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.     

Caspase-14 but not caspase-3 is processed during the development of fetal mouse epidermis

The activation of caspases is a central step in apoptosis and may also be critical for terminal differentiation of epidermal keratinocytes (KC). In particular, caspase-3 has been implicated in the differentiation of embryonic KC as well as in programmed cell death of KC, and caspase-14 has been suggested to function in the formation or homeostasis of the stratum corneum (SC). To test the putative roles of these proteases, we determined their expression level and activation status during development of fetal mouse epidermis. The level of procaspase-3 did not change significantly during epidermal development, and enzyme activation was undetectable at any timepoint investigated. Despite the lack of active caspase-3, the newly formed stratum granulosum and the regressing periderm contained cells positive in the terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick end labeling assay, indicating that nuclear DNA was degraded without activation of caspase-3, thereby arguing against a proteolytic function of caspase-3 in embryonic KC differentiation. By contrast, caspase-14 increased in abundance from embryonic day 14.5 (E14.5) onwards and consistently localized to the suprabasal layers of fetal epidermis. The caspase-14 pro-enzyme was processed into its catalytic subunits, a step required for enzyme activity, on day E17.5, coinciding with SC formation. Thus, processing of procaspase-14 is not confined to air-exposed mature skin but also occurs during epidermal development in utero. In summary, this study demonstrates that caspase-14, but not caspase-3 activation coincides temporally and spatially with embryonic KC differentiation, suggesting a role for caspase-14 in terminally differentiated KC.     

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.     

The elusive indigo precursors in woad (Isatis tinctoria L.)--identification of the major indigo precursor, isatan A, and a structure revision of isatan B

A metabolite-profiling study of shock-frozen leaves of Isatis tinctoria L., an old indigo dye plant and medicinal herb, revealed a complex pattern of indigo-forming compounds with higher polarities than the known indigo precursors isatan B and indican. These highly unstable compounds underwent rapid post-harvest transformation and were not detected in air-dried leaves. The major indigo precursor, named isatan A (4), was isolated by rapid normal-phase and gel chromatography, along with isatan B (3). A full spectral data set of 3 showed that the previous structure assignment as 'indoxyl-5-ketogluconate' has to be revised to 1H-indol-3-yl beta-D-ribohex-3-ulopyranoside. Isatan A (4) was identified as 1H-indol-3-yl 6'-O-(carboxyacetyl)-beta-D-ribohex-3'-ulopyranoside. In aqueous solution, glycosides 3 and 4 occur as hydrates and undergo rapid hydrolysis under very mild acidic or basic conditions.     

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.