Comparison of multivariate analysis methods for extracting the paraffin component from the paraffin-embedded cancer tissue spectra for Raman imaging.

This study aimed to extract the paraffin component from paraffin-embedded oral cancer tissue spectra using three multivariate analysis (MVA) methods; Independent Component Analysis (ICA), Partial Least Squares (PLS) and Independent Component - Partial Least Square (IC-PLS). The estimated paraffin components were used for removing the contribution of paraffin from the tissue spectra. These three methods were compared in terms of the efficiency of paraffin removal and the ability to retain the tissue information. It was found that ICA, PLS and IC-PLS could remove the paraffin component from the spectra at almost the same level while Principal Component Analysis (PCA) was incapable. In terms of retaining cancer tissue spectral integrity, effects of PLS and IC-PLS on the non-paraffin region were significantly less than that of ICA where cancer tissue spectral areas were deteriorated. The paraffin-removed spectra were used for constructing Raman images of oral cancer tissue and compared with Hematoxylin and Eosin (H&E) stained tissues for verification. This study has demonstrated the capability of Raman spectroscopy together with multivariate analysis methods as a diagnostic tool for the paraffin-embedded tissue section.

Critical Review Upon the Role and Potential of Fluorescence and Near-Infrared Imaging and Absorption Spectroscopy in Cancer Related Cells, Serum, Saliva, Urine and Tissue Analysis.

During the last years, non-invasive or minimally invasive diagnostic tools in cancer diagnostics have become more important. Many fluorescence spectroscopic methodologies have been established for nearly all different kinds of cancer. The reason therefore is its high sensitivity, low amount of sample required, short testing time, and the suitability for in situ testing. The potential influence factors for cancer diagnostics and the subsequent suitability of the method to different applications are well described. Near-Infrared spectroscopy (NIRS) is based on differences of endogenous chromophores between cancer and normal tissues using either oxyhaemoglobin or deoxy-haemoglobin, lipid or water bands, or a combination of two or more of these diagnostic markers. These marker bands are known to provide the fundamental for the diagnosis of several cancers and the spectroscopic setup can be applied for the analysis of cells, urine and tissue. For the preparation of this review the literature published during the last fifteen years has been taken into consideration. It will provide an overview on the importance of the fluorescence and NIRS tools in cancer analysis giving hints about how these techniques can play a crucial role in cancer diagnosis, treatment decisions and therapy. The two techniques, fluorescence and near-infrared spectroscopy (NIRS) are faced to each other and individual advantages and/or drawbacks are discussed. Finally, it will be taken into consideration; how the synergistic combination of different approaches can give additional information related to development and progression stages of cancer.

Near infrared spectroscopy compared to liquid chromatography coupled to mass spectrometry and capillary electrophoresis as a detection tool for peptide reaction monitoring.

Peptide interaction is normally monitored by liquid chromatography (LC), liquid chromatography coupled to mass spectrometry (LC-MS), mass spectrometric (MS) methods such as MALDI-TOF/MS or capillary electrophoresis (CE). These analytical techniques need to apply either high pressure or high voltages, which can cause cleavage of newly formed bondages. Therefore, near infrared reflectance spectroscopy (NIRS) is presented as a rapid alternative to monitor the interaction of glutathione and oxytocin, simulating physiological conditions. Thereby, glutathione can act as a nucleophile with oxytocin forming four new conjugates via a disulphide bondage. Liquid chromatography coupled to UV (LC-UV) and mass spectrometry via an electrospray ionisation interface (LC-ESI-MS) resulted in a 82% and a 78% degradation of oxytocin at pH 3 and a 5% and a 7% degradation at pH 6.5. Capillary electrophoresis employing UV-detection (CE-UV) showed a 44% degradation of oxytocin. LC and CE in addition to the NIRS are found to be authentic tools for quantitative analysis. Nevertheless, NIRS proved to be highly suitable for the detection of newly formed conjugates after separating them on a thin layer chromatography (TLC) plate. The recorded fingerprint in the near infrared region allows for a selective distinct qualitative identification of conjugates without the need for expensive instrumentation such as quadrupole or MALDI-TOF mass spectrometers. The performance of the established NIRS method is compared to LC and CE; its advantages are discussed in detail.