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At least 1,423 records · Page 79Linked to original sources
PubMed2000

Transformation of mono- and dichlorinated phenoxybenzoates by phenoxybenzoate-dioxygenase in pseudomonas pseudoalcaligenes POB310 and a modified diarylether-metabolizing bacterium.

Pseudomonas pseudoalcaligenes POB310 contains genes that encode phenoxybenzoate dioxygenase. The enzyme transforms mono- and dichlorinated phenoxybenzoates to yield protocatechuate that is used as a growth substrate and chlorophenols that are nonmetabolizable. Mass spectral analysis of (18)O metabolites obtained from the protocatechuate 3,4-dioxygenase-deficient mutant, POB310-B1, suggested that the reaction mechanism is a regioselective angular dioxygenation. A cloning vector containing reaction relevant genes (pD30.9) was transferred into Pseudomonas sp. strain B13 containing a modified ortho-cleavage pathway for aromatic compounds. The resultant Pseudomonas sp. strain B13-D5 (pD30.9) completely metabolized 3-(4-chlorophenoxy)benzoate. During growth on 3-phenoxybenzoate, strain B13-D5 (pD30.9) (K(s) = 0.70+/-0.04 mM, mu(max) = 0.45+/-0.03 h(-1), t(d) = 1.5 h, Y = 0.45+/-0.03 g bio- mass x g substrate(-1)) was better adapted to low substrate concentrations, had a faster rate of growth, and a greater yield than POB310 (K(s) = 1.13+/-0.06 mM, mu(max) = 0.31+/-0.02 h(-1), t(d) = 2.2 h, Y = 0.39+/-0.02 g biomass. g substrate(-1)).

Bacterial Proteins↗
PubMedDate not supplied

[Growth of Rhodococcus opacus on mixtures of monohalogenated benzenes and phenols].

The growth of Rhodococcus opacus GM-14 on mixtures of 2-chloro- and 2-bromophenol, of 4-chloro, 4-bromo-, and 4-iodophenol, and of chloro-, bromo-, and iodobenzenes was accompanied by consumption of the substrates and excretion of halogen ions to the medium. During the growth on monochlorophenols, the substrates were consumed sequentially in the following order: 4-chloro-, 3-chloro-, and then 2-chlorophenol. Chlorine ions were excreted in a two-phase manner in amounts comprising 79% of the theoretical yield. The diauxic growth of R. opacus GM-14 can be explained by the existence in this bacterium of two modified metabolic pathways for the ortho-cleavage of halogenated pyrocatechols. The first pathway included 4-halogeno- or dihalogenopyrocatechols as intermediates, whereas the second pathway included 3-halogenopyrocatechols.

Benzene Derivatives↗
PubMed2000

[Development of ELISAs for endocrine disrupting chemicals].

Six kinds of ELISA systems were developed for the quantitative analysis for endocrine disrupting chemicals, such as bisphenol A(BPA), diethylhexylphthalate (DEHP), dibutylphthalate(DBP), alkylphenol(AP), alkylphenol ethoxylate(APE) and chlorophenols(CP). The detection limit of ELISAs were 5, 150, 200, 10, 20 and 2 ng/ml, respectively. The specificities of monoclonal antibodies used for ELISA systems were confirmed with the cross-reaction test using several compounds which have structural resemblance.

Endocrine System↗
PubMedDate not supplied

Determination of phenolic disinfectant agents in commercial formulations by liquid chromatography.

