Protein/lipid interactions in phospholipid monolayers containing the bacterial antenna protein B800-850

Studies on monomolecular layers of phospholipids containing the antenna protein B800-850 (LHCP) and in some cases additionally the reaction center of the photosynthetic bacterium Rhodopseudomonas sphaeroides are reported. Information on monolayer preparation as well as on protein /lipid and protein/protein interaction is obtained by means of fluorescence spectroscopy and microscopy at the air/water interface in combination with film balance experiments. It is shown that a homogeneous distribution of functional proteins can be achieved. This can be transformed into a regular pattern-like distribution by inducing a phospholipid phase transition. Although the LHCP preferentially partitions into the fluid lipid phase, it decreases the lateral pressure necessary to crystallize the lipid. This is probably due to an increase in order of the fluid phase. A pressure-induced conformation change of the LHCP is detected via a drastic change in fluorescence yield. A highly efficient energy transfer from LHCP to the reaction center is observed. This proves the quantitative reconstitution of both types of proteins and indicates protein aggregation also in the monolayer

Do Aspirin and Other Antiplatelet Drugs Reduce the Mortality in Critically Ill Patients?

Platelet activation has been implicated in microvascular thrombosis and organ failure in critically ill patients. In the first part the present paper summarises important data on the role of platelets in systemic inflammation and sepsis as well as on the beneficial effects of antiplatelet drugs in animal models of sepsis. In the second part the data of retrospective and prospective observational clinical studies on the effect of aspirin and other antiplatelet drugs in critically ill patients are reviewed. All of these studies have shown that aspirin and other antiplatelet drugs may reduce organ failure and mortality in these patients, even in case of high bleeding risk. From the data reviewed here interventional prospective trials are needed to test whether aspirin and other antiplatelet drugs might offer a novel therapeutic option to prevent organ failure in critically ill patients

Microstructure and Optical Properties of Mixed Monolayers Containing a J-band Forming Cyanine Dye and Various Cosurfactants

Mixed monolayers of stearic acid and the dye 1-methyl-1'-octadecyl-2,2'-cyanine iodide (S120) at the air-water interface and on a solid support are studied by fluorescence microscopy and spectroscopy, by electron microscopy and diffraction and by synchroton X-ray reflection. Rotationally symmetric arrangements of needle-like J-aggregates observed by fluorescence microscopy can also be observed by electron microscopy. Electron diffraction again shows rotational symmetry of the crystallographic axes within domains of dimensions 100 ωm. The sharpness of the electron diffraction lines indicates a high degree of positional order. Yet structures at the centre and near the periphery of a domain differ in that the lattice constants are slightly larger in the latter case.X-ray reflection measurements demonstrate and quantify the rearrangement of the chromophore groups during pressure-induced growth of a J-band, forming either in a 1:2 S120:stearic acid mixture or purely from S120 with no discernible difference in the fluorescence spectrum.The fluorescence emission and excitation spectra depend strongly on the temperature, which can be understood within a model considering thermally assisted detrapping of excitons. A molecular picture of the nature of these traps, which are distinguished by a very large Stokes shift, will be given in conjunction with studies of exciton-surface plasmon interactions