An AFM study of solid-phase bilayers of unsaturated PC lipids and the lateral distribution of the transmembrane model peptide WALP23 in these bilayers

An altered lipid packing can have a large influence on the properties of the membrane and the lateral distribution of proteins and/or peptides that are associated with the bilayer. Here, it is shown by contact-mode atomic force microscopy that the surface topography of solid-phase bilayers of PC lipids with an unsaturated cis bond in their acyl chains shows surfaces with a large number of line-type packing defects, in contrast to the much smoother surfaces observed for saturated PC lipids. Di-n:1-PC (n = 20, 22, 24) and (16:0,18:1)-PC (POPC) were used. Next, the influence of an altered lipid environment on the lateral distribution of the single α-helical model peptide WALP23 was studied by incorporating the peptide in the bilayers of di-n:1-PC (n = 20, 22, 24) and (16:0,18:1)-PC unsaturated lipids. The presence of WALP23 leads to an increase in the number of packing defects but does not lead to the formation of the striated domains that were previously observed in bilayers of saturated PC lipids and WALP. This is ascribed to the less efficient lateral lipid packing of the unsaturated lipids, while the increase in packing defects is probably an indirect effect of the peptide. Finally, the fact that an altered lipid packing affects the distribution of WALP23 is also confirmed in an additional experiment where the solvent TFE (2,2,2-trifluorethanol) is added to bilayers of di-16:0-PC/WALP23. At 3.5 vol% TFE, the previous striated ordering of the peptide is abolished and replaced by loose lines

C-reactive protein as a new parameter of mastitis

The C-reactive protein (CRP) is an acute phase protein. Its deposit can be seen on several animal species. Following the development of a test system (enzyme-immunoassay/EIA) for the quantitative determination of bovine CRP, it was possible to detect this protein in bovine raw milk for the first time. It was shown in the first extensive investigations that the CRP concentration in raw milk was increased, sometimes as much as tenfold as a result of udder inflammation (mastitis). In several screening analyses of a herd of cows, the CRP-values were compared with the somatic cell number, fat, protein and lactose content. The degree of CRP concentrations in raw milk in cows suffering from mastitis during the antibiotic treatment was reflected in the treatment success. When CRP was used as an additional parameter of selection, a better average udder health could be seen after five months. The first results of our investigations demonstrate that CRP is a practicable indicator of inflammation and may be effectively used to determine and control udder illness in cows

Metal-Free, Cooperative Asymmetric Organophotoredox Catalysis with Visible Light

The dawn of old stars: Classic xanthene dyes like eosin Y (gr. εoς=goddess of dawn) and green-light irradiation can replace precious metal complexes for the organocatalytic asymmetric -alkylation of aldehydes rendering the process purely organic

Green-Light Photocatalytic Reduction using Dye-Sensitized TiO2 and Transition Metal Nanoparticles

Nitrobenzenes are cleanly reduced to anilines using Ru-sensitized TiO2 photocatalysts and green light irradiation, if very small amounts of transitions metal salts are added, which form metal nanoparticles of narrow size distribution under the experimental conditions. The catalyst system is prepared by simple mixing of the components and is therefore easy to apply in organic synthesis. As light sources, commercial high power LEDs or sunlight are used.We report the optimization of the reaction conditions, the effect of trace amounts of added metal salts and demonstrate the use of green light photoreduction in the conversion of several nitrobenzene derivatives

Inflammatory cell recruitment after experimental thromboembolic stroke in rats

Inflammatory mechanisms were recently identified as contributors to delayed neuronal damage after ischemic stroke. However, therapeutic strategies are still lacking, probably related to the outstanding standardization on inflammatory cell recruitment emerging from predominantly artificial stroke models, and the uncertainty on functional properties of distinct subpopulations. Using a rodent model of stroke that closely reflects human embolic ischemia, this study was focused on the local recruitment of immunoreactive cells as well as their functional and regional characterization. Wistar rats underwent thromboembolic middle cerebral artery occlusion, followed by intravenous injection of the blood-brain barrier permeability marker fluorescein-conjugated albumin at 24h. One hour later, brain tissue was subjected to multi-parameter flow cytometry and Pappenheim staining to characterize cells invaded into the ischemia-affected hemisphere, compared to the contralateral side. Immunofluorescence labeling was applied to explore the distribution patterns of recruited cells and their spatial relationships with the vasculature. One day after ischemia onset, a 6.12-fold increase of neutrophils and a 5.43-fold increase of monocytes/macrophages was found in affected hemispheres, while these cells exhibited enhanced major histocompatibility complex class II expression and allocation with vessels exhibiting impaired blood-brain barrier integrity. Microglia remained numerically unaltered in ischemic hemispheres, but shifted to an activated phenotype indicated by CD45/CD86 expression and morphological changes toward an ameboid appearance in the bordering zone. Ischemia caused an increase of lymphoid cells in close vicinity to the affected vasculature, while further analyses allowed separation into natural killer cells, natural killer T cells, T cells (added by an unconventional CD11b(+)/CD3(+) population) and two subpopulations of B cells. Taken together, our study provides novel data on the local inflammatory response to experimental thromboembolic stroke. As concomitantly present neutrophils, monocytes/macrophages and lymphoid cells in the early stage after ischemia induction correspond to changes seen in human stroke, future stroke research should preferably use animal models with relevance for clinical translation

Air-Con Metal-Organic Frameworks in Binder Composites for Water Adsorption Heat Transformation Systems

Metal–organic frameworks (MOFs) currently receive high interest for cycling water adsorption applications like adsorption heat transformation for air-conditioning purposes. For practical use in adsorption heat pumps (AHPs), the microcrystalline powders must be formulated such that their high porosity and pore accessibility are retained. In this work, the preparation of millimeter-scaled pellets of MIL-160(Al), Al-fumarate (Basolite A520), UiO-66(Zr), and Zr-fumarate (MOF-801) is reported by applying the freeze granulation method. The use of poly(vinyl alcohol) (PVA) as a binder reproducibly resulted in highly stable, uniformly shaped PVA/MOF pellets with 80 wt % MOF loading, with essentially unchanged MOF porosity properties after shaping. The shaped pellets were analyzed for the application in AHPs by water adsorption isotherms, over 1000 water adsorption/desorption cycles, and thermal and mechanical stability tests. Furthermore, the Al-fum pellets were applied in a fixed-bed, full-scale heat exchanger, yielding specific cooling powers from 349 up to 431 W/kg (adsorbent), which outperforms the current commercially used silica gel grains in AHPs under comparable operating conditions