Showing papers by "Ruth Duncan published in 1990"

Methods for the evaluation of biocompatibility of soluble synthetic polymers which have potential for biomedical use: 1 - Use of the tetrazolium-based colorimetric assay (MTT) as a preliminary screen for evaluation of in vitro cytotoxicity

Abstract: A tetrazolium-based colorimetric assay (MTT) was first introduced by Mossman in 1983 to assess the potential of novel antitumour agents, and it has been used here to evaluate the cytotoxicity of several soluble synthetic polymers proposed as drug carriers Polymers including poly-l-lysine (molecular weight 57 000) were incubated (up to 1 mg ml−1) with two human cell lines, hepatocellular carcinoma (HepG2) and lymphoblastoid leukaemia (CCRF), adherent and suspension cells, respectively Tests were carried out in the presence and absence of serum proteins The assay was first modified to optimize the colorimetric profiles produced by the cell lines following incubation with MTT, to increase both the test sensitivity and the reproducibility of the method Polymer toxicity observed using the MTT test was compared with data obtained using other methods; [3H]thymidine or [3H]leucine incorporation and counting cell numbers Poly-l-lysine was very toxic to both cell lines with approximate IC50-values of 60 and 30 µg ml−1 for HepG2 and CCRF, respectively, the values obtained being similar for each of the three different viability methods used In the absence of serum proteins the toxicity of poly-l-lysine increased, the IC50-values falling to 255 µg ml−1 for the adherent and 08 µg ml−1 for the suspension cell line Other polymers such as poly-l-proline, polyethylene glycol, dextran, polyvinylpyrrolidone and poly-l-glutamic acid were not cytotoxic (MTT assay), either in the presence or in the absence of serum proteins The MTT assay is a useful technique for the primary and rapid evaluation of the cytotoxicity of soluble polymers

Effect of the Chemical Modification of Dextran on the Degradation by Dextranase

Abstract: Dextran was modified using three different methods: a) partial periodate oxidation and subsequent reduction of the aldehyde groups, b) suc cinoylation and c) chloroformate activation with subsequent reaction with 2- hydroxypropylamine, ethylenediamine and tris(2-aminoethyl)amine. Degrada tion of these dextran derivatives by dextranases was investigated. It was observed that the rate of degradation decreased with increasing degree of chemical modification of the parent polysaccharide. The nature of modification had no significant influence on the rate of degradation.

Immunogenicity of protein-N-(2-hydroxypropyl)methacrylamide copolymer conjugates in A/J and B10 mice

Abstract: Two proteins (model targeting residues) human immunoglobulin fraction (IgG) and human transferrin have been conjugated to N-(2-hydroxy propyl)methacrylamide (HPMA) copolymer and the antibody titer elicited, after subcutaneous or intraperitoneal administration to A/J and B10 mice of free and conjugated protein, was measured using the ELISA technique. The measured IgG titer against protein-HPMA copolymer conjugates was always higher than the IgM titer. Also, the titer (IgG) measured against native protein was up to 250-fold greater than that raised against protein-HPMA copolymer conjugates. This reduction in antibody titer against conjugate had a limited de pendence on its molecular weight.