Using liquid chromatography (LC), a convenient and versatile method was developed for the assay of disinfectant products containing the commonly used phenolic agents, alone or in combination, including phenol, 2-phenylphenol, 4-t-amylphenol, 4-chloro-3,5-dimethylphenol (PCMX), 2-benzyl-4-chlorophenol, and triclosan. The procedure involves a simple dilution or dissolution of the product aliquot or portion followed by membrane filtration and LC. The method was applied to 19 different products representing 17 manufacturers and containing from one to 4 phenolic agents. Chromatography was performed using a Zorbax SB-C18 column, acetonitrile-0.05M KH2PO4 (55 + 45, v/v) pH 3.00, as mobile phase and UV detection at 280 nm. The intralaboratory precision of the product assays ranged form 0.34-5.35% (n = 5) and recoveries via fortification varied from 96.1-103.8%. The limits of quantitation (LOQ) and detection (LOD) ranged from 5.58 x 10(-5) to 2.50 x 10(-4) mg/mL and from 1.76 x 10(-5) to 0.67 x 10(-4) mg/mL, respectively, for the 6 analytes. The response for all analytes was observed to be linear for at least a 50-fold range in concentration (0.001-0.05 mg/mL). The proposed method provides an efficient means for the isolation and quantitation of these phenolic compounds.

Chromatography, Liquid↗
PubMed2001

[Epidemiology of soft tissue sarcomas in adults].

INCIDENCE: Soft tissue sarcoma accounts for a approximately 1% of all cancers. Excluding Kaposi sarcoma, the incidence of soft tissue sarcoma has remained stable in Europe (3-4/100,000). ENDOGENOUS FACTORS: Endogenous factors are related to rare genetic syndromes (Li-Fraumeni syndrome, neurofibromatosis, Werner syndrome, bilateral retinoblastom). EXOGENOUS FACTORS: Exogenous factors associated with soft tissue sarcoma are essentially iatrogenic: radiation therapy (prevalence of radiation-induced sarcoma: 0.17-0.21%) and chronically edematous arms after radical mastectomy for breast cancer (Stewart-Treves syndrome). Many studies suggest that environmental or occupational exposure to chlorophenol, phenoxy-herbicides or dioxin increase the risk of soft tissue sarcoma. FURTHER RESEARCH: Little is known about the epidemiology of soft tissue sarcoma. Case-control studies are needed.

Adult↗
PubMed2001

Treating an aged pentachlorophenol- (PCP-) contaminated soil through three sludge handling processes, anaerobic sludge digestion, post-sludge digestion and sludge land application.

The extensive pentachlorophenol (PCP) contamination and its increasing treatment costs motivate the search for a more competitive treatment alternative. In a municipal wastewater treatment plant, anaerobic sludge-handling processes comprises three bio-processes, namely the anaerobic sludge digestion, post-sludge digestion and sludge land application, which reduce sludge organic content and make sludge a good fertilizer for land application. Availability and effectiveness make the anaerobic sludge handling processes potential technologies to treat PCP-contaminated soil. The technical feasibility of using anaerobic sludge bioprocesses was studied by treating PCP soil in two pilot digesters to simulate the primary sludge digestion, in serum bottles to mimic the post-sludge digestion, and in glass pans to represent the on-site sludge application. For primary digestion, the results showed that up to 0.98 and 0.6 mM of chemical and soil PCP, respectively, were treated at nearly 100% and 97.5% efficiencies. The PCP was transformed 95% to 3-MCP, 4.5% to 3,4-DCP, and 0.5% to 3,5-DCP. For post-digestion, 100% pure chemical PCP and greater than 95% soil PCP were removed in less than 6 months with no chlorophenol residues of any kind. Complete removal of PCP by-products makes this process a good soil cleanup method. For on-site treatment, PCP was efficiently treated by multiple sludge application; however, the PCP residue was observed due to the high initial PCP content in soil. Overall, more mass PCP per unit sludge per day was processed using the primary sludge digestion than the on-site soil treatment or post-sludge digestion. And, sludge acclimation resulted in better PCP treatment efficiencies with all three processes.

Agriculture↗
PubMed2001

Monitoring temporal and spatial trends in polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in eggs of great blue heron (Ardea herodias) on the coast of British Columbia, Canada, 1983-1998.

