PubMed · 576445
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J A Ward, J Mendeloff, J C Coberly. 1977-03-14. Hyperthyroidism followed by scleroderma.. https://pubmed.ncbi.nlm.nih.gov/576445/
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Determining the DNA content of cultured cells with the fluorochrome diaminobenzoic acid (DABA) has been shown to be a sensitive and selective method. A procedure is described which applies this method to cells cultured in 96-well and 24-well plates. After removal of the medium, the cells are disrupted by sonication, dried and reacted with DABA. For the final read-out the DABA-DNA solution is transferred to standard cuvettes and the fluorescence intensity determined with a conventional fluorometer. The method is highly reproducible and suitable for the cell concentrations usually employed in microculture systems. It is an easy non-radioactive method for determining the numbers of both adherent and non-adherent cells, especially when comparing different stages of activation or differentiation.
Transforming growth factor-beta (TGF-beta) exerts several effects on cultured airway epithelial cells including inhibition of proliferation and stimulation of fibronectin gene expression. ADP-ribosylation is one potential regulatory mechanism of gene expression by TGF-beta. We tested this possibility by exposing cultured bovine bronchial epithelial cells to the chemical inhibitor of ADP-ribosyl transferase enzymes, 3-aminobenzamide (3-AB) and, for comparison, 3-aminobenzoic acid (3-ABA), which is structurally similar to 3-AB but which does not inhibit ADP-ribosyl transferases. Exponential cell growth rate (1.2 doublings/day) or cellular morphology observed by phase contrast microscopy were not affected by 3 mM 3-AB or 3-ABA. Neither compound antagonized inhibition of cell division or induction of squamous morphology by TGF-beta 1. In contrast, the sixfold stimulation of fibronectin production by exposure of cells to 30 pM TGF-beta 1 for 48 h was reduced by 50% in the presence of 3 mM 3-AB, whereas 3 mM 3-ABA had no effect. The antagonistic effect was augmented by administration of 3-AB 24 h prior to induction by TGF-beta 1. Northern blot hybridization analyses demonstrated that 3-AB, but not 3-ABA, attenuated the induction of fibronectin mRNA by TGF-beta 1 by up to 50%. These observations may implicate a role of cellular ADP-ribosylation in the regulation of some gene expression by TGF-beta.
The effects of various commercial and model surfactants of different structure and hydrophilicity were studied on water-in-oil (w/o) emulsion stability, potassium cation leakage and permeation of 6-nitro-3-phenylacetamide benzoic acid in a model system using Penicillin acylase (EC 3.5.1.11) immobilized in a liquid membrane. Both emulsion stability, potassium leakage and permeation of organic substances depend upon hydrophilicity of surfactants. Hydrophilic surfactants may be used to stabilize emulsions only in mixtures with hydrophobic emulsifiers. Additions of small quantities of hydrophilic surfactants to the system in which permeation occurs together within an enzymatic process may be advantageous. Both the rate of permeation and potassium transfer significantly increase when hydrophilic surfactants are present. There was no relationship observed between potassium cation transfer from the internal phase and emulsion stability in the storage test.