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Biomedical subjects

Antonius Kettrup

Publications and source records attributed to Antonius Kettrup.

At least 37 records · Page 2Linked to original sources
PubMed2004

Effect of linear alkyl benzene sulfonates (LAS) on the fate of phenanthrene in a model ecosystem (water-lava-plant-air).

Advanced closed chamber system was used to study the fate of phenanthrene (3-rings PAHs) in the presence of linear alkylbenzene sulphonates (LAS). The results showed mineralization and metabolism of phenanthrene are fast in the "culture solution-lava-plant-air" model ecological system. The distribution proportions of applied 14C-activity in this simulative ecological system were 41%-45%, 14% to 10% and 1% in plant, lava and culture solution respectively, and 18% to 29%, 11% to 8% recovered in the forms of VOCs and CO2. Main parts of the applied 14C-activity exist in two forms, one is polar metabolites (25%) which mainly distribute in the root (23%), the other is unextractable part (23%) which have been constructed into plant root (8.98%), shoot (0.53%) or bonded to lava (13.2%). The main metabolites of phenanthrene were polar compounds (25% of applied 14C-activity), and small portion of 14C-activity was identified as non-polar metabolites (6% of applied 14C-activity) and apparent phenanthrene (1.91% of applied 14C-activity). Phenanthrene and its metabolites can be taken up through plant roots and translocated to plant shoots. The presence of LAS significantly increased the the concentration of 14C-activity in the plant and production of VOCs, at the same time it decreased the phenanthrene level in the plant and the production of CO2 at the concentration of 200 mg/L.

Air↗
PubMed2003

A simple and robust set-up for on-column sample preconcentration--nano-liquid chromatography--electrospray ionization mass spectrometry for the analysis of N-acylhomoserine lactones.

A simple method for the simultaneous, rapid and sensitive determination of N-acylhomoserine lactone signaling molecules in bacterial isolates, without prior sample preconcentration and with minimal sample cleanup, is presented. The analysis relies on the combination of analyte preconcentration and separation on a single device: a relatively large sample volume (1-5 microL) is directly loaded onto a laboratory-made, miniaturized (75 microm i. d.) reverse phase nano-liquid chromatography column, connected on-line to a microelectrospray-ionization ion trap mass spectrometer. In a first step the analyte is adsorbed (and so concentrated) at the beginning of the column, and is eluted and selectively separated in a second step by the organic mobile phase. Sample preconcentration follows the mechanisms of solid phase extraction on a nano-scale, while separation takes place according to classical liquid chromatography separation principles. The columns can be manufactured easily, are simply connected, and used with minimal solvent amounts; this makes this method extremely robust and cost-effective. The analytical setup was found to be routinely quantitative down to a concentration of 10 ng/mL (corresponding to a total analyte amount of 10 pg or ca. 50 fmol). The limit of detection was reached at 1 ng/mL (1 pg, ca. 5 fmol). Compared to the classical AHL analysis of bacterial cultures with biosensors, where selectivity and sensitivity is often limited, this rapid analytical technique is a substantial qualitative and quantitative improvement. Two unsubstituted N-acylhomoserine lactones could be identified and quantified from a Burkholderia cepacia culture supernatant in a chloroform extract.

4-Butyrolactone↗
PubMed2003

On-line analysis of the size distribution of fine and ultrafine aerosol particles in flue and stack gas of a municipal waste incineration plant: effects of dynamic process control measures and emission reduction devices.

