= Heide Tullberg-Reinert
{c}
\b[Heide Tullberg-Reinert] coauthored the 2002 study of chemical interference with the <MTT assay>. Washing treated <cells> before adding <MTT> reduced the direct <redox> interference observed with <kaempferol>.<Interference of plant extracts, phytoestrogens and antioxidants with the MTT tetrazolium assay by Regina Bruggisser and others>[2002, byline and final sentences of Abstract]{ref}
That experimental comparison connects the readout to the presence of the test substance during measurement. Washing is an intervention on assay conditions, rather than proof that the earlier exposure had no biological effect. It may remove extracellular material while leaving changes in <cell viability> or cellular metabolism.
In an original model, let the cellular contribution to <absorbance> be $0.30$ and removable chemical interference be $0.25$. Before washing the total is $0.55$. Removing 90 percent of the interference leaves $0.30+0.025=0.325$, still above the cellular contribution. A smaller signal after washing supports an interference explanation, but residual signal and loss of loosely attached <cells> must also be considered. Paired <negative controls> and independent counts make the interpretation stronger than washing alone.
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