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In research, pharmacologic drug-screening and medical diagnostics, the trend towards the utilization of functional assays using living cells is persisting. Research groups working with living cells are confronted with the problem, that common endpoint measurement methods are not able to map dynamic changes. With consideration of time as a further dimension, the dynamic and networked molecular processes of cells in culture can be monitored. These processes can be investigated by measuring several extracellular parameters. This paper describes a high-content system that provides real-time monitoring data of cell parameters (metabolic and morphological alterations), e.g., upon treatment with drug compounds. Accessible are acidification rates, the oxygen consumption and changes in adhesion forces within 24 cell cultures in parallel. Addressing the rising interest in biomedical and pharmacological high-content screening assays, a concept has been developed, which integrates multi-parametric sensor readout, automated imaging and probe handling into a single embedded platform. A life-maintenance system keeps important environmental parameters (gas, humidity, sterility, temperature) constant. [ABSTRACT FROM AUTHOR]

The flexible and modular setup of an intelligent mobile lab (IMOLA) that can be equipped with biosensor chips for monitoring of cellular metabolism is described. An application as an environmental monitoring system is described by recording the extracelluar acidification and cellular respiration of Chlorella kessleri after exposure to the herbicide metamitron. The adaptability of the IMOLA system to future developments in the field of biosensors or cellular metabolism analysis is emphasized. [ABSTRACT FROM AUTHOR]

Purpose: To study the interplay of drugs and energy metabolism of tumor cells, metabolic changes induced by chloroacetaldehyde and cytochalasin B were analyzed in colon carcinoma cells LS174T. Methods: O2-consumption and extracellular acidification were recorded using a bioelectronic sensor-chip system, which monitors these parameters in a culture continuously for at least 24 h. In parallel cultures cell number, cellular ATP-content, mitochondrial transmembrane potential, and the content of reactive oxygen species (ROS) were determined. Results: When cell death was induced by chloroacetaldehyde (50 μM), the rate of acidification declined gradually for the next 15 h, while O2-consumption decreased rapidly within 30 min. This correlated with a loss in mitochondrial potential. However, cellular ATP-level showed a transient increase at 2 h; also ROS levels increased up to 6 h. In cells treated with cytochalasin B (2 μM), which inhibits glucose uptake, the rate of O2-consumption increased and the acidification activity dropped, even upon glutamine depletion. Mitochondrial membrane potential transiently increased after 1 h, while ATP-content decreased; there was no change in the level of ROS. Conclusion: The pattern of changes in basic energy metabolism differs with the type of cell death and growth inhibition involved in the cytotoxic action of two different drugs. [ABSTRACT FROM AUTHOR]

The identification of drug targets for pharmaceutical screening can be greatly accelerated by gene databases and expression studies. The identification of lead-ing compounds from growing libraries is realized by high throughput screening platforms. Subsequently, for optimization and validation of identified leading compounds studies of their functionality have to be carried out, and just these functionality tests are a limiting factor. A rigorous preselection of identified compounds by in vitro cellular screening is necessary prior to using the drug candidates for the further time consuming and expensive stage, e.g. in animal models. Our efforts are focused to the parallel development, adaptation and integration of different microelectronic sensors into miniaturized biochips for a multiparametric, functional on-line analysis of living cells in physiologically environments. Parallel and on-line acquisition of data related to different cellular targets is required for advanced stages of drug screening and for economizing animal tests. [ABSTRACT FROM AUTHOR]

Critical parameters to be assessed in cell culture are the number of viable cells and cell viability. Growth, product formation, toxicity effects and the overall success of cell culture can depend largely on these. With interdigitated electrode structures (IDES) adherent cells are cultured directly on a pair of interdigitated electrodes, and the impedance of the system gives insight into the adhesive behaviour of the cells. The signal is influenced by the changes in number, growth and morphological behaviour of adherently growing cells, mainly owing to the insulating effects of the cell membranes. Five different cell lines are used, and their divergent behaviour is monitored over a period of four days, from inoculation of the cells to killing of the cells at the end of the experiments. Even when the cells from close monolayers, great fluctuations in the impedance signal can be observed. Nevertheless, for a more complete description of cellular systems, other parameters, such as acidification and respiration, have to be included in the measuring system. [ABSTRACT FROM AUTHOR]