The size distribution of particles in the waste gas of a municipal waste incineration plant (23 MW) was measured on-line at two sampling points in the flue-gas duct (700 and 300 degrees C) as well as in the stack gas (80 degrees C). The measurements were performed during both stable combustion conditions and transient operating conditions. The particle measurements were carried out by a mobile system consisting of a home-designed sampling system with dilution device and a scanning mobility particle sizer (SMPS) for the particle size range 17-600 nm as well as an aerodynamic particle sizer (APS) for the size range 500 nm-30 microm. The APS and SMPS data were combined using a special method and a home written software tool. The maximum of the particle-size distribution in the flue gas of the incinerator shifts from about 90 nm at the 700 degrees C sampling point to about 140 nm at the 300 degrees C point, showing the particle growth by coagulation processes and condensation of inorganic and organic gaseous species with decreasing temperature. This finding is consistent with the measured concentration profiles of gaseous organic chemical species in the flue gas. While at flue-gas temperatures of 600-800 degrees C a rich pattern of polycyclic aromatic hydrocarbon species (PAH) is observable, the PAH concentrations are considerably reduced further downstream of the flue-gas channel, where the temperature drops below 500 degrees C. Condensation and reactive bonding of gaseous chemicals onto particulate matter is, among other reasons, responsible for the depletion of gas-phase species. Process control measures, such as firing the backup burners or cleaning of the grate with pressurized air, can cause dynamic changes of the particle-size distribution. Furthermore the flue-gas cleaning measures have great impact onto both the particle concentration and the size distribution. For this reason the impact of one particular emission reduction device, the wet electrostatic dust precipitator (wet-ESP), is evaluated. The wet-ESP reduces considerably the particle concentration over the whole size range. Behind the flue-gas processing units a broad maximum in the particle-size distribution occurs at about 70 nm, but no pronounced particle-size distribution could be observed. The particle concentration level atthis maximum is about 3 magnitudes lower than in the raw flue gas. However, intermittent periods lasting for several minutes of high emissions of ultrafine particles with d < 40 nm were observed. These particles are most likely formed by nucleation processes behind the wet-ESP from gas-phase constituents of the stack gas.

Aerosols↗
PubMed2003

Real-time monitoring of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting by resonant laser ionization time-of-flight mass spectrometry.

The formation of 4-vinylguaiacol, guaiacol, and phenol during coffee roasting was monitored in real-time, using resonance enhanced multiphoton ionization and time-of-flight mass spectrometry. A model is proposed, based on two connected reaction channels. One channel, termed the "low activation energy" channel, consists of ester hydrolysis of 5-FQA followed by decarboxylation of the ferulic acid to form 4-vinylguaiacol, and finally polymerization at the vinyl group to form partly insoluble polymers (coffee melanoidins). The second "high activation energy" channel opens up once the beans have reached higher temperatures. It leads to formation of guaiacol, via oxidation of 4-vinylguaiacol, and subsequently to phenol and other phenolic VOCs. This work aims at developing strategies to modify the composition of coffee flavor compounds based on the time-temperature history during roasting.

Coffea↗
PubMed2003

Evaluation of glycoalkaloids in tubers of genetically modified virus Y-resistant potato plants (var. Désirée) by non-aqueous capillary electrophoresis coupled with electrospray ionization mass spectrometry (NACE-ESI-MS).

The glycoalkaloid content of transgenic potatoes was evaluated by an optimised method based on non-aqueous capillary electrophoresis coupled on-line with electrospray ionization-mass spectrometry (NACE-ESI-MS). The potato material consisted of tubers from a conventional cv. Désirée and from three lines of modified plants resistant, intermediate and susceptible to infection by potato virus Y (PVY). The main glycoalkaloids were confirmed to be alpha-solanine and alpha-chaconine with parent ion masses m/z 852 and 868, respectively. In addition, an unknown minor peak at m/z 850.6 was found both in conventional (control) and susceptible line potato tubers. Such a compound exhibited an MS(2) spectrum with fragments ions at 704 and 396 m/z derived by loss of two ions, i.e. m/z 146 and 307, most likely corresponding to a rhamnose unit and a [glucose-(rhamnose)(2)] moiety, respectively. Up to 30-80-fold higher concentrations of total glycoalkaloids were found in the peel compared to flesh samples of all tubers examined. TGA content was nearly doubled in peel samples of resistant compared to control lines, and these levels were lower than the limit recommended for food safety, i.e. 20-60 mg of TGA per 100 g fresh weight. Moreover, it was established that tubers produced by virus-resistant clones are substantially equivalent in glycoalkaloid contents to those produced by conventional potato varieties.

