Colloidal transport and agglomeration in column studies for advanced run-off filtration facilities--particle size and time resolved monitoring of effluents with flow-field-flow-fractionation.

The efficiency of road run-off filtration facilities based on ion-exchange materials is reduced by pollutants which are transported bound to particles. To quantify the factors governing particle transport phenomena, a simplified model consisting of quartz sand-filled columns representing the filter/soil was set up. Suspensions of artificial clays, cold water-extracted natural clays, and real run-off were used as model effluents. Five experiments were performed: breakthrough of a natural soil suspension, remobilization of a natural soil suspension after ionic strength-drop, the same two experiments with a suspension of the artificial clay mineral Laponite, and the remobilization of run-off accumulated on a column at high ionic strength with an ionic strength down-gradient. Short-interval effluent fractions were analysed by flow-field-flow-fractionation (F4) to obtain the size distributions of the colloids present. The size distributions of subsequent fractions were then plotted in a staggered arrangement to give three-dimensional graphs that are time- and particle size-resolved. With this method the subsequent release of different agglomerate sizes formed on the column could be shown for the artificial clay mineral, questioning its use as a model colloid. The combined particle size- and time-resolved plots proved to be a powerful tool for monitoring colloidal solids in column effluents.

Impact of natural nanophases on heavy-metal retention in zeolite-supported reactive filtration facilities for urban run-off treatment.

The retention of lead in zeolite-supported sand-filter columns has been tested with focus on the effect of potentially mobile natural nanophases (natural colloids, humic substances). It could be shown that interaction of lead with natural nanophases enhanced the mobility of the contaminant. In the presence of iron oxide particles (goethite) a normal breakthrough of lead was observed. Humic substance can act as a carrier for lead itself and can enhance the mobility of lead bound to inorganic nanophases, because of the increased mobility of the nanophases in the presence of humic substances.

Increased sensitivity of the inositol-phospholipid system in neutrophils from patients with acute major depressive episodes.

Evidence from in vitro and in vivo studies suggests that the therapeutic and prophylactic effects of lithium in recurrent affective disorders are due to an attenuation of the inositol-phospholipid (IPL) second messenger system. An increased sensitivity of this signal transduction system might therefore constitute a risk factor for affective illness. The extent of the agonist-induced release of intracellular Ca2+ (Ca2+ response) can be used as an indicator of the sensitivity of the IPL system. Using this paradigm, we have measured the agonist-induced Ca2+ response in neutrophils of 17 unmedicated patients who were experiencing an acute major depressive episode. The neutrophils were stimulated by the chemotactic peptide formylmethionylleucylphenylalanine, which activates the IPL system in the cells. The sensitivity of the IPL system in these patients was significantly greater (dose-response curve shifted to the left) compared with its sensitivity in healthy age- and sex-matched control subjects. The results indicate that acute episodes of major depression are associated with an increased sensitivity of the IPL system.

Decreased agonist-stimulated Ca2+ response in neutrophils from patients under chronic lithium therapy.

The agonist-stimulated increase in the intracellular concentration of free Ca2+ ([Ca2+]i) was determined in neutrophils from patients under chronic lithium therapy and a control group of age- and sex-matched healthy drug-free subjects. Cells were stimulated with the chemotactic peptide formylmethionylleucylphenylalanin (fMLP) and the Ca2+ concentrations measured with the fluorescent Ca2+ indicator Fura-2. The Ca2+ response to stimulation with fMLP was significantly attenuated in neutrophils from patients chronically treated with lithium. The data suggest that lithium treatment inhibits the inositol phospholipid second messenger generating system in human cells and support the results of earlier inositol phosphate measurements in fMLP-stimulated neutrophils.

Increased sensitivity to agonist stimulation of the Ca2+ response in neutrophils of manic-depressive patients: effect of lithium therapy.

The agonist-stimulated increase of intracellular free-Ca2+ concentration, an indicator of the sensitivity of the inositol phospholipid second-messenger generating system, was measured in neutrophils from patients with manic-depressive disorder, and controls. Dose-response curves of the calcium response were determined by measuring the fluorescence of neutrophils loaded with fura-2 and stimulated with various concentrations of the chemotactic tripeptide formylmethionylleucylphenylalanine. EC50 values were obtained for 14 medication-free patients (5 acutely depressive, and 9 symptom free remitted patients with a history of manic-depression or recurrent major depression), 9 lithium-treated, euthymic manic-depressive patients and 10 drug-free healthy controls. The EC50 values of the untreated patients were significantly lower than in the controls. Lithium-treated patients had EC50 values significantly higher than controls. These results suggest that manic-depressive disorder is associated with an increased sensitivity of the inositol phospholipid second-messenger generating system, which is counteracted by lithium treatment.

Lake sediments as indicators of heavy-metal pollution.

Heavy metals are one of the most toxic forms of environmental pollutants, constituting a threat both to aquatic life and the quality of drinking water. By analyzing lake sediments, it is possible to determine the provenance, distribution, extent, and also the possible hazards of metal contamination. Sedimentary cores, in particular, provide the means for evaluating the different influences from natural and civilizational sources; they represent a historical record of the metal accumulations which have taken place during the past decades as a result of population growth and industrial development.