An antagonist of lipid A action in mammals has complex effects on lipid A induction of defence responses in the model plant Arabidopsis thaliana

Lipopolysaccharides, the ubiquitous part of the outer membrane of Gram-negative bacteria, and their derivatives are recognised by plants to trigger or potentiate particular defence responses such as induction of genes encoding pathogenesis-related proteins. The molecular mechanisms of LPS perception that underpin these effects in plants are, however, unknown. Here, lipid A from Halomonas magadiensis, which is an antagonist of lipid A action in human cells, was used to investigate lipid A action in plants. Our findings offer an insight into the different structural requirements for direct induction and potentiation of plant defences by lipid A.     

Impact of different exercise training modalities on the coronary collateral circulation and plaque composition in patients with significant coronary artery disease (EXCITE trial): study protocol for a randomized controlled trial

ABSTRACT: BACKGROUND: Exercise training (ET) in addition to optimal medical therapy (OMT) in patients with stable coronary artery disease (CAD) has been demonstrated to be superior to percutaneous coronary interventions (PCI) with respect to the composite endpoint of death, myocardial infarction, stroke, revascularization and hospitalization due to worsening of angina. One mechanism leading to this superiority discussed in the literature is the increase in coronary collateral blood flow due to ET. Until now, data demonstrating the positive effect of ET on the collateral blood flow and the functional capacity of the coronary collateral circulation are still lacking.Methods/designThe EXCITE trial is a three-armed randomized, prospective, single-center, open-label, controlled study enrolling 60 patients with stable CAD and at least one significant coronary stenosis (fractional flow reserve <=0.75). The study is designed to compare the influence and efficacy of two different 4-week ET programs [high-intensity interval trainings (IT) versus moderate-intensity exercise training (MT) in addition to OMT] versus OMT only on collateral blood flow (CBF). The primary efficacy endpoint is the change of the CBF of the target vessel after 4 weeks as assessed by coronary catheterization with a pressure wire during interruption of the antegrade flow of the target vessel by balloon occlusion. Secondary endpoints include the change in plaque composition as assessed by intravascular ultrasound (IVUS) after 4 weeks, myocardial perfusion as analyzed in MRI after 4 weeks and 12 months, peak oxygen uptake (V02 peak), change in endothelial function and biomarkers after 4 weeks, 3, 6 and 12 months. The safety endpoint addresses major adverse cardiovascular events (death from cardiovascular cause, myocardial infarction, stroke, TIA, target vessel revascularization or hospitalization) after 12 months. DISCUSSION: The trial investigates whether ET for 4 weeks increases the CBF in patients with significant CAD compared to a sedentary control group. It also examines the impact of two intensities of ET on the CBF as well as the histological plaque composition. The trial started recruitment in June 2009 and will complete recruitment until June 2012. First results are expected in December 2012 (4-week follow-up), final results (12-month long-term secondary endpoint) in December 2013.Trial registrationClinical trial registration information-URL: www.clinicaltrials.gov.Unique identifier: NCT01209637.     

Effects of the thermal environment on metabolism of deoxynivalenol and thermoregulatory response of sheep fed on corn silage grown at enriched atmospheric carbon dioxide and drought

Future livestock production is likely to be affected by both rising ambient temperatures and indirect effects mediated by modified growth conditions of feed plants such as increased atmospheric CO₂ concentrations and drought. Corn was grown at elevated CO₂ concentrations of 550?ppm and drought stress using free air carbon dioxide enrichment technology. Whole plant silages were generated and fed to sheep kept at three climatic treatments. Differential blood count was performed. Plasma DON and de-epoxy-DON concentration were measured. Warmer environment increased rectal and skin temperatures and respiration rates (p?<?0.001 each) but did not affect blood parameters and the almost complete metabolization of DON into de-epoxy-DON. Altered growth conditions of the corn fed did not have single effects on sheep body temperature measures and differential blood count. Though the thermoregulatory activity of sheep was influenced by the thermal environment, the investigated cultivation factors did not indicate considerable impacts on the analysed parameters.     

Active site mapping of yeast aspartyl-tRNA synthetase by in vivo selection of enzyme mutations lethal for cell growth.

The active site of yeast aspartyl-tRNA synthetase has been characterised by structural and functional approaches. However, residues or structural elements that indirectly contribute to the active site organisation have still to be described. They have not been assessed by simple analysis of structural data or site-directed mutagenesis analysis, since rational targetting has proven difficult. Here, we attempt to locate these functional features by using a genetic selection method to screen a randomly mutated yeast AspRS library for mutations lethal for cell growth. This approach is an efficient method to map the active site residues, since of the 23 different mutations isolated, 13 are in direct contact with the substrates. Most of the mutations are located in a 15 A radius sphere around the ATP molecule, where they affect the very conserved residues of the class-defining motifs. The results also showed the importance of the dimer interface for the enzyme activity: a single mutation of the invariant proline residue of motif 1 led to a structural defect inactivating the enzyme. From in vivo complementation studies it appeared that the enzyme activity can be recovered by reconstitution of an intact interface through the formation of heterodimers. We also show that a single mutation affecting an interaction with G34 of the tRNA can inactivate the enzyme by inducing a relaxation of the tRNA recognition specificity. Finally, several mutants whose functional importance could not be assessed from the structural data were selected, demonstrating the importance of this type of approach in the context of a structure-function relationship study.     

Decreased expression of leukotriene B4 receptor sites on polymorphonuclear granulocytes of severely burned patients

Polymorphonuclear granulocytes were isolated from patients with burn injury and the specific binding of (3H)leukotriene B4 was assessed. We observed a decreased receptor expression as compared to healthy donor cells, which may be the result of receptor downregulation as a consequence of cellular preactivation. In addition, leukotriene B4-synthesis was also reduced and differential cell counts demonstrated a shift from segmented neutrophils to immature cells. In survivors the values returned to normal parameters whereas nonsurvivors who succumbed in the course of generalized sepsis showed depressed cellular functions up to their death.     

Plant Functional Types Differ in Their Long-term Nutrient Response to eCO2 in an Extensive Grassland

Ecosystems - Increasing atmospheric CO2 enhances plant biomass production and may thereby change nutrient concentrations in plant tissues. The objective of this study was to identify the effect of...