Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FLUORENES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed1986

The role of DNA damage in chemical carcinogenesis of aromatic amines.

Many findings support the notion that the generation of DNA adducts by aromatic amines is causally related to carcinogenesis. Adducts have been identified in most cases and representative examples are reviewed. However, extent and persistence of DNA adducts (DNA dose) does not correlate satisfactorily with the tumor response of different tissues. Distribution of DNA damage, repair, indirect and secondary DNA damage are discussed as possible explanations for the observed noncorrelations. In addition, however, it is proposed to pay attention to specific mechanisms such as receptor mediated cellular effects which are not related to the generation of electrophiles. The effects of trans-4-aminostilbene and 2-amino-fluorene derivatives on rat liver are compared. It is concluded that trans-4-acetylamino-stilbene is a strong liver tumor initiator but an incomplete liver carcinogen lacking tumor promoting properties, and that 2-acetylaminofluorene is a complete liver carcinogen with initiating and promoting properties.

2-Acetylaminofluorene↗
PubMed1986

The significance of the relative effects of loop diuretics and anti-brain edema agents on the Na+,K+,Cl- cotransport system and the Cl-/NaCO3- anion exchanger.

3-Amino-5-sulfamoylbenzoic acids and several series of (aryloxy)alkanoic acids were evaluated for their inhibitory effects on two human erythrocyte ion transport systems--the Na+,K+ cotransport system and the DIDS-sensitive anion carrier. Several classic loop diuretics, including the (aryloxy)alkanoic acid-ethacrynic acid and several 3-amino-5-sulfamoylbenzoic acids, like bumetanide and furosemide, displayed relatively strong inhibitory activity versus the cotransport system with relatively weaker action versus the anion carrier. Furthermore, diuretic potency correlated with cotransport inhibitory potency. Another class of (aryloxy)alkanoic acids, namely the [(2,3-dihydro-1H-inden-5-yl)oxy]acetic acids, such as indacrinone and MK-473, which exhibit less potent loop diuretic activity, were less potent cotransport inhibitors and more effective inhibitors of the anion carrier. Still other (aryloxy)alkanoic acids, with little saliuretic activity, namely a sub-class of [(2,3-dihydro-1H-inden-5-yl)oxy]alkanoic acids and a series of [(2,3,9,9a-tetrahydro-1H-fluoren-7-yl)oxy]acetic acids displayed little or no inhibitory action on the cotransport system but enhanced inhibitory action on the anion carrier. Most interestingly, the relative anion carrier inhibitory potency correlated well with the relative inhibitory activity of each compound on bicarbonate-stimulated cell swelling in cat cerebrocortical slices.

Bumetanide↗
PubMed1996

The microbiological fate of polycyclic aromatic hydrocarbons: carbon and oxygen balances for bacterial degradation of model compounds.

A series of pure bacterial strains belonging mainly to the Rhodococcus and Pseudomonas genera were grown on one of the following polycyclic aromatic hydrocarbons (PAH) supplied as sole carbon and energy source; naphthalene, fluorene, phenanthrene, anthracene, fluoranthene and pyrene. In each case, a quantitative evaluation of the carbon repartition of the PAH degraded into CO2, biomass and water-soluble metabolites was carried out. In addition, the kinetics of oxygen consumption and of water-soluble metabolite accumulation during PAH biodegradation was followed with respirometric equipment. Satisfactory carbon balances were obtained and the data correlated well with oxygen consumption values. The results show that growth on PAH presents high mineralization yields (from 56% to 77% of carbon) and sizeable production of biomass (from 16% to 35% of carbon) and limited but significant accumulation of metabolites (from 5% to 23% of carbon). The mineralization yields were higher and biomass yields lower in the case of higher PAH. Some differences between strains were also observed.

Biodegradation, Environmental↗
PubMedDate not supplied

Cryopreservation and long-term storage of primary rat hepatocytes: effects on substrate-specific cytochrome P450-dependent activities and unscheduled DNA synthesis.

