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Flow Immunocytochemistry: Reducing False Negatives

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  2. Flow Immunocytochemistry: Reducing False Negatives
  3. A Lipophilic Fluorescent Substrate for Bacteria

In diagnostic cytology based on examination of cells from body cavity fluids under a microscope, approximately 50% of patients with a proven malignancy are reported as negative (false negative) for malignancy. Although immunohistochemistry is often used to confirm the malignancy based on expression of specific markers, the conventional methods are slow and time consuming. In the present report, Krishan and co-workers have combined DNA flow cytometry with flow cytometric detection of marker expression to analyze cells from body cavity fluids. Statistical analysis of 79 samples in which data from cytology, DNA aneuploidy and expression of at least one of the markers was available showed that by combined analysis of marker expression and aneuploidy, the sensitivity for detection of malignancy was increased from 58.5% to 100%. Flow cytometry offers the means for rapid analysis of DNA aneuploidy and marker expression in cells from body cavity fluids without observer bias.

In this issue: page 132

A Lipophilic Fluorescent Substrate for Bacteria

  1. Top of page
  2. Flow Immunocytochemistry: Reducing False Negatives
  3. A Lipophilic Fluorescent Substrate for Bacteria

NBDT is a green fluorescent toluene analogue with similar chemical characteristics as the unlabeled lipophilic compound. It is used to measure toluene uptake in bacteria which are able to grow on this substance. In the first place, NBDT enters the cell membranes by passive diffusion. Carbonyl cyanide 3-chlorophenylhydrazone (CCCP) needs to be added to inactivate NBDT efflux pumps, in this way enabling analysis of the NBDT related green fluorescence of the cells' membranes. Additionally, porin mediated influx of toluene was proven and shown to be responsible for up to 45% toluene uptake. Shot gun proteome measurements gave evidence for the presence of toluene transporting porins in the bacterium Pseudomonas putida mt-2 when grown on toluene but not when grown on glucose.

In this issue: page 113