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PubMed1995

Comparative toxicity of (+)-(R)- and (-)-(S)-1,2-dibromo-3-chloropropane.

The haloalkane 1,2-dibromo-3-chloropropane (DBCP), an environmental pollutant that was widely used as a soil fumigant, is a carcinogen and a mutagen and displays target-organ toxicity to the testes and the kidneys. Because little is known about effects of stereochemistry on the metabolism and toxicity of halogenated alkyl compounds and because DBCP, which has a chiral center at C-2, may show enantioselectivity in its metabolism and/or toxicities, the optically pure enantiomers of DBCP were tested in vivo in rats for organ toxicity as well as for bacterial mutagenicity. Organ toxicity studies showed that (S)-DBCP was slightly more renal toxic than (R)-DBCP but was not significantly more toxic than the racemate, and that no significant differences were observed in the extents of testicular necrosis and atrophy caused by either enantiomer or the racemate. In contrast, (R)-DBCP was more mutagenic than either (S)-DBCP or the racemate to Salmonella typhimurium (S. typhimurium) strains TA 100 and TA104. However, there was little or no enantioselectivity in glutathione S-transferase (GST)-catalyzed conjugation reactions of glutathione with DBCP based on the lack of selectivity in the rates of disappearance of the enantiomers of DBCP in the presence of glutathione (GSH) and GSTs as monitored by chiral gas chromatography (GC).

Animals↗
PubMed1995

Mutation spectra in salmonella of chlorinated, chloraminated, or ozonated drinking water extracts: comparison to MX.

Drinking water samples were prepared in a pilot-scale treatment plant by chlorination (Cl2), chloramination (NH2Cl), ozonation (O3), or O3 followed by Cl2 or NH2Cl; and the nonvolatile acidic organics of the raw and treated waters were extracted by XAD/ethyl acetate and evaluated for mutagenicity in Salmonella (-S9). The extracts were 2-8 times more mutagenic in TA100 than in TA98, and the mutagenic potencies of the water extracts ranked similarly in both strains: Cl2 > O3 + Cl2 > NH2Cl > O3 + NH2Cl > O3 > raw. 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), which was estimated to account for approximately 20% of the mutagenic activity of the extracts, was shown to be the most potent compound tested thus far in a prophage-induction assay in Escherichia coli and a forward-mutation assay in Salmonella TM677. The mutations in approximately 2,000 revertants of TA98 and TA100 induced by MX and the water extracts were analyzed by colony probe hybridization and polymerase chain reaction/DNA sequence analysis. The water extracts and MX produced similar mutation spectra, which consisted in TA100 of predominantly of GC-->TA transversions in the second position of the CCC (or GGG) target of the hisG46 allele. This spectrum resembles that produced by large aromatic compounds and is distinct from that produced by alkylating agents and the semivolatile drinking water mutagen dichloroacetic acid. In TA98, MX and those water extracts resulting from the introduction of the chlorine atom produced 50-70% hotspot 2-base deletions and 30-50% complex frameshifts (frameshifts with an adjacent base substitution--mostly GC-->TA transversions as found in TA100). No other compound or mixture is known to induce such high frequencies of complex frameshifts. These results suggest that MX and "MX-like" compounds (possibly halogenated aromatics, such as halogenated polycyclic aromatic hydrocarbons) account for much of the mutagenic activity and specificity of the nonvolatile organics in drinking water and that these halogenated organics are especially capable of promoting misincorporation by the DNA replication complex. This study provides further evidence that the mutation spectrum of a complex mixture reflects the dominance of one or a few classes of chemical mutagens within the mixture.

Alleles↗
PubMed1991

[Mass spectrometric structure analysis of fatty acid mixtures from biological material after gas capillary chromatographical separation].

The identification of mixtures of fatty acids from biological materials is possible by electron impact ionization mass spectra of methyl esters after their capillary gas chromatographic separation. Mass spectra of pyrrolidine derivatives are used for the determination of double bond positions in unsaturated fatty acids. 97 different fatty acids (saturated, unsaturated, branched, cyclic, hydroxy, oxo, epoxy and methoxy) and other compounds (alkanes, halogens, phthalates, ketones, aldehydes) were identified in yeast and bacterial biomasses, lipid-containing animal tissues and human sera as well as fish and plant oils (77 preparations).

Animals↗
PubMed2003

Inhibition of CYP 1A2-dependent MROD activity in rat liver microsomes: an explanation of the hepatic sequestration of a limited subset of halogenated aromatic hydrocarbons.