The effects of cryopreservation and long-term storage on substrate-specific cytochrome P450-dependent activities and unscheduled DNA synthesis were studied in freshly isolated and cryopreserved hepatocytes derived from adult male Fischer 344 and Sprague-Dawley rats. Primary rat hepatocytes were isolated via an in situ collagenase perfusion technique, cryopreserved at -196 degrees C, and thawed at 5 weeks and 104 and 156 weeks post-freezing. In Fischer 344 and Sprague-Dawley rats, cryopreserved hepatocytes were equivalent or similar to freshly isolated hepatocytes in substrate-specific activities for 7-ethoxyresorufin-O-deethylase and dimethylnitrosamine-N-demethylase and unscheduled DNA synthesis responses. No significant differences in activities toward 7-ethoxyresorufin-O-deethylase and dimethylnitrosamine-N-demethylase, the substrate-specific activities for cytochromes P4501A1 and P4501A2 and cytochrome P4502E1, respectively, were observed between freshly isolated and cryopreserved hepatocytes. Similar unscheduled DNA synthesis responses, a measure of DNA damage and repair, were observed after exposure to the genotoxic carcinogens 2-acetylamino-fluorene, 7,12-dimethylbenz[a]anthracene, and dimethylnitrosamine; although some decreases were also observed in Fischer 344 hepatocytes after 104 weeks and Sprague-Dawley hepatocytes after 156 weeks in the highest concentrations tested. These results suggest that cryopreserved hepatocytes, stored for extended periods of time in liquid nitrogen, are metabolically equivalent to freshly isolated hepatocytes in their ability to activate precarcinogens.

Animals↗
PubMed1992

Synthesis of bombyxin-IV, an insulin superfamily peptide from the silkworm, Bombyx mori, by stepwise and selective formation of three disulfide bridges.

We report the synthesis of bombyxin-IV, a disulfide-linked, heterodimeric, insulin superfamily peptide from the silkworm, Bombyx mori. The two chains (A- and B-chains) were synthesized separately by the solid-phase method using fluoren-9-ylmethoxycarbonyl (Fmoc) group as a protecting group for alpha-amino group. Three disulfide bonds were bridged step by step (A6-A11, A20-B22, and A7-B10) in a good yield. Synthetic bombyxin-IV was identical with natural one with regard to the retention time on a reversed-phase column and the molecular weight measured by mass spectrometry. Circular dichroism (CD) spectrum of the synthetic bombyxin-IV was very similar to that of the natural one. The specific activity of synthetic bombyxin-IV is equal to that of natural one (0.1 ng/Samia unit). These results suggest that the synthetic bombyxin-IV has the tertiary structure identical with the natural peptide. Our method developed for synthesis of bombyxin-IV would be generally applicable to the synthesis of insulin-like heterodimeric peptides.

Amino Acid Sequence↗
PubMed1986

Polycyclic aromatic compounds (PAC) in leaf lettuce.

Twenty-three samples of leaf lettuce (Lactuca sativa var. crispa) cultivated in private gardens in southern Finland were analyzed for polycyclic aromatic hydrocarbons (PAH) and derivatives. The total PAH concentrations varied from 4.8 to 94 micrograms/kg fresh weight. Nitro derivatives of PAH were detected in only five samples. One lettuce sample was also analyzed for PAH oxy-derivatives. 9H-Fluoren-9-one (1.3 microgram/kg) and 6 H-benzo[cd]pyren-6-one (0.3 microgram/kg) were found. The profiles of PAH in lettuce were compared with those in ambient air. It was concluded that PAH in lettuce originate from deposition of PAH-containing particles present in ambient air.

Finland↗
PubMed1992

Detoxification of polycyclic aromatic hydrocarbons by fungi.

