Biomedical subjects

M Möder

Publications and source records attributed to M Möder.

10 recordsLinked to original sources

PubMed2003

Sequential fractionation procedure for the identification of potentially cytochrome P4501A-inducing compounds.

A multistep fractionation procedure for the separation of nonpolar aromatic compounds with respect to cytochrome P4501A induction is presented. Normal-phase HPLC on nitrophenylpropyl silica and cyanopropyl silica was tested for group-specific separation as a first fractionation step. Subsequent individual compound-specific PAH fractionation was done by means of reversed-phase HPLC. Electron-donor-acceptor HPLC and size-exclusion chromatography were applied to separate PAHs, PCBs, PCNs and PCDD/Fs according to their number of aromatic carbon atoms, their hydrophobicity, their degree of chlorination, their planarity and their molecular size. The method was validated for complex environmental mixtures on the basis of two sediment extracts.

Chromatography, Gel↗

PubMed2003

The pattern of urinary acylcarnitines determined by electrospray mass spectrometry: a new tool in the diagnosis of diabetes mellitus.

l-Carnitine and its esters are products of intermediary metabolism of organisms. The distribution pattern or the favored excretion of individual acylcarnitines tells something about metabolic diseases. The determination of the urinary acylcarnitine pattern by flow injection analysis (FIA)-electrospray ionization (ESI)-mass spectrometry (MS) is presented. Groups of healthy probands and patients suffering from diabetes mellitus were investigated due to their significant acylcarnitine profile. The statistical analysis of data sets obtained clearly shows a difference in the acylcarnitine pattern of healthy and sick probands. In comparison to the controls, diabetes mellitus patients excrete more long-chain carnitine esters ranging from dodecanoyl to palmitoylcarnitine. Thus, the urinary acylcarnitine pattern determined by ESI-MS can be a useful tool in the diagnosis and therapy monitoring of diabetes mellitus.

Adult↗

PubMed2003

Plant--rhizosphere-microflora association during phytoremediation of PAH-contaminated soil.

The capability of plants to promote the microbial degradation of pollutants in rhizosphere soil is a principal mechanism of phytoremediation of PAH-contaminated soil. The formation of a specific rhizosphere microbocenosis with a high degradative potential toward contaminants is largely determined by plant species. The comparative PAH-degradation in unplanted soil and in soil planted with reed (Phragmites australis) and alfalfa (Medicago sativa) was studied in pot experiments during 2 years. Both alfalfa and reed successfully remediated contaminated soil by degrading 74.5 and 68.7% of PAHs, respectively. The study of the rhizosphere, rhizoplane, and unplanted-soil microflora in experimental pots showed that alfalfa stimulated the rhizosphere microflora of PAH-contaminated soil more effectively than did reed. Alfalfa clearly enhanced both the total number of microorganisms (1.3 times, according to fluorescence microscopy data) and the rate of the PAH-degrading population (almost seven times, according to plate counting). The degradative potential of its rhizosphere microflora toward PAHs was higher than the degradative activity of the reed rhizosphere. This study provides relevant information for the successful application of alfalfa to phytoremediate PAH-contaminated soil.

Bacteria↗

PubMed2000

Determination of polycyclic aromatic hydrocarbons in waste water by off-line coupling of solid-phase microextraction with column liquid chromatography.

A new method for the determination of polycyclic aromatic hydrocarbons (PAHs) in waste water using solvent-free solid-phase microextraction (SPME) is described. The PAHs are extracted with a 100 microm polydimethylsiloxane (PDMS) fiber, desorbed in 40 microl acetonitrile and measured with LC and fluorescence detection. The detection limits of this very simple method under the given conditions (extraction from 5 ml sample, extraction time 1 h) are in the range of 1-6 ng l(-1). The standard deviations (n = 6) at a concentration level of 0.8 microg l(-1) are between 1.8 and 14.4%. The procedure was used for the determination of PAHs in contaminated water samples.

Chromatography, Liquid↗

PubMed2000

Determination of chlorophenols in soils using accelerated solvent extraction combined with solid-phase microextraction.

A method for the determination of chlorophenols in soil samples using accelerated solvent extraction (ASE) with water as the solvent combined with solid-phase microextraction (SPME) and GC/MS has been developed. Important ASE parameters, such as extraction temperature and time, were optimized using a spiked wetland soil. The effect of small amounts of organic modifiers on the extraction yields was studied. An extraction temperature of 125 degrees C and 10 min extractions performed three times proved optimal. Two ASE-SPME procedures without and with an organic modifier (5% acetonitrile) were evaluated with respect to precision and detection limits (LOD). The reproducibility of replicate water extractions/SPME determinations (n = 6) was in the range 7-20% relative standard deviation for the nine chlorophenols investigated. LOD values in the low-ppb range were achieved for all chlorophenols. The ASE-SPME procedure presented here was applied to the determination of chlorophenols in soil samples taken from contaminated areas near Bitterfeld, Germany.

Chlorophenols↗

PubMed2000

Peroxidative degradation of selected PCB: a mechanistic study.

