Increase in fragmented phosphatidylcholine in blood plasma by oxidative stress

Oxidatively modified phospholipids with fragmented acyl chains have attracted much interest because of their proinflammatory activity and their potential involvement in atherosclerosis. They can be formed in vitro by free radical treatment of unsaturated phospholipids but it is not known under which conditions they accumulate in vivo. We assayed one species of fragmented phosphatidylcholine (PC) in human blood plasma by high performance liquid chromatography after precolumn derivatization with chloromethylanthracene. Structural analysis suggested that fragmented PC was a diacyl species with a palmitoyl group and a short oxidized residue, which most likely had four carbons. The concentration of fragmented PC was higher in elderly individuals with coronary heart disease than in young healthy controls. Smoking one cigarette acutely increased the concentration of fragmented PC in healthy adults. Fragmented PC also increased in the reperfusion period after treatment with cardiopulmonary bypass. The increase coincided with a surge of circulating neutrophils. In rats, the plasma concentration of fragmented PC was elevated by vitamin E deficiency and exposure to high oxygen.The data demonstrate that fragmented PC increases in blood plasma in response to various forms of oxidative stress.     

Zur Phototaxis von Mougeotia (Mesocarpus)

Summary Mosebach undertook a quantitative study of the light intensity which changes the positive phototaxis of theMougeotia chloroplast into a negative one (this intensity is the so-called, Umschlagspunkt = UP). The UP has no definite value but depends upon the pre-treatment of the plant. The UP is lowered by pre-darkening and is raised by a few hours or even less of pre-illumination.This light effect is a double one: a) the UP depends on the concentration of CO₂ in the medium, which of course is influenced by the ratio of respiration and photosynthesis, and b) in running-water experiments there still exists an influence of the pre-illumination on the UP, which must therefore be a direct light effect and which, it is suggested, is an adaptation.The CO₂-sensitivity of the UP is not an unspecific p_H effect and cannot be duplicated by citric, oxalic or hydrochloric acid. Only acetic acid has a similar effect.The cases in which the chloroplast is found to be oblique to the light beam are discussed from a new point of view.This summary is only a very short review by the editor; for further information compare the German summary by the author, page 41.

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Mit 16 Textabbildungen

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Mit einem Nachwort vonW. Haupt

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Vor seinem letzten Abschied legte mir mein Mann die Manuskripte zweier Arbeiten in die Hand mit der Bitte, wenn nötig, statt seiner für ihre Veröffentlichung zu sorgen. Die erste Arbeit (Über die Polarisierung derEquisetum-Spore durch das Licht, Planta33, 1943) war so gut wie druckfertig. Die zweite, hier vorliegende Arbeit war vonGeorg Mosebach in dieser Fassung noch nicht für die Veröffentlichung bestimmt; trotzdem ist sie nun doch in der ursprünglichen Form erschienen — abgesehen von wenigen oder unbedeutenden Änderungen, die Herr ProfessorBuder und Herr ProfessorRuhland, Leipzig, die Güte hatten vorzunehmen. Herrn Professor Dr.J. Buder und Herrn Professor Dr.W. Ruhland spreche ich auch an dieser Stelle meinen Dank aus für alle selbstlose Hilfe, die mir bei meiner Aufgabe zuteil wurde.Erna Mosebach, 1944.     

Activity of enzymes immobilized in colloidal spherical polyelectrolyte brushes

We investigate the enzymatic activity of glucoamylase and beta-glucosidase adsorbed on a novel type of colloidal particles. The particles used consist of a poly(styrene) core onto which long chains of poly(acrylic acid) or of poly(styrene sulfonic acid) are grafted ("spherical polyelectrolyte brush"). Proteins adsorb spontaneously onto these particles from aqueous solutions if the ionic strength is low. Moreover, the colloidal stability is not impeded by the adsorbed proteins despite the fact that up to 600 mg of enzyme is adsorbed per gram of the carrier particles. The activity of immobilized glucoamylase and beta-glucosidase adsorbed onto these particles is analyzed in terms of the Michaelis-Menten parameters. This analysis shows that both enzymes keep nearly their full activity. The Michaelis constant K(M) differs only slightly from the K(M) value of the native enzyme when the amount of adsorbed enzyme is raised despite the high local concentration of immobilized enzymes. All data demonstrate that spherical polyelectrolyte brushes present a novel way to immobilize enzymes.     