Many classes of halogenated aromatic compounds (HACs) are highly lipophilic environmental contaminants that exert toxic effects via the Ah receptor signal transduction pathway and whose metabolism generally involves monooxygenase enzymes of the CYP 1A family. Despite their lipophilicity, a high proportion of the body burden of certain polychlorinated dibenzo-p-dioxins and coplanar polychlorinated biphenyls is sequestered in liver, a process believed to involve CYP 1A2. In this work we examined HAC-induced inhibition of the demethylation of 7-methoxyresorufin, a process that is selectively catalyzed by CYP 1A2. 2,3,7,8-Tetrachlorodibenzo-p-dioxin, 3,3',4,4'-tetrachlorobiphenyl (PCB 77) and 3,3',4,4',5-pentachlorobiphenyl (PCB 126) were found to be strong competitive inhibitors of methoxyresorufin-O-demethylase activity, consistent with the high ability of hepatic tissue to sequester these compounds selectively.

Animals↗
PubMed1987

The distribution of carcinogen metabolizing enzymes in the mouse liver: comparison of parenchymal and non-parenchymal cell populations.

The distribution of aminopyrine N-demethylase (APND), ethoxyresorufin O-deethylase (ERRD), epoxide hydrolase (EH) and glutathione transferase (GST) activities in parenchymal (PC) and non-parenchymal (NPC) cell populations of control and Aroclor 1254-treated C57BL/6N and DBA/2N mice was determined. Furthermore, the metabolism of benzo(a)-pyrene (BP) in PC and NPC of both Aroclor 1254-treated mice strains was examined. Measurable activities of all enzymes investigated were detected in control PC as well as NPC of both mice strains; in all instances the PC possessed greater enzyme activities than did the NPC. The PC and NPC of DBA/2N of C57BL/6N mice. In NPC of both strains a low ratio of oxidative (APND and ERRD) to post-oxidative (EH and GST) enzyme activities was observed. Hence, NPC of C57BL/6N and DBA/2N mice might have a relatively lower ability to oxidize xenobiotics to reactive electrophiles and a greater ability to conjugate or hydrolyze those products that may be formed. Treatment with Aroclor 1254 enhanced all the enzyme activities measured in PC and NPC of both mice strains with the exception of ERRD in PC and NPC of DBA/2N mice. This is due to the fact that the induction process of ERRD by aromatic and halogenated aromatic compounds such as Aroclor 1254 depends upon the presence of a cytosolic receptor with a high affinity for this type of inducers and the DBA/2N mice have a very poor affinity receptor. After incubating BP with PC or NPC of Aroclor 1254-treated C57BL/6N mice significant amounts of 9,10-dihydrodiol, 4,5-dihydrodiol, 7,8-dihydrodiol, quinone, 9-hydroxy and 3-hydroxy derivatives of BP were detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopyrine N-Demethylase↗
PubMed1996

Viability and Metabolic Features of Bacteria Indigenous to a Contaminated Deep Aquifer

The quantitation and characterization of indigenous bacteria of a deep aquifer, located in the southwestern United States and contaminated with halogenated aliphatic compounds, was undertaken. Water samples were obtained aseptically from depths of 45 to 151 m from four sites that ranged from 260 to 1,800 m in distance from the location of contaminant release. Sediment samples were also obtained from the proximal and distal sites for analyses. Results for aerobic and anaerobic colony-forming units were obtained on four agar media that were used to retrieve heterotrophs, oligotrophs, and pseudomonads. Most probable number estimates were obtained from a liquid medium favorable for oligotrophs. Representative isolates were tested against Biolog plates (Biolog, Inc., Hayward, Calif.) for patterns of carbon source utilization. Of 103 Gram-negative (GN) isolates, 48 could not be identified and the others were only tentatively identified via the Biolog database, and none of the 35 Gram-positive (GP) isolates were identifiable. However, the metabolic patterns were subjected to average cluster linkage analyses; the GN and GP bacteria were separable into eight and four groups, respectively. The oligotroph group comprised one-third of the GN and one-half of the GP isolates. The consensus carbon source utilization pattern for each group was determined and will be useful in future characterization of additional aquifer bacterial isolates. Although predominantly aerobic and oligotrophic, the microbial community of this aquifer was highly diverse with discernible viability and metabolic features of the microbiota distinctive to each of the four water and two sediment samples.

Journal Article↗
PubMed1992

Risk factors for small bowel cancer in Crohn's disease.