The polycyclic aromatic hydrocarbons (PAHs) are a group of hazardous environmental pollutants, many of which are acutely toxic, mutagenic, or carcinogenic. A diverse group of fungi, including Aspergillus ochraceus, Cunninghamella elegans, Phanerochaete chrysosporium, Saccharomyces cerevisiae, and Syncephalastrum racemosum, have the ability to oxidize PAHs. The PAHs anthracene, benz[a]anthracene, benzo[a]pyrene, fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene, as well as several methyl-, nitro-, and fluoro-substituted PAHs, are metabolized by one or more of these fungi. Unsubstituted PAHs are oxidized initially to arene oxides, trans-dihydrodiols, phenols, quinones, and tetralones. Phenols and trans-dihydrodiols may be further metabolized, and thus detoxified, by conjugation with sulfate, glucuronic acid, glucose, or xylose. Although dihydrodiol epoxides and other mutagenic and carcinogenic compounds have been detected as minor fungal metabolites of a few PAHs, most transformations performed by fungi reduce the mutagenicity and thus detoxify the PAHs.

Biodegradation, Environmental↗
PubMed2002

Reversion mutation in dark variants of luminous bacteria and its application in gene toxicant monitoring.

The luminous intensity of dark variant (S1) separated from photobacterium phosphoreum (A2) was 1/10,000 less than that of wild-type. Ethidium bromide (EB) (0.6 mg/L), Mytomycin C (MC, 0.05 mg/L), 2-amino fluorene (2-AF, 1.0 mg/L) all could strongly induce reversion mutation for S1 within 24 h and increase reversion ratio significantly. The results of experiments indicated that these revertants had stable genetic characteristic and the mutation may take place at gene levels. The mutagenesis to S1 caused by EB, MC and 2-AF was detected and it may be used as a new rapid, simple and sensitive method for gene toxicant monitoring.

Ethidium↗
PubMed2003

Rapid analysis of aromatic contaminants in water samples by means of laser ionization mass spectrometry.

Three different approaches to laser ionization mass spectrometric analysis of aromatic compounds in water samples are described and their performances are compared. Whereas the first two methods are based on direct laser desorption and subsequent laser ionization of either frozen or adsorbed samples in a time-of-flight mass analyzer, the third performs laser ionization in a quadrupole ion-trap into which the sample is transferred from a GC injector via a short piece of capillary tubing. For the laser-desorption method a detection limit in the 100 microg L(-1) range was determined for fluorene in frozen samples. The easier to handle analysis of adsorbed samples yielded sensitivities which were lower by about two orders of magnitude. As both direct techniques do not reach the sensitivity required for ultra trace analysis in water a preconcentration step in form of solid-phase microextraction was added before measurement using the laser ionization quadrupole ion-trap mass spectrometer. Sensitivity in the desired ng L(-1) range was easily achieved.

Journal Article↗
PubMed2002

Dietary exposure of finfish to aromatic contaminants and tissue distribution.

Large rainbow trout (400 g) were exposed to food pellets spiked with four polycyclic aromatic compounds (PACs). Muscle, liver, internal organs, fatty tissue, and blood were analyzed after 5, 10, 15, and 19 weeks for PAC, lipid, and moisture content. At all collection times, concentrations expressed on a per gram basis were higher in fatty tissue and internal organs, followed by liver and muscle, and lowest levels were observed in blood. When examining the tissue burden, the highest bioaccumulations of carbazole, dibenzofuran, dibenzothiophene, and fluorene were in muscle and internal organs, intermediate in fatty tissue, and lowest in blood and liver. Carbazole with the lowest log K(OW) showed the lowest concentration within any tissue. Levels in tissues were significantly correlated to log K(OW) (> 5% level of significance), especially with longer exposure, and were more highly correlated when examining muscle, fatty tissue, and internal organs (> 0.05%). Different tissues displayed different time trends, and ratios between organs help determine the length of exposure. The most striking change in levels observed with time was in internal organs relative to other tissues, particularly when compared to daily exposure. The elimination of contaminants in feces and gallbladder bile was also compared, because they represent additional tools to assess recent exposure.

Animals↗
PubMed2002

Quantitative biomonitoring of PAHs using the Barnes mussel (Elliptio complanata).