Electrophoresis, Capillary↗
PubMed2003

Capillary electrophoresis--electrospray ionization--mass spectrometry for the characterization of natural organic matter: an evaluation with free flow electrophoresis-off-line flow injection electrospray ionization-mass spectrometry.

The separation of Suwannee River natural organic matter (NOM) with capillary zone electrophoresis hyphenated to electrospray ionization-mass spectrometry (CZE-ESI-MS) is presented. The obtained electropherograms and signal distributions are comparable to the mobility distributions obtained with more classical UV detection. A direct comparison of the results was possible with free-flow electrophoresis (FFE), which allows an upscaling of the CZE method and the analysis of the collected fractions in an off-line modus with flow-injection electrospray ionization-mass spectrometry (FI-ESI-MS). The changes of the m/z distributions with mobility are very similar with both methods and show a decrease of the m/z with increasing electrophoretic mobility in the humic hump at alkaline pH; superimposed on this hump a low-molecular-weight fraction migrates at lower mobility. The analysis of benzene carboxylic acids, glycerrhycic acid as well as oligomers of polystyrene sulfonic acid and polyacrylic acid additionally illustrates possible fragmentation, formation of adducts and multiplicity of the charges of the molecules prior to MS detection. These hardly controllable difficulties add a challenge to the interpretation of the obtained m/z distributions of NOM in terms of charge and mass distributions of molecules present in the NOM mixture.

Acrylic Resins↗
PubMed2003

Analysis of N-acyl-L-homoserine lactones produced by Burkholderia cepacia with partial filling micellar electrokinetic chromatography--electrospray ionization-ion trap mass spectrometry.

A method for the analysis of N-acyl-L-homoserine lactones (AHLs) with micellar electrokinetic chromatography coupled to electrospray ionization-ion trap mass spectrometry, combining the flexibility of capillary electrophoresis with the unmatched structural information provided by mass spectrometry is presented. Different surfactants were evaluated, with sodium dodecyl sulfate (SDS) yielding the best results considering sensitivity and flexibility. We examined the interaction of AHLs with the SDS micelles at different analysis conditions and applied the optimized method to the analysis of a real bacterial sample. Two AHLs from Burkholderia cepacia colonizing the rhizosphere of traditional Indian rice cultivars could be unambiguously determined in an ethyl acetate extract with high resolution flexibility.

4-Butyrolactone↗
PubMed2003

Separation of selected humic degradation compounds by capillary electrochromatography with monolithic and packed columns.

The separation of selected lignin/humic substance (HS) degradation compounds by capillary electrochromatography (CEC) with a methacrylate-based monolithic column and a conventional column packed with 5 microm octadecyl silica (ODS) particles is presented. The effects of organic modifier concentration, pH of the mobile phase, ionic strength, applied voltage, and temperature on the separation were investigated to determine the optimal separation conditions. With the increase of pH in the mobile phase, some of analytes start to ionize and both chromatographic partition and electrophoresis can play roles in separation simultaneously. Accordingly, different selectivity from high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) could be achieved. The performances of both kinds of columns were compared. The results showed that the peaks of compounds obtained on the former column were much wider than those on the latter one, although good separation efficiency of alkylbenzenes could be readily achieved; the most probable reasons for this behavior and method to solve this problem were briefly discussed. The CEC of a soil fulvic acid with a monolithic column produced partly resolved broad bands; by means of nuclear magnetic resonance (NMR) analysis a wide range of oxygen derived aromatic substitution patterns was found with prominent contributions from phenolic and carboxylic groups.

Benzopyrans↗
PubMed2003

Ozonation of an azo dye C.I. Remazol Black 5 and toxicological assessment of its oxidation products.

