ACPA fine-specificity profiles in early rheumatoid arthritis patients do not correlate with clinical features at baseline or with disease progression.

Introduction: Autoantibodies against citrullinated peptides/proteins (ACPA) are found in approximately 75% of the sera of patients with rheumatoid arthritis (RA). The RA-specific ACPA are frequently present prior to disease onset and their presence associates with a more erosive disease course. ACPA can therefore be used to aid the diagnosis and prognosis of RA.

Method for estimating the single molecular affinity.

Affinity constants (k(d), k(a), and K(D)) can be determined by methods that apply immobilized ligands such as immunoassays and label-free biosensor technologies. This article outlines a new surface plasmon resonance (SPR) array imaging method that yields affinity constants that can be considered as the best estimate of the affinity constant for single biomolecular interactions. Calculated rate (k(d) and k(a)) and dissociation equilibrium (K(D)) constants for various ligand densities and analyte concentrations are extrapolated to the K(D) at the zero response level (K(D)(R0)).

Surface modification of elastomeric stamps for microcontact printing of polar inks.

Chemical modification of the surface of a stamp used for microcontact printing (microCP) is interesting for controling the surface properties, such as the hydrophilicity. To print polar inks, plasma polymerization of allylamine (PPAA) was employed to render the surface of poly(dimethylsiloxane) (PDMS), polyolefin plastomers (POP), and Kraton elatomeric stamps hydrophilic for long periods of time. A thin PPAA film of about 5 nm was deposited on the stamps, which increased the hydrophilicity, and which remained stable for at least several months.

Release of anti-restenosis drugs from poly(ethylene oxide)-poly(DL-lactic-co-glycolic acid) nanoparticles.

Dexamethasone- or rapamycin-loaded nanoparticles based on poly(ethylene oxide) and poly(dl-lactic-co-glycolic acid) block copolymers (PEO-PLGA) were prepared without additional stabilizer using the salting-out method. A fast release of drug in PBS (pH 7.4) at 37 degrees C resulting in 100% release within 5 h was observed for both drugs.

Tailoring the properties of asymmetric cellulose acetate membranes by gas plasma etching.

Cellulose triacetate (CTA) ultrafilters and cellulose acetate blend (CAB) desalination membranes were treated with a radiofrequency gas plasma (tetrafluoromethane (CF(4)) or carbon dioxide (CO(2)), 47-49 W, 0.04-0.08 mbar).

Development of polymer membranes with improved haemocompatibility for biohybrid organ technology.

Biomedical technology has opened up possibilities of treating the failure of internal organs like kidney and liver by artificial organ therapy. Most of these techniques are based on polymer membranes, which allow the removal of excess of water, salts and toxins from the circulation. However, haemodialysis for the replacement of kidney function results in an increased morbidity and mortality of patients after long-term application.

Biodegradable polymersomes as a basis for artificial cells: encapsulation, release and targeting.

The encapsulation of biofunctional compounds, release properties and targetability of polymersomes of amphiphilic block-copolymers based on poly(ethylene glycol) (PEG) and biodegradable polyesters or polycarbonate are described. Carboxyfluorescein (CF), as a model for hydrophilic biofunctional compounds, could be readily incorporated in the polymersomes by adding the compound to the aqueous phase during polymersome preparation. The release of encapsulated material from the polymersomes can be adjusted by changing the copolymer composition, especially the molecular weight and type of hydrophobic block of the copolymer.

In vitro degradation of nanoparticles prepared from polymers based on DL-lactide, glycolide and poly(ethylene oxide).

Nanoparticles of poly(DL-lactic acid) (PDLLA), poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene oxide)-PLGA diblock copolymer (PEO-PLGA) were prepared by the salting-out method. The in vitro degradation of PDLLA, PLGA and PEO-PLGA nanoparticles in PBS (pH 7.4) at 37 degrees C was studied.

Electroosmotic guiding of sample flows in a laminar flow chamber.

The so-called address-flow principle is described: a valveless, electroosmotically driven technology used for controlling the stream profile in a laminar flow chamber. The method is explained, and a theoretical description and experimental verification are presented. Adjustment of the flow of two electroosmotically controlled guiding streams, running parallel to a central sample stream, can be used for positioning the sample stream in the dimension perpendicular to the flow direction.

