Microarray analysis identifies a set of CXCR3 and CCR2 ligand chemokines as early IFNβ-responsive genes in peripheral blood lymphocytes in vitro: an implication for IFNβ-related adverse effects in multiple sclerosis

BACKGROUND: A substantial proportion of multiple sclerosis (MS) patients discontinue interferon-beta (IFNβ) treatment due to various adverse effects, most of which emerge at the early phase after initiation of the treatment and then diminish with time. At present, the molecular mechanism underlying IFNβ-related adverse effects remains largely unknown. The aim of this study is to identify a comprehensive list of early IFNβ-responsive genes (IRGs) in peripheral blood mononuclear cells (PBMC) that may play a key role in induction of adverse effects. METHODS: Total RNA of PBMC exposed to 50 ng/ml recombinant human IFNβ for 3 to 24 hours in vitro was processed for cDNA microarray analysis, followed by quantitative real-time RT-PCR analysis. RESULTS: Among 1,258 genes on the array, IFNβ elevated the expression of 107 and 87 genes, while it reduced the expression of 22 and 23 genes at 3 and 24 hours, respectively. Upregulated IRGs were categorized into conventional IFN-response markers, components of IFN-signaling pathways, chemokines, cytokines, growth factors, and their receptors, regulators of apoptosis, DNA damage, and cell cycle, heat shock proteins, and costimulatory and adhesion molecules. IFNβ markedly upregulated CXCR3 ligand chemokines (SCYB11, SCYB10 and SCYB9) chiefly active on effector T helper type 1 (Th1) T cells, and CCR2 ligand chemokines (SCYA8 and SCYA2) effective on monocytes, whereas it downregulated CXCR2 ligand chemokines (SCYB2, SCYB1 and IL8) primarily active on neutrophils. CONCLUSION: IFNβ immediately induces a burst of gene expression of proinflammatory chemokines in vitro that have potential relevance to IFNβ-related early adverse effects in MS patients in vivo

Isolation, Cloning and Structural Characterisation of Boophilin, a Multifunctional Kunitz-Type Proteinase Inhibitor from the Cattle Tick

Inhibitors of coagulation factors from blood-feeding animals display a wide variety of structural motifs and inhibition mechanisms. We have isolated a novel inhibitor from the cattle tick Boophilus microplus, one of the most widespread parasites of farm animals. The inhibitor, which we have termed boophilin, has been cloned and overexpressed in Escherichia coli. Mature boophilin is composed of two canonical Kunitz-type domains, and inhibits not only the major procoagulant enzyme, thrombin, but in addition, and by contrast to all other previously characterised natural thrombin inhibitors, significantly interferes with the proteolytic activity of other serine proteinases such as trypsin and plasmin. The crystal structure of the bovine α-thrombin·boophilin complex, refined at 2.35 Å resolution reveals a non-canonical binding mode to the proteinase. The N-terminal region of the mature inhibitor, Q16-R17-N18, binds in a parallel manner across the active site of the proteinase, with the guanidinium group of R17 anchored in the S1 pocket, while the C-terminal Kunitz domain is negatively charged and docks into the basic exosite I of thrombin. This binding mode resembles the previously characterised thrombin inhibitor, ornithodorin which, unlike boophilin, is composed of two distorted Kunitz modules. Unexpectedly, both boophilin domains adopt markedly different orientations when compared to those of ornithodorin, in its complex with thrombin. The N-terminal boophilin domain rotates 9° and is displaced by 6 Å, while the C-terminal domain rotates almost 6° accompanied by a 3 Å displacement. The reactive-site loop of the N-terminal Kunitz domain of boophilin with its P1 residue, K31, is fully solvent exposed and could thus bind a second trypsin-like proteinase without sterical restraints. This finding explains the formation of a ternary thrombin·boophilin·trypsin complex, and suggests a mechanism for prothrombinase inhibition in vivo