c-Abl regulates p53 levels under normal and stress conditions by preventing its nuclear export and ubiquitination

The p53 protein is subject to Mdm2-mediated degradation by the ubiquitin-proteasome pathway. This degradation requires interaction between p53 and Mdm2 and the subsequent ubiquitination and nuclear export of p53. Exposure of cells to DNA damage results in the stabilization of the p53 protein in the nucleus. However, the underlying mechanism of this effect is poorly defined. Here we demonstrate a key role for c-Abl in the nuclear accumulation of endogenous p53 in cells exposed to DNA damage. This effect of c-Abl is achieved by preventing the ubiquitination and nuclear export of p53 by Mdm2, or by human papillomavirus E6. c-Abl null cells fail to accumulate p53 efficiently following DNA damage. Reconstitution of these cells with physiological levels of c-Abl is sufficient to promote the normal response of p53 to DNA damage via nuclear retention. Our results help to explain how p53 is accumulated in the nucleus in response to DNA damage.     

Macromolecular trafficking between Nicotiana tabacum and the holoparasite Cuscuta reflexa

Transgenic tobacco plants expressing green fluorescent protein (GFP) under the control of the companion cell-specific promoter, AtSUC2, were parasitized by the holoparasite Cuscuta reflexa (dodder). GFP, moving in the translocation stream of the host, was transferred to the Cuscuta phloem via the absorbing hyphae of the parasite. An identical pattern of transfer was observed for the phloem-mobile probe, carboxyfluorescein. Following uptake by the parasite, GFP was translocated and unloaded from the Cuscuta phloem in meristematic sink tissues. Contrary to published data, these observations suggest the presence of a functional symplastic pathway between Cuscuta and its hosts, and demonstrate a considerable capacity for macromolecular exchange between plant species.     

Beitr?ge zur Zytologie der GattungMarchantia (L.)

Ohne Zusammenfassung

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Mit 44 Textfiguren und Tafel I     

Quality of Life as an outcome in Alzheimer's disease and other dementias- obstacles and goals

Background  

The number of individuals at risk for dementia will probably increase in ageing societies as will the array of preventive and therapeutic options, both however within limited economic resources. For economic and medical purposes valid instruments are required to assess disease processes and the efficacy of therapeutic interventions for different forms and stages of illness. In principal, the impact of illness and success of an intervention can be assessed with biomedical variables, e.g. severity of symptoms or frequency of complications of a disease. However, this does not allow clear judgement on clinical relevance or comparison across different diseases.     

Role of emergent and submerged vegetation and algal communities on nutrient retention and management in a subtropical urban stormwater treatment wetland

A 4.6-ha urban stormwater treatment wetland complex in southwest Florida has been investigated for several years to understand its nutrient retention dynamics. This study investigates the role of aquatic vegetation, both submerged vegetation (such as benthic macrophytic and algal communities) and emergent plant communities, on changes in nutrient fluxes through the wetlands. Gross and net primary productivity of water column communities and net primary productivity of emergent macrophytes were used to estimate nutrient fluxes through vegetation in these wetlands using biannual biomass, nutrient concentrations of plant material, and areal coverage data. Emergent macrophyte net primary productivity was estimated as the difference between the increase of productivity during the wet season and the loss during the dry season which, in turn, suggested approximately 0.11g-N m^??2 y^??1 and 0.09g-P m^??2 yr^??2 being removed, primarily from the soil, by emergent vegetation. Water column primary productivity accounted for a much larger flux of nutrients with approximately 39.6g-N m^??2 yr^??1 and 2.4g-P m^??2 yr^??1 retained in algal communities. These fluxes, combined with measurements in parallel studies, allowed us to develop preliminary nutrient budgets for these wetlands and identify gaps, or missing fluxes, in our models for these wetlands. The results further validated previous findings that suggested that there are large inputs of nitrogen (up to 62.3g-N m^??2 yr^??1) that are not accounted for by the pumped inflow. Additionally, management suggestions are provided to improve water quality by identifying vegetative species that are most effective at retaining nutrients.