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Reinhard Niessner

Publications and source records attributed to Reinhard Niessner.

17 recordsLinked to original sources
PubMed2003

Methods for studying synaptosomal copper release.

Cu is thought to play an important role in the pathogenesis of several neurodegenerative diseases, such as Wilson's, Alzheimer's, and probably in prion protein diseases like Creutzfeld-Jakob's disease. Until now, no method existed to determine the concentration of this cation in vivo. Here, we present two possible approaches combined with a critical comparison of the results. The successful use of fluorescent ligands for the determination of Ca2+-concentrations in recent years encouraged us to seek a fluorophore which specifically reacts to Cu2+ and to characterize it for our purposes. We found that the emission of TSPP (tetrakis-(4-sulfophenyl)porphine) at an emission wavelength of 645 nm is in vitro highly specific to Cu2+ (apparent dissociation constant Kd=0.43 +/- 0.07 microM at pH 7.4). It does not react with the most common divalent cations in the brain, Ca2+ and Mg2+, unlike most of the other dyes examined. In addition, Zn2+ quenches TSPP fluorescence at a different emission wavelength (605 nm) with a Kd of 50 +/- 2.5 microM (pH 7.0). With these findings, we applied the measurement of Cu with TSPP to a biological system, showing for the first time in vivo that there is release of copper by synaptosomes upon depolarisation. Our findings were validated with a completely independent analytical approach based on ICP-MS (inductively-coupled-plasma mass-spectrometry).

Animals↗
PubMed2003

Spatial and temporal observations of adsorption and remobilization of heavy metal ions in a sandy aquifer matrix using Magnetic Resonance Imaging.

The exploration of the transport and matrix interactions of heavy metal ions in the subsurface environment under natural conditions is an important field of research in environmental science and technology. Most commonly, column tests are used for a first assessment of the transport behavior. Classical column tests fall short with regard to the spatial and temporal resolution; however, these detailed data are needed for proper upscaling. Hence, providing spatially and temporally resolved data on the distribution of environmentally relevant concentrations of heavy metal ions in a water-wet aquifer matrix poses a major challenge to analytical chemistry. In this contribution, we present the results of Magnetic Resonance Imaging (MRI) studies in which submilligram quantities of heavy metal ions where either fed conventially through the column or locally injected into saturated sand packings. The subsequent transport and mobilization was monitored at a high spatial and temporal resolution. The results from a local injection show that the test design of column tests has not yet come to an end and that column tests under MRI-control may be used as a model system for, e.g., remediation techniques.

Adsorption↗
PubMed2003

Residue analysis of the pharmaceutical diclofenac in different water types using ELISA and GC-MS.

A highly sensitive and specific indirect competitive enzyme-linked immunosorbent assay (ELISA) for the determination of diclofenac in water samples was developed. With pure water, the limit of detection (LOD, S/N = 3) and IC50 were found to be 6 ng/L and 60 ng/L, respectively. The analytical working range was about 20-400 ng/L. Highest cross-reactivity (CR) of 26 tested pharmaceuticals, metabolites, and pesticides was found for 5-hydroxydiclofenac (100%). Other estimated values were well below 4% and, therefore, are negligible. The assay was applied for the determination of diclofenac in tap and surface water samples as well as wastewater collected at 20 sewage treatment plants (STPs) in Austria and Germany. Humic substances were identified as main interference in surface water. Wastewater samples which were only submitted to filtration and dilution yielded about 25% higher diclofenac concentrations using the ELISA compared to GC-MS. However, the ELISA turned out to be a simple, inexpensive, and accurate method for the determination of diclofenac both in influent and effluent wastewater after rather simple sample preparation, i.e., filtration, acidification, and readjustment to neutral pH-value, and at least 10-fold dilution with pure water.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2003

Polycyclic aromatic hydrocarbons in urban air particulate matter: decadal and seasonal trends, chemical degradation, and sampling artifacts.