Signal amplification on planar and gel-type sensor surfaces in surface plasmon resonance-based detection of prostate-specific antigen.

This article describes surface plasmon resonance (SPR)-based detection of prostate-specific antigen (PSA), comparing amplification with colloidal gold (10nm diameter) and latex microspheres (120 nm diameter) on planar- and gel-type sensor surfaces. As matrix, 3% BSA in PBS was used. Experimental data were compared with model calculations that predict the SPR signal that results from covering of the different sensor surfaces with each of the particles used.

Pegylated polystyrene particles as a model system for artificial cells.

Pegylated polystyrene particles (PS-PEG) were prepared as a model system for artificial cells, by modification of carboxyl polystyrene particles (PS-COOH) with homo- and hetero-bifunctional polyethylene glycols (PEG, MW 1500, 3400, and 5000) containing an amino end group for immobilization and an amino, hydroxyl, or methoxy end group that is exposed at the surface after immobilization. Protein adsorption from human plasma dilutions (85 v %) onto PS-PEG with a PEG surface concentration higher than 40 pmol/cm2 was reduced up to 90-95% compared with protein adsorption onto PS-COOH with a final protein surface concentration of approximately 30 ng/cm2. Two-dimensional gel electrophoresis analyses showed that 30% of the total amount of adsorbed proteins onto PS-PEG are dysopsonins (i.

Polyethylene glycol-grafted polystyrene particles.

Densely pegylated particles that can serve as a model system for artificial cells were prepared by covalently grafting amino polyethylene glycol (PEG, molecular weight 3400 or 5000) onto carboxyl polystyrene particles (PS-COOH) using carbodiimide chemistry. PEG-modified particles (PS-PEG) were characterized by determination of the PEG surface concentration, zeta-potential, size, and morphology. Under optimized grafting conditions, a dense "brush-like" PEG layer was formed.

The preparation of monodisperse biodegradable polyester nanoparticles with a controlled size.

In local drug delivery, nanoparticles based on biodegradable polymers can function as vehicles with controlled drug-release properties. To achieve a well-controlled drug-release profile, control over the particle size is of great importance. Therefore, biodegradable polyester nanoparticles were prepared by the salting-out method.

Gas plasma etching of PEO/PBT segmented block copolymer films.

A series of poly(ethylene oxide)/poly(butylene terephthalate) (PEO/PBT) segmented block copolymer films was treated with a radio-frequency carbon dioxide (CO(2)) or with argon (Ar) plasma. The effects of (preferential) etching on surface structure, topography, chemistry, and wettability were studied by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. In all cases, a granular-type nanostructure was formed after prolonged CO(2) plasma etching.

Enhanced bone marrow stromal cell adhesion and growth on segmented poly(ether ester)s based on poly(ethylene oxide) and poly(butylene terephthalate).

In previous studies in rats and goats, hydrophilic compositions of the PEOT/PBT block copolymer family have shown in vivo calcification and bone bonding. These copolymers are therefore interesting candidates as scaffolding materials in bone tissue engineering applications. Model studies using goat bone marrow stromal cells, however, showed that it was not possible to culture bone marrow stromal cells in vitro on these hydrophilic copolymers.

Binding and release of basic fibroblast growth factor from heparinized collagen matrices.

Endothelial cell seeding is a promising method to improve the performance of small-diameter vascular grafts. Growth of endothelial cells seeded on the luminal surface of synthetic vascular grafts, coated with a matrix suitable for cell seeding (e.g.

Relation between cell density and the secretion of von Willebrand factor and prostacyclin by human umbilical vein endothelial cells.

In this study, the relation between the density of human umbilical vein endothelial cells (HUVECs) cultured on TCPS and (crosslinked) collagen, and the secretion of von Willebrand factor (vWF) and prostacyclin (PGI2) was determined. Collagen was crosslinked using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) in combination with N-hydroxy-succinimide (NHS), resulting in a matrix containing 14 free primary amino groups per 1000 amino acid residues after crosslinking (E/N14C). HUVECs were seeded on E/N14C, non-crosslinked collagen (N-Coll) and fibronectin-coated TCPS at densities ranging from 2500 to 50,000 cells/cm2.