Suspected risk factors for adenocarcinoma of the small bowel in Crohn's disease include surgically excluded small bowel loops, chronic fistulous disease, and male sex. Review of all seven University of Chicago cases failed to confirm any suspected risk factor. A case-control study was performed to identify possible alternatives. Each case was matched to four randomly selected controls from an inflammatory bowel disease registry matched for year of birth, sex, and confirmed small bowel Crohn's disease. Three factors were significantly associated with the development of cancer: (1) Four cancers developed in the jejunum, and jejunal Crohn's disease was associated with the development of cancer [odds ratio (OR) 8.0, 95% confidence interval (CI) 1.6-39.3]. (2) There was an association between the development of cancer and occupations known to be associated with an increased colorectal cancer risk (OR 20.3, CI 2.7-150.5). Three cases (a chemist with exposure to halogenated aromatic compounds and aliphatic amines, a pipefitter with exposure to asbestos, and a machinist with exposures to cutting oils, solvents, and abrasives) and one of 28 controls (a fireman with multiple hazardous exposures) had an occupational risk factor. (3) Among medications taken for at least six months, only 6-mercaptopurine use was associated with cancer (OR 10.8, CI 1.1-108.7). In conclusion, proximal small bowel disease, 6-mercaptopurine use, and hazardous occupations are associated with cancer of the small bowel in patients with Crohn's disease and can be added to the list of suspected risk factors.

Adenocarcinoma↗
PubMed1999

Tetrachloroethene-dehalogenating bacteria.

Tetrachloroethene is a frequent groundwater contaminant often persisting in the subsurface environments. It is recalcitrant under aerobic conditions because it is in a highly oxidized state and is not readily susceptible to oxidation. Nevertheless, at least 15 organisms from different metabolic groups, viz. halorespirators (9), acetogens (2), methanogens (3) and facultative anaerobes (2), that are able to metabolize tetrachloroethene have been isolated as axenic cultures to-date. Some of these organisms couple dehalo-genation to energy conservation and utilize tetrachloroethene as the only source of energy while others dehalogenate tetrachloroethene fortuitously. Halorespiring organisms (halorespirators) utilize halogenated organic compounds as electron acceptors in an anaerobic respiratory process. Different organisms exhibit differences in the final products of tetrachloroethene dehalogenation, some strains convert tetrachloroethene to trichloroethene only, while others also carry out consecutive dehalogenation to dichloroethenes and vinyl chloride. Thus far, only a single organism, 'Dehalococcoides ethenogenes' strain 195, has been isolated which dechlorinates tetrachloroethene all the way down to ethylene. The majority of tetrachloroethene-dehalogenating organisms have been isolated only in the past few years and several of them, i.e., Dehalobacter restrictus, Desulfitobacterium dehalogenans, 'Dehalococcoides ethenogenes', 'Dehalospirillum multivorans', Desulfuromonas chloroethenica, and Desulfomonile tiedjei, are representatives of new taxonomic groups. This contribution summarizes the available information regarding the axenic cultures of the tetrachloroethene-dehalogenating bacteria. The present knowledge about the isolation of these organisms, their physiological characteristics, morphology, taxonomy and their ability to dechlorinate tetrachloroethene is presented to facilitate a comprehensive comparison.

Bacteria↗
PubMed1998

[Shampoos: composition and clinical applications].

Shampooing is the most common form of hair treatment. Shampoos have primarily been products aimed at cleansing the hair and scalp. The diversity of qualities demanded from a good shampoo by today's consumer go far beyond this general function. A cosmetic benefit is expected, and the shampoo formulation has to be tailored to all the possible variations associated with hair quality (dry, greasy, permed, bleached, dyed), age (baby shampoo), care habit (frequency of shampooing) and specific problems relating to the superficial condition of the scalp (dandruff, seborrhea). Selected ingredients of shampoos that have been popular with the consumer are currently under attack because of potential risks associated with their use (e.g. halogenated organic compounds, formaldehyde, musk fragrances, and crude coal tar). Our standard graduate training programs devote limited attention to the subject of shampoos, and much of the readily available information concerning shampoos is supplied by the industry. We should be increasingly aware that our patients look to us to supply independent information on what can be expected from a shampoo to enable them to make more informed choices at the consumer level.

Hair↗
PubMed2001

Hyphenation of a near-infrared Echelle spectrometer to a microplasma for element-selective detection in gas chromatography.

