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Biomedical subjects

D Gibbs

Publications and source records attributed to D Gibbs.

At least 73 records · Page 4Linked to original sources
PubMed1990

All-trans retinoic acid stimulates growth and extracellular matrix production in growth-inhibited cultured human skin fibroblasts.

All-trans retinoic acid was examined for effects on human dermal fibroblast proliferation and for effects on fibroblast production and expression of non-collagenous and collagenous components of the extracellular matrix in vitro. Fibroblast proliferation was blocked when the cells were cultured in the presence of a serum-free culture medium containing epidermal growth factor, hydrocortisone, insulin, ethanolamine, phosphoethanolamine, and bovine pituitary extract as growth supplements and 0.15 mM Ca++. This level of extracellular Ca++ is lower than that needed to support fibroblast growth. Under these conditions, growth was stimulated by all-trans retinoic acid. Proliferation was also stimulated in the same basal medium without the growth supplements. Growth-promoting concentrations of all-trans retinoic acid ranged from 0.5-2.0 micrograms/ml (1.7-6.6 X 10(-6) M). Stimulation of proliferation was not seen at higher or lower concentrations. Concentrations of all-trans retinoic acid that stimulated proliferation also induced increased production of fibronectin as indicated by biosynthetic labeling/immunoprecipitation and by enzyme-linked immunosorbent assay. Increased production was associated with increased staining for fibronectin in the extracellular matrix. Increased production of two other non-collagenous extracellular matrix component, i.e., thrombospondin and laminin, also occurred in all-trans retinoic acid-treated cells. At 0.5 micrograms/ml, all-trans retinoic acid also stimulated production of type I collagen by the dermal fibroblasts, but at higher concentrations (2.5 micrograms/ml) production of type I collagen was inhibited. These data indicate that all-trans retinoic acid can induce changes in dermal fibroblasts in vitro (i.e., increased proliferation and extracellular matrix production) that mimic the major changes seen in the dermis after topical treatment with this agent.

Cell Division↗
PubMed1989

Formation and use of poly-L-histidine-catalase complexes: protection of cells from hydrogen peroxide-mediated injury.

Insoluble complexes of poly-L-histidine (polyhistidine) and catalase were prepared by mixing the two reactants together in solution at pH 5.5 and subsequently elevating the pH to approximately 7.0, at which point they precipitated. Complexes formed at optimal ratios of polyhistidine to catalase contained essentially all of the catalase present in the original solution. The catalase present in such complexes contained greater than 50% of the H2O2-inhibiting activity of the native catalase used to prepare the complexes. The insoluble complexes rapidly bound to viable endothelial cells and were resistant to removal by extensive washing. The presence of polyhistidine-catalase complexes on the cell surface protected the cells against injury mediated by H2O2 or activated polymorphonuclear leukocytes. These data show that polyhistidine-catalase complexes can be prepared that have a high affinity for cells and that retain catalase activity. These complexes may be useful in treating inflammatory conditions in which it is necessary to maintain a high local concentration of inhibitor.

Animals↗