Eggs from 21 resident great blue heron (Ardea herodias) rookeries were monitored from 1983 to 1998 along the coast of British Columbia, Canada, for contamination with polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs). Dominant congeners (1,2,3,7,8-PnCDD, 1,2,3,6,7,8-HxCDD, 2,3,7,8-TCDD, 2,3,7,8-TCDF, 1,2,3,7,8,9-HxCDD and 2,3,4,7,8-PnCDF) fell markedly in the early 1990s after pulp mills changed from molecular chlorine bleaching to alternative bleaching technologies, and the use of chlorophenolic wood preservatives and anti-sapstains was severely restricted. Strong positive linear regressions between prey fish and heron egg contaminant levels suggested that local dietary uptake was an important route of exposure for herons. Toxic equivalent concentrations (TEQs) sufficient to produce embryotoxicity in great blue heron chicks were measured in eggs from 1985 to 1991 at some colonies. Despite reduction in PCDD/Fs, estimated TEQs remained elevated throughout the 1980s at some urban colonies due to contributions from PCBs.

Animals↗
PubMed2002

A multiple-antibiotic resistance-independent active chloramphenicol efflux in an Escherichia coli clinical isolate.

The clinical isolate, Escherichia coli 1941, exhibits high resistance to chloramphenicol and tetracycline (minimum inhibitory concentrations of 512 micrograms/ml). Neither resistance is linked to the large conjugative plasmid present in the strain. The intracellular accumulation of radiolabeled chloramphenicol increased about 9-fold after the addition of the energy uncoupler carbonyl cyanide m-chlorophenol-hydrazone to an E. coli 1941 culture, indicating the presence of an active efflux mechanism. Sequence analysis and expression study suggested that the multiple-antibiotic resistance marRAB locus and the AcrAB drug-efflux pump were not involved in this active efflux of chloramphenicol.

Anti-Bacterial Agents↗
PubMed2002

Thermodynamic study of adsorption of phenolic compounds onto Amberlite XAD-4 polymeric adsorbents and its acetylized derivative MX-4.

Adsorption equilibrium isotherms of phenolic compounds, phenol, p-cresol, p-chlorophenol and p-nitrophenol, from aqueous solutions by Amberlite XAD-4 polymeric adsorbent and its acetylized derivative MX-4 within temperature range of 283-323K were obtained and fitted to the Freundlich isotherms. The capacities of equilibrium adsorption for all four phenolic compounds from their aqueous solutions increased around 20% on the acetylized resin, which may be contributed to the specific surface area and the partial polarity on the network. Estimations of the isosteric enthalpy, free energy, and entropy for the adsorption process were reported.

Acetylation↗
PubMed1999

[Preparation and chromatographic characteristics of linear [60] fullerene polysiloxane stationary phase for capillary gas chromatography].

Hydrosilylation of polymethylhydrosiloxane (active hydrogen content was 0.05%) and reactions with allylbromide (or undecenyl bromide), sodium azide and [60] fullerene in their given orders is described. Two kinds of fullerene-containing polysiloxanes were obtained [polymer(3)]. Their [60] fullerene contents were 30 mg (C60-PSO-1) and 60 mg (C60-PSO-2) respectively. These polymers (3) were characterized by FT-IR, 1H-NMR, UV-V, 13C-NMR and used as stationary phase for capillary chromatography. Two fused-silica capillary columns (0.25 mm i.d.) were coated with a 5 g/L solution of polymer (3) in dichloromethane by the static method. The column efficiencies were 3,450 plates/m (C60-PSO-1) and 3,020 plates/m (C60-PSO-2), for naphthalene at 120 degrees C. The average polarities of these columns, represented by the McReynold's Constant, were 79 and 93 respectively. The polarity of C60-PSO-2 was a little higher than that of C60-PSO-1, which was in turn a little higher than that of SE-30(43). These columns showed wide operation temperature range (100-360 degrees C) and outstanding thermostability. It could be used at 360 degrees C with a baseline drift of 30-40 fA. Grob test mixtures eluted on these columns in the ordre of 1,3-butanediol, n-decane, 1-octanol, n-undecane, 2,6-dimethylphenol, n-dodecane, 2,4-dimethylaniline, naphthalene, indicating that the strong pi-pi interaction of [60] fullerene with aromatic moieties played an important role in separation mechanism. The columns exhibited unique selectivity for many organic compounds, such as alkanes, alcohols, ketones and anilines. It can well separate benzene homologues, naphthalene homologues and polyaromatic hydrocarbons(PAHs) due to the pi-pi interaction of three-dimensional pi system of C60 and aromatic hydrocabons. And the columns are especially good for the separation of positional isomers(nonanol, butanediol, nitrotoluene, nitrochlorobenzene, nitroethylbenzene, dinitrobenzene, chlorophenol). The columns also have excellent thermostability and are particularly suitable for the separation of high boiling compounds. For example, polycyclic aromatic hydrocarbons and fatty acid methyl esters are well separated on them.