The elimination rate constants (k(2)) of nine polycyclic aromatic hydrocarbons (PAHs) were examined for the freshwater mussel Elliptio complanata. The concentrations of fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benzo[ a]anthracene, chrysene, benzo[ b]fluoranthene, and indeno[1,2,3-c,d]pyrene revealed a significant inverse relationship with time and their k(2) values ranged from 0.10 to 0.22 day(-1). The k(2) values of these significantly cleared PAHs were similar to k(2) values observed for nonmetabolized organochlorines in mussels previously reported in the literature. The inverse relationship between k(2) and K(ow) provides evidence that the nine PAHs were being passively eliminated from the mussels and that they can be used to calibrate the mussel as a quantitative biomonitor. A general expression relating elimination rate constants and chemical K(ow) is derived for hydrophobic contaminants in E. complanata. The k(2) versus log K(ow) regression equation for mussels developed herein was similar to other studies documenting the elimination of PCBs and PAHs in a number of bivalve species.

Animals↗
PubMed2002

Lipid analysis of the response of a sedimentary microbial community to polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons (PAH) are widespread environmental contaminants that can, under proper conditions, be degraded by microorganisms. The responses of a riverine sedimentary microbial community to PAH contamination were examined using an integrated biochemical assay that yielded data on PAH concentration, total microbial biomass, and microbial community structure and were interpreted using perturbation theory and the subsidy-stress gradient. Microbial mineralization of naphthalene, anthracene, fluorene, and phenanthrene was observed 24 h after their addition to all sediments sampled and ranged from 0.9 to 16.3% in ambient sediments and from 14.8 to 35.8% in contaminated sediments. Total microbial biomass, determined by phospholipid phosphate, increased in response to intermediate PAH concentration and decreased at sites with the highest PAH concentration (p < 0.05) during seven out of nine (78%) seasonal sampling periods. The two sampling periods that were not statistically different followed periods of high water and cold temperatures. Phospholipid fatty acid analysis of microbial community structure analysis indicated that increases in the relative abundance of gram-negative aerobes and heterotrophic eukaryotes were responsible, in part, for these observed increases in total microbial biomass. These findings (increased degradation rates, increased biomass at intermediate PAH concentrations, and altered community structure) indicate that a component of the microbial community responded to PAH as a usable input and are consistent with the predictions of perturbation theory and a subsidy-stress gradient.

Biomass↗
PubMed2002

Phthalate catabolic gene cluster is linked to the angular dioxygenase gene in Terrabacter sp. strain DBF63.

Phthalate is a metabolic intermediate of the pathway of fluorene (FN) degradation via angular dioxygenation. A gene cluster responsible for the conversion of phthalate to protocatechuate was cloned from the dibenzofuran (DF)- and FN-degrading bacterium Terrabacter sp. strain DBF63 and sequenced. The genes encoding seven catabolic enzymes, oxygenase large subunit of phthalate 3,4-dioxygenase (phtA1), oxygenase small subunit of phthalate 3,4-dioxygenase (phtA2), cis-3,4-dihydroxy-3,4-dihydrophthalate dehydrogenase (phtB), [3Fe-4S] or [4Fe-4S] type of ferredoxin (phtA3), ferredoxin reductase (phtA4), 3,4-dihydroxyphthalate decarboxylase (phtC) and putative regulatory protein (phtR), were found in the upstream region of the angular dioxygenase gene (dbfA1A2), encoded in this order. Escherichia coli carrying phtA1A2BA3A4 genes converted phthalate to 3,4-dihydroxyphthalate, and the 3,4-dihydroxyphthalate decarboxylase activity by E. coli cells carrying phtC was finally detected with the introduction of a Shine-Dalgarno sequence in the upstream region of its initiation codon. Homology analysis on the upstream region of the pht gene cluster revealed that there was an insertion sequence (IS) (ISTesp2; ORF14 and its flanking region), part of which was almost 100% identical to the orf1 and its flanking region adjacent to the extradiol dioxygenase gene ( bphC1) involved in the DF degradation of Terrabacter sp. strain DPO360 [Schmid et al. (1997) J Bacteriol 179:53-62]. This suggests that ISTesp2 plays a role in the metabolism of aromatic compounds in Terrabacter sp. strains DBF63 and DPO360.

