitrotoluene, methyl chloride, 5-methylchrysene, mono(2-ethylhexyl)phthalate, 2-methyl-2-P-(1,2,3,4-tetrahydro-1-naphthyl)phenoxypropionic acid (nafenopin), beta-naphthylamine, nitrobenzene, 2-nitrobenzyl alcohol, 2-nitrotoluene, 2,3,7,8-tetrachlorodibenzo-p-dioxin, unleaded gasoline, and 4-chloro-6-(2,3-xylidino)-2-pyrimidinylthioacetic acid (Wy-14,643). In only one of eight cases did some of the chemicals generally regarded as genotoxic fail to give a positive response. For purposes of comparison, all test chemicals were evaluated in the in vitro rat hepatocyte DNA repair assay. Individual-to-individual variation in the DNA repair response was far greater for the human cultures than for cultures derived from rats. For only three chemicals was there a qualitative difference in the response between the rodent and the human cells; beta-naphthylamine was positive in the rat but in none of the human cultures examined, whereas the opposite was seen for 2,6-diaminotoluene and 5-methylchrysene. Clofibric acid, mono(2-ethylhexyl)phthalate, and Wy-14,643 induced enzymes indicative of peroxisomal proliferation in primary rat hepatocyte cultures, but not in two human hepatocyte cultures. These results indicate that, in general, the in vitro rat hepatocyte DNA repair assay is a valid model for predicting potential genotoxic effects in human beings. However, rodent hepatocytes may not be appropriate for assessing the potential of chemicals to elicit nongenotoxic effects in human beings such as the induction of hepatocyte peroxisomal proliferation.
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PMID:Use of primary cultures of human hepatocytes in toxicology studies. 291 45

Intact periportal (pp) or perivenous (pv) hepatocytes were prepared by digitonin-collagenase liver perfusion. The degree of separation was indicated by significant differences between the pp and pv cells in their activity of the pp markers, alanine aminotransferase (pp/pv = 2.1), gamma-glutamyltranspeptidase (3.4) and lactate dehydrogenase (1.3), and of the pv markers, glutamate dehydrogenase (0.73) and pyruvate kinase (0.81). This pattern was not altered by a 3-day pretreatment with phenobarbital (PB). The hepatocytes isolated from the pv area contained higher activities of microsomal NADPH-cytochrome c reductase, 7-ethoxycoumarin O-deethylase, 7-ethoxyresorufin O-deethylase and benzo(a)pyrene hydroxylase, and of cytosolic glutathione transferase. Cytochrome P-450 and UDP-glucuronosyltransferase were slightly higher in pv cells. Treatment with PB induced NADPH-cytochrome c reductase, glutathione transferase, cytochrome P-450 and UDP-glucuronosyltransferase but the degree of induction was found to be at least as strong in pp cells as in pv cells. The induction of 7-ethoxyresorufin O-deethylase and 7-ethoxycoumarin O-deethylase was clearly more prominent in pp cells. On the other hand, PB reduced the activities of benzo(a)pyrene hydroxylase and alcohol dehydrogenase in both cell types. These results demonstrate by direct enzyme assay of separated cells the dominance of the pv-region for metabolizing drugs in the normal liver. Contrary to several other studies, however, our data indicate that induction by PB occurs panacinarily, i.e., relatively more in the pp region, thus diminishing rather than exaggerating the original pv dominance.
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PMID:Effect of phenobarbital on the distribution of drug metabolizing enzymes between periportal and perivenous rat hepatocytes prepared by digitonin-collagenase liver perfusion. 302 20

The ability of polycyclic aromatic hydrocarbons and glucocorticoids to regulate monooxygenase activity of human fetal liver has been studied using hepatocytes prepared by collagenase digestion of liver samples from human abortuses of 13 to 19 weeks of gestational age, and maintained in primary monolayer culture for periods up to 5 days. Addition of 1,2-benzanthracene to the cells caused an increase in monooxygenase activity (3-hydroxylation of benzo[a]pyrene and O-deethylation of 7-ethoxycoumarin) in a time-and concentration-dependent fashion. The concentration of 1,2-benzanthracene required to achieve half-maximal induction was 5 microM. The inductive effect of the polycyclic hydrocarbon was potentiated approximately 2.5-fold when dexamethasone (250 nM) or other glucocorticoids were included in the culture medium. Dexamethasone alone had little or no effect on the induction of monooxygenase activity. The concentration of dexamethasone required for half-maximal stimulation of monooxygenase activity in the presence of 1,2-benzanthracene was 5-10 nM, and the action of dexamethasone was reversed by the addition of cortisol 21-mesylate, consistent with the concept that the action of dexamethasone was mediated by binding to a glucocorticoid receptor. These results are suggestive that glucocorticoids, which are produced by the fetal adrenal and have an important role in the regulation of fetal development, act synergistically with polycyclic aromatic hydrocarbons to induce the activity of liver monooxygenases in the human fetus.
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PMID:Synergistic induction of monooxygenase activity by glucocorticoids and polycyclic aromatic hydrocarbons in human fetal hepatocytes in primary monolayer culture. 375 39

Human livers were removed at immediate autopsy (IA) from brain death patients within 1 h after cessation of cardiac function. Viable hepatocytes were isolated successfully from these IA livers by perfusion of an intact lobe with collagenase or by digestion of a small tissue wedge with collagenase-dispase. The yields of hepatocytes ranged from 1 to 3 X 10(6) cells/g liver in the five cases studied. Approximately 70 to 90% of the cells excluded trypan blue dye. In the isolated hepatocytes, 632 pmol/mg protein of cytochrome p450 and 536 pmol/mg protein cytochrome b5 were measured. The cells attached to the dishes in 4 h and produced monolayer cultures with a high success rate. The cells maintained in primary cultures for several days and developed ultrastructural features characteristic of human hepatocytes in vivo. The cultured hepatocytes can hydroxylate benzo[a]pyrene, conjugate the metabolites, and have a benzo[a]pyrene hydroxylase activity of 48.7 pmol/mg DNA per h, which is comparable to that of rat hepatocytes. The liver cells repaired DNA damage caused by exposures to aminofluorene and acetylaminofluorene in culture.
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PMID:Isolation and culture of hepatocytes from human liver of immediate autopsy. 400 31

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

A sensitive cell-mediated assay has been developed for testing the mutagensis of liver carcinogens. Mutagenesis was detected in Chinese hamster V79 cells that were cocultivated with hepatocytes isolated after collagenase/hyaluronidase digestion of rat liver slices. Mutations were characterized by resistance to ouabain and 6-thioguanine. Seven of the nitrosamines, which are potent liver carcinogens, exhibited a mutagenic response. Mutagensis with the carcinogens could be detected at micromolar doses. The polyaromatic hydrocarbon benzo(a)pyrene, which is not a liver carcinogen, but can cause fibrosarcomas, was not mutagenic in this assay, but was mutagenic in a fibroblast-mediated assay. The liver carcinogen, aflatoxin B1, which usually does not induce fibrosarcomas, exhibited an inverse situation; it was mutagenic for V79 cells in the presence of liver cells but not in the presence of fibroblasts. We suggest that the use of various cell types, including hepatocytes prepared by the slicing method for carcinogen metabolism, and mutable V79 cells offers a sensitive assay for determining the mutagenic potential of chemical carcinogens, and may also allow a study of their organ specificity.
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PMID:The use of liver cell cultures in mutagenesis studies. 678 35


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