Aerosol filter samples collected at a major urban traffic junction (LKP) and at a suburban residential location (IWC) in the metropolitan area of Munich (Germany) throughout the years 2001 and 2002 have been analyzed for 12 of the 16 EPA priority polycyclic aromatic hydrocarbon (PAH) pollutants by liquid chromatography with fluorescence detection. The mean mass concentration of the sum of all investigated PAH in the sampled air at LKP (1.9-5.0 ng m(-3)) was roughly two times higher than at IWC (0.8-2.9 ng m(-3)), and at both locations it was about 2-3 times higher in winter (heating season) than in summer and spring or autumn. Comparisons with earlier measurement campaigns indicate a steep decrease of PAH abundance by almost an order of magnitude from 1980 to 1993 and a much slower decrease since then. Distinctly different seasonal trends and short-term fluctuations have been observed for semivolatile 3- and 4-ring PAH and for particle-bound 5- and 6-ring PAH. Based on systematic correlation analyses with a wide range of air quality parameters, most of the differences can be attributed to not only varying emissions but also chemical reactions with atmospheric oxidants which were found to play an important role. The results of denuder experiments prove that substantial degradation of the particularly toxic tracer benzo[a]pyrene and of the other investigated 5- and 6-ring PAH can occur during filter sampling and on airborne particles (formation of oxygenated and nitrated derivatives). Filter reaction artifacts are shown to lead to an underestimation of the actual PAH content of urban air particulate matter by up to 100% of the measurement value or more, with a near-linear dependence on ozone volume mixing ratio. The role and applicability of ozone as a tracer of atmospheric oxidizing capacity for particle-bound PAH is discussed and confirmed by comparison with earlier investigations and by complementary laboratory experiments (reaction kinetics and product studies).

Air Pollutants↗
PubMed2003

Microarrays for the screening of allergen-specific IgE in human serum.

The described in vitro test system for allergy diagnosis is based on microscope glass slides activated with (3-glycidyloxypropyl)trimethoxysilane. Allergen solutions are immobilized as small droplets (approximately 10 nL) on the activated glass slides with a piezoelectric arrayer. In contrast to other tests for specific IgE, such as Pharmacia CAP FEIA, AlaSTAT, or FAST, only a 25-microL serum sample is needed for the screening of allergen-specific IgE against a multitude of allergens and the test can be performed in less than 1 h. Compared with multiallergen dipstick screening tests (e.g., IgEquick, CMG Immunodot) based on multiallergen-coated nitrocellulose strips, the measurement of the microarray-based system can be performed automatically. The chemiluminescence intensities are detected with a sensitive CCD camera. Allergen extracts and recombinant/purified allergens (24 preparations) have been used on the same modified surface for the screening of allergen-specific IgE. With these disposable microarray slides, it is possible to distinguish between patients with and without elevated levels of allergen-specific IgE. Repeated measurements of serum samples demonstrated a sufficient reproducibility. Detection limits (microg/L) of 0.35 (r Betvl), 0.16 (PLA2), and 1.9 (Der p1) were achieved.

Allergens↗
PubMed2003

Oxygen determination in oxygen-supersaturated drinking waters by NMR relaxometry.

In recent years, a rising number of different table waters supersaturated with oxygen have hit the market with claims of both positive health effects and an increase in athletic performance. In addition to research on the correctness of these claims and their possible physiological reasons, the appearance of oxygen supersaturation as a marketing promise also creates a need for appropriate analytical techniques allowing a rapid and reliable determination of oxygen contents in such waters. Here, we present NMR relaxometry as a possible analytical tool for such studies. NMR relaxation in oxygen supersaturated water is not only of interest in the context of monitoring the oxygen content in such drinking water products, but also might offer some interesting possibilities in medical and environmental science MRI applications. As a contact-less measuring method, NMR relaxometry avoids disturbance of the measurement due to outgassing. The method was applied in the concentration range from 10 mg l(-1) to over 100 mg l(-1) dissolved oxygen. In addition to freshly sampled drinking waters, also oxygen losses during storage of the water in open drinking vials was studied.

Beverages↗
PubMed2003

Enzyme immunoassays for the investigation of protein nitration by air pollutants.

