On the other hand, history of recent cytotoxic chemotherapy was associated with decreased CTC levels. This may be due to systemic chemotherapy clearing CTCs from the circulation, or the diminished ability of dead or dying cancer cells to express fluorescence. Additional studies would be needed to determine the ideal interval after chemotherapy to perform the assay and/or if the assay��s ability to detect live cancer cells and exclude dead or dying cells proves advantageous for determining prognosis. Detection of CTCs was achieved in patients with eitherWT or mutant BRAF melanoma. In the univariate analysis, BRAF mutation showed a trend toward association with higher CTC counts, possibly reflecting the biological A 68930 hydrochloride aggressiveness of mutant BRAF disease. The association however was not significant in multivariate analysis, likely due to the 7-Chlorokynurenic acid larger influence of other factors such as increased burden of disease. CTC detection and isolation techniques are useful not only because the number of CTCs may mirror the burden or clinical aggressiveness of the existing disease, but also because they can potentially supply biological material from the tumor with no additional risk to patients. Towards the latter, we have established microcapillary-based procedures that enable the collection of melanoma CTCs rendered fluorescent by the telomerase-based assay. We have further shown that DNA extracted and amplified from the collected CTCs enable BRAFV600E mutational analysis, the result of which match the BRAF status of the originating tumor. This potentially paves the way for sequential analyses of disease status in patients undergoing BRAFtargeting agents, and may complement or represent an advance over previous efforts at tracking genetic changes in melanoma. These data demonstrate significant variability in observed peptide masses and the discontinuous nature of the analog-to-digital detector system in the MALDI-TOF mass spectrometer. When restarting acquisition, the AD detector system resets the position of the bins within the electronic error of the system, thus shifting the data by a small amount. This error impacts both flight time measurement and calibration function, both of which require interpolation from the discontinuous data observed in the mass spectrum. The data suggest this small error is still significant and contributes to the observed variability in the MALDI-TOF data. While the mechanisms underlying the variability observed in the MALDI-TOF data appear complex, the data indicate the method to resolve this variability is simple. The bin repositioning for each independent spectrum and calibration follow a normal Gaussian distribution. Therefore, mass spectral measurements can be analyzed by averaging populations of individual spectra and using simple descriptive statistics appropriate for normally distributed data.