Supernatant cytotoxicity and proteolytic activity of selected oral bacteria against human gingival fibroblasts in vitro.

The purpose of this study was to determine if endodontic bacterial act in vitro on human gingival fibroblast functions via extracellular products. The bacteria used were Prevotella nigrescens, Capnocytophaga ochracea, Peptostreptoccocus micros and Actinobacillus actinomycetemcomitans. Supernatants were collected from bacterial cultures at the beginning of the stationary phase when their density was similar.

Modulation by hypergravity of extracellular matrix macromolecules in in vitro human dermal fibroblasts.

In vitro human dermal fibroblasts were submitted to normal gravity (1 g) or to chronic hypergravity (20 g) over a period of 8 days. Changes in organization of extracellular matrix molecules were seen by indirect immunofluorescence. In the fibronectin layer, bundles of fibrils were gathered together leading to a disorganisation of the normal parallel pattern of fibers seen in control cultures.

Effects of hypergravity on the cell shape and on the organization of cytoskeleton and extracelluar matrix molecules of in vitro human dermal fibroblasts.

In vitro human dermal fibroblasts were submitted to normal gravity (1 g) or to chronic hypergravity ranging from 2 to 20 g for 8 days. Changes only appeared above 15 g. The majority of 20 g-subjected cells showed fine filipods in the shape of a star whereas most control cells had rounded shapes and spread by forming lamellipodia.

Influence of a long duration exposure, 69 months, to the space flight factors in Artemia cysts, tobacco and rice seeds.

Three french laboratories have participated in the Free Flyer Biostack experiment. Artemia cysts, tobacco seeds and rice caryopsis and embryos were used. Biological objects in monolayers were dead.

Effects of hypergravity on adherent human cells.

In recent years, accumulating evidence has shown that microgravity or hypergravity may affect cell growth and differentiation. Since it is not easy to carry out researches in space or to simulate weightlessness on earth, we conducted experiments on simulated hypergravity (2 to 15 g) by using a centrifuge (radius: 80 cm; speed motor: 180 rpm). We looked for the effects of chronic hypergravity (7 to 10 days) on cultures of three human cell lines: lung or dermic fibroblasts and lung adenocarcinoma A 549 cells.