Improved platelet compatiblity of water vapour glow discharge treated non-woven poly(ethylene terephthalate) leukocyte-reduction filters for different types of platelet concentrates.

Non-woven poly[ethylene terephthalate] (NW-PET) filter fabric, usually used for leucocyte removal of red cells, was modified by water vapour glow discharge (WVGD) treatment to improve platelet compatibility. Modified filter material was evaluated with different kinds of platelet concentrates (PCs). In addition, modified filter materials were gamma-sterilized and tested after different time intervals at different storage conditions.

Immobilized salt-tolerant yeasts: application of a new polyethylene-oxide support in a continuous stirred-tank reactor for flavour production.

Immobilization of salt-tolerant yeasts considerably decreases the total time required for the flavour development in soy-sauce processes. For immobilization of cells, alginate gel is mostly used as support material. However, alginate is not very suitable for use in soy-sauce processes because alginate is sensitive to abrasion and chemically unstable towards the high salt content of the soy-sauce medium.

In vivo biocompatibility of carbodiimide-crosslinked collagen matrices: Effects of crosslink density, heparin immobilization, and bFGF loading.

Collagen matrices, crosslinked using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (E) and N-hydroxysuccinimide (N), were previously developed as a substrate for endothelial cell seeding of small-diameter vascular grafts. In the present study, the biocompatibility of various EN-crosslinked collagen matrices was evaluated following subcutaneous implantation in rats for periods up to 10 weeks. The effects of the crosslink density, referred to as the number of free primary amino groups per 1,000 amino acid residues (EN10, EN14, EN18, or EN22), the amount of heparin immobilized to EN14, and the effect of preloading heparinized EN14 with basic fibroblast growth factor (bFGF) on the induced tissue reaction were studied.

Immobilization of heparin to EDC/NHS-crosslinked collagen. Characterization and in vitro evaluation.

In the present study, heparin immobilization to a non-cytotoxic crosslinked collagen substrate for endothelial cell seeding was investigated. Crosslinking of collagen using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) resulted in a material containing 14 free primary amino groups per 1000 amino acid residues (E/N14C). At a fixed molar ratio NHS:EDC of 0.

Endothelial cell seeding on crosslinked collagen: effects of crosslinking on endothelial cell proliferation and functional parameters.

Endothelial cell seeding, a promising method to improve the performance of small-diameter vascular grafts, requires a suitable substrate, such as crosslinked collagen. Commonly used crosslinking agents such as glutaraldehyde and formaldehyde cause, however, cytotoxic reactions and thereby hamper endothelialization of currently available collagen-coated vascular graft materials. The aim of this study was to investigate the effects of an alternative method for crosslinking of collagen, using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) in combination with N-hydroxysuccinimide (NHS), on various cellular functions of human umbilical vein endothelial cells (HUVECs) in vitro.

Immobilized soy-sauce yeasts: development and characterization of a new polyethylene-oxide support.

Entrapment of cells in alginate gel is a widely used mild immobilization procedure. However, alginate gel is not very suitable for use in long-term continuous soy-sauce processes because alginate is sensitive to abrasion and chemically unstable towards the high salt content of soy-sauce medium. Therefore, a chemically crosslinked polyethylene-oxide gel was used instead.

In vitro and in vivo evaluation of gelatin-chondroitin sulphate hydrogels for controlled release of antibacterial proteins.

Chemically cross-linked gelatin-chondroitin sulphate (ChS) hydrogels, impregnated in Dacron, were evaluated as drug delivery systems for antibacterial proteins. The gelatin-chondroitin sulphate gels, plain or impregnated in Dacron, were cross-linked with a water-soluble carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The release of lysozyme and recombinant thrombocidin (rTC-1), an antibacterial protein derived from human blood platelets, from the gelatin-ChS gels in Dacron in phosphate-buffered saline at 37 degrees C was determined, and compared to the release from gelatin gels in Dacron and plain gelatin-ChS gels.