Oral tissue samples were studied using mid-IR fiber-optic attenuated total reflectance spectroscopy and other spectral techniques. The 1745 cm(-1) band, which is assigned to the ester group (C==O) vibration of triglycerides, is a reliable marker that is present in normal tissues but absent or a weak band in malignant oral tissues. Other bands such as C--H stretching bands and the amide bands are also helpful in distinguishing malignant tissues from normal tissues. Subtraction spectra confirmed the above conclusion. In addition, Raman spectroscopic measurements were in agreement with the results observed from FTIR spectra.

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Spectroscopic studies of various types of gallstones carried out in China are reviewed. Three basic classes of gallstones are surveyed: cholesterol stones, brown pigment stones, and black pigment stones. The emphasis of this review is on brown gallstones. The primary spectroscopic methods used in the studies surveyed are Fourier transform infrared absorption and Fourier transform Raman scattering. Chemical components studied in gallstones include cholesterol, bile pigments, glycoproteins, proteins, bilirubin metal complexes, and salts of calcium and other metals. Further studies are needed characterize the relationship of these components to more complex features of gallstones.