Wet Chemical Treatment of Solar Grade CZ Silicon Prior to Surface Passivation

We have performed a systematic variation of the wet chemical oxidation and the subsequent oxide etching steps during the cleaning of Czochralski CZ single crystalline silicon wafers prior to surface passivation. The optimization of these preconditioning steps was carried out on saw damage etched or textured Si wafers subsequently passivated by amorphous silicon nitride a SiNx H or chemical passivation by an iodine ethanol I E solution. Measuring the carrier lifetime using the spatially resolved microwave detected photoconductance decay, we monitored the impact of the wet chemical surface conditioning on the surface morphology and wafer base doping type. For damage etched surfaces in alkaline potassium oxide solutions and passivated by iodine ethanol, an optimum surface passivation is obtained by omitting the last water rinse as used in the standard clean and adding a hot water treatment as final step in the cleaning procedure. While this results was found for both p type and n type wafers, suggesting that the passivation mechanism is based on the saturation of dangling bonds, a strong dependence on the doping type was observed for the passivation by a SiNx H. Prior to passivation by a SiNx H, the best preconditioning for n type was achieved by adding a hot water treatment and subsequent etching of the oxide by hydrofluoric acid HF . For p type however, no improvement was achieved with respect to the standard cleaning step. This dependency on the base doping type could be attributed to the passivation mechanism of a SiNx H based on the field effect. By employing ammonium fluoride as final etching solution instead HF, followed by hot water treatment, compared to the standard treatment, an improvement of the lifetime can be observed for both surface structures, indicating that the surface micro roughness can be reduced and the contamination can be remove

Conditioning of Textured Silicon Solar Cell Substrates by Wet Chemical Treatments

Different wet chemical treatments of crystalline Si wafers for the preparation of heterojunction solar cells are optimized with respect to low reflection losses, low recombination losses and long carrier lifetimes. It is demonstrated that a joint optimization of both saw damage etch and texture etch is necessary to control the pyramid morphology. Best results are reached for intermediate saw damage removals and texture etch times. Wet chemical preconditioning by oxidation in hot water and by using ozone at ambient temperatures is found to yield high quality surfaces with low defect densities. These methods are considered as low cost alternatives to conventional approaches. The surface photovoltage SPV technique is established as efficient tool for technology optimization and allows a fast and reliable interface characterization and the quantitative determination of interface defect densities

Wet chemical preparation of textured silicon solar cell substrates Surface conditioning and electronic interface properties

Decisive preconditions to the development of economically attractive solar cells are further improvements of the energy conversion efficiency by appropriate interface preparation and passivation meth ods as well as the reduction of material consumption by the application of thin film technologies [ ]. For this purpose also the simplification of technological proc esses, particularly the suitability and cost effectiveness of wet chemical cleaning and etching processes has to be taken carefully into consideration. This paper reports on the investigation of wet chemical etching und surface conditioning of different Si sub strates, carried out before preparation of thin oxides, amorphous crystalline a Si H c Si hetero junctions, Si nitride a SiNx H passivation layers and contacts. Wet chemical smoothing and hydrogen termination procedures were investigated in order to reduce surface micro roughness, surface charge and densities of inter face states Dit E on textured surfaces. . According to our results wet chemical smooth ing prior to a Si H deposition for amorphous crystalline hetero junction solar cells ZnO a Si H n c Si p Al increases significantly the fill factor and energy conver sion efficiency [5]. Electronic interface properties of textured Si substrates for solar cells application were found to be mainly influenced by the crystallographic surface configuration of light trapping structures and secondly, the effective ness of wet chemical smoothing, H termination or oxidation procedures. Strong effects of surface condi tioning were found on c Si a Si H, on Si carbide a SiC H and also on c Si a SiNx H interfaces, even though the field effect passivation is based on the band bending caused by a fixed charge in the film [6

Wet chemical conditioning of H terminated silicon solar cell substrates investigated by surface photovoltage measurements

In high efficiency crystalline Si solar cells textured mono and multi crystalline substrates are commonly used to reduce reflection losses and to increase the absorption probability by light trapping. The improvement of the optical properties, however, is related to a larger effective surface area and to an increased surface micro roughness. It inherently corresponds to an increased number of electrically active defect states in the band gap and thereby results in higher interface recombina tion losses. Consequently, surface texturing has to be combined with appropriate surface passivation to minimise electronically active interface defects. This contribution reports on a very sensitive electrical method, namely field depended large signal surface photo voltage SPV , which is utilised to detect the small number of defects in the range from 1010 cm 2eV 1 to 1014 cm 2eV 1. The capabilities of the large signal surface photovoltage SPV method for detailed investigations of interface recombination losses and the development of efficient interface passivation methods was shown for wet chemical surface conditioning processes. Electronic interface properties of Si solar cell substrates were found to be mainly influenced by complete removal of saw damage and mini mization of surface micro roughness on different crystallographic surface configurations. The se quences of wet chemical oxidation, oxide removal and H termination processes have to be carefully optimised with respect to the substrate configuration and subsequent deposition processe