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Biomedical subjects

A Kettrup

Publications and source records attributed to A Kettrup.

At least 91 records · Page 5Linked to original sources
PubMed2000

Polychlorinated organic compounds (PCOCs) in waters, suspended solids and sediments of the Yangtse River.

The contamination levels of polychlorinated organic compounds (PCOCs) in waters, suspended solids and sediments of the Yangtse River (Nanjing part) were analyzed in this paper. Their concentrations determined by GC/MS were very low in comparison with those in European River. The average concentration of total HCH (alpha-HCH, beta-HCH, gamma-HCH) was much higher than that of other PCOCs in all waters, which made up 65% of total amount of PCOCs. Due to the complete dilution and mixture of pollutants in the mighty Yangtse River, the content of PCOCs at each sampling station demonstrated very similar spatial pattern for waters and suspended solids. Since the small suspended solid (<0.7 microm) passed through the filter was also considered as dissolved part, the dominant parts of HCHs, PCA and PCBs were found in dissolved phase with percentage proportion of 85-94%, 72-85% and 61-78%, respectively. For DDTs, HCB and PeCB, their contents in dissolved phase were slightly higher than in particulate phase. The contents of PCOCs in sediments were also very low and varied with high fluctuation at different sampling points, indicating the heterogeneous deposition. HCB and its metabolite (PeCB) presented the highest contamination levels among PCOCs in sediments.

Anisoles↗
PubMed2000

Prediction of the retentions of polybrominated dibenzo-p-dioxins (PBDDs) by using the retentions of polychlorinated dibenzo-p-dioxins (PCDDs).

The retention equations In k' = A + B/T of 49 polychlorinated dibenzo-p-dioxins (PCDDs) and 4 polybrominated dibenzo-p-dioxins (PBDDs) in gas chromatography (GC) have been investigated to evaluate the properties of regression coefficients A and B. The quantitative relationships between A and B values of PCDDs and those of PBDDs are found. The regression equations derived have correlation coefficients greater than 0.997. The A, B values of any PBDD can be predicted by using the A, B values of the PCDD according to these relationships. Using these predicted A and B values, the retention times of all PBDDs can be predicted at any temperature program. It is very useful to identify the peak position of any PBDD because at present there are only a few standards of PBDDs available.

Bromine Compounds↗
PubMed2000

Quantitative relationship between chromatographic retentions and molecular structures of polychlorinated dibenzo-p-dioxins (PCDDs).

A new approach to study the quantitative relationships between chromatographic retentions and molecular structures of polychlorinated dibenzo-p-dioxins (PCDDs) is described. The retention equations of PCDDs log k' = A + B/T in gas chromatography (GC) are used to evaluate the properties of the regression coefficients A and B, which have been widely accepted as highly reliable chromatographic retentions. The quantitative relationships between the A, B values and the molecular structures are found. The molecular descriptors given for the first time in this article are very effective. As a result, the regression equations are derived with correlation coefficients greater than 0.9995. The A, B values of PCDDs with no standards available have been predicted according to these relationships. They are very useful in chromatographic identification. The retention times of all PCDDs can be conveniently predicted at any temperature program. Compared with the data obtained from the relevant experiments, the results of prediction are very accurate.

Chromatography, Gas↗
PubMed2000

Chromatographic properties of the ion-exclusion column IonPac ICE-AS6 and its application in environmental analysis, Part II: application in environmental analysis

Biological processes, geochemical reactions, anthropogenic emissions, and transformation reactions of xenobiotics are responsible for the widespread occurrence of aliphatic carboxylic acids in the environment. To study the performance of the ion-exclusion chromatography column IonPac ICE-AS6 in the analysis of environmental and environmental-technical samples, organic acids are investigated in composting seepage, silage effluents, aqueous extracts of sewage sludge, molasses hydrolysate, and alkaline cellulose hydrolysates. With respect to the diverse sample matrix and composition, different chromatographic conditions are applied. It is possible to determine various volatile fatty acids, dicarboxylic acids, (poly)hydroxy acids, and keto acids as main and trace components in samples with very high and low dissolved organic carbon content. Low baseline noise allows the determination of malic and succinic acid in the concentration range of approximately 1 microM/L in the presence of higher concentrations of fully ionized compounds. The applicability of the column in environmental analysis may be limited by the poor retardation of strong organic acids, insufficient separation of some relevant substance combinations (i.e., citric and isocitric acid), and very strong hydrophobic interactions with straight-chain monocarboxylic acids containing four or more carbon atoms.