The coupling of a near-infrared Echelle spectrometer (NIRES) with a gas chromatograph for element-selective detection is introduced. The miniaturized capacitive plasma device is operated at a frequency of 40.68 MHz and is mounted directly on an Hewlett-Packard HP6890 GC. First results with a mixture of halogenated standard compounds are presented and discussed in terms of the advantages and problems with this system.

Journal Article↗
PubMed2000

Biochemical responses of fish sac fry and a primary cell culture of fish hepatocytes exposed to polychlorinated naphthalenes.

Chlorinated naphthalenes are planar halogenated aromatic compounds, which are widespread in the environment. Knowledge of their biochemical and toxicological actions in aquatic biota is, however, limited. The objective of this study was to assess the toxicity of highly chlorinated naphthalene congeners found in the aquatic environment on fish sac fry and to study their effects on xenobiotic metabolizing enzymes (CYP) using a short-term primary culture of fish hepatocytes and liver microsomes. A few days after hatching, rainbow trout sac fry were administered either Hallovax 1014, a mixture of 1,2,3,4,6,7-hexachloronaphthalene and 1,2,3,5,6, 7-hexachloronaphthalene (HxCN-mix), or 1,2,3,4,5,6, 7-heptachloronaphthalene (HpCN) (0.08, 0.8, and 4 microg/sac fry injected into the yolk sac). The exposure was terminated 2 weeks later. The naphthalene preparations did not cause any clinical signs of toxicity or difference in mortality rates between the control and treated groups. Immunohistochemical analysis of CYP1A expression in the treated sac fry revealed that staining was most pronounced in the hepatocytes and thereafter in kidney tubular epithelial cells. Moderate CYP1A staining was also seen in the mucosal epithelium of pyloric caecae and mild staining in the epithelium of olfactory organ. Staining in control sac fry was weak or absent. Exposure of the primary cell culture of trout hepatocytes to a low doses (</=10 ng/ml) of the chlorinated naphthalenes increased significantly CYP1A-associated EROD activity and CYP1A mRNA content, HxCN-mix being the most potent and thereafter HpCN and Hallovax 1014. The higher doses (50-100 ng/ml) of each naphthalene also inhibited EROD activity. However, the content of CYP1A mRNA or the intensity of the CYP1A protein band (58 kDa) recognized by anti-trout CYP1A peptide antibodies were not decreased with increasing polychlorinated naphthalene (PCN) concentration, indicating that the inhibition was not due to reduced protein synthesis. Furthermore, in vitro analyses of the inhibitory potential of PCNs on CYP1A activity with trout liver microsomes suggested that these naphthalene preparations may be CYP1A substrates and act as competitive inhibitors of CYP1A catalyst. Our results demonstrate that highly chlorinated naphthalenes are potent modulators of fish CYP1A enzyme and suggest that hepatocytes and tubular epithelial cells are the cell types that may be vulnerable to their metabolic products for cell injury in fish sac fry.

Animals↗
PubMed2000

Dechlorination of polychlorinated methanes by a sequential methanogenic-denitrifying bioreactor system.

A two-stage bioreactor has been developed to link dechlorination of halogenated methane compounds to the anaerobic processes of methanogenesis and denitrification. A digester methanogenic consortium was shown to dechlorinate chloroform (CF) and carbon tetrachloride (CT) to dichloromethane (DCM), and DCM was then mineralized by an acclimated denitrifying biological activated carbon consortium. Combining these two processes, a sequential methanogenic-denitrifying bioreactor (SMDB) system that completely degraded polychlorinated methanes including CT, CF, and DCM was developed. More than 95% of the added CT and CF was dechlorinated in the methanogenic bioreactor with methanol as the primary substrate, and the resultant DCM was biodegraded in the denitrifying bioreactor with nitrate as the electron acceptor. In the denitrifying bioreactor, the residual CF was completely removed, and the DCM removal efficiency was more than 95%. This novel bioreactor system eliminates the need for aeration and so avoids the air contamination associated with aerobic biotreatment of volatile chlorinated pollutants. This SMDB system provides an alternative to conventional biotreatment of wastewaters and other matrices contaminated with polychlorinated methanes and is, to our knowledge, the first report on such a sequential anoxic system.

Bacteria↗
PubMed2001

Amphitrite ornata, a marine worm, contains two dehaloperoxidase genes.

