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At least 1,081 records · Page 60Linked to original sources
PubMed1998

Aggrecan immobilization onto polystyrene plates through electrostatic interactions with spermine.

A new procedure for the immobilization of proteoglycans and the core protein thereof via their carbohydrate chains onto enzyme-linked immunosorbent assay (ELISA) plate wells is presented. The aggrecan was immobilized via electrostatic interactions with spermine coupled to glutaraldehyde via Schiff's base, the latter being directly anchored onto ELISA wells. The amounts of aggrecan bound by this procedure measured immunochemically were 10-fold greater than those adsorbed by direct coating. The interaction of aggrecan and spermine may be inhibited by very small amounts of sulfated glycosaminoglycans or proteoglycans in a competitive manner, and therefore the system may be used for their quantitation. Bound aggrecan could react with link protein and therefore the system may be used for studying interactions of cartilage macromolecules. The method may also be used for direct quantitation of proteoglycans since the amounts adsorbed, in a given range of concentrations, are directly proportional to the amounts in solution.

Aggrecans↗
PubMed1999

A turbidimetric assay for quantitating functional fibrin(ogen) using polystyrene-divinylbenzene microparticles.

A sensitive assay has been developed to quantitate fibrinogen in plasma or in other aqueous solutions. Microscopic latex particles, modified with a mixed monomolecular film of lecithin and fibrinogen, are used as a solid-phase reagent. These lecithin/fibrinogen-coated beads aggregate when stirred in the presence of thrombin and, when solution-phase fibrinogen is added, the increased rate of aggregation is proportional to the concentration of soluble fibrinogen. Using a sample volume of 200 microl, as little as 15 nM ( approximately 5 microg ml-1) fibrinogen can be measured. Fibrinogen determinations using the bead assay compared favorably with those derived from a standard clinical assay, with a correlation coefficient (r2) of 0.9710 over a range of 2.5 to 28.0 microM. Analytic precision was comparable to available assays, with typical coefficients of variation of 12.7 and 7.1% for fibrinogen concentrations of 30 nM and 15.0 microM, respectively. The method has a dynamic range of 15 nM to over 3.0 microM and offers the advantage of being sensitive to 20-fold lower concentrations of fibrinogen compared to routine clot-based methods. Unlike immunological assays, e.g., ELISA, it measures only the functional protein. This bead method should prove to be of greatest use to investigators measuring low levels of functional fibrin(ogen).

Enzyme-Linked Immunosorbent Assay↗
PubMed2002

Resin dynamics contributes to the NMR line broadening of organic molecules grafted onto a polystyrene resin.

Despite the use of high resolution magic angle spinning NMR, the NMR linewidth of anchored molecules on the commonly used Merrifield solid phase resins remains larger than that of the corresponding molecules in solution. We investigate the different mechanisms that might be at the origin of this line broadening. Experimentally, we use the CPMG method to determine the (15)N relaxation times of a tethered tripeptide and show that the slow resin dynamics significantly contributes to the transverse relaxation.

Anisotropy↗
PubMed2006

Short polystyrene monolith-fritted micro-liquid chromatography columns for rapid isocratic analysis of pharmaceuticals direct from plasma.

The manufacture of micro-HPLC columns with combined stationary phases, a body of 3.5-microm XTerra-C18 particles, and poly(styrene-divinylbenzene) (PS-DVB) frits is described in detail. The efficiency of the columns was assessed by rapid separation of neutral and acid compound mixtures. Direct analysis of some pharmaceuticals in plasma resulted in lower limits of detection (LOD) for salmeterol xinofate of 12.5 nanograms on-column.

Albuterol↗
PubMed2005

Enhancement of liver-specific functions of primary rat hepatocytes co-cultured with bone marrow cells on tissue culture-treated polystyrene surfaces.

Primary rat hepatocytes were co-cultured with bone marrow cells (BMCs) in a tissue culture-treated culture well (TCW) or a collagen-coated culture well (CCW). Although a medium containing serum was used, the co-cultured cells formed spheroids on the TCW within 2 days, and ammonia metabolism and albumin secretion activities were well maintained for 3 weeks. The co-cultured cells formed a monolayer on the CCW within 2 days, and liver functions were maintained for 3 weeks. The ammonia metabolism activities and albumin secretion activities of co-cultured cells on the CCWs were slightly inferior to those on the TCWs. This co-culture system of hepatocytes and BMCs is an appropriate culture system for the expression and maintenance of liver-specific functions in vitro, and is expected to be applicable to bioartificial liver systems, regenerative medicine, and liver function simulators.

Albumins↗