The effect of ozonation (20.5 mgl(-1)) on the degradation processes of an azo dye, Remazol Black 5 (RB5; CI) was studied. Conventional parameters such as chemical oxygen demand (COD), total organic carbon (TOC), pH, conductivity, colour removal, biodegradability (BOD(5/28)), and toxic potential of the dye and its degradation products were monitored during the process. The results obtained indicated that ozonation is a highly effective way to remove the colour of a corresponding dye solution. However, a considerable organic load still remained as indicated by high COD and TOC residues. The COD, TOC reductions were about 40% and 25% for 6 h ozonation of 2 gl(-1) RB5 aqueous solution. During the ozonation process the rapid decrease of pH and the sharp increase of conductivity indicated the formation of acidic by-products and small fragments and ions which were identified by high performance ion chromatography. The BOD28 data revealed that first by-products after partial ozonation (10-150 min) of RB5 were more biodegradable than the parent compound and ozonation can enhance the biodegradability of azo dyes. During the first 150 min of total 360 min of oxidation, the formation of first by-products with high toxic potential took place as it could be confirmed by two acute toxicity-screening tests, the bioluminescence test (Vibrio fischerii) and the neutral red cytotoxicity assay (rat hepatoma cells). The significant enhancement of microbial biodegradability after long-term ozonation could also be seen as a decrease of toxic intermediates in correlation with the ozonation time as indicated in BOD28 biological degradation test results.

Animals↗
PubMed2003

Quantitative structure-property relationships for octanol-air partition coefficients of polychlorinated naphthalenes, chlorobenzenes and p,p'-DDT.

The octanol-air partition coefficient (K(OA)) is a key descriptor of chemicals partitioning between the atmosphere and environmental organic phases. Quantitative structure-property relationships (QSPR) are necessary to model and predict K(OA) from molecular structures. Based on 12 quantum chemical descriptors computed by the PM3 Hamiltonian, using partial least squares (PLS) analysis, a QSPR model for logarithms of K(OA) to base 10 (logK(OA)) for polychlorinated naphthalenes (PCNs), chlorobenzenes and p,p'-DDT was obtained. The cross-validated Q(2)(cum) value of the model is 0.973, indicating a good predictive ability of the model. The main factors governing logK(OA) of the PCNs, chlorobenzenes, and p,p'-DDT are, in order of decreasing importance, molecular size and molecular ability of donating/accepting electrons to participate in intermolecular interactions. The intermolecular dispersive interactions play a leading role in governing logK(OA). The more chlorines in PCN and chlorobenzene molecules, the greater the logK(OA) values. Increasing E(LUMO) (the energy of the lowest unoccupied molecular orbital) of the molecules leads to decreasing logK(OA) values, implying possible intermolecular interactions between the molecules under study and octanol molecules.

Journal Article↗
PubMed2003

Effects of 17alpha-ethinylestradiol on the reproduction of the cladoceran species Ceriodaphnia reticulata and Sida crystallina.

Single-species tests allow the assessment of chronical effects of endocrine disruptors on organisms under laboratory conditions. In the current study, three-generation tests with Ceriodaphnia reticulata and Sida crystallina were carried out to examine the influence of the synthetic hormone 17alpha-ethinylestradiol (EE) on the reproduction of these cladoceran species. For each species, six different concentrations (10-500 microg/l EE) and two controls were tested with eight replicates for a duration of 4 weeks. The test was initiated by transferring one neonate individual into a test vessel which was incubated under standardized conditions. Every 2 days, the medium was renewed and life history parameters such as survivorship of the adults and juveniles, clutch size, first appearance and number of produced offspring were investigated. Acute toxicity tests showed that C. reticulata (EC50 (24 h) 1814 microg/l) was more sensitive towards the substance compared to S. crystallina (EC50 (24 h) >4100 microg/l). The juvenile phase of S. crystallina was significantly shorter at concentrations above 100 microg/l EE. For C. reticulata, 17alpha-ethinylestradiol caused a higher mortality of the newly hatched juveniles at EE concentrations above 200 microg/l. No effects were found for mortality of adult animals, birth rate, number of juveniles per female and net reproduction rate of S. crystallina and C. reticulata. Thus, sublethal effects on parental generation exposed to EE lead to disturbances in reproduction and to affection of their offspring. Negative consequences for the population dynamic cannot be excluded, e.g. the decrease of a population.