Journal Article↗
PubMed1999

Fast, sensitive and selective liquid chromatographic-tandem mass spectrometric determination of tumor-promoting diterpene esters.

A liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed to detect tumor-promoting diterpene esters of the tigliane and ingenane types within plant extracts. Fractionation on a C18 high-performance liquid chromatography (HPLC) column was followed by MS-MS-multiple reaction monitoring (MRM) using the precursor-->product ion pairs of m/z 311-->293 and 293-->265 for phorbol esters. The ion pairs m/z 313-->295 and 295-->267 were used for ingenol and deoxyphorbol esters. In a second run, the characteristic ions at m/z 311 and 313 were followed in precursor ion scan mode. These quasi-molecular ions were utilized to obtain full scan spectra of the compounds in product ion scan mode. Due to its selectivity, the present on-line method can be applied for plant cultivar selection and plant product control without time-consuming extraction procedures and complex bioassays.

Carcinogens↗
PubMed1999

Interactions of hydroxy-s-triazines with sodium dodecyl sulfate-micelles investigated by micellar capillary electrophoresis.

The electrophoretic behavior of fourteen 4,6-diamino-s-triazines was investigated in the presence of an anionic surfactant (sodium dodecyl sulfate, SDS) using micellar capillary electrophoresis (MCE). The measurements were performed at the pH of zero charge of the hydroxytriazines and the existence of strong ionic and H-bond interactions of hydroxy-s-triazine species with the anionic micelles could be shown. Their migration behavior was compared to the n-octanol-water partition coefficients (log Kow) measured with reverse-phase HPLC and calculated with different fragment contribution methods. A partition model was proposed to understand the interactions of the three major hydroxy-s-triazine species: cationic, anionic and neutral (presenting enol and keto forms) with the charged SDS micelles taken as model for charged natural polyelectrolytes like humic substances. These results strongly indicate that hydroxy-striazines are polarized in the presence of the charged micelles and that they are essentially present in their keto form in the micellar phase (and enol form in the water phase), confirming previous studies suggesting the presence of zwitterionic resonance structures at a neutral pH around their isoelectric point.

Algorithms↗
PubMed1999

Effect of natural dissolved humic material on bioavailability and acute toxicity of fenpropathrin to the grass carp, Ctenopharyngodon idellus.

The effects of aquatic humic acids on the bioconcentration and acute toxicity of fenpropathrin were evaluated using grass carp, Ctenopharyngodon idellus, in laboratory freshwater systems. The results demonstrated that both bioavailability and acute toxicity decreased in the presence of aquatic humic acid 5 and 10 mg/liter. In addition, the extent of influence increased with increasing concentration of aquatic humic acid.

Animals↗
PubMed1999

Cytological and biochemical alterations in Carassius auratus hepatocytes from exposure to sediment containing dioxins and related compounds.

Cytological and biochemical alterations of crucial carp (Carassius auratus) hepatocytes were characterized after exposure to sediments from a lake contaminated with dioxins and other industrial chemicals. Carp were exposed in 20 L water containing 25, 50, or 100 g of contaminated sediment for 2 and 4 weeks. Ultrastructural changes in the liver were characterized by severe enlargement of hepatocytes. Alterations in the cell included formation of condensed and irregular cell nucleus, polynuclei, dispersed heterochromatin, enlargement of the nucleolus, and degeneration of the nucleus. Mitochondrial numbers were reduced and cristae were deformed. Myelin figures and lysosomes were increased, and sometimes cell organelles and cell matrix were totally lost after 4 weeks of exposure. The ultrastructural alterations were correlated with exposure time and sediment concentrations. Hepatosometic index was significantly increased in experimental groups at 2 and 4 weeks as compared with the control group. EROD enzyme activities were strongly induced in liver. A trend from rough endoplasmic reticulum (RER) to SER was observed. Our results suggest that the dioxin-like compounds bound by sediment were bioavailable to C. auratus and cause sublethal effects.

