Other Tubular Function Tests

Therefore, differences between properties of PTC in vivo in the normal adult kidney and in vitro properties of PTC and stem cell-derived proximal tubular-like cells may not just reflect dedifferentiation or lack of full terminal differentiation. Rather, altered marker expression patterns seem to be related to the biology of these cells and their response to altered conditions. It is important to keep in mind that human and animal PTC are probably always different under in vitro conditions (compared to the in vivo situation), unless the in vivo simation can be exactly mimicked. This is also important with respect to the interpretation of the differentiation status of stem cell-derived proximal tubular-like cells, as the expression of progenitor markers and markers specific for other renal cell types is normal under in vitro conditions, also in HPTC. For practical reasons we suggest to always compare stem cell-derived cells carefully to respective primary cells cultivated in vitro, which gives a realistic impression of the best possible differentiation state that can be achieved under the conditions used. In addition, rigorous functional tests (e.g., of transporter functions) are often more informative than marker expression patterns in terms of the applicability of stem cell-derived cells for drug screening. 

These equations hold if an Ignition Curve test consists of measuring conversion (X) as the unique function of temperature (T). This is done by a series of short, steady-state experiments at various temperature levels. Since this is done in a tubular, isothermal reactor at very low concentration of pollutant, the first order kinetic applies. In this case, results should be listed as pairs of corresponding X and T values. (The first order approximation was not needed in the previous ethylene oxide example, because reaction rates were measured directly as the total function of temperature, whereas all other concentrations changed with the temperature.) The example is from Appendix A, in Berty (1997). In the Ignition Curve measurement a graph is made to plot the temperature needed for the conversion achieved. 

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