Animals↗
PubMed2003

Photolysis of polycyclic aromatic hydrocarbons adsorbed on spruce [Picea abies (L) Karst] needles under sunlight irradiation.

Photolysis of polycyclic aromatic hydrocarbons (PAHs) sorbed on surfaces of spruce [Picea abies (L.) Karst.] needles under sunlight irradiation was investigated. PAHs were produced by combustion of polyvinyl chloride (PVC), wood, high-density polyethylene (HDPE), and styrene in a stove. The factors of sunlight irradiation on the surfaces of spruce needles were taken into consideration when investigating the kinetic parameters. The photolysis of the 18 PAHs under study follows first-order kinetics. The photolysis half-lives range from 15 h for dibenzo(a,h)anthracene to 75 h for phenanthrene. Photolysis of some PAHs on surfaces of spruce needles may play an important role on the fate of PAHs in the environment.

Adsorption↗
PubMed2003

Decolorization of synthetic dyes and production of manganese-dependent peroxidase by new fungal isolates.

Two yeasts, Debaryomyces polymorphus, Candida tropicalis, and two filamentous fungi, Umbelopsis isabellina, Penicillium geastrivorus, could completely decolorize 100 mg Reactive Black 5 (RB 5) l-1 within 16-48 h. Manganese-dependent peroxidase (MnP) activities between 60 and 424 U l-1 were detected in culture supernatants of three of these organisms indicating the color removal by enzymatic biodegradation but with P. geastrivorus there was no ligninolytic enzyme activity in its culture and the decolorization was mainly due to biosorption to mycelium. Extensive decolorization by D. polymorphus (69-94%) and C. tropicalis (30-97%) was obtained with five other azo dyes and one anthraquinone dye. Except for Reactive Brilliant Blue KNR and Reactive Yellow M-3R, the four azo dyes, Reactive Red M-3BE, Procion Scharlach H-E3G, Procion Marine H-EXL and Reactive Brilliant Red K-2BP, induced D. polymorphus to produce MnP (105-587 U l-1). However, MnP activities of 198-329 U l-1 were only detected in the culture of C. tropicalis containing Reactive Red M-3BE and Reactive Brilliant Red K-2BP, respectively.

Azo Compounds↗
PubMed2003

Optimisation of extraction procedures for metallothionein-isoforms and superoxide dismutase from liver samples using spiking experiments.

The speciation of trace element species in solid matrices like liver samples is still problematic due to two reasons. On the one hand direct methods with sufficient selectivity and sensitivity are currently not available. Therefore extraction procedures have to be applied which are often problematic in respect to species stability. On the other hand there are no reference materials with known amounts of metal proteins like metallothionein-isoforms (MT) and superoxide dismutase (SOD) for quality control. So the aim of this study was to develop and optimise procedures for the species-preserving extraction of the model compounds MT and SOD from liver samples. Spiking experiments were performed to overcome the lack of appropriate reference materials. In a first step the stability of the model species without liver matrix was investigated by the variation of several extraction parameters. The extractant and exposure to ultrasonic energy especially had a great influence on the recovery of the species while temperature, buffer concentration and atmospheric conditions were less critical. In a second step spiked liver samples were extracted with a selection of procedures taken from the literature. Most of these methods provided recoveries between 70% and 100%. Additionally the buffer concentration and the extractant-to-liver ratio were varied for optimisation. The metal balance of an extraction showed recoveries of 81% for Cd, 94% for Cu and 87% for Zn.

Animals↗
PubMed2003

Controlled release experiments with nonylphenol in aquatic microcosms.