Actinomycetales↗
PubMed2002

Purification, molecular characterization and reactivity with aromatic compounds of a laccase from basidiomycete Trametes sp. strain AH28-2.

A recently isolated basidiomycete, Trametes sp. strain AH28-2, can be induced to produce a high level of laccases when grown on a cellobiose-asparagine liquid medium. After induction by kraft lignin, two major isozymes were detected in the fermentation supernatant of the fungus. The principal component laccase A, which accounts for about 85% of the total activity, can be purified to electrophoretic homogeneity by three chromatographic steps: DEAE-Sepharose FF, Superdex-200 and Mono-Q. The solution containing purified laccase is blue in color, and the ratio of absorbance at 280 nm to that at 600 nm is 22. The molecular mass of laccase A is estimated to be 62 kDa by SDS-PAGE, 57 kDa by FPLC, and measured as 58522 Da by MALDI mass spectrum. Laccase A is a monomeric glycoprotein with a carbohydrate content of 11-12% and an isoelectric point of 4.2. The optimum pH and temperature for oxidizing guaiacol are 4.5 and 50 degrees C, respectively. The half-life of the enzyme at 75 degrees C is 27 min. The enzyme shows a good stability from pH 4.2 to pH 8.0. The K(m) values of the enzyme toward substrates 2,2'-azino-bis (3-ethylbenzothazoline-6-sulfonate) (ABTS), guaiacol and 2,6-dimethoxyphenol are 25, 420 and 25.5 microM, respectively, and the corresponding V(max) values are 670, 66.8, and 79 microM min(-1) x mg(-1), respectively. Laccase A activity is strongly inhibited by 0.1 mM NaN(3) or 0.1 mM cyanide. Two units of laccase A alone is able to completely oxidize 100 micromol 2,6-chlorophenol in 6 h. In the presence of 1 mM ABTS and 1-hydroxybenzotriazole, 15.0 U laccase A is able to oxidize 45% and 70% of 50 micromol fluorene in 12 and 18 h, respectively. The laccase A gene was cloned by a PCR method, and preliminary analysis of its sequence indicates 87.0% similarity to the corresponding segment in the phenoloxidase gene from Coriolus hirsutus.

Amino Acid Sequence↗
PubMed2004

Isolation and characterization of novel bacteria degrading polycyclic aromatic hydrocarbons from polluted Greek soils.

Three bacterial strains, designated as Wphe1, Sphe1, and Ophe1, were isolated from Greek soils contaminated with polycyclic aromatic hydrocarbon (PAH)-containing waste from the wood processing, steel, and oil refinery industries. Wphe1, Sphe1, and Ophe1 were characterized and identified as species of Pseudomonas, Microbacterium, and Paracoccus, respectively, based on Gram staining, biochemical tests, phospholipid analysis, FAME analysis, G+C content and 16S rRNA gene sequence analysis. The results of gas chromatography showed that strain Wphe1 degraded naphthalene, phenanthrene, and m-cresol over a wide temperature range; strain Sphe1 was a degrader of phenanthrene and n-alkanes; most interestingly, strain Ophe1 degraded anthracene, phenanthrene, fluorene, fluoranthene, chrysene, and pyrene, as well as cresol compounds and n-alkanes as sole carbon source. This is the first report of a representative of the genus Paracoccus capable of degrading PAHs with such versatility. These three strains may be useful for bioremediation applications.

Actinomycetales↗
PubMed2005

Isolation and characterization of a novel polychlorinated biphenyl-degrading bacterium, Paenibacillus sp. KBC101.

