Opposing effects of monomeric and pentameric C-reactive protein on endothelial progenitor cells

C-reactive protein (CRP) has been linked to the pathogenesis of atherosclerosis. The dissociation of native, pentameric (p)CRP to monomeric (m)CRP on the cell membrane of activated platelets has recently been demonstrated. The dissociation of pCRP to mCRP may explain local pro-inflammatory reactions at the site of developing atherosclerotic plaques. As a biomarker, pCRP predicts cardiovascular adverse events and so do reduced levels and function of circulating endothelial progenitor cells (EPCs). We hypothesised that mCRP and pCRP exert a differential effect on EPC function and differentiation. EPCs were treated with mCRP or pCRP for 72 h, respectively. Phenotypical characterisation was done by flow cytometry and immunofluorescence microscopy, while the effect of mCRP and pCRP on gene expression was examined by whole-genome gene expression analysis. The functional capacity of EPCs was determined by colony forming unit (CFU) assay and endothelial tube formation assay. Double staining for acetylated LDL and ulex lectin significantly decreased in cells treated with pCRP. The length of tubuli in a matrigel assay with HUVECs decreased significantly in response to pCRP, but not to mCRP. The number of CFUs increased after pCRP treatment. RNA expression profiling demonstrated that mCRP and pCRP cause highly contradictory gene regulation. Interferon-responsive genes (IFI44L, IFI44, IFI27, IFI 6, MX1, OAS2) were among the highly up-regulated genes after mCRP, but not after pCRP treatment. In conclusion, EPC phenotype, genotype and function were differentially affected by mCRP and pCRP, strongly arguing for differential roles of these two CRP conformations. The up-regulation of interferon-inducible genes in response to mCRP may constitute a mechanism for the local regulation of EPC function.

Enhanced bio-compatibility of ferrofluids of self-assembled superparamagnetic iron oxide-silica core-shell nanoparticles

Self-assembled magnetic colloidal suspensions are sought after by material scientists owing to its huge application potential. The biomedical applications of colloidal nanoparticles necessitate that they are biocompatible, non-interacting, monodispersed and hence the synthesis of such nanostructures has great relevance in the realm of nanoscience. Silica-coated superparamagnetic iron oxide nanoparticles based ferrofluids were prepared using polyethylene glycol as carrier fluid by employing a controlled co-precipitation technique followed by a modified sol-gel synthesis. A plausible mechanism for the formation of stable suspension of SiO2-coated Iron Oxide nanoparticles with a size of about 9 nm dispersed in polyethylene glycol (PEG) is proposed. Core-shell nature of the resultant SiO2-Iron Oxide nanocomposite was verified using transmission electron microscopy. Fourier transform-infrared spectroscopy studies were carried out to understand the structure and nature of chemical bonds. The result suggests that Iron Oxide exist in an isolated state inside silica matrix. Moreover, the presence of silanol bonds establishes the hydrophilic nature of silica shell confirming the formation of stable ferrofluid with PEG as carrier fluid. The magnetic characterization reveals the superparamagnetic behavior of the nanoparticles with a rather narrow distribution of blocking temperatures. These properties are not seen in ferrofluids prepared from Iron Oxide nanoparticles without SiO2 coating. The latter suggests the successful tuning of the inter-particle interactions preventing agglomeration of nanoparticles. Cytotoxicity studies on citric acid coated water based ferrofluid and silica-coated PEG-based ferrofluid were evaluated by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium chloride assay and it shows an enhanced compatibility for silica modified nanoparticles.

Evaluation of the Interface Structure During Stranski-Krastanov Growth of GE(SI) on Si (001)

The initial stages of heteroepitaxial growth of Ge0.85 Si0.15 on Si(001) grown from Bi solution (liquid phase epitaxy) are studid by transmission electron microscopy. Stranski-Krastanov growth is observed to take place. After growth of a pseudomorphic Ge0.85 Si0.15 layer of 4 monolayer thickness, islands form and grow pseudomorphically up to a thickness of 30 nm. Then first misfit dislocations form. The formation process of these dislocations is analyzed and discussed in terms of half loop nucleation at the surface and dislocation glide. Evidence for glide on (110) planes is put forward.

Misfit Dislocations and Elastic Relaxation

Prior to relaxation of misfit strain by formation of misfit dislocations, a growing heteroepitaxial layer can relax elastically by forming surface undulations called ripples. With increasing amplitude of the ripples the misfit strain and thus stress fields grow markedly inhomogeneous, and dislocation formation may thus be triggered in areas of maximum shear stress. The surface directly above such a new dislocation then represents a band of preferential growth and develops into a ridge, which in turn redistributes the strain in the growing layer. This interwoven elastic/plastic relaxation mechanism can comparably easily be deduced from transmission electron and atomic force microscopy studies of SiGe layers grown onto silicon by liquid phase epitaxy. This growth technique exerts only very small driving forces and thus operates very near thermodynamical equilibrium. The local strain tensor and strain energy density are calculated for the actual layer geometries by three dimensional finite element method and provide for quantification of the mechanism.

Synthesis and catalytic activity of histidine-based NHC ruthenium complexes

Main-chain C,N-protected histidine has been successfully alkylated at both side-chain nitrogens. The corresponding histidinium salt was metallated with ruthenium(II) by a transmetalation procedure, thus providing histidine-derived NHC ruthenium complexes. These bio-inspired complexes show appreciable activity in the catalytic transfer hydrogenation of ketones.

Percolation Threshold in Superhard Nanocrystalline Transition Metal-Amorphous Silicon Nitride Composites: The Control and Understanding of the Superhardness

The hardness of the recently developed novel superhard nanocrystalline composites exceeds 5000 kg/mm2 (50 GPa) and the elastic modulus 550 GPa. This is due to a special microstructure which is formed when the fraction of the amorphous component reaches the percolation threshold. Experimental data are presented and discussed.

Luminescence Related to Stacking Faults in Heterepitaxially Grown Wurtzite GaN

We correlate structure analyzed by transmission electron microscopy with photo- and cathodoluminescence studies of GaN/Al2O3(0001) and GaN/SiC(0001) and show that an additional UV line at 364nm/3.4eV can be connected to the occurrence of stacking faults. We explain the occurrence of this line by a model that is based on the concept of excitons bound to stacking faults that form a quantum well of cubic material in the wurtzite lattice of the layer material. The model is in reasonable agreement with the experimental observations.

Vouchers for health: A demand side output-based aid approach to reproductive health services in Kenya

Reaching the United Nation's Millennium Development Goals has been a focus for many countries and development partners. In Kenya, as in many other countries with low levels of development, access to and equity of basic quality health services is limited, especially for the very poor. Among poor populations, maternal mortality is high as access to medical care and financial means are lacking. In 2005, the Governments of Kenya and Germany in cooperation with KfW Banking Group made funds available for the Reproductive Health OBA Voucher Programme offering vouchers for Safe Motherhood, Family Planning and Gender Violence Recovery Services. This programme, herein referred to as Vouchers for Health, was launched in June of 2006 in five Kenyan districts with the aim of providing health services for safe deliveries, long-term family planning methods and victims of gender violence. The way that the programme is being implemented in Kenya demonstrates that the voucher-based approach comprises a variety of key structural elements of a national health insurance scheme: accreditation; quality assurance; reimbursement system; claims processing; integrating the private sector; client choice; provider competition; and access to and equity of services provided.