A method of controlled release of technical nonylphenol (tNP) was developed to simulate realistic exposure in ecotoxicological studies on aquatic organisms. The direct addition of tNP from an aqueous stock solution into 50 ml of water led to a concentration decrease of 80 to 90% weight/volume (w/v) from nominal values within 48 h. The inclusion of tNP in semipermeable low-density polyethylene (LDPE) lay-flat tubing (controlled-release devices [CRDs]) of different length allowed a continuous release into pure water at a rate of about 30 microg/cm2/d. Using CRDs in aquaria containing 15 L of 63-microm-filtered lake water, eight different concentrations with maxima between 38.1 and 326.7 microg/L were maintained for 11 d. During a second experiment in 15-L aquaria, five replicates of three concentrations were maintained using CRDs of the same length. Concentrations after 38 d varied between 0.1 and 6.7, 26.1 and 41.9, and 49.9 and 76.0 microg/L. In aquatic microcosms containing 230 L of lake water, a natural plankton community, 50 L of sediment, and macrophytes, seven different tNP concentrations (maxima 11-120.1 microg/L) were maintained over 45 d using CRDs of different length. They were replaced after 14 and 25 d because release of tNP was slower than predicted from laboratory experiments. Concentrations in the top 1-cm sediment layer were on average 19 times higher during the dosing period than concentrations in the water at the same time. In the sediments, different levels of applications led to concentrations that differed less distinctly than in the water. This method is suitable for exposing aquatic organisms continuously to constant, ecologically relevant concentrations of NP and represents an improvement over previous dosing methods in which exposure varied.

Environmental Exposure↗
PubMed2003

The bioaccumulation and fate of a branched 14C-p-nonylphenol isomer in Lymnaea stagnalis L.

A single branched isomer of p-nonylphenol, 4(3',6'-dimethyl-3'-heptyl)-phenol, previously identified by gas chromatography-mass spectrometry as one of the major constituent isomers in p-nonylphenol (constituting approximately 10% of all its isomers), was synthesized and used in studies of its bioaccumulation and excretion in the hermophroditic pond snail Lymnaea stagnalis L. Branched isomers of nonylphenol are perceived to have more estrogenlike toxicity than the straight-chain isomers in addition to being more resistant to biodegradation in the environment. With an average static exposure concentration of 104 microg/L (range: 92-116 microg/L) in water at 19 degrees C for 8 d, the uptake of the compound was found to be fairly rapid, reaching a peak concentration of 23,548 microg/kg of whole tissue wet weight after 5 d and a peak bioaccumulation factor (BAFw) of 242 (5,562, based on lipid weight) after 3 d. The uptake data fitted into a logarithmic expression C(t) = 5,231 ln(t) + 11,956, where C(t) is the amount of residues accumulated in whole tissue in micrograms per kilogram tissue wet weight after a period of time, t, and t is the period of exposure in days. By determination of the excretion of 14C-residues released in water and in feces, an average loss of 96% of the accumulated residues was achieved after 22 d of continuous exposure to clean water. By first-order kinetics analysis of the excretion data, an average half-life of excretion of 4.9 d was obtained. By high-performance liquid chromatography and gas-liquid chromatography-mass spectrometry, a catechol metabolite, 4(3',6'-dimethyl-3'-heptyl)-catechol, was detected in tissue extracts (after hydrolysis with beta-glucuronidase) and in feces, in addition to the parent isomer, suggesting that the isomer may have been metabolized by glucuronic acid conjugation and hydroxylation at the ortho position of its phenolic ring.

Animals↗
PubMed2002

Estimation of soil organic partition coefficients: from retention factors measured by soil column chromatography with water as eluent.

The retention factors (k) of 104 hydrophobic organic chemicals (HOCs) were measured in soil column chromatography (SCC) over columns filled with three naturally occurring reference soils and eluted with Milli-Q water. A novel method for the estimation of soil organic partition coefficient (Koc) was developed based on correlations with k in soil/water systems. Strong log Koc versus log k correlations (r>0.96) were found. The estimated Koc values were in accordance with the literature values with a maximum deviation of less than 0.4 log units. All estimated Koc values from three soils were consistent with each other. The SCC approach is promising for fast screening of a large number of chemicals in their environmental applications.

Organic Chemicals↗