The enzyme-induced decomposition and biodegradation of PCB were investigated. 2,5-Dichlorobiphenyl (PCB 9) and 2,2',5,5'-tetrachlorobiphenyl (PCB 52) were used as example compounds to study efficiency and mechanism of the degradation processes. It was found that the application of horseradish peroxidase (HRP) together with defined amounts of hydrogen peroxide removed 90%, of the initial concentration of PCB 9 and 55% of the initial concentration of PCB 52 from an aqueous solution after a reaction period of 220 min. Dechlorination was observed as the initial step. Although the metabolites identified were mainly chlorinated hydroxybiphenyls, benzoic acids and non-substituted 1,1'-biphenyl, some higher chlorinated biphenyl isomers also appeared. The biodegradation of PCB 9 using the white rot fungus Trametes multicolor took about four weeks and reduction was about 80%, of the initial concentration. The metabolites produced (dichlorobenzenes, chlorophenols and alkylated benzenes) were not quite the same as those observed upon incubation with HRP.

Benzoic Acid↗

PubMed2000

Deuterium labelled nonylphenols in an in-vitro model of percutaneous absorption of environmental xenoestrogens.

A technical mixture of isomeric nonylphenols NP is formed as rather persistent degradation product of nonionic surfactants and has become widespread in the environment, e.g., in surface waters. Information about possible pathways for incorporation is needed for risk assessments, as NP has estrogenic properties. NP uptake after skin contact was determined using isolated and perfused bovine udders as models for human skin. NP-d2 labelled in the positions ortho to the OH-group was prepared by an exchange procedure which did not measurably change the relative amount of isomers. Samples of udder perfusate, milk equivalent produced during the experiments and skin tissue were taken immediately before administration of 500 mg or 50 mg NP-d2 on an udder skin area of 200 cm2 and then for 5 h. They were analyzed by GC-MS for NP and NP-d2 after cleanup by steam distillation and final extraction with SPME fibres. The results are an unambiguous proof of the penetration of NP into the capillary system of living mammals after skin contact.

Administration, Cutaneous↗

PubMed1999

Application of deuterated compounds for investigations of percutaneous absorption of chemical substances.

The percutaneous absorption of the xenoestrogen 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol A) 1 has been studied and compared with results on dibenzoyl peroxide 2, a component of drug formulations for topical application. Isolated perfused bovine udders from slaughtered cows were employed as models for human skin. The deuterium labelled compounds 1-d14 and 2-d10 were applied to enhance the reliability of GC-MS trace determinations by use of reverse isotope dilution analysis. 1-d14 was found in perfusate and milk equivalent samples obtained between 60 and 300 min after topical application with maximum concentrations between 120 and 180 min. 1-d14 was enriched in the milk samples by a factor of about 300 compared with the perfusate. The results confirm a possible penetration of 1 from the environment through the skin into the capillary system. 2 studied on the same model system penetrated faster than 1 by a factor of about three.

Animals↗

PubMed1997

Determination of urinary acylcarnitines by ESI-MS coupled with solid-phase microextraction (SPME).

The determination of selected short-, medium- and long-chain acylcarnitines by electrospray ionization mass spectrometry (ESI-MS) is discussed. The differences in fragmentation behaviour and ionization efficiency are described in dependence on collision induced dissociation (CID) conditions and mixture composition. A new method combination, solid-phase microextraction (SPME)-ESI-MS, is introduced to characterize acylcarnitines in body fluids. This method utilizes SPME for pre-concentration of acylcarnitines from complex biological samples and ESI-MS for a selective and sensitive detection. The method is presented by standard experiments determining of acylcarnitines in aqueous solutions and urine samples from patients with secondary carnitine deficiency syndromes or related disorders.

Calibration↗

PubMed1996

Analytical characterization of the persistent residues after microbial degradation of mineral oils.

The residual fractions remaining after microbial degradation of diesel fuel, different deparaffinized raffinates and extracts from long-term contaminated soils were analyzed by liquid chromatography, gas chromatography, infrared spectrometry and mass spectrometry. The quantity of saturated hydrocarbons decreased after the microbial treatment, whereas the portion of polar compounds increased. The total content of aromatics changed only insignificantly. n-Paraffins < C26 were found to be no longer present in mineral oils degraded to exhaustion. Infrared spectrometry revealed oxygen compounds in the residues, mainly ketones, fatty acids and esters. Elementary analysis confirms the presence of nitrogen, oxygen and sulphur compounds in the degraded products. The gas chromatograms of high boiling oils, as well as of residues and extracts, consist mainly of a large base "envelope" (about 95% of the total area); thus gc/ms coupling reaches the limits of its applicability. However, mass spectrometry with direct inlet gives valuable information regarding hydrocarbon type analysis. The results revealed the preferable degradation of alkanes, 1-ring aliphatics and benzenes and an enrichment of condensed cycloaliphatics and aromatics. The latter compounds are known to be resistant to microbial attack.

Journal Article↗