Biosensor-controlled perfusion culture to estimate the viability of cells

Cellular and molecular markers in monitoring the fate of lymphoid cell culture from Penaeus monodon Fabricius (1798)

Lymphoid cell culture from penaeid shrimps has gained much acceptance as an in vitro platform to facilitate research on the development of prophylaxis, and therapeutic strategies against viruses and for cell line development. However, lymphoid cells can be used as platform for in vitro research, only if they are in metabolically and mitotically active state in vitro with unaltered cell surface receptors. Through this study, we addressed the response of lymphoid cells to a new microenvironment at cellular and molecular levels; including the study of mitotic events, DNA synthesis, expression profile of cell cycle genes, cytoskeleton organization, metabolic activity and viral susceptibility. The S-phase entry and synthesis of new DNA was recorded by immunoflourescent technique. Cdc2, CycA, CycB, EF-1α and BUB3 genes involved in cell cycle were studied in both the cells and tissue, of which EF-1α showed an elevated expression in cells in vitro (∼ 19.7%). Cytoskeleton network of the cell was examined by studying the organization of actin filaments. As the markers for metabolic status, mitochondrial dehydrogenase, protein synthesis and glucose assimilation by the cells were also assessed. Viral susceptibility of the cell was determined using WSSV to confirm the preservation of cellular receptors. This study envisages to strengthen the shrimp cell line research and to bring forth lymphoid cell culture system as a 'model' in vitro system for shrimp and crustaceans altogether.

Comparison of different biological methods for the assessment of ecotoxicological risks

To test the effects of heavy metals in river water, we compared the sensitivity of seven different biological test methods, using bacteria (Vibrio fischeri), human FL cells, protozoans (Paramecium spp.), nematodes (Rhabditis oxycerca), aquatic plants (Lemna minor), and fishes (Leuciscus idus melanotus). As test substance we used a representative mixture of 3.0 microg/l As, 2.5 microg/l Pb, 0.8 microg/l Cd, 1.7 microg/l Cr, 3.9 microg/l Cu, 6.7 microg/l Ni, 0.4 microg/l Hg, and 23.0 microg/l Zn, imitating the detectable heavy metal contamination of the Odra estuary (NE Germany/NW Poland). This mixture was defined as normal concentration (NC). Most sensitive was the test with L. minor (exposure time 10 d). The plants already showed phytotoxic effects at the heavy metal concentration found in the Odra estuary. Test systems with human cells, protozoans, and nematodes (exposure time 1-7 d) reacted at concentrations 85-100 times above the NC. Fish toxicity (exposure time 2 d) occurred from 130-fold concentration upwards. In contrast, the standard test carried out with luminescent bacteria (exposure time 30 min) was affected only at > 1000-fold concentrations. This test is therefore not suitable as an early warning system to detect ecological risks. Even the NC of heavy metals measured in the Odra estuary inhibits cells and the growth of aquatic plants. Of the single heavy metals tested, copper produced the strongest effects. Therefore, the reduction of heavy metal emissions, especially of copper-which can amplify the toxicity of other heavy metals-should be a task of highest priority.

The influence of antimicrobial treatments on the cytocompatibility of polyurethane biosensor membranes

The cytocompatibility of polyurethane membranes was tested following ultraviolet or gamma irradiation as well as treatment with hydrogen peroxide or glutaraldehyde containing solutions. Despite the fact that all of the methods had been recommended for antimicrobial treatment of glucose biosensors, the treatments investigated significantly influenced cytocompatibility characteristics. Cytotoxicity of membrane eluates was not observed following irradiation treatments. This was also the case when the membranes were repeatedly washed following chemical treatment. Cell growth upon the membranes was stimulated to a different extent after gamma and UV irradiation as well as following hydrogen peroxide treatments. Residues of an urea-based hydrogen peroxide inclusion compound caused a restriction in cell growth upon the membranes as was similarly observed with 2 and 4% glutaraldehyde solutions acting over 2 and 4 h, respectively. It is concluded that cytocompatibility in vitro reflecting the host response against a biomaterial in vivo does not only depend upon the material itself but also upon antimicrobial treatments which could have consequences for its bioperformance characteristics.