Two enzyme immunoassays have been developed, characterised, and applied to investigate protein nitration in birch pollen extract (BPE) and bovine serum albumin (BSA) samples exposed to air pollutants. The monoclonal antibody CAY-189542 against nitrotyrosine (raised against peroxynitrite-treated keyhole limpet hemocyanine) was characterised in an indirect competitive assay (affinity and cross-reactivities) and applied in a new one-sided enzyme immunoassay for nitrated proteins. The one-sided assay was calibrated against a nitrated BSA standard with an average of 14 nitrotyrosine residues per molecule (nitro-(14)-BSA; detection limit 8.3 pmol L(-1)), and the sensitivity of the test was found to be significantly enhanced by a multivalent binding mode of the monoclonal antibody (bonus effect of multivalency). The same antibody and a polyclonal antibody against Bet v 1, the most prominent birch pollen allergen, were used in a new sandwich immunoassay for specific determination of nitrated Bet v 1. This assay was calibrated against a nitrated Bet v 1 standard with an average of 3 nitrotyrosine residues per molecule (nitro-(3)-Bet v 1; detection limit 0.2 nmol L(-1)). Bet v 1 and BSA exposed to polluted urban outdoor air and to synthetic gas mixtures containing NO2 and O3 at atmospherically relevant concentration levels were found to be efficiently nitrated within hours to days. Pronounced correlations of nitro-(14)-BSA equivalent concentrations with exposure time and with nitro-(3)-Bet v 1 equivalent concentrations in nitrated BPE samples were observed. Test experiments indicated that the efficiency of protein nitration was strongly enhanced by reactive species formed upon interaction of NO2 with O3 and H2O (e.g. NO3 and HNO3). Potential implications of protein nitration by air pollutants are outlined and discussed.

Air Pollutants↗
PubMed2002

Selective trace analysis of sulfonylurea herbicides in water and soil samples based on solid-phase extraction using a molecularly imprinted polymer.

A molecularly imprinted polymer (MIP) was synthesized using the herbicide metsulfuron-methyl (MSM) as a template, 2-(trifluoromethyl)acrylic acid as a functional monomer, divinylbenzene as a cross-linker, and dichloromethane as a porogen. This polymer was used as a solid-phase extraction material for the quantitative enrichment of five sulfonylureas (nicosulfuron, thifensulfuron-methyl, metsulfuron-methyl, sulfometuron-methyl, and chlorsulfuron) in natural water and soil samples and off-line coupled to a reversed-phase HPLC/diode array detection (HPLC/DAD). Washing solvent was optimized in terms of kind and volume for removing the matrix constituents nonspecifically adsorbed on the MIP. It has been shown that the nonspecific binding ability of the sulfonylureas to the polymer largely increased along with increasing the concentration of Ca2+ ions in the water sample, whereas complexation of divalent ions with EDTA eliminated this interference completely. The stability of MIP was tested by consecutive percolation of water sample, and it was shown that the performance of the MIP did not vary even after 200 enrichment and desorption cycles. Recoveries of the five sulfonylureas extracted from 1 L of tap water and surface water samples such as river water and rainwater at a 50 ng/L spike level were not lower than 96%. The recoveries of sulfonylureas extracted from 10-g soil sample at the 50 microg/kg level were in the range of 71-139%. Depending on the particular compound, the limit of detection varied from 2 to 14 ng/L in water and from 5 to 12 microg/kg in soil samples. The MIP was also compared with a commercially available C-18 column and an immunoaffinity support with encapsulated polyclonal anti-MSM antibodies in sol-gel glass.

Acrylates↗
PubMed2002

Photocatalytic atrazine degradation by synthetic minerals, atmospheric aerosols, and soil particles.

In this work, the photocatalytic atrazine degradation by seven synthetic minerals and five environmental particle samples was examined to investigate a possible contribution of photocatalysis to the abiotic degradation of atrazine in the environment. Particle suspensions containing 500 ng/L atrazine were irradiated with a sun simulator, and the atrazine degradation was monitored by enzyme-linked immunosorbent assay (ELISA). Atrazine detection by ELISA proved to be an useful analytical tool because of low cross-reactivity of atrazine metabolites and high sensitivity with detection limits in the lower nanograms per liter range. The atrazine degradation followed first-order kinetics, and the obtained rate coefficients were compared with the rate of direct photolysis. Known photocatalysts, such as TiO2 and ZnO, showed the expected fast photocatalytic degradation (k = 27-327 x 10(-3) min(-1)) of atrazine. The degradation rates detected upon irradiation of titanium-, zinc-, or iron-containing minerals were orders of magnitudes lower (k = 0.15-0.70 x 10(-3) min(-1)) but still significantly faster than direct photolysis without particles (k = 0.10 x 10(-3) min(-1)). With environmental particle samples (soot, fly ash, sand, road dust, and volcanic ash), however, no significant photocatalytic activity was observed (k = 0.07-0.16 x 10(-3) min(-1)). The atrazine degradation rates were in the range of direct photolysis. Thus photocatalysis by aerosol or soil particles appears not to enhance abiotic atrazine degradation in the environment.

