PubMed · 2749307
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S Taurand. 1989. [Topical corticosteroids].. https://pubmed.ncbi.nlm.nih.gov/2749307/
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The toxicity of sulphur mustard (HD) was characterized in first passage cultures of human neonatal foreskin keratinocytes and then several arginine analogues were investigated to ascertain their efficacies in protecting against HD toxicity in this system. d- and l-nitroarginine methyl ester (d/l-NAME), l-phosphoarginine, and l-nitroarginine were all found to confer concentration-related protective effects against HD in confluent cultures. l-NAME was used to further characterize this protection and was only effective in cultures that were not actively proliferating. This compound was also found to be efficacious when added to the cultures up to several hours after HD exposure, although its continued presence was required in order for protection to be effective. The protective effects of l-thiocitrulline (l-TC) against HD toxicity were also assessed. This arginine analogue was extremely potent in preventing HD toxicity in actively proliferating, just-confluent, and postconfluent cultures in a concentration-dependent fashion (0.1-15 mM), with little HD toxicity apparent at high l-TC concentrations. Protection was prophylactic in nature, with l-TC having almost maximal effect when added to the cultures only 1 min prior to HD culture exposure. Efficacy then declined rapidly so that no protection was evident when l-TC was added 30 min post-HD. The effects of this drug were persistent, with no decrease in protective efficacy up to 4 days after HD exposure, even when l-TC was removed from the cultures. l-TC did not protect against the antimitotic effects of HD; while l-TC-protected cells were subcultured successfully, they displayed no clonogenic activity. Although l-TC is closely related structurally to protective nitroarginine derivatives, the characteristics of l-TC protection against HD were markedly different and suggest that they exert their protective activities at different sites. Administration of l-NAME and l-TC by a variety of routes did not result in consistent protection against topical vapor challenges of HD in hairless guinea pigs. However, both compounds were effective in preventing the toxicity of HD in primary cultures of hairless guinea pig skin keratinocytes, indicating that species differences were not likely to be responsible for the poor efficacy of these compounds in vivo.
Endothelial cell seeding, a promising method to improve the performance of small-diameter vascular grafts, requires a suitable substrate, e.g. crosslinked collagen. In addition, the growth of seeded endothelial cells can be improved by local release of a heparin-binding protein, basic fibroblast growth factor (bFGF). In this study, the influence of immobilization of heparin to collagen, crosslinked using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) in combination with N-hydroxysuccinimide (NHS), on the binding and release of bFGF was determined. Heparin was immobilized also using EDC and NHS. Furthermore, the effects of the release of bFGF from (heparinized) EDC/NHS-crosslinked collagen on the proliferation of seeded endothelial cells was studied in vitro. Immobilization of increasing amounts of heparin to EDC/NHS-crosslinked collagen (containing 14 free epsilon-amino groups per 1000 amino acid residues, E/N14C) resulted in binding of increasing amounts of bFGF to the material. Maximal bFGF binding was observed for E/N14C containing 20-30 mg heparin immobilized per gram of collagen which was obtained using a molar ratio of EDC to heparin-carboxylic acid groups of 0.4 for heparin immobilization (E/N14C-H(0.4)). Up to concentrations of 320 ng bFGF/ml, 10% of the added bFGF bound to E/N14C, while binding of bFGF to E/N14C-H(0.4) was 22%. The initial release rate of bFGF bound to E/N14C was much higher compared to bFGF bound to E/N14C-H(0.4): respectively, 30 vs. 2% in the first 6 h. After 10 days, the bFGF release from E/N14C and E/N14C-H(0.4) amounted to 83 vs. 42%, respectively. Binding of increasing amounts of bFGF resulted in increased growth of human umbilical vein endothelial cells (HUVECs) seeded on both E/N14C and E/N14C-H(0.4). Nevertheless, after 6 and 10 days of proliferation cell numbers on E/N14C-H(0.4) where higher than cell numbers on E/N14C, irrespective of the bFGF concentration used for loading of the matrix. It is concluded that heparinized, EDC/NHS-crosslinked collagen is a good synthetic vascular graft coating for in vivo endothelial cell seeding.
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