Amphitrite ornata, a terebellid polychaete, inhabits marine environments that are contaminated by biogenically produced halometabolites. These halogenated organic compounds are toxic and quite diverse. To survive in this environment, A. ornata produces a novel dehaloperoxidase (DHP I) that detoxifies haloaromatic compounds. In this study we identified and characterized two dehaloperoxidase genes, designated dhpA and dhpB, from an A. ornata complementary DNA library. The deduced amino acid sequences (DHP A and DHP B) of the two dhp genes both contain 137 amino acid residues, but they differ at 5 amino acid positions. Allelic variation was observed for both genes as well. Polymerase chain reaction-restriction fragment length polymorphism assays of genomic DNA from 19 in individuals showed that each individual contains both the dhpA and the dhpB genes. Therefore, the two types of DHP are encoded by separate genes and are not alleles of a single gene. Furthermore, DHP A and DHP B may have different substrate specificities since they have amino acid differences in the active site.

Journal Article↗
PubMed2006

Predicting infinite dilution activity coefficients of organic compounds in water by quantum-connectivity descriptors.

Quantitative structure-property relationship (QSPR) models are developed to predict the logarithm of infinite dilution activity coefficient of hydrocarbons, oxygen containing organic compounds and halogenated hydrocarbons in water at 298.15 K. The description of the molecular structure in terms of quantum-connectivity descriptors allows to obtain more simple QSPR models because of the quantum-chemical and topological information coded in this type of descriptors. The models developed in this paper have fewer descriptors and better statistics than other models reported in literature. The current models allow a more transparent physical interpretation of the phenomenon in terms of intermolecular interactions which occur in solution and which explain the respective deviations from ideality.

Hydrocarbons↗
PubMed1995

Catalytic and immunologic characterization of hepatic and lung cytochromes P450 in the polar bear.

The Arctic Ocean is subject to considerable influx of anthropogenic pollutants including halogenated organic compounds. The polar bear (Ursus maritimus) is at the top of the arctic marine food web and is an ideal species for monitoring the level and distribution of contaminants in the arctic ecosystem. As the first step in the development of a biological method for assessing the functional exposure of polar bears to xenobiotics, biochemical studies were undertaken to characterize polar bear cytochromes P450. Liver and lung samples were obtained in the field from four, freshly killed, adult, male polar bears and immediately frozen at -196 degrees. Microsomes were subsequently prepared and used for the measurement of total cytochrome P450 content and aminopyrine N-demethylase, benzphetamine N-demethylase, ethylmorphine N-demethylase, p-nitrophenol hydroxylase and testosterone hydroxylase activities. Immunoblots containing hepatic and lung microsomal samples from the polar bears were probed using antibodies generated against several purified rat cytochrome P450 isozymes. Monoclonal antibody to rat cytochrome P450 1A1 and polyclonal antibodies to rat cytochromes P450 1A1, 2B1 and 3A1, as well as antibody to epoxide hydrolase, cross-reacted to varying degrees with polar bear hepatic microsomes. In addition, polyspecific antibody to the rat cytochrome P450 2C subfamily gave several immunostained protein bands, but antibodies specific to rat cytochrome P450 2C7 and 2C13 did not react, while antibody specific to cytochrome P450 2C11 yielded an ambiguous result. Except for anticytochrome P450 2B1 and polyspecific antibody to the cytochrome P450 2C subfamily, the antibodies listed above did not cross-react with polar bear lung microsomes at the protein concentrations used. The results demonstrate that polar bear liver contains multiple forms of cytochrome P450 that are catalytically active toward diverse substrates and that several of these forms are immunochemically related to rat cytochrome P450 isozymes. Immunochemical homologues of rat cytochrome P450 1A, 2B, 2C and 3A subfamilies, and of rat epoxide hydrolase are present in polar bear liver. In addition, the polar bears all had high levels of immunoreactive cytochrome P450 1A and 2B proteins, probably as a consequence of induction by environmental contaminants.

Animals↗
PubMed1992

Adenocarcinoma of the retinal pigment epithelium in the guppy Poecilia reticulata Peters.

A single case of adenocarcinoma of the retinal pigment epithelium occurred in a guppy, Poecilia reticulata, Peters. This is the first such tumour reported from fishes. The left eye of the affected fish was severely exophthalmic because of a large intraocular tumour mass. The tumour, which displaced normal retina anteriorly, consisted mainly of melanin-containing epithelial cells. Neoplastic cells were bilayered and arranged in a tubular pattern. The tumour was confined to the orbit. Although the specimen was from a group exposed to a mixture of halogenated organic compounds, the lesion was not considered to have been chemically induced because of its rare occurrence within the group as a whole.

Adenocarcinoma↗