Animals↗
PubMed1999

A new enzyme immunoassay for PCDD/F TEQ screening in environmental samples: comparison to micro-EROD assay and to chemical analysis.

A new Enzyme ImmunoAssay (EIA) for PCDD/F TEQ measurement in extracts of environmental samples was described. The bioassay TEQ which derived from EIA and EROD were compared with each other and with results from chemical analysis. For all environmental samples, the EROD-TEQ is higher than the value from chemical analysis. However, the EIA-TEQ is much more identical with the value from chemical analysis. Our results indicate that the EIA assay is a complementary method to the EROD assay and should be useful as a rapid and sensitive screening tool for environmental samples in many situations.

Benzofurans↗
PubMed1999

Determination photostability of selected agrochemicals in water and soil.

The photolysis of selected pesticides in aqueous solutions has been investigated. The photolysis produced different intermediate substances, which were also found to be soil and microbial degradation products. The phototransformation in the presence of TiO2 and humic substances leads to a disappearance of these compounds. The reaction rate is dependent on the semiconductor oxide and concentration. Photoproducts were isolated and characterized by different spectroscopic methods. Results from this study indicate that degradation products of isoproturon are more toxic on Daphnia magna than on the parent compound.

Animals↗
PubMed1999

Predicting bioconcentration factors (BCFs) of polychlorinated bornane (Toxaphene) congeners in fish and comparison with bioaccumulation factors (BAFs) in biota from the aquatic environment.

Polychlorinated bornanes, the main components of Toxaphene, are bioconcentrated in aquatic organisms to a high extent. However, up to this time no bioconcentration tests with individual chlorinated bornanes in aquatic organisms have been performed. Therefore, the bioconcentration factors (BCFs) of seven selected persistent chlorinated bornane congeners which are regularly found in aquatic organisms, were predicted from their n-octanol/water partition coefficients (log Kow). Furthermore, these BCF values were compared with the measured bioaccumulation factors (BAFs) in zooplankton and different fish species from the aquatic environment.

Animals↗
PubMed1999

The effect of wind direction on the observed size distribution of particle adsorbed polycyclic aromatic hydrocarbons on an inner city sampling site.

An investigation of the variability in the size distribution of particle adsorbed polycyclic aromatic hydrocarbons (PAHs) on an inner city sampling site showed differences depending on the wind direction. Particle size distributions of PAHs from outdoor air sampling were measured in Munich from 1994 to 1997. The sampling site is located northeast of a crossing with heavy traffic and southwest of a large inner city park. Depending on the wind direction, three different size distributions of particle adsorbed PAHs were observed. The maximum PAH concentration on very small particles (geometric mean diameter 75 nm) was observed with wind from west to southwest coming directly from the crossing area or the roads with heavy traffic. The maximum PAH concentration on particles with geometric mean diameter of 260 nm was found on days with wind from the built-up area north of the sampling site. On particles with geometric mean diameter of 920 nm the maximum PAH concentration was found on days with main wind directions from northeast to east. On these days the wind is blowing from the direction of the city park nearby. The distribution of particle adsorbed PAHs within different particle size classes is substantially influenced by the distance of the sampling site from strong sources of PAH loaded particulate matter.

Cities↗
PubMed1999

Pentachlorophenol in indoor environments. Does a single measurement of air and dust concentrations represent the contamination?