Aerosols↗
PubMed2002

Process analysis of recycled thermoplasts from consumer electronics by laser-induced plasma spectroscopy.

An experimental setup for direct elemental analysis of recycled thermoplasts from consumer electronics by laser-induced plasma spectroscopy (LIPS, or laser-induced breakdown spectroscopy, LIBS) was realized. The combination of a echelle spectrograph, featuring a high resolution with a broad spectral coverage, with multivariate methods, such as PLS, PCR, and variable subset selection via a genetic algorithm, resulted in considerable improvements in selectivity and sensitivity for this complex matrix. With a normalization to carbon as internal standard, the limits of detection were in the ppm range. A preliminary pattern recognition study points to the possibility of polymer recognition via the line-rich echelle spectra. Several experiments at an extruder within a recycling plant demonstrated successfully the capability of LIPS for different kinds of routine on-line process analysis.

Electronics↗
PubMed2002

Effects of fractions of traffic particulate matter on TH2-cytokines, IgE levels, and bronchial hyperresponsiveness in mice.

In recent decades an increased prevalence of allergic conditions has been observed in developed countries. Although lifestyles, exposure to infection, and diet are all likely important factors, many studies have also shown a strong link between industrialization and allergy. The aim of this study was to investigate which extract fractions from traffic particulate matter (TPM, collected in a tunnel in Prague) have the greatest impact on different inflammatory and immunological parameters, such as cytokine production, levels of immunoglobulin E (IgE) antibodies, and bronchial hyperresponsiveness (BHR) in mice, when the extracts are used together with birch pollen for immunization. BP2 mice were immunized with birch pollen and different fractions of TPM (fractions 1-8). They were provoked intranasally with a mixture of pollen and TPM or pollen alone before they were challenged with methacholine. The BHR was evaluated in a whole-body plethysmograph. Th2 cytokines and fibronectin concentrations were measured, and differential cell counts were performed in the bronchioalveolar lavage (BAL) fluid. Sera were collected for determination of antibody titers. The highest titers of IgE and the highest BHR were found in the positive control mice (immunized and provoked with a mixture of pollen and TPM), followed by mice immunized with pollen and fraction 2 (which contains organic acids). Fraction 2 also induced the highest number of eosinophils and increased levels of interleukin 5 (IL-5) in the BAL fluid. The highest levels of IL-5, in BAL fluid and sera, were obtained in mice immunized with fraction 6 (moderately polar compounds), a somewhat surprising result since those mice did not produce any IgE, did not have any eosinophils in their BAL, or showed almost no BHR. Our data demonstrate that fractions 2 (organic acids) and 7 (highly polar compounds) seem to contain potential adjuvants stimulating the IL-5 production, the IgE synthesis, the eosinophil recruitment, and the bronchial hyperreactivity. Further characterization at the molecular level is now necessary to be able to identify the exact nature of those potential adjuvants. This will be of help in the future to improve the quality of the urban air aerosol.

Air Pollutants, Occupational↗
PubMed2002

Sol-gel glass immunosorbent-based determination of s-triazines in water and soil samples using gas chromatography with a nitrogen phosphorus detection system.