The biphenyl-utilizing bacterial strain KBC101 has been newly isolated from soil. Biphenyl-grown cells of KBC101 efficiently degraded di- to nonachlorobiphenyls. The isolate was identified as Paenibacillus sp. with respect to its 16S rDNA sequence and fatty acid profiles, as well as various biological and physiological characteristics. In the case of highly chlorinated biphenyl (polychlorinated biphenyl; PCB) congeners, the degradation activities of this strain were superior to those of the previously reported strong PCB degrader, Rhodococcus sp. RHA1. Recalcitrant coplanar PCBs, such as 3,4,3',4'-CB, were also efficiently degraded by strain KBC101 cells. This is the first report of a representative of the genus Paenibacillus capable of degrading PCBs. In addition to growth on biphenyl, strain KBC101 could grow on dibenzofuran, xanthene, benzophenone, anthrone, phenanthrene, naphthalene, fluorene, fluoranthene, and chrysene as sole sources of carbon and energy. Paenibacillus sp. strain KBC101 presented heterogeneous degradation profiles toward various aromatic compounds.

Bacillaceae↗
PubMed2005

Characterization of [3Fe-4S] ferredoxin DbfA3, which functions in the angular dioxygenase system of Terrabacter sp. strain DBF63.

Dibenzofuran 4,4a-dioxygenase (DFDO) from Terrabacter sp. strain DBF63 is comprised of three components, i.e., terminal oxygenase (DbfA1, DbfA2), putative [3Fe-4S] ferredoxin (ORF16b product), and unidentified ferredoxin reductase. We produced DbfA1 and DbfA2 using recombinant Escherichia coli BL21(DE3) cells as a native form and purified the complex to apparent homogeneity. We also produced and purified a putative [3Fe-4S] ferredoxin encoded by ORF16b, which is located 2.5 kb downstream of the dbfA1A2 genes, with E. coli as a histidine (His)-tagged form. The reconstructed DFDO system with three purified components, i.e., DbfA1A2, His-tagged ORF16b product, and His-tagged PhtA4 (which is a tentative reductase derived from the phthalate dioxygenase system of strain DBF63) could convert fluorene to 9-fluorenol (specific activity: 14.4 nmol min(-1) mg(-1)) and convert dibenzofuran to 2,2',3-trihydroxybiphenyl. This indicates that the ORF16b product can transport electrons to the DbfA1A2 complex; and therefore it was designated DbfA3. Based on spectroscopic UV-visible absorption characteristics and electron paramagnetic resonance spectra, DbfA3 was elucidated to contain a [3Fe-4S] cluster. Ferredoxin interchangeability analysis using several types of ferredoxins suggested that the redox partner of the DbfA1A2 complex may be rather specific to DbfA3.

Actinomycetales↗
PubMed2007

Influence of growth medium on cometabolic degradation of polycyclic aromatic hydrocarbons by Sphingomonas sp. strain PheB4.

The influence of growth medium on cometabolic degradation of polycyclic aromatic hydrocarbons (PAHs) was investigated when Sphingomonas sp. strain PheB4 isolated from surface mangrove sediments was grown in either phenanthrene-containing mineral salts medium (PMSM) or nutrient broth (NB). The NB-grown culture exhibited a more rapid cometabolic degradation of single and mixed non-growth substrate PAHs compared to the PMSM-grown culture. The concentrations of PAH metabolites were also lower in NB-grown culture than in PMSM-grown culture, suggesting that NB-grown culture removed metabolites at a faster rate, particularly, for metabolites produced from cometabolic degradation of a binary mixture of PAHs. Cometabolic pathways of single PAH (anthracene, fluorene, or fluoranthene) in NB-grown culture showed similarity to that in PMSM-grown culture. However, cometabolic pathways of mixed PAHs were more diverse in NB-grown culture than that in PMSM-grown culture. These results indicated that nutrient rich medium was effective in enhancing cometabolic degradation of mixed PAHs concomitant with a rapid removal of metabolites, which could be useful for the bioremediation of mixed PAHs contaminated sites using Sphingomonas sp. strain PheB4.

Avicennia↗