In order to be able to make a decision, as to whether a room or building has a health-endangering pentachlorophenol (PCP) concentration, usually the PCP concentrations in air and settled dust are measured. The variability of the PCP concentration in indoor air and dust was studied. Air and dust samples were taken from 75 rooms in 30 buildings with suspicion of application of PCP-containing wood preservatives. Sampling was repeated four times within 18 months. Thirty-six rooms were reconstructed within the study; 39 rooms had unchanged contamination status during the study. The four times repeated measurements of PCP concentrations in air and dust in these rooms showed large variations of the measured values. The variability of the results is to a large extent in the same range as the measured values. The observed relative standard deviation of the PCP concentrations in air and dust does not depend on the average PCP concentration detected in the individual rooms.

Air Pollution, Indoor↗
PubMed1999

Chromatographic properties of the ion-exclusion column IonPac ICE-AS6 and application in environmental analysis. Part I: Chromatographic properties.

The chromatographic performance of the Dionex IonPac ICE-AS6 ion exclusion column is investigated. Therefore, capacity factors, efficiency, peak symmetry, resolution, and selectivity are determined for various mono- and polyfunctional aliphatic carboxylic acids under selected chromatographic conditions. Except for the stronger acids (pKa1 < 3.75), the highest chromatographic efficiency is achieved at a column temperature of 40 or 50 degrees C, and peak shape is found to be optimal at approximately 60 degrees C. The separation of the stronger acids is favored by an eluent pH below 3.0 and column temperatures below 40 degrees C. The maximal effective plate numbers range between 126 (tartronic acid) and 6380 (4-oxovaleric acid). Hydroxy-substituted acids are less retained and less influenced by temperature changes than the unsubstituted compounds. It is estimated that size exclusion effects take part in the separation of aldonic acids. The addition of 1% isopropanol to the acidic eluent increases the chromatographic efficiency generally, whereas higher concentrations reduce the retention of several acids drastically.

Acids↗
PubMed1998

Soil Adsorption Coefficients of s-Triazines Estimated with a New Gradient HPLC Method.

A high-performance liquid chromatography (HPLC) method employing gradient elution was developed to predict soil adsorption coefficients (K(oc)) from HPLC capacity factors. The gradient method allows for the determination of K(oc) values over a range of 4.4 orders of magnitude in a single experiment without adjustment of the solvent composition, as is required in isocratic HPLC measurements. The range of K(oc) estimated can easily be extended by using reference compounds with lower or higher log K(oc) values. Therefore, gradient HPLC is an appropriate screening method for K(oc) and was used to investigate s-triazine herbicides and their degradation products. Log K(oc) ranged from 0.8 for cyromazine to a maximum of 2.6 for anilazine and aziprotryne. HPLC-derived K(oc) values of s-triazines containing an azido group were higher than and those of hydroxy-s-triazines were lower than K(oc) values estimated according to the fragment contribution method of Meylan et al. (1992). According to this method, the log K(oc) of the keto form of hydroxy-s-triazines was >1 log unit higher than that of the enol form.

Journal Article↗
PubMed1998

Influence of dioxin and metal-contaminated sediment on phase I and II biotransformation enzymes in silver crucian carp.

Several biochemical responses were measured in silver crucian carp (Carassius auratus gibelio) after exposure to sediments obtained from contaminated Ya-Er Lake, No. 1 pond, and an unpolluted reference site, Honglian Lake. After 1 week of exposure, a significant induction of the phase I biotransformation enzyme (ethoxylresorufin-o-deethylase, EROD) was found (83-fold of control), whereas the phase II biotransformation enzyme (glutathione S-transferase, GST) exhibited a slight, but significant induction (1.4-fold of control) after 4 weeks of exposure. The level of cellular glutathione in the liver was also slightly elevated after 4 weeks of exposure. The delayed response of GST to the contaminants indicates that the phase I and phase II biotransformation enzymes are regulated differently in fish. The results suggest that EROD is a sensitive bioindicator to assess the toxicity of dioxin-contamined sediment in the laboratory.

Animals↗