A rapid and efficient method for the selective extraction of s-triazine herbicides in environmental samples was developed using an immunosorbent of monoclonal antiatrazine antibodies, which were encapsulated in a sol-gel glass matrix. The cross-reactivity of the antibody for analytes structurally related with atrazine enabled the simultaneous extraction of several s-triazine herbicides (atrazine, propazine, terbuthylazine, cyanazine, desethyl atrazine). After trace enrichment on the immunoextraction column, the s-triazines were desorbed by means of an acidic buffer (pH 2.5) and further extracted with ethyl acetate before being injected into the GC. Compared to liquid-liquid extraction and solid-phase extraction with a hydrophobic SDB-L support, the GC-NPD chromatograms obtained after immunoaffinity enrichment of surface water (river water) samples or soil extracts and analysis were free from matrix interferences. Nonspecific adsorption of humic acids was not observed. The method allows for the determination of the herbicides in linear ranges up to 1.5 microg/L with correlation coefficients higherthan 0.99 and relative standard deviations between 4% and 7% (n = 5). The LODs for 50-mL water samples were in the range 0.02 microg/L (atrazine, propazine) to 0.1 microg/L (desethyl atrazine) (S/N = 3). In addition to its high selectivity, the immunosorbent proved to be reusable for a significant number of preconcentration runs. However, the composition of samples may influence the lifetime of the column.

Chromatography, Gas↗
PubMed2002

Migration of dissolved heavy metal compounds and PCP in the presence of colloids through a heterogeneous calcareous gravel and a homogeneous quartz sand-pilot scale experiments.

In preparation to field experiments with in situ mobilized colloids, a set of pilot scale aquifer tank experiments was performed to gain an insight into the mass transfer of several heavy metal ions and pentachlorophenol (PCP) in a heterogeneous gravel aquifer and a homogeneous sandy aquifer. The experiments simulate a spill of dissolved contaminants and their subsequent transport with in situ mobilized colloids that are not yet in equilibrium with the contaminant. Contaminants with a weak tendency to adsorb to the stationary sediment matrix, e.g., PCP, establish a dynamic equilibrium with the mobile colloidal phase. The fraction of contaminants sorbed to colloids remains constant along the observed flow path. In contrast, for contaminants that strongly sorb to the sediment matrix, the fraction associated with colloids increases with increasing flow distance. In either case, the filtration of colloids is the limiting factor for the colloidal mass transfer. It is also shown that the recovery rates decrease rapidly within both sediments, and that the transport parameters (flow velocity, dispersivity) are only representative for the mobile fraction of the contaminant. On the given experimental scale, there was no evidence of a preferred colloidal transport, or even a transport of colloids ahead of the conservative tracer.

Adsorption↗
PubMedDate not supplied

MRI observation of oxygen-supersaturated water transport in a geological matrix.

The oxygen content of groundwater is a crucial property for many geochemical and biogeochemical processes including environmental remediation measures. In this contribution, we present results of a direct MRI observation of the propagation of a locally administered oxygen supersaturation through a water saturated sediment column.

Geologic Sediments↗
PubMedDate not supplied

MRI observation of heavy metal transport in aquifer matrices down to sub-mg quantities.

In this contribution, we report results from MRI studies of the propagation of heavy metal ions through columns packed with sandy aquifer materials. Both sorption of low concentrations of heavy metal ions from water flowing through the column and the formation of sorption traces produced from initially localized higher concentrations of heavy metal ions, and the remobilisation of adsorbed ions with time and changing hydrochemical conditions were studied. Multislice spin-echo and FLASH techniques were used for the imaging experiments. Advantages and problems of the different imaging protocols for the study of aquifer materials are discussed.

Adsorption↗
PubMedDate not supplied

Flow and diffusion measurements in natural porous media using magnetic resonance imaging.

Flow and diffusion of water in natural porous media, quartz sand, and calcareous gravel were measured using a 1.5-T clinical magnetic resonance tomograph. The spatial resolution of the dynamic measurements was 1.32 x 1.32 x 5 mm3, and the time between two cross-sectional measurements was approximately 10 s. The measured coefficients of molecular diffusion for water were in good agreement with theoretical data. Flow was measured without any tracer at velocities between 0.15 and 6.67 mm/s. The results, based on a calibration within one part of the column, were in good agreement with data obtained from a tracer experiment and from a numerical model. It was possible to measure the flow velocity in larger pores and preferential flow paths directly. The results of the flow measurements in smaller pores reflected the mean velocity within that volume element. In that case the obtained values were close to the average linear velocity. Since the time resolution is high a monitoring of flow processes is possible. The pore space was imaged with a spatial resolution of 0.5 x 0.5 x 0.5 mm3. Here, the porosity of pores that are larger than 0.2 mm can be measured directly; for smaller pores a calibration is necessary.

Calibration↗