title: FTIR Microspectroscopy Coupled with Two-Class Discrimination Segregates Markers Responsible for Inter- and Intra-Category Variance in Exfoliative Cervical Cytology.
abstract: Infrared (IR) absorbance of cellular biomolecules generates a vibrational spectrum, which can be exploited as a "biochemical fingerprint" of a particular cell type. Biomolecules absorb in the mid-IR (2-20 mum) and Fourier-transform infrared (FTIR) microspectroscopy applied to discriminate different cell types (exfoliative cervical cytology collected into buffered fixative solution) was evaluated. This consisted of cervical cytology free of atypia (i.e. normal; n = 60), specimens categorised as containing low-grade changes (i.e. CIN1 or LSIL; n = 60) and a further cohort designated as high-grade (CIN2/3 or HSIL; n = 60). IR spectral analysis was coupled with principal component analysis (PCA), with or without subsequent linear discriminant analysis (LDA), to determine if normal versus low-grade versus high-grade exfoliative cytology could be segregated. With increasing severity of atypia, decreases in absorbance intensity were observable throughout the 1,500 cm(-1) to 1,100 cm(-1) spectral region; this included proteins (1,460 cm(-1)), glycoproteins (1,380 cm(-1)), amide III (1,260 cm(-1)), asymmetric (nu(as)) PO(2) (-) (1,225 cm(-1)) and carbohydrates (1,155 cm(-1)). In contrast, symmetric (nu(s)) PO(2) (-) (1,080 cm(-1)) appeared to have an elevated intensity in high-grade cytology. Inter-category variance was associated with protein and DNA conformational changes whereas glycogen status strongly influenced intra-category. Multivariate data reduction of IR spectra using PCA with LDA maximises inter-category variance whilst reducing the influence of intra-class variation towards an objective approach to class cervical cytology based on a biochemical profile.
authors.affiliation: Biomedical Sciences Unit, Department of Biological Sciences, Lancaster University, Lancaster, U.K.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Walsh
authors.forename: Maneesh N
authors.initials: MN
authors.lastname: Singh
authors.forename: Helen F
authors.initials: HF
authors.lastname: Stringfellow
authors.forename: Hubert M
authors.initials: HM
authors.lastname: Pollock
authors.forename: Azzedine
authors.initials: A
authors.lastname: Hammiche
authors.forename: Olaug
authors.initials: O
authors.lastname: Grude
authors.forename: Nigel J
authors.initials: NJ
authors.lastname: Fullwood
authors.forename: Mark A
authors.initials: MA
authors.lastname: Pitt
authors.forename: Pierre L
authors.initials: PL
authors.lastname: Martin-Hirsch
authors.forename: Francis L
authors.initials: FL
authors.lastname: Martin