Carbon↗
PubMed2003

Effects of chlorine content and position of chlorinated phenols on their oxidation kinetics by potassium permanganate.

Chlorine content and position of chlorinated phenols have many significant effects on the reactivity of oxido-reduction. The effects of chlorine content and position of chlorinated phenols on their oxidation kinetics by potassium permanganate were evaluated through different kinetics studies. Since chlorine was an electron withdrawing atom, the substitution of chlorine on the aromatic ring decreased the oxidation rate constant by sigma-electron withdrawing conductive effect. The substitution of chlorine at ortho or para position on the aromatic ring increased the oxidation rate constant by pi-electron donating conjugative effect, and the conjugative effect could counteract the negative impact of the conductive effect to some extent. On the other hand, the substitution of chlorine at ortho position on the aromatic ring decreased the oxidation rate constant by steric hindrance effect. The oxidation rate constants of phenol and chlorinated phenol studied decreased as follow order: 4-chlorophenol > 2,4-dichlorophenol > phenol > 2,6-dichlorophenol.

Chlorine Compounds↗
PubMed2003

[The reactions between acidic phenolsulfonphthaleins and human serum albumin].

The reactions between HSA and acidic phenolsulfonphthaleins, including phenol red, cresol red, chlorophenol red, bromocresol purple and m-cresol purple, have been investigated by fluorescence spectrometry. The experiments showed that all of the selected acidic phenolsulfonphthaleins strongly quenched the fluorescence produced by HSA, and this fluorescence quenching could be interpreted in terms of statistic quenching. From the calculation results of binding constants K for these dyes at various temperatures, it could be found that the increase in the functional groups numbers of dyes molecules resulted in an increase in K, while the increase in reaction temperature led to a decrease in K. The interactions between dyes and HSA were attributed to static-electricity gravitation, which was confirmed by the calculation results of enthalpy and entropy for these reactions. According to the non-radiation energy transfer theory, the distances and energy transfer efficiencies between dyes and protein at various temperatures were obtained. These results further supported the conclusion that these reactions belonged to the single static quenching caused by the energy transfer.

Binding Sites↗
PubMed1962

Ammoniacal dermatitis. Clinical observations on an efficacious, economical and neglected treatment.

Several pediatricians in one community began instructing mothers of infants with ammoniacal diaper rash to use o-benzyl-p-chlorophenol (OBPC) in laundering diapers. This simple, previously reported item of management was prescribed in 87 cases of ammoniacal rash. In almost all uncomplicated cases the rash cleared in an average of four days; when complicated by Staphylococcus aureus or Monilia albicans infection, clearing took a few days longer. The few cases of less than satisfactory results were attributable to improper use of the chemical. Several of the mothers had mild irritation of the hands from use of OBPC.

Candidiasis↗
PubMed1992

Non-Hodgkin's lymphoma and occupational exposure.

A case-control study was conducted to assess the effect of occupational exposures on the risk of non-Hodgkin's lymphoma. Interviews were conducted with 303 persons with non-Hodgkin's lymphoma newly diagnosed from January 1, 1980, to May 31, 1982, among residents of the Boston, MA, metropolitan area and 303 age and gender matched controls. The study found an increased risk of disease among persons employed in the agriculture, forestry, and fishing industry [relative risk (RR) = 3.0]; the construction industry [RR = 2.1]; and the leather industry [RR = 2.1]. The particular job groupings at increased risk were plant farmers and gardeners (RR unbounded); painters and plasterers (RR = 6.0); and carpenters, brick and stone masons, plumbers, and roofers (RR = 12.0). Although other exposures may have led to these increased risks, the findings in this study are consistent with an increased risk of non-Hodgkin's lymphoma for workers who may be exposed to chlorophenols or phenoxyacetic acids.

