Culture of primary human gingival fibroblasts on biodegradable membranes.

Repair and regeneration of periodontal tissues by tissue engineering is dependent on the use of biodegradable polymer scaffolds which serve as a carrier for cells or bioactive substances. There is a need to understand how a specific biomaterial may influence gene expression. The aim of this investigation was to develop and to optimize an in vitro technique for the adherance and proliferation of primary human gingivaL cells on implantable and biodegradable matrices.

Prevention of adriamycin-induced mdr1 gene amplification and expression in mouse leukemia cells by simultaneous treatment with the anti-recombinogen bromovinyldeoxyuridine.

The anti-recombinogenic substance (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) was tested for its ability to prevent adriamycin-induced mdr1 gene amplification and expression in mouse leukemia cells in vitro. F4-6 cells that were treated with stepwise enhanced doses of adriamycin acquired resistance against adriamycin. While 20 ng/ml adriamycin showed strong toxic effects in sensitive cells, the same dose was tolerated at the end of the long-term experiment following treatment with stepwise enhanced doses of adriamycin.

Use of Primary Rat and Human Hepatocyte Sandwich Cultures for Activation of Indirect Carcinogens: Monitoring of DNA Strand Breaks and Gene Mutations in Co-cultured Cells.

Loss of cytochrome P-450 content is a common feature in conventional culture systems of primary hepatocytes. In contrast to the standard in vitro situation, in vivo each hepatocyte is exposed to an extracellular matrix (space of Disse) at two opposing basolateral surfaces. This in vivo symmetry has been reconstructed in vitro by culturing rat or human hepatocytes within two layers of collagen, thus forming a sandwich configuration.

Induction or suppression of SV40 amplification by genotoxic carcinogens, non-genotoxic carcinogens or tumor promoters.

Carcinogens are generally classified into two groups: genotoxic and non-genotoxic. As the final product of genotoxic and non-genotoxic carcinogens is the same, i.e.

Co-recombinogenic and anti-mutagenic effects of diethylhexylphthalate, inactiveness of pentachlorophenol in the spot test with mice.

In in vivo experiments using the spot test with mice, diethylhexylphthalate (DEHP) was co-recombinogenic and anti-mutagenic. In two independent experiments, DEHP was able to increase in combination with ethylnitrosourea (ENU) the frequency of animals with spots of genetic relevance from about 12% (ENU alone) to about 15% (ENU+DEHP). This enhancement can be exclusively attributed to an enhancement of recombination.