Understanding cellular signaling mediated by cell surface receptors is key to modern biomedical research and drug development. The discovery of a growing number of potential molecular targets and therapeutic compounds requires downscaling and accelerated functional screening. Receptor-mediated cellular responses are typically investigated on single cells or cell populations. Here, we show how to monitor cellular signaling reactions at a yet unreached miniaturization level. On the basis of our observations, cytochalasin induces mammalian cells to extrude from their plasma membrane submicrometer-sized native vesicles. They comprise functional cell surface receptors correctly exposing their extracellular ligand binding sites on the outer vesicle surface and retaining cytosolic proteins in the vesicle interior. As a prototypical example, ligand binding to the ionotropic 5-HT(3) receptor and subsequent transmembrane Ca(2+) signaling were monitored in single attoliter vesicles. Thus, native vesicles are the smallest autonomous containers capable of performing cellular signaling reactions under physiological conditions. Because a single cell delivers about 50 native vesicles, which can be isolated and addressed as individuals, our concept allows multiple functional analyses of individual cells having a limited availability and opens new vistas for miniaturized bioanalytics.

Reversible and oriented immobilization of proteins in a functionally active form on solid surfaces is a prerequisite for the investigation of molecular interactions by surface-sensitive techniques. We demonstrate a method generally applicable for the attachment of proteins to oxide surfaces. A nitrilotriacetic acid group serving as a chelator for transition metal ions was covalently bound to the surface via silane chemistry. Reversible binding of the green fluorescent protein, modified with a hexahistidine extension, was monitored in situ using total internal reflection fluorescence. The association constant and kinetic parameters of the binding process were determined. The reversible, directed immobilization of proteins on surfaces as described here opens new ways for structural investigation of proteins and receptor-ligand interactions.

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In this study, the general suitability of quantum dot (QD)-DNA conjugates for the surface plasmon enhanced fluorescence spectroscopy technique is demonstrated. Furthermore, the QD-DNA system is transferred to the platform of surface plasmon enhanced fluorescence microscopy. Using this technique together with a microarray format, in which the sensor-bound single-stranded catcher probes are organized in individual surface spots, results in a simultaneous qualitative analysis of QD-conjugated analyte DNA strands as multicolor images. A clear decomposition of different QD(x)()-DNA(y)() mixtures can be achieved for sequential, as well as mixture injections. Besides this, the study describes the successful approach of measuring spectrally resolved surface plasmon enhanced fluorescence signals derived from catcher probe hybridized QD-DNA conjugates.

The screening of ligands for membrane receptor proteins is central to the discovery of new pharmaceutical drugs. We present a general method to reversibly attach receptor proteins via an affinity tag to a quartz surface and subsequently detect with high sensitivity the real-time binding of ligands by total internal reflection fluorescence. A serotonin-gated ion channel protein was immobilized, and the binding of a fluorescent ligand was investigated. The affinity and the kinetic parameters of binding were measured, and the effect of unlabeled compounds was determined by competition. The pharmacology of the immobilized receptor was identical to that of the native receptor. The affinity of unlabeled ligands was rapidly and effectively determined. The method described here is generally applicable for membrane proteins and opens new ways for the discovery of pharmacologically active compounds.

We isolated, characterised, and cloned an enantio-specific amidase from Klebsiella oxytoca and used it to resolve (R,S)-3,3,3-trifluoro-2-hydroxy-2-methylpropionamide, giving (R)-3,3,3-trifluoro-2-hydroxy-2-methylpropionic acid and (S)-3,3,3trifluoro-2-hydroxy-2-methylpropionamide. The (S)-amide could then be hydrolysed chemically to (S)-3,3,3-trifluoro-2-hydroxy-2-methylpropionic acid. The process can therefore be adapted to produce both (R)-and (S)-enantiomers of 3,3,3-trifluoro-2hydroxy-2-methylpropionic acid, or (S)-3,3,3-trifluoro-2-hydroxy-2-methylpropionamide. The biocatalytic step is part of a combined chemical and biocatalytic route that starts from ethyl trifluoroacetoacetate. The products typically have a purity of greater than 98% and ee values of essentially 100% after isolation. The process has been used to produce 100-g amounts of the (S)-acid, and successfully scaled up to produce 100-kg amounts of the (R)-acid, with the biotransformation carried out at the 1500-L scale.

Is the neglect of economic, social and cultural abuses in international criminal law a problem of positive international law or the result of choices made by lawyers involved in mechanisms such as criminal prosecutions or truth commissions? Evelyne Schmid explores this question via an assessment of the relationship between violations of economic, social and cultural rights and international crimes. Based on a thorough examination of the elements of international crimes, she demonstrates how a situation can simultaneously be described as a violation of economic, social and cultural rights and as an international crime. Against the background of the emerging debates on selectivity in international criminal law and the role of socio-economic and cultural abuses in transitional justice, she argues that international crimes overlapping with violations of economic, social and cultural rights deserve to be taken seriously, for much the same reasons as other international crimes.

Increasing numbers of academics and practitioners are employing the language of economic and social rights (ESR) when conceptualizing the aims, scope and implementation mechanisms of transitional justice. Their contributions have added to an evolving debate on the boundaries of transitional justice. However, when employing rights language, the current debate on the economic and social dimensions of transitional justice frequently suffers from terminological and conceptual confusion. Problematically, it is not unusual for the claims made by transitional justice commentators with regard to ESR to be founded on apparent misconceptions about both the legal framework and the existing scholarship relating to ESR. Addressing these misconceptions in terms of four key dichotomies and suggesting the way forward, we prepare the ground for a more effective debate on the desirability and feasibility of incorporating ESR into transitional justice processes. In doing so, we assert that such a debate must be based on an accurate understanding of ESR and the obligations they impose. We conclude by demonstrating how inclusion of ESR considerations in transitional justice does not necessitate rethinking transitional justice as a whole.