Adolescent↗
PubMed2004

Design and application of a GC-SNIff/MS system for solving taste and odour episodes in drinking water.

This paper describes the implementation of a GC-Sniff/MS system that allows the simultaneous determination of the odorous properties of compounds eluting from a GC column and their identification by MS. The technique was first tested with standard compounds then applied to real cases of taste and odour episodes. This approach allowed the identification of geosmin at low levels and suggested the possible implication of methylnaphthalene in the development of chemical odours. It provided the first clue of the presence of a halophenol with a very low odour threshold involved in a chlorophenolic odour episode. The chemical was finally identified as 2,6-dibromophenol. The method was also applied to the characterization of a complex mixture of additives leaching from a flexible rubber pipe. In the latter case, Time-of-Flight MS was also used to confirm the identity of the additives.

Automation↗
PubMed2004

Role of oxidants and disinfectants on the removal, masking and generation of tastes and odours.

This paper summarises the positive and negative effects of the most commonly used oxidants and disinfectants: chlorine, chloramines, chlorine dioxide, potassium permanganate ozone, and advanced oxidation with ozone/hydrogen peroxide on tastes and odours present in natural and drinking waters. The case studies reported illustrate the generation of odorous by-products such as chlorophenols, iodoforms, aldehydes, the masking effect between earthy-musty and chlorinous odours, and the removal of odorous algal metabolites or anthropogenic pollutants by ozone alone or by ozone coupled with hydrogen peroxide.

Disinfectants↗
PubMed2005

[Health risk related to municipal waste incineration].

There are exposures to various organic and inorganic xenobiotics related to municipal waste incineration in work places and environment close to incinerators. Among others, these are polychlorinated biphenyls, dioxins, furans, chlorophenols, mono- and polycyclic aromatic hydrocarbons, toxic metals and irritation gases. Numerous studies revealed that these chemicals and their metabolites were generally not elevated in worker's blood and urine and in persons living near incinerators. The epidemiological studies indicate increased cancer risk and excess of ischemic heart disease in incinerator workers. In residents living in the vicinity of incinerators, a slightly increased cancer risk, respiratory symptoms, multiple pregnancy, congenital abnormalities, and disturbances in thyroid hormone levels were observed. However, these data do not provide univocal evidence that the cause-effect relationship between exposure and health risk does really exist.

Air Pollutants↗
PubMed2005

A pilot-scale photocatalyst-membrane hybrid reactor: performance and characterization.

We developed and tested a pilot-scale photocatalyst-membrane hybrid reactor for water treatment. The performance of the pilot-scale reactor was evaluated by monitoring the degradation efficiency of several organic pollutants and the membrane suction pressure at different operating conditions. The concentration of humic acids rather increased in the initial period of UV illumination and then decreased gradually, which could be ascribed to the photoinduced desorption of humic acids from the TiO2 surface. The decoloring rate of methylene blue was faster than that of rhodamine B, whereas the order of mineralization rates of the dyes was reversed. 4-chlorophenol of 100 ppb was fully degraded under UV irradiation in 2 hours, which suggests that this hybrid reactor would be more suitable in removing micropollutants in water. The reactor was operated with either continuous or intermittent suction mode. In a continuous suction mode, the formation of TiO2 cake layers on the membrane surface occurred and caused a substantial increase in suction pressure. However, no further fouling (or suction pressure build-up) took place with an intermittent suction mode with the 9-min suction and 3-min pause period. The photocatalyst-membrane hybrid reactor system developed in this study could be an attractive option for controlling micropollutants